Handle possible null pointers from malloc/strdup/strndup()

[zfs.git] / module / os / linux / zfs / zfs_vnops_os.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or https://opensource.org/licenses/CDDL-1.0.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
 * Copyright (c) 2015 by Chunwei Chen. All rights reserved.
 * Copyright 2017 Nexenta Systems, Inc.
 */

/* Portions Copyright 2007 Jeremy Teo */
/* Portions Copyright 2010 Robert Milkowski */


#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/sysmacros.h>
#include <sys/vfs.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/kmem.h>
#include <sys/taskq.h>
#include <sys/uio.h>
#include <sys/vmsystm.h>
#include <sys/atomic.h>
#include <sys/pathname.h>
#include <sys/cmn_err.h>
#include <sys/errno.h>
#include <sys/zfs_dir.h>
#include <sys/zfs_acl.h>
#include <sys/zfs_ioctl.h>
#include <sys/fs/zfs.h>
#include <sys/dmu.h>
#include <sys/dmu_objset.h>
#include <sys/spa.h>
#include <sys/txg.h>
#include <sys/dbuf.h>
#include <sys/zap.h>
#include <sys/sa.h>
#include <sys/policy.h>
#include <sys/sunddi.h>
#include <sys/sid.h>
#include <sys/zfs_ctldir.h>
#include <sys/zfs_fuid.h>
#include <sys/zfs_quota.h>
#include <sys/zfs_sa.h>
#include <sys/zfs_vnops.h>
#include <sys/zfs_rlock.h>
#include <sys/cred.h>
#include <sys/zpl.h>
#include <sys/zil.h>
#include <sys/sa_impl.h>

/*
 * Programming rules.
 *
 * Each vnode op performs some logical unit of work.  To do this, the ZPL must
 * properly lock its in-core state, create a DMU transaction, do the work,
 * record this work in the intent log (ZIL), commit the DMU transaction,
 * and wait for the intent log to commit if it is a synchronous operation.
 * Moreover, the vnode ops must work in both normal and log replay context.
 * The ordering of events is important to avoid deadlocks and references
 * to freed memory.  The example below illustrates the following Big Rules:
 *
 *  (1) A check must be made in each zfs thread for a mounted file system.
 *      This is done avoiding races using zfs_enter(zfsvfs).
 *      A zfs_exit(zfsvfs) is needed before all returns.  Any znodes
 *      must be checked with zfs_verify_zp(zp).  Both of these macros
 *      can return EIO from the calling function.
 *
 *  (2) zrele() should always be the last thing except for zil_commit() (if
 *      necessary) and zfs_exit(). This is for 3 reasons: First, if it's the
 *      last reference, the vnode/znode can be freed, so the zp may point to
 *      freed memory.  Second, the last reference will call zfs_zinactive(),
 *      which may induce a lot of work -- pushing cached pages (which acquires
 *      range locks) and syncing out cached atime changes.  Third,
 *      zfs_zinactive() may require a new tx, which could deadlock the system
 *      if you were already holding one. This deadlock occurs because the tx
 *      currently being operated on prevents a txg from syncing, which
 *      prevents the new tx from progressing, resulting in a deadlock.  If you
 *      must call zrele() within a tx, use zfs_zrele_async(). Note that iput()
 *      is a synonym for zrele().
 *
 *  (3) All range locks must be grabbed before calling dmu_tx_assign(),
 *      as they can span dmu_tx_assign() calls.
 *
 *  (4) If ZPL locks are held, pass TXG_NOWAIT as the second argument to
 *      dmu_tx_assign().  This is critical because we don't want to block
 *      while holding locks.
 *
 *      If no ZPL locks are held (aside from zfs_enter()), use TXG_WAIT.  This
 *      reduces lock contention and CPU usage when we must wait (note that if
 *      throughput is constrained by the storage, nearly every transaction
 *      must wait).
 *
 *      Note, in particular, that if a lock is sometimes acquired before
 *      the tx assigns, and sometimes after (e.g. z_lock), then failing
 *      to use a non-blocking assign can deadlock the system.  The scenario:
 *
 *      Thread A has grabbed a lock before calling dmu_tx_assign().
 *      Thread B is in an already-assigned tx, and blocks for this lock.
 *      Thread A calls dmu_tx_assign(TXG_WAIT) and blocks in txg_wait_open()
 *      forever, because the previous txg can't quiesce until B's tx commits.
 *
 *      If dmu_tx_assign() returns ERESTART and zfsvfs->z_assign is TXG_NOWAIT,
 *      then drop all locks, call dmu_tx_wait(), and try again.  On subsequent
 *      calls to dmu_tx_assign(), pass TXG_NOTHROTTLE in addition to TXG_NOWAIT,
 *      to indicate that this operation has already called dmu_tx_wait().
 *      This will ensure that we don't retry forever, waiting a short bit
 *      each time.
 *
 *  (5) If the operation succeeded, generate the intent log entry for it
 *      before dropping locks.  This ensures that the ordering of events
 *      in the intent log matches the order in which they actually occurred.
 *      During ZIL replay the zfs_log_* functions will update the sequence
 *      number to indicate the zil transaction has replayed.
 *
 *  (6) At the end of each vnode op, the DMU tx must always commit,
 *      regardless of whether there were any errors.
 *
 *  (7) After dropping all locks, invoke zil_commit(zilog, foid)
 *      to ensure that synchronous semantics are provided when necessary.
 *
 * In general, this is how things should be ordered in each vnode op:
 *
 *      zfs_enter(zfsvfs);              // exit if unmounted
 * top:
 *      zfs_dirent_lock(&dl, ...)       // lock directory entry (may igrab())
 *      rw_enter(...);                  // grab any other locks you need
 *      tx = dmu_tx_create(...);        // get DMU tx
 *      dmu_tx_hold_*();                // hold each object you might modify
 *      error = dmu_tx_assign(tx, (waited ? TXG_NOTHROTTLE : 0) | TXG_NOWAIT);
 *      if (error) {
 *              rw_exit(...);           // drop locks
 *              zfs_dirent_unlock(dl);  // unlock directory entry
 *              zrele(...);             // release held znodes
 *              if (error == ERESTART) {
 *                      waited = B_TRUE;
 *                      dmu_tx_wait(tx);
 *                      dmu_tx_abort(tx);
 *                      goto top;
 *              }
 *              dmu_tx_abort(tx);       // abort DMU tx
 *              zfs_exit(zfsvfs);       // finished in zfs
 *              return (error);         // really out of space
 *      }
 *      error = do_real_work();         // do whatever this VOP does
 *      if (error == 0)
 *              zfs_log_*(...);         // on success, make ZIL entry
 *      dmu_tx_commit(tx);              // commit DMU tx -- error or not
 *      rw_exit(...);                   // drop locks
 *      zfs_dirent_unlock(dl);          // unlock directory entry
 *      zrele(...);                     // release held znodes
 *      zil_commit(zilog, foid);        // synchronous when necessary
 *      zfs_exit(zfsvfs);               // finished in zfs
 *      return (error);                 // done, report error
 */
int
zfs_open(struct inode *ip, int mode, int flag, cred_t *cr)
{
        (void) cr;
        znode_t *zp = ITOZ(ip);
        zfsvfs_t *zfsvfs = ITOZSB(ip);
        int error;

        if ((error = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (error);

        /* Honor ZFS_APPENDONLY file attribute */
        if ((mode & FMODE_WRITE) && (zp->z_pflags & ZFS_APPENDONLY) &&
            ((flag & O_APPEND) == 0)) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EPERM));
        }

        /* Keep a count of the synchronous opens in the znode */
        if (flag & O_SYNC)
                atomic_inc_32(&zp->z_sync_cnt);

        zfs_exit(zfsvfs, FTAG);
        return (0);
}

int
zfs_close(struct inode *ip, int flag, cred_t *cr)
{
        (void) cr;
        znode_t *zp = ITOZ(ip);
        zfsvfs_t *zfsvfs = ITOZSB(ip);
        int error;

        if ((error = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (error);

        /* Decrement the synchronous opens in the znode */
        if (flag & O_SYNC)
                atomic_dec_32(&zp->z_sync_cnt);

        zfs_exit(zfsvfs, FTAG);
        return (0);
}

#if defined(_KERNEL)
/*
 * When a file is memory mapped, we must keep the IO data synchronized
 * between the DMU cache and the memory mapped pages.  What this means:
 *
 * On Write:    If we find a memory mapped page, we write to *both*
 *              the page and the dmu buffer.
 */
void
update_pages(znode_t *zp, int64_t start, int len, objset_t *os)
{
        struct inode *ip = ZTOI(zp);
        struct address_space *mp = ip->i_mapping;
        struct page *pp;
        uint64_t nbytes;
        int64_t off;
        void *pb;

        off = start & (PAGE_SIZE-1);
        for (start &= PAGE_MASK; len > 0; start += PAGE_SIZE) {
                nbytes = MIN(PAGE_SIZE - off, len);

                pp = find_lock_page(mp, start >> PAGE_SHIFT);
                if (pp) {
                        if (mapping_writably_mapped(mp))
                                flush_dcache_page(pp);

                        pb = kmap(pp);
                        (void) dmu_read(os, zp->z_id, start + off, nbytes,
                            pb + off, DMU_READ_PREFETCH);
                        kunmap(pp);

                        if (mapping_writably_mapped(mp))
                                flush_dcache_page(pp);

                        mark_page_accessed(pp);
                        SetPageUptodate(pp);
                        ClearPageError(pp);
                        unlock_page(pp);
                        put_page(pp);
                }

                len -= nbytes;
                off = 0;
        }
}

/*
 * When a file is memory mapped, we must keep the IO data synchronized
 * between the DMU cache and the memory mapped pages.  What this means:
 *
 * On Read:     We "read" preferentially from memory mapped pages,
 *              else we default from the dmu buffer.
 *
 * NOTE: We will always "break up" the IO into PAGESIZE uiomoves when
 *       the file is memory mapped.
 */
int
mappedread(znode_t *zp, int nbytes, zfs_uio_t *uio)
{
        struct inode *ip = ZTOI(zp);
        struct address_space *mp = ip->i_mapping;
        struct page *pp;
        int64_t start, off;
        uint64_t bytes;
        int len = nbytes;
        int error = 0;
        void *pb;

        start = uio->uio_loffset;
        off = start & (PAGE_SIZE-1);
        for (start &= PAGE_MASK; len > 0; start += PAGE_SIZE) {
                bytes = MIN(PAGE_SIZE - off, len);

                pp = find_lock_page(mp, start >> PAGE_SHIFT);
                if (pp) {
                        ASSERT(PageUptodate(pp));
                        unlock_page(pp);

                        pb = kmap(pp);
                        error = zfs_uiomove(pb + off, bytes, UIO_READ, uio);
                        kunmap(pp);

                        if (mapping_writably_mapped(mp))
                                flush_dcache_page(pp);

                        mark_page_accessed(pp);
                        put_page(pp);
                } else {
                        error = dmu_read_uio_dbuf(sa_get_db(zp->z_sa_hdl),
                            uio, bytes);
                }

                len -= bytes;
                off = 0;
                if (error)
                        break;
        }
        return (error);
}
#endif /* _KERNEL */

static unsigned long zfs_delete_blocks = DMU_MAX_DELETEBLKCNT;

/*
 * Write the bytes to a file.
 *
 *      IN:     zp      - znode of file to be written to
 *              data    - bytes to write
 *              len     - number of bytes to write
 *              pos     - offset to start writing at
 *
 *      OUT:    resid   - remaining bytes to write
 *
 *      RETURN: 0 if success
 *              positive error code if failure.  EIO is returned
 *              for a short write when residp isn't provided.
 *
 * Timestamps:
 *      zp - ctime|mtime updated if byte count > 0
 */
int
zfs_write_simple(znode_t *zp, const void *data, size_t len,
    loff_t pos, size_t *residp)
{
        fstrans_cookie_t cookie;
        int error;

        struct iovec iov;
        iov.iov_base = (void *)data;
        iov.iov_len = len;

        zfs_uio_t uio;
        zfs_uio_iovec_init(&uio, &iov, 1, pos, UIO_SYSSPACE, len, 0);

        cookie = spl_fstrans_mark();
        error = zfs_write(zp, &uio, 0, kcred);
        spl_fstrans_unmark(cookie);

        if (error == 0) {
                if (residp != NULL)
                        *residp = zfs_uio_resid(&uio);
                else if (zfs_uio_resid(&uio) != 0)
                        error = SET_ERROR(EIO);
        }

        return (error);
}

static void
zfs_rele_async_task(void *arg)
{
        iput(arg);
}

void
zfs_zrele_async(znode_t *zp)
{
        struct inode *ip = ZTOI(zp);
        objset_t *os = ITOZSB(ip)->z_os;

        ASSERT(atomic_read(&ip->i_count) > 0);
        ASSERT(os != NULL);

        /*
         * If decrementing the count would put us at 0, we can't do it inline
         * here, because that would be synchronous. Instead, dispatch an iput
         * to run later.
         *
         * For more information on the dangers of a synchronous iput, see the
         * header comment of this file.
         */
        if (!atomic_add_unless(&ip->i_count, -1, 1)) {
                VERIFY(taskq_dispatch(dsl_pool_zrele_taskq(dmu_objset_pool(os)),
                    zfs_rele_async_task, ip, TQ_SLEEP) != TASKQID_INVALID);
        }
}


/*
 * Lookup an entry in a directory, or an extended attribute directory.
 * If it exists, return a held inode reference for it.
 *
 *      IN:     zdp     - znode of directory to search.
 *              nm      - name of entry to lookup.
 *              flags   - LOOKUP_XATTR set if looking for an attribute.
 *              cr      - credentials of caller.
 *              direntflags - directory lookup flags
 *              realpnp - returned pathname.
 *
 *      OUT:    zpp     - znode of located entry, NULL if not found.
 *
 *      RETURN: 0 on success, error code on failure.
 *
 * Timestamps:
 *      NA
 */
int
zfs_lookup(znode_t *zdp, char *nm, znode_t **zpp, int flags, cred_t *cr,
    int *direntflags, pathname_t *realpnp)
{
        zfsvfs_t *zfsvfs = ZTOZSB(zdp);
        int error = 0;

        /*
         * Fast path lookup, however we must skip DNLC lookup
         * for case folding or normalizing lookups because the
         * DNLC code only stores the passed in name.  This means
         * creating 'a' and removing 'A' on a case insensitive
         * file system would work, but DNLC still thinks 'a'
         * exists and won't let you create it again on the next
         * pass through fast path.
         */
        if (!(flags & (LOOKUP_XATTR | FIGNORECASE))) {

                if (!S_ISDIR(ZTOI(zdp)->i_mode)) {
                        return (SET_ERROR(ENOTDIR));
                } else if (zdp->z_sa_hdl == NULL) {
                        return (SET_ERROR(EIO));
                }

                if (nm[0] == 0 || (nm[0] == '.' && nm[1] == '\0')) {
                        error = zfs_fastaccesschk_execute(zdp, cr);
                        if (!error) {
                                *zpp = zdp;
                                zhold(*zpp);
                                return (0);
                        }
                        return (error);
                }
        }

        if ((error = zfs_enter_verify_zp(zfsvfs, zdp, FTAG)) != 0)
                return (error);

        *zpp = NULL;

        if (flags & LOOKUP_XATTR) {
                /*
                 * We don't allow recursive attributes..
                 * Maybe someday we will.
                 */
                if (zdp->z_pflags & ZFS_XATTR) {
                        zfs_exit(zfsvfs, FTAG);
                        return (SET_ERROR(EINVAL));
                }

                if ((error = zfs_get_xattrdir(zdp, zpp, cr, flags))) {
                        zfs_exit(zfsvfs, FTAG);
                        return (error);
                }

                /*
                 * Do we have permission to get into attribute directory?
                 */

                if ((error = zfs_zaccess(*zpp, ACE_EXECUTE, 0,
                    B_TRUE, cr))) {
                        zrele(*zpp);
                        *zpp = NULL;
                }

                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        if (!S_ISDIR(ZTOI(zdp)->i_mode)) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(ENOTDIR));
        }

        /*
         * Check accessibility of directory.
         */

        if ((error = zfs_zaccess(zdp, ACE_EXECUTE, 0, B_FALSE, cr))) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        if (zfsvfs->z_utf8 && u8_validate(nm, strlen(nm),
            NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EILSEQ));
        }

        error = zfs_dirlook(zdp, nm, zpp, flags, direntflags, realpnp);
        if ((error == 0) && (*zpp))
                zfs_znode_update_vfs(*zpp);

        zfs_exit(zfsvfs, FTAG);
        return (error);
}

/*
 * Attempt to create a new entry in a directory.  If the entry
 * already exists, truncate the file if permissible, else return
 * an error.  Return the ip of the created or trunc'd file.
 *
 *      IN:     dzp     - znode of directory to put new file entry in.
 *              name    - name of new file entry.
 *              vap     - attributes of new file.
 *              excl    - flag indicating exclusive or non-exclusive mode.
 *              mode    - mode to open file with.
 *              cr      - credentials of caller.
 *              flag    - file flag.
 *              vsecp   - ACL to be set
 *
 *      OUT:    zpp     - znode of created or trunc'd entry.
 *
 *      RETURN: 0 on success, error code on failure.
 *
 * Timestamps:
 *      dzp - ctime|mtime updated if new entry created
 *       zp - ctime|mtime always, atime if new
 */
int
zfs_create(znode_t *dzp, char *name, vattr_t *vap, int excl,
    int mode, znode_t **zpp, cred_t *cr, int flag, vsecattr_t *vsecp)
{
        znode_t         *zp;
        zfsvfs_t        *zfsvfs = ZTOZSB(dzp);
        zilog_t         *zilog;
        objset_t        *os;
        zfs_dirlock_t   *dl;
        dmu_tx_t        *tx;
        int             error;
        uid_t           uid;
        gid_t           gid;
        zfs_acl_ids_t   acl_ids;
        boolean_t       fuid_dirtied;
        boolean_t       have_acl = B_FALSE;
        boolean_t       waited = B_FALSE;

        /*
         * If we have an ephemeral id, ACL, or XVATTR then
         * make sure file system is at proper version
         */

        gid = crgetgid(cr);
        uid = crgetuid(cr);

        if (zfsvfs->z_use_fuids == B_FALSE &&
            (vsecp || IS_EPHEMERAL(uid) || IS_EPHEMERAL(gid)))
                return (SET_ERROR(EINVAL));

        if (name == NULL)
                return (SET_ERROR(EINVAL));

        if ((error = zfs_enter_verify_zp(zfsvfs, dzp, FTAG)) != 0)
                return (error);
        os = zfsvfs->z_os;
        zilog = zfsvfs->z_log;

        if (zfsvfs->z_utf8 && u8_validate(name, strlen(name),
            NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EILSEQ));
        }

        if (vap->va_mask & ATTR_XVATTR) {
                if ((error = secpolicy_xvattr((xvattr_t *)vap,
                    crgetuid(cr), cr, vap->va_mode)) != 0) {
                        zfs_exit(zfsvfs, FTAG);
                        return (error);
                }
        }

top:
        *zpp = NULL;
        if (*name == '\0') {
                /*
                 * Null component name refers to the directory itself.
                 */
                zhold(dzp);
                zp = dzp;
                dl = NULL;
                error = 0;
        } else {
                /* possible igrab(zp) */
                int zflg = 0;

                if (flag & FIGNORECASE)
                        zflg |= ZCILOOK;

                error = zfs_dirent_lock(&dl, dzp, name, &zp, zflg,
                    NULL, NULL);
                if (error) {
                        if (have_acl)
                                zfs_acl_ids_free(&acl_ids);
                        if (strcmp(name, "..") == 0)
                                error = SET_ERROR(EISDIR);
                        zfs_exit(zfsvfs, FTAG);
                        return (error);
                }
        }

        if (zp == NULL) {
                uint64_t txtype;
                uint64_t projid = ZFS_DEFAULT_PROJID;

                /*
                 * Create a new file object and update the directory
                 * to reference it.
                 */
                if ((error = zfs_zaccess(dzp, ACE_ADD_FILE, 0, B_FALSE, cr))) {
                        if (have_acl)
                                zfs_acl_ids_free(&acl_ids);
                        goto out;
                }

                /*
                 * We only support the creation of regular files in
                 * extended attribute directories.
                 */

                if ((dzp->z_pflags & ZFS_XATTR) && !S_ISREG(vap->va_mode)) {
                        if (have_acl)
                                zfs_acl_ids_free(&acl_ids);
                        error = SET_ERROR(EINVAL);
                        goto out;
                }

                if (!have_acl && (error = zfs_acl_ids_create(dzp, 0, vap,
                    cr, vsecp, &acl_ids)) != 0)
                        goto out;
                have_acl = B_TRUE;

                if (S_ISREG(vap->va_mode) || S_ISDIR(vap->va_mode))
                        projid = zfs_inherit_projid(dzp);
                if (zfs_acl_ids_overquota(zfsvfs, &acl_ids, projid)) {
                        zfs_acl_ids_free(&acl_ids);
                        error = SET_ERROR(EDQUOT);
                        goto out;
                }

                tx = dmu_tx_create(os);

                dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
                    ZFS_SA_BASE_ATTR_SIZE);

                fuid_dirtied = zfsvfs->z_fuid_dirty;
                if (fuid_dirtied)
                        zfs_fuid_txhold(zfsvfs, tx);
                dmu_tx_hold_zap(tx, dzp->z_id, TRUE, name);
                dmu_tx_hold_sa(tx, dzp->z_sa_hdl, B_FALSE);
                if (!zfsvfs->z_use_sa &&
                    acl_ids.z_aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                        dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                            0, acl_ids.z_aclp->z_acl_bytes);
                }

                error = dmu_tx_assign(tx,
                    (waited ? TXG_NOTHROTTLE : 0) | TXG_NOWAIT);
                if (error) {
                        zfs_dirent_unlock(dl);
                        if (error == ERESTART) {
                                waited = B_TRUE;
                                dmu_tx_wait(tx);
                                dmu_tx_abort(tx);
                                goto top;
                        }
                        zfs_acl_ids_free(&acl_ids);
                        dmu_tx_abort(tx);
                        zfs_exit(zfsvfs, FTAG);
                        return (error);
                }
                zfs_mknode(dzp, vap, tx, cr, 0, &zp, &acl_ids);

                error = zfs_link_create(dl, zp, tx, ZNEW);
                if (error != 0) {
                        /*
                         * Since, we failed to add the directory entry for it,
                         * delete the newly created dnode.
                         */
                        zfs_znode_delete(zp, tx);
                        remove_inode_hash(ZTOI(zp));
                        zfs_acl_ids_free(&acl_ids);
                        dmu_tx_commit(tx);
                        goto out;
                }

                if (fuid_dirtied)
                        zfs_fuid_sync(zfsvfs, tx);

                txtype = zfs_log_create_txtype(Z_FILE, vsecp, vap);
                if (flag & FIGNORECASE)
                        txtype |= TX_CI;
                zfs_log_create(zilog, tx, txtype, dzp, zp, name,
                    vsecp, acl_ids.z_fuidp, vap);
                zfs_acl_ids_free(&acl_ids);
                dmu_tx_commit(tx);
        } else {
                int aflags = (flag & O_APPEND) ? V_APPEND : 0;

                if (have_acl)
                        zfs_acl_ids_free(&acl_ids);
                have_acl = B_FALSE;

                /*
                 * A directory entry already exists for this name.
                 */
                /*
                 * Can't truncate an existing file if in exclusive mode.
                 */
                if (excl) {
                        error = SET_ERROR(EEXIST);
                        goto out;
                }
                /*
                 * Can't open a directory for writing.
                 */
                if (S_ISDIR(ZTOI(zp)->i_mode)) {
                        error = SET_ERROR(EISDIR);
                        goto out;
                }
                /*
                 * Verify requested access to file.
                 */
                if (mode && (error = zfs_zaccess_rwx(zp, mode, aflags, cr))) {
                        goto out;
                }

                mutex_enter(&dzp->z_lock);
                dzp->z_seq++;
                mutex_exit(&dzp->z_lock);

                /*
                 * Truncate regular files if requested.
                 */
                if (S_ISREG(ZTOI(zp)->i_mode) &&
                    (vap->va_mask & ATTR_SIZE) && (vap->va_size == 0)) {
                        /* we can't hold any locks when calling zfs_freesp() */
                        if (dl) {
                                zfs_dirent_unlock(dl);
                                dl = NULL;
                        }
                        error = zfs_freesp(zp, 0, 0, mode, TRUE);
                }
        }
out:

        if (dl)
                zfs_dirent_unlock(dl);

        if (error) {
                if (zp)
                        zrele(zp);
        } else {
                zfs_znode_update_vfs(dzp);
                zfs_znode_update_vfs(zp);
                *zpp = zp;
        }

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        zfs_exit(zfsvfs, FTAG);
        return (error);
}

int
zfs_tmpfile(struct inode *dip, vattr_t *vap, int excl,
    int mode, struct inode **ipp, cred_t *cr, int flag, vsecattr_t *vsecp)
{
        (void) excl, (void) mode, (void) flag;
        znode_t         *zp = NULL, *dzp = ITOZ(dip);
        zfsvfs_t        *zfsvfs = ITOZSB(dip);
        objset_t        *os;
        dmu_tx_t        *tx;
        int             error;
        uid_t           uid;
        gid_t           gid;
        zfs_acl_ids_t   acl_ids;
        uint64_t        projid = ZFS_DEFAULT_PROJID;
        boolean_t       fuid_dirtied;
        boolean_t       have_acl = B_FALSE;
        boolean_t       waited = B_FALSE;

        /*
         * If we have an ephemeral id, ACL, or XVATTR then
         * make sure file system is at proper version
         */

        gid = crgetgid(cr);
        uid = crgetuid(cr);

        if (zfsvfs->z_use_fuids == B_FALSE &&
            (vsecp || IS_EPHEMERAL(uid) || IS_EPHEMERAL(gid)))
                return (SET_ERROR(EINVAL));

        if ((error = zfs_enter_verify_zp(zfsvfs, dzp, FTAG)) != 0)
                return (error);
        os = zfsvfs->z_os;

        if (vap->va_mask & ATTR_XVATTR) {
                if ((error = secpolicy_xvattr((xvattr_t *)vap,
                    crgetuid(cr), cr, vap->va_mode)) != 0) {
                        zfs_exit(zfsvfs, FTAG);
                        return (error);
                }
        }

top:
        *ipp = NULL;

        /*
         * Create a new file object and update the directory
         * to reference it.
         */
        if ((error = zfs_zaccess(dzp, ACE_ADD_FILE, 0, B_FALSE, cr))) {
                if (have_acl)
                        zfs_acl_ids_free(&acl_ids);
                goto out;
        }

        if (!have_acl && (error = zfs_acl_ids_create(dzp, 0, vap,
            cr, vsecp, &acl_ids)) != 0)
                goto out;
        have_acl = B_TRUE;

        if (S_ISREG(vap->va_mode) || S_ISDIR(vap->va_mode))
                projid = zfs_inherit_projid(dzp);
        if (zfs_acl_ids_overquota(zfsvfs, &acl_ids, projid)) {
                zfs_acl_ids_free(&acl_ids);
                error = SET_ERROR(EDQUOT);
                goto out;
        }

        tx = dmu_tx_create(os);

        dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
            ZFS_SA_BASE_ATTR_SIZE);
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);

        fuid_dirtied = zfsvfs->z_fuid_dirty;
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);
        if (!zfsvfs->z_use_sa &&
            acl_ids.z_aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                    0, acl_ids.z_aclp->z_acl_bytes);
        }
        error = dmu_tx_assign(tx, (waited ? TXG_NOTHROTTLE : 0) | TXG_NOWAIT);
        if (error) {
                if (error == ERESTART) {
                        waited = B_TRUE;
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                zfs_acl_ids_free(&acl_ids);
                dmu_tx_abort(tx);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }
        zfs_mknode(dzp, vap, tx, cr, IS_TMPFILE, &zp, &acl_ids);

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);

        /* Add to unlinked set */
        zp->z_unlinked = B_TRUE;
        zfs_unlinked_add(zp, tx);
        zfs_acl_ids_free(&acl_ids);
        dmu_tx_commit(tx);
out:

        if (error) {
                if (zp)
                        zrele(zp);
        } else {
                zfs_znode_update_vfs(dzp);
                zfs_znode_update_vfs(zp);
                *ipp = ZTOI(zp);
        }

        zfs_exit(zfsvfs, FTAG);
        return (error);
}

/*
 * Remove an entry from a directory.
 *
 *      IN:     dzp     - znode of directory to remove entry from.
 *              name    - name of entry to remove.
 *              cr      - credentials of caller.
 *              flags   - case flags.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      dzp - ctime|mtime
 *       ip - ctime (if nlink > 0)
 */

static uint64_t null_xattr = 0;

int
zfs_remove(znode_t *dzp, char *name, cred_t *cr, int flags)
{
        znode_t         *zp;
        znode_t         *xzp;
        zfsvfs_t        *zfsvfs = ZTOZSB(dzp);
        zilog_t         *zilog;
        uint64_t        acl_obj, xattr_obj;
        uint64_t        xattr_obj_unlinked = 0;
        uint64_t        obj = 0;
        uint64_t        links;
        zfs_dirlock_t   *dl;
        dmu_tx_t        *tx;
        boolean_t       may_delete_now, delete_now = FALSE;
        boolean_t       unlinked, toobig = FALSE;
        uint64_t        txtype;
        pathname_t      *realnmp = NULL;
        pathname_t      realnm;
        int             error;
        int             zflg = ZEXISTS;
        boolean_t       waited = B_FALSE;

        if (name == NULL)
                return (SET_ERROR(EINVAL));

        if ((error = zfs_enter_verify_zp(zfsvfs, dzp, FTAG)) != 0)
                return (error);
        zilog = zfsvfs->z_log;

        if (flags & FIGNORECASE) {
                zflg |= ZCILOOK;
                pn_alloc(&realnm);
                realnmp = &realnm;
        }

top:
        xattr_obj = 0;
        xzp = NULL;
        /*
         * Attempt to lock directory; fail if entry doesn't exist.
         */
        if ((error = zfs_dirent_lock(&dl, dzp, name, &zp, zflg,
            NULL, realnmp))) {
                if (realnmp)
                        pn_free(realnmp);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        if ((error = zfs_zaccess_delete(dzp, zp, cr))) {
                goto out;
        }

        /*
         * Need to use rmdir for removing directories.
         */
        if (S_ISDIR(ZTOI(zp)->i_mode)) {
                error = SET_ERROR(EPERM);
                goto out;
        }

        mutex_enter(&zp->z_lock);
        may_delete_now = atomic_read(&ZTOI(zp)->i_count) == 1 &&
            !(zp->z_is_mapped);
        mutex_exit(&zp->z_lock);

        /*
         * We may delete the znode now, or we may put it in the unlinked set;
         * it depends on whether we're the last link, and on whether there are
         * other holds on the inode.  So we dmu_tx_hold() the right things to
         * allow for either case.
         */
        obj = zp->z_id;
        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_zap(tx, dzp->z_id, FALSE, name);
        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        zfs_sa_upgrade_txholds(tx, zp);
        zfs_sa_upgrade_txholds(tx, dzp);
        if (may_delete_now) {
                toobig = zp->z_size > zp->z_blksz * zfs_delete_blocks;
                /* if the file is too big, only hold_free a token amount */
                dmu_tx_hold_free(tx, zp->z_id, 0,
                    (toobig ? DMU_MAX_ACCESS : DMU_OBJECT_END));
        }

        /* are there any extended attributes? */
        error = sa_lookup(zp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs),
            &xattr_obj, sizeof (xattr_obj));
        if (error == 0 && xattr_obj) {
                error = zfs_zget(zfsvfs, xattr_obj, &xzp);
                ASSERT0(error);
                dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
                dmu_tx_hold_sa(tx, xzp->z_sa_hdl, B_FALSE);
        }

        mutex_enter(&zp->z_lock);
        if ((acl_obj = zfs_external_acl(zp)) != 0 && may_delete_now)
                dmu_tx_hold_free(tx, acl_obj, 0, DMU_OBJECT_END);
        mutex_exit(&zp->z_lock);

        /* charge as an update -- would be nice not to charge at all */
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);

        /*
         * Mark this transaction as typically resulting in a net free of space
         */
        dmu_tx_mark_netfree(tx);

        error = dmu_tx_assign(tx, (waited ? TXG_NOTHROTTLE : 0) | TXG_NOWAIT);
        if (error) {
                zfs_dirent_unlock(dl);
                if (error == ERESTART) {
                        waited = B_TRUE;
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        zrele(zp);
                        if (xzp)
                                zrele(xzp);
                        goto top;
                }
                if (realnmp)
                        pn_free(realnmp);
                dmu_tx_abort(tx);
                zrele(zp);
                if (xzp)
                        zrele(xzp);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        /*
         * Remove the directory entry.
         */
        error = zfs_link_destroy(dl, zp, tx, zflg, &unlinked);

        if (error) {
                dmu_tx_commit(tx);
                goto out;
        }

        if (unlinked) {
                /*
                 * Hold z_lock so that we can make sure that the ACL obj
                 * hasn't changed.  Could have been deleted due to
                 * zfs_sa_upgrade().
                 */
                mutex_enter(&zp->z_lock);
                (void) sa_lookup(zp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs),
                    &xattr_obj_unlinked, sizeof (xattr_obj_unlinked));
                delete_now = may_delete_now && !toobig &&
                    atomic_read(&ZTOI(zp)->i_count) == 1 &&
                    !(zp->z_is_mapped) && xattr_obj == xattr_obj_unlinked &&
                    zfs_external_acl(zp) == acl_obj;
        }

        if (delete_now) {
                if (xattr_obj_unlinked) {
                        ASSERT3U(ZTOI(xzp)->i_nlink, ==, 2);
                        mutex_enter(&xzp->z_lock);
                        xzp->z_unlinked = B_TRUE;
                        clear_nlink(ZTOI(xzp));
                        links = 0;
                        error = sa_update(xzp->z_sa_hdl, SA_ZPL_LINKS(zfsvfs),
                            &links, sizeof (links), tx);
                        ASSERT3U(error,  ==,  0);
                        mutex_exit(&xzp->z_lock);
                        zfs_unlinked_add(xzp, tx);

                        if (zp->z_is_sa)
                                error = sa_remove(zp->z_sa_hdl,
                                    SA_ZPL_XATTR(zfsvfs), tx);
                        else
                                error = sa_update(zp->z_sa_hdl,
                                    SA_ZPL_XATTR(zfsvfs), &null_xattr,
                                    sizeof (uint64_t), tx);
                        ASSERT0(error);
                }
                /*
                 * Add to the unlinked set because a new reference could be
                 * taken concurrently resulting in a deferred destruction.
                 */
                zfs_unlinked_add(zp, tx);
                mutex_exit(&zp->z_lock);
        } else if (unlinked) {
                mutex_exit(&zp->z_lock);
                zfs_unlinked_add(zp, tx);
        }

        txtype = TX_REMOVE;
        if (flags & FIGNORECASE)
                txtype |= TX_CI;
        zfs_log_remove(zilog, tx, txtype, dzp, name, obj, unlinked);

        dmu_tx_commit(tx);
out:
        if (realnmp)
                pn_free(realnmp);

        zfs_dirent_unlock(dl);
        zfs_znode_update_vfs(dzp);
        zfs_znode_update_vfs(zp);

        if (delete_now)
                zrele(zp);
        else
                zfs_zrele_async(zp);

        if (xzp) {
                zfs_znode_update_vfs(xzp);
                zfs_zrele_async(xzp);
        }

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        zfs_exit(zfsvfs, FTAG);
        return (error);
}

/*
 * Create a new directory and insert it into dzp using the name
 * provided.  Return a pointer to the inserted directory.
 *
 *      IN:     dzp     - znode of directory to add subdir to.
 *              dirname - name of new directory.
 *              vap     - attributes of new directory.
 *              cr      - credentials of caller.
 *              flags   - case flags.
 *              vsecp   - ACL to be set
 *
 *      OUT:    zpp     - znode of created directory.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      dzp - ctime|mtime updated
 *      zpp - ctime|mtime|atime updated
 */
int
zfs_mkdir(znode_t *dzp, char *dirname, vattr_t *vap, znode_t **zpp,
    cred_t *cr, int flags, vsecattr_t *vsecp)
{
        znode_t         *zp;
        zfsvfs_t        *zfsvfs = ZTOZSB(dzp);
        zilog_t         *zilog;
        zfs_dirlock_t   *dl;
        uint64_t        txtype;
        dmu_tx_t        *tx;
        int             error;
        int             zf = ZNEW;
        uid_t           uid;
        gid_t           gid = crgetgid(cr);
        zfs_acl_ids_t   acl_ids;
        boolean_t       fuid_dirtied;
        boolean_t       waited = B_FALSE;

        ASSERT(S_ISDIR(vap->va_mode));

        /*
         * If we have an ephemeral id, ACL, or XVATTR then
         * make sure file system is at proper version
         */

        uid = crgetuid(cr);
        if (zfsvfs->z_use_fuids == B_FALSE &&
            (vsecp || IS_EPHEMERAL(uid) || IS_EPHEMERAL(gid)))
                return (SET_ERROR(EINVAL));

        if (dirname == NULL)
                return (SET_ERROR(EINVAL));

        if ((error = zfs_enter_verify_zp(zfsvfs, dzp, FTAG)) != 0)
                return (error);
        zilog = zfsvfs->z_log;

        if (dzp->z_pflags & ZFS_XATTR) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EINVAL));
        }

        if (zfsvfs->z_utf8 && u8_validate(dirname,
            strlen(dirname), NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EILSEQ));
        }
        if (flags & FIGNORECASE)
                zf |= ZCILOOK;

        if (vap->va_mask & ATTR_XVATTR) {
                if ((error = secpolicy_xvattr((xvattr_t *)vap,
                    crgetuid(cr), cr, vap->va_mode)) != 0) {
                        zfs_exit(zfsvfs, FTAG);
                        return (error);
                }
        }

        if ((error = zfs_acl_ids_create(dzp, 0, vap, cr,
            vsecp, &acl_ids)) != 0) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }
        /*
         * First make sure the new directory doesn't exist.
         *
         * Existence is checked first to make sure we don't return
         * EACCES instead of EEXIST which can cause some applications
         * to fail.
         */
top:
        *zpp = NULL;

        if ((error = zfs_dirent_lock(&dl, dzp, dirname, &zp, zf,
            NULL, NULL))) {
                zfs_acl_ids_free(&acl_ids);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        if ((error = zfs_zaccess(dzp, ACE_ADD_SUBDIRECTORY, 0, B_FALSE, cr))) {
                zfs_acl_ids_free(&acl_ids);
                zfs_dirent_unlock(dl);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        if (zfs_acl_ids_overquota(zfsvfs, &acl_ids, zfs_inherit_projid(dzp))) {
                zfs_acl_ids_free(&acl_ids);
                zfs_dirent_unlock(dl);
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EDQUOT));
        }

        /*
         * Add a new entry to the directory.
         */
        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_zap(tx, dzp->z_id, TRUE, dirname);
        dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
        fuid_dirtied = zfsvfs->z_fuid_dirty;
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);
        if (!zfsvfs->z_use_sa && acl_ids.z_aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0,
                    acl_ids.z_aclp->z_acl_bytes);
        }

        dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
            ZFS_SA_BASE_ATTR_SIZE);

        error = dmu_tx_assign(tx, (waited ? TXG_NOTHROTTLE : 0) | TXG_NOWAIT);
        if (error) {
                zfs_dirent_unlock(dl);
                if (error == ERESTART) {
                        waited = B_TRUE;
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                zfs_acl_ids_free(&acl_ids);
                dmu_tx_abort(tx);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        /*
         * Create new node.
         */
        zfs_mknode(dzp, vap, tx, cr, 0, &zp, &acl_ids);

        /*
         * Now put new name in parent dir.
         */
        error = zfs_link_create(dl, zp, tx, ZNEW);
        if (error != 0) {
                zfs_znode_delete(zp, tx);
                remove_inode_hash(ZTOI(zp));
                goto out;
        }

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);

        *zpp = zp;

        txtype = zfs_log_create_txtype(Z_DIR, vsecp, vap);
        if (flags & FIGNORECASE)
                txtype |= TX_CI;
        zfs_log_create(zilog, tx, txtype, dzp, zp, dirname, vsecp,
            acl_ids.z_fuidp, vap);

out:
        zfs_acl_ids_free(&acl_ids);

        dmu_tx_commit(tx);

        zfs_dirent_unlock(dl);

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        if (error != 0) {
                zrele(zp);
        } else {
                zfs_znode_update_vfs(dzp);
                zfs_znode_update_vfs(zp);
        }
        zfs_exit(zfsvfs, FTAG);
        return (error);
}

/*
 * Remove a directory subdir entry.  If the current working
 * directory is the same as the subdir to be removed, the
 * remove will fail.
 *
 *      IN:     dzp     - znode of directory to remove from.
 *              name    - name of directory to be removed.
 *              cwd     - inode of current working directory.
 *              cr      - credentials of caller.
 *              flags   - case flags
 *
 *      RETURN: 0 on success, error code on failure.
 *
 * Timestamps:
 *      dzp - ctime|mtime updated
 */
int
zfs_rmdir(znode_t *dzp, char *name, znode_t *cwd, cred_t *cr,
    int flags)
{
        znode_t         *zp;
        zfsvfs_t        *zfsvfs = ZTOZSB(dzp);
        zilog_t         *zilog;
        zfs_dirlock_t   *dl;
        dmu_tx_t        *tx;
        int             error;
        int             zflg = ZEXISTS;
        boolean_t       waited = B_FALSE;

        if (name == NULL)
                return (SET_ERROR(EINVAL));

        if ((error = zfs_enter_verify_zp(zfsvfs, dzp, FTAG)) != 0)
                return (error);
        zilog = zfsvfs->z_log;

        if (flags & FIGNORECASE)
                zflg |= ZCILOOK;
top:
        zp = NULL;

        /*
         * Attempt to lock directory; fail if entry doesn't exist.
         */
        if ((error = zfs_dirent_lock(&dl, dzp, name, &zp, zflg,
            NULL, NULL))) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        if ((error = zfs_zaccess_delete(dzp, zp, cr))) {
                goto out;
        }

        if (!S_ISDIR(ZTOI(zp)->i_mode)) {
                error = SET_ERROR(ENOTDIR);
                goto out;
        }

        if (zp == cwd) {
                error = SET_ERROR(EINVAL);
                goto out;
        }

        /*
         * Grab a lock on the directory to make sure that no one is
         * trying to add (or lookup) entries while we are removing it.
         */
        rw_enter(&zp->z_name_lock, RW_WRITER);

        /*
         * Grab a lock on the parent pointer to make sure we play well
         * with the treewalk and directory rename code.
         */
        rw_enter(&zp->z_parent_lock, RW_WRITER);

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_zap(tx, dzp->z_id, FALSE, name);
        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
        zfs_sa_upgrade_txholds(tx, zp);
        zfs_sa_upgrade_txholds(tx, dzp);
        dmu_tx_mark_netfree(tx);
        error = dmu_tx_assign(tx, (waited ? TXG_NOTHROTTLE : 0) | TXG_NOWAIT);
        if (error) {
                rw_exit(&zp->z_parent_lock);
                rw_exit(&zp->z_name_lock);
                zfs_dirent_unlock(dl);
                if (error == ERESTART) {
                        waited = B_TRUE;
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        zrele(zp);
                        goto top;
                }
                dmu_tx_abort(tx);
                zrele(zp);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        error = zfs_link_destroy(dl, zp, tx, zflg, NULL);

        if (error == 0) {
                uint64_t txtype = TX_RMDIR;
                if (flags & FIGNORECASE)
                        txtype |= TX_CI;
                zfs_log_remove(zilog, tx, txtype, dzp, name, ZFS_NO_OBJECT,
                    B_FALSE);
        }

        dmu_tx_commit(tx);

        rw_exit(&zp->z_parent_lock);
        rw_exit(&zp->z_name_lock);
out:
        zfs_dirent_unlock(dl);

        zfs_znode_update_vfs(dzp);
        zfs_znode_update_vfs(zp);
        zrele(zp);

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        zfs_exit(zfsvfs, FTAG);
        return (error);
}

/*
 * Read directory entries from the given directory cursor position and emit
 * name and position for each entry.
 *
 *      IN:     ip      - inode of directory to read.
 *              ctx     - directory entry context.
 *              cr      - credentials of caller.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      ip - atime updated
 *
 * Note that the low 4 bits of the cookie returned by zap is always zero.
 * This allows us to use the low range for "special" directory entries:
 * We use 0 for '.', and 1 for '..'.  If this is the root of the filesystem,
 * we use the offset 2 for the '.zfs' directory.
 */
int
zfs_readdir(struct inode *ip, zpl_dir_context_t *ctx, cred_t *cr)
{
        (void) cr;
        znode_t         *zp = ITOZ(ip);
        zfsvfs_t        *zfsvfs = ITOZSB(ip);
        objset_t        *os;
        zap_cursor_t    zc;
        zap_attribute_t zap;
        int             error;
        uint8_t         prefetch;
        uint8_t         type;
        int             done = 0;
        uint64_t        parent;
        uint64_t        offset; /* must be unsigned; checks for < 1 */

        if ((error = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (error);

        if ((error = sa_lookup(zp->z_sa_hdl, SA_ZPL_PARENT(zfsvfs),
            &parent, sizeof (parent))) != 0)
                goto out;

        /*
         * Quit if directory has been removed (posix)
         */
        if (zp->z_unlinked)
                goto out;

        error = 0;
        os = zfsvfs->z_os;
        offset = ctx->pos;
        prefetch = zp->z_zn_prefetch;

        /*
         * Initialize the iterator cursor.
         */
        if (offset <= 3) {
                /*
                 * Start iteration from the beginning of the directory.
                 */
                zap_cursor_init(&zc, os, zp->z_id);
        } else {
                /*
                 * The offset is a serialized cursor.
                 */
                zap_cursor_init_serialized(&zc, os, zp->z_id, offset);
        }

        /*
         * Transform to file-system independent format
         */
        while (!done) {
                uint64_t objnum;
                /*
                 * Special case `.', `..', and `.zfs'.
                 */
                if (offset == 0) {
                        (void) strcpy(zap.za_name, ".");
                        zap.za_normalization_conflict = 0;
                        objnum = zp->z_id;
                        type = DT_DIR;
                } else if (offset == 1) {
                        (void) strcpy(zap.za_name, "..");
                        zap.za_normalization_conflict = 0;
                        objnum = parent;
                        type = DT_DIR;
                } else if (offset == 2 && zfs_show_ctldir(zp)) {
                        (void) strcpy(zap.za_name, ZFS_CTLDIR_NAME);
                        zap.za_normalization_conflict = 0;
                        objnum = ZFSCTL_INO_ROOT;
                        type = DT_DIR;
                } else {
                        /*
                         * Grab next entry.
                         */
                        if ((error = zap_cursor_retrieve(&zc, &zap))) {
                                if (error == ENOENT)
                                        break;
                                else
                                        goto update;
                        }

                        /*
                         * Allow multiple entries provided the first entry is
                         * the object id.  Non-zpl consumers may safely make
                         * use of the additional space.
                         *
                         * XXX: This should be a feature flag for compatibility
                         */
                        if (zap.za_integer_length != 8 ||
                            zap.za_num_integers == 0) {
                                cmn_err(CE_WARN, "zap_readdir: bad directory "
                                    "entry, obj = %lld, offset = %lld, "
                                    "length = %d, num = %lld\n",
                                    (u_longlong_t)zp->z_id,
                                    (u_longlong_t)offset,
                                    zap.za_integer_length,
                                    (u_longlong_t)zap.za_num_integers);
                                error = SET_ERROR(ENXIO);
                                goto update;
                        }

                        objnum = ZFS_DIRENT_OBJ(zap.za_first_integer);
                        type = ZFS_DIRENT_TYPE(zap.za_first_integer);
                }

                done = !zpl_dir_emit(ctx, zap.za_name, strlen(zap.za_name),
                    objnum, type);
                if (done)
                        break;

                /* Prefetch znode */
                if (prefetch) {
                        dmu_prefetch(os, objnum, 0, 0, 0,
                            ZIO_PRIORITY_SYNC_READ);
                }

                /*
                 * Move to the next entry, fill in the previous offset.
                 */
                if (offset > 2 || (offset == 2 && !zfs_show_ctldir(zp))) {
                        zap_cursor_advance(&zc);
                        offset = zap_cursor_serialize(&zc);
                } else {
                        offset += 1;
                }
                ctx->pos = offset;
        }
        zp->z_zn_prefetch = B_FALSE; /* a lookup will re-enable pre-fetching */

update:
        zap_cursor_fini(&zc);
        if (error == ENOENT)
                error = 0;
out:
        zfs_exit(zfsvfs, FTAG);

        return (error);
}

/*
 * Get the basic file attributes and place them in the provided kstat
 * structure.  The inode is assumed to be the authoritative source
 * for most of the attributes.  However, the znode currently has the
 * authoritative atime, blksize, and block count.
 *
 *      IN:     ip      - inode of file.
 *
 *      OUT:    sp      - kstat values.
 *
 *      RETURN: 0 (always succeeds)
 */
int
zfs_getattr_fast(struct user_namespace *user_ns, struct inode *ip,
    struct kstat *sp)
{
        znode_t *zp = ITOZ(ip);
        zfsvfs_t *zfsvfs = ITOZSB(ip);
        uint32_t blksize;
        u_longlong_t nblocks;
        int error;

        if ((error = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (error);

        mutex_enter(&zp->z_lock);

        zpl_generic_fillattr(user_ns, ip, sp);
        /*
         * +1 link count for root inode with visible '.zfs' directory.
         */
        if ((zp->z_id == zfsvfs->z_root) && zfs_show_ctldir(zp))
                if (sp->nlink < ZFS_LINK_MAX)
                        sp->nlink++;

        sa_object_size(zp->z_sa_hdl, &blksize, &nblocks);
        sp->blksize = blksize;
        sp->blocks = nblocks;

        if (unlikely(zp->z_blksz == 0)) {
                /*
                 * Block size hasn't been set; suggest maximal I/O transfers.
                 */
                sp->blksize = zfsvfs->z_max_blksz;
        }

        mutex_exit(&zp->z_lock);

        /*
         * Required to prevent NFS client from detecting different inode
         * numbers of snapshot root dentry before and after snapshot mount.
         */
        if (zfsvfs->z_issnap) {
                if (ip->i_sb->s_root->d_inode == ip)
                        sp->ino = ZFSCTL_INO_SNAPDIRS -
                            dmu_objset_id(zfsvfs->z_os);
        }

        zfs_exit(zfsvfs, FTAG);

        return (0);
}

/*
 * For the operation of changing file's user/group/project, we need to
 * handle not only the main object that is assigned to the file directly,
 * but also the ones that are used by the file via hidden xattr directory.
 *
 * Because the xattr directory may contains many EA entries, as to it may
 * be impossible to change all of them via the transaction of changing the
 * main object's user/group/project attributes. Then we have to change them
 * via other multiple independent transactions one by one. It may be not good
 * solution, but we have no better idea yet.
 */
static int
zfs_setattr_dir(znode_t *dzp)
{
        struct inode    *dxip = ZTOI(dzp);
        struct inode    *xip = NULL;
        zfsvfs_t        *zfsvfs = ZTOZSB(dzp);
        objset_t        *os = zfsvfs->z_os;
        zap_cursor_t    zc;
        zap_attribute_t zap;
        zfs_dirlock_t   *dl;
        znode_t         *zp = NULL;
        dmu_tx_t        *tx = NULL;
        uint64_t        uid, gid;
        sa_bulk_attr_t  bulk[4];
        int             count;
        int             err;

        zap_cursor_init(&zc, os, dzp->z_id);
        while ((err = zap_cursor_retrieve(&zc, &zap)) == 0) {
                count = 0;
                if (zap.za_integer_length != 8 || zap.za_num_integers != 1) {
                        err = ENXIO;
                        break;
                }

                err = zfs_dirent_lock(&dl, dzp, (char *)zap.za_name, &zp,
                    ZEXISTS, NULL, NULL);
                if (err == ENOENT)
                        goto next;
                if (err)
                        break;

                xip = ZTOI(zp);
                if (KUID_TO_SUID(xip->i_uid) == KUID_TO_SUID(dxip->i_uid) &&
                    KGID_TO_SGID(xip->i_gid) == KGID_TO_SGID(dxip->i_gid) &&
                    zp->z_projid == dzp->z_projid)
                        goto next;

                tx = dmu_tx_create(os);
                if (!(zp->z_pflags & ZFS_PROJID))
                        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
                else
                        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);

                err = dmu_tx_assign(tx, TXG_WAIT);
                if (err)
                        break;

                mutex_enter(&dzp->z_lock);

                if (KUID_TO_SUID(xip->i_uid) != KUID_TO_SUID(dxip->i_uid)) {
                        xip->i_uid = dxip->i_uid;
                        uid = zfs_uid_read(dxip);
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_UID(zfsvfs), NULL,
                            &uid, sizeof (uid));
                }

                if (KGID_TO_SGID(xip->i_gid) != KGID_TO_SGID(dxip->i_gid)) {
                        xip->i_gid = dxip->i_gid;
                        gid = zfs_gid_read(dxip);
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_GID(zfsvfs), NULL,
                            &gid, sizeof (gid));
                }

                if (zp->z_projid != dzp->z_projid) {
                        if (!(zp->z_pflags & ZFS_PROJID)) {
                                zp->z_pflags |= ZFS_PROJID;
                                SA_ADD_BULK_ATTR(bulk, count,
                                    SA_ZPL_FLAGS(zfsvfs), NULL, &zp->z_pflags,
                                    sizeof (zp->z_pflags));
                        }

                        zp->z_projid = dzp->z_projid;
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_PROJID(zfsvfs),
                            NULL, &zp->z_projid, sizeof (zp->z_projid));
                }

                mutex_exit(&dzp->z_lock);

                if (likely(count > 0)) {
                        err = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
                        dmu_tx_commit(tx);
                } else {
                        dmu_tx_abort(tx);
                }
                tx = NULL;
                if (err != 0 && err != ENOENT)
                        break;

next:
                if (zp) {
                        zrele(zp);
                        zp = NULL;
                        zfs_dirent_unlock(dl);
                }
                zap_cursor_advance(&zc);
        }

        if (tx)
                dmu_tx_abort(tx);
        if (zp) {
                zrele(zp);
                zfs_dirent_unlock(dl);
        }
        zap_cursor_fini(&zc);

        return (err == ENOENT ? 0 : err);
}

/*
 * Set the file attributes to the values contained in the
 * vattr structure.
 *
 *      IN:     zp      - znode of file to be modified.
 *              vap     - new attribute values.
 *                        If ATTR_XVATTR set, then optional attrs are being set
 *              flags   - ATTR_UTIME set if non-default time values provided.
 *                      - ATTR_NOACLCHECK (CIFS context only).
 *              cr      - credentials of caller.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      ip - ctime updated, mtime updated if size changed.
 */
int
zfs_setattr(znode_t *zp, vattr_t *vap, int flags, cred_t *cr)
{
        struct inode    *ip;
        zfsvfs_t        *zfsvfs = ZTOZSB(zp);
        objset_t        *os = zfsvfs->z_os;
        zilog_t         *zilog;
        dmu_tx_t        *tx;
        vattr_t         oldva;
        xvattr_t        *tmpxvattr;
        uint_t          mask = vap->va_mask;
        uint_t          saved_mask = 0;
        int             trim_mask = 0;
        uint64_t        new_mode;
        uint64_t        new_kuid = 0, new_kgid = 0, new_uid, new_gid;
        uint64_t        xattr_obj;
        uint64_t        mtime[2], ctime[2], atime[2];
        uint64_t        projid = ZFS_INVALID_PROJID;
        znode_t         *attrzp;
        int             need_policy = FALSE;
        int             err, err2 = 0;
        zfs_fuid_info_t *fuidp = NULL;
        xvattr_t *xvap = (xvattr_t *)vap;       /* vap may be an xvattr_t * */
        xoptattr_t      *xoap;
        zfs_acl_t       *aclp;
        boolean_t skipaclchk = (flags & ATTR_NOACLCHECK) ? B_TRUE : B_FALSE;
        boolean_t       fuid_dirtied = B_FALSE;
        boolean_t       handle_eadir = B_FALSE;
        sa_bulk_attr_t  *bulk, *xattr_bulk;
        int             count = 0, xattr_count = 0, bulks = 8;

        if (mask == 0)
                return (0);

        if ((err = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (err);
        ip = ZTOI(zp);

        /*
         * If this is a xvattr_t, then get a pointer to the structure of
         * optional attributes.  If this is NULL, then we have a vattr_t.
         */
        xoap = xva_getxoptattr(xvap);
        if (xoap != NULL && (mask & ATTR_XVATTR)) {
                if (XVA_ISSET_REQ(xvap, XAT_PROJID)) {
                        if (!dmu_objset_projectquota_enabled(os) ||
                            (!S_ISREG(ip->i_mode) && !S_ISDIR(ip->i_mode))) {
                                zfs_exit(zfsvfs, FTAG);
                                return (SET_ERROR(ENOTSUP));
                        }

                        projid = xoap->xoa_projid;
                        if (unlikely(projid == ZFS_INVALID_PROJID)) {
                                zfs_exit(zfsvfs, FTAG);
                                return (SET_ERROR(EINVAL));
                        }

                        if (projid == zp->z_projid && zp->z_pflags & ZFS_PROJID)
                                projid = ZFS_INVALID_PROJID;
                        else
                                need_policy = TRUE;
                }

                if (XVA_ISSET_REQ(xvap, XAT_PROJINHERIT) &&
                    (xoap->xoa_projinherit !=
                    ((zp->z_pflags & ZFS_PROJINHERIT) != 0)) &&
                    (!dmu_objset_projectquota_enabled(os) ||
                    (!S_ISREG(ip->i_mode) && !S_ISDIR(ip->i_mode)))) {
                        zfs_exit(zfsvfs, FTAG);
                        return (SET_ERROR(ENOTSUP));
                }
        }

        zilog = zfsvfs->z_log;

        /*
         * Make sure that if we have ephemeral uid/gid or xvattr specified
         * that file system is at proper version level
         */

        if (zfsvfs->z_use_fuids == B_FALSE &&
            (((mask & ATTR_UID) && IS_EPHEMERAL(vap->va_uid)) ||
            ((mask & ATTR_GID) && IS_EPHEMERAL(vap->va_gid)) ||
            (mask & ATTR_XVATTR))) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EINVAL));
        }

        if (mask & ATTR_SIZE && S_ISDIR(ip->i_mode)) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EISDIR));
        }

        if (mask & ATTR_SIZE && !S_ISREG(ip->i_mode) && !S_ISFIFO(ip->i_mode)) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EINVAL));
        }

        tmpxvattr = kmem_alloc(sizeof (xvattr_t), KM_SLEEP);
        xva_init(tmpxvattr);

        bulk = kmem_alloc(sizeof (sa_bulk_attr_t) * bulks, KM_SLEEP);
        xattr_bulk = kmem_alloc(sizeof (sa_bulk_attr_t) * bulks, KM_SLEEP);

        /*
         * Immutable files can only alter immutable bit and atime
         */
        if ((zp->z_pflags & ZFS_IMMUTABLE) &&
            ((mask & (ATTR_SIZE|ATTR_UID|ATTR_GID|ATTR_MTIME|ATTR_MODE)) ||
            ((mask & ATTR_XVATTR) && XVA_ISSET_REQ(xvap, XAT_CREATETIME)))) {
                err = SET_ERROR(EPERM);
                goto out3;
        }

        if ((mask & ATTR_SIZE) && (zp->z_pflags & ZFS_READONLY)) {
                err = SET_ERROR(EPERM);
                goto out3;
        }

        /*
         * Verify timestamps doesn't overflow 32 bits.
         * ZFS can handle large timestamps, but 32bit syscalls can't
         * handle times greater than 2039.  This check should be removed
         * once large timestamps are fully supported.
         */
        if (mask & (ATTR_ATIME | ATTR_MTIME)) {
                if (((mask & ATTR_ATIME) &&
                    TIMESPEC_OVERFLOW(&vap->va_atime)) ||
                    ((mask & ATTR_MTIME) &&
                    TIMESPEC_OVERFLOW(&vap->va_mtime))) {
                        err = SET_ERROR(EOVERFLOW);
                        goto out3;
                }
        }

top:
        attrzp = NULL;
        aclp = NULL;

        /* Can this be moved to before the top label? */
        if (zfs_is_readonly(zfsvfs)) {
                err = SET_ERROR(EROFS);
                goto out3;
        }

        /*
         * First validate permissions
         */

        if (mask & ATTR_SIZE) {
                err = zfs_zaccess(zp, ACE_WRITE_DATA, 0, skipaclchk, cr);
                if (err)
                        goto out3;

                /*
                 * XXX - Note, we are not providing any open
                 * mode flags here (like FNDELAY), so we may
                 * block if there are locks present... this
                 * should be addressed in openat().
                 */
                /* XXX - would it be OK to generate a log record here? */
                err = zfs_freesp(zp, vap->va_size, 0, 0, FALSE);
                if (err)
                        goto out3;
        }

        if (mask & (ATTR_ATIME|ATTR_MTIME) ||
            ((mask & ATTR_XVATTR) && (XVA_ISSET_REQ(xvap, XAT_HIDDEN) ||
            XVA_ISSET_REQ(xvap, XAT_READONLY) ||
            XVA_ISSET_REQ(xvap, XAT_ARCHIVE) ||
            XVA_ISSET_REQ(xvap, XAT_OFFLINE) ||
            XVA_ISSET_REQ(xvap, XAT_SPARSE) ||
            XVA_ISSET_REQ(xvap, XAT_CREATETIME) ||
            XVA_ISSET_REQ(xvap, XAT_SYSTEM)))) {
                need_policy = zfs_zaccess(zp, ACE_WRITE_ATTRIBUTES, 0,
                    skipaclchk, cr);
        }

        if (mask & (ATTR_UID|ATTR_GID)) {
                int     idmask = (mask & (ATTR_UID|ATTR_GID));
                int     take_owner;
                int     take_group;

                /*
                 * NOTE: even if a new mode is being set,
                 * we may clear S_ISUID/S_ISGID bits.
                 */

                if (!(mask & ATTR_MODE))
                        vap->va_mode = zp->z_mode;

                /*
                 * Take ownership or chgrp to group we are a member of
                 */

                take_owner = (mask & ATTR_UID) && (vap->va_uid == crgetuid(cr));
                take_group = (mask & ATTR_GID) &&
                    zfs_groupmember(zfsvfs, vap->va_gid, cr);

                /*
                 * If both ATTR_UID and ATTR_GID are set then take_owner and
                 * take_group must both be set in order to allow taking
                 * ownership.
                 *
                 * Otherwise, send the check through secpolicy_vnode_setattr()
                 *
                 */

                if (((idmask == (ATTR_UID|ATTR_GID)) &&
                    take_owner && take_group) ||
                    ((idmask == ATTR_UID) && take_owner) ||
                    ((idmask == ATTR_GID) && take_group)) {
                        if (zfs_zaccess(zp, ACE_WRITE_OWNER, 0,
                            skipaclchk, cr) == 0) {
                                /*
                                 * Remove setuid/setgid for non-privileged users
                                 */
                                (void) secpolicy_setid_clear(vap, cr);
                                trim_mask = (mask & (ATTR_UID|ATTR_GID));
                        } else {
                                need_policy =  TRUE;
                        }
                } else {
                        need_policy =  TRUE;
                }
        }

        mutex_enter(&zp->z_lock);
        oldva.va_mode = zp->z_mode;
        zfs_fuid_map_ids(zp, cr, &oldva.va_uid, &oldva.va_gid);
        if (mask & ATTR_XVATTR) {
                /*
                 * Update xvattr mask to include only those attributes
                 * that are actually changing.
                 *
                 * the bits will be restored prior to actually setting
                 * the attributes so the caller thinks they were set.
                 */
                if (XVA_ISSET_REQ(xvap, XAT_APPENDONLY)) {
                        if (xoap->xoa_appendonly !=
                            ((zp->z_pflags & ZFS_APPENDONLY) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_APPENDONLY);
                                XVA_SET_REQ(tmpxvattr, XAT_APPENDONLY);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_PROJINHERIT)) {
                        if (xoap->xoa_projinherit !=
                            ((zp->z_pflags & ZFS_PROJINHERIT) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_PROJINHERIT);
                                XVA_SET_REQ(tmpxvattr, XAT_PROJINHERIT);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_NOUNLINK)) {
                        if (xoap->xoa_nounlink !=
                            ((zp->z_pflags & ZFS_NOUNLINK) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_NOUNLINK);
                                XVA_SET_REQ(tmpxvattr, XAT_NOUNLINK);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_IMMUTABLE)) {
                        if (xoap->xoa_immutable !=
                            ((zp->z_pflags & ZFS_IMMUTABLE) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_IMMUTABLE);
                                XVA_SET_REQ(tmpxvattr, XAT_IMMUTABLE);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_NODUMP)) {
                        if (xoap->xoa_nodump !=
                            ((zp->z_pflags & ZFS_NODUMP) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_NODUMP);
                                XVA_SET_REQ(tmpxvattr, XAT_NODUMP);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_AV_MODIFIED)) {
                        if (xoap->xoa_av_modified !=
                            ((zp->z_pflags & ZFS_AV_MODIFIED) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_AV_MODIFIED);
                                XVA_SET_REQ(tmpxvattr, XAT_AV_MODIFIED);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_AV_QUARANTINED)) {
                        if ((!S_ISREG(ip->i_mode) &&
                            xoap->xoa_av_quarantined) ||
                            xoap->xoa_av_quarantined !=
                            ((zp->z_pflags & ZFS_AV_QUARANTINED) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_AV_QUARANTINED);
                                XVA_SET_REQ(tmpxvattr, XAT_AV_QUARANTINED);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_REPARSE)) {
                        mutex_exit(&zp->z_lock);
                        err = SET_ERROR(EPERM);
                        goto out3;
                }

                if (need_policy == FALSE &&
                    (XVA_ISSET_REQ(xvap, XAT_AV_SCANSTAMP) ||
                    XVA_ISSET_REQ(xvap, XAT_OPAQUE))) {
                        need_policy = TRUE;
                }
        }

        mutex_exit(&zp->z_lock);

        if (mask & ATTR_MODE) {
                if (zfs_zaccess(zp, ACE_WRITE_ACL, 0, skipaclchk, cr) == 0) {
                        err = secpolicy_setid_setsticky_clear(ip, vap,
                            &oldva, cr);
                        if (err)
                                goto out3;

                        trim_mask |= ATTR_MODE;
                } else {
                        need_policy = TRUE;
                }
        }

        if (need_policy) {
                /*
                 * If trim_mask is set then take ownership
                 * has been granted or write_acl is present and user
                 * has the ability to modify mode.  In that case remove
                 * UID|GID and or MODE from mask so that
                 * secpolicy_vnode_setattr() doesn't revoke it.
                 */

                if (trim_mask) {
                        saved_mask = vap->va_mask;
                        vap->va_mask &= ~trim_mask;
                }
                err = secpolicy_vnode_setattr(cr, ip, vap, &oldva, flags,
                    (int (*)(void *, int, cred_t *))zfs_zaccess_unix, zp);
                if (err)
                        goto out3;

                if (trim_mask)
                        vap->va_mask |= saved_mask;
        }

        /*
         * secpolicy_vnode_setattr, or take ownership may have
         * changed va_mask
         */
        mask = vap->va_mask;

        if ((mask & (ATTR_UID | ATTR_GID)) || projid != ZFS_INVALID_PROJID) {
                handle_eadir = B_TRUE;
                err = sa_lookup(zp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs),
                    &xattr_obj, sizeof (xattr_obj));

                if (err == 0 && xattr_obj) {
                        err = zfs_zget(ZTOZSB(zp), xattr_obj, &attrzp);
                        if (err)
                                goto out2;
                }
                if (mask & ATTR_UID) {
                        new_kuid = zfs_fuid_create(zfsvfs,
                            (uint64_t)vap->va_uid, cr, ZFS_OWNER, &fuidp);
                        if (new_kuid != KUID_TO_SUID(ZTOI(zp)->i_uid) &&
                            zfs_id_overquota(zfsvfs, DMU_USERUSED_OBJECT,
                            new_kuid)) {
                                if (attrzp)
                                        zrele(attrzp);
                                err = SET_ERROR(EDQUOT);
                                goto out2;
                        }
                }

                if (mask & ATTR_GID) {
                        new_kgid = zfs_fuid_create(zfsvfs,
                            (uint64_t)vap->va_gid, cr, ZFS_GROUP, &fuidp);
                        if (new_kgid != KGID_TO_SGID(ZTOI(zp)->i_gid) &&
                            zfs_id_overquota(zfsvfs, DMU_GROUPUSED_OBJECT,
                            new_kgid)) {
                                if (attrzp)
                                        zrele(attrzp);
                                err = SET_ERROR(EDQUOT);
                                goto out2;
                        }
                }

                if (projid != ZFS_INVALID_PROJID &&
                    zfs_id_overquota(zfsvfs, DMU_PROJECTUSED_OBJECT, projid)) {
                        if (attrzp)
                                zrele(attrzp);
                        err = EDQUOT;
                        goto out2;
                }
        }
        tx = dmu_tx_create(os);

        if (mask & ATTR_MODE) {
                uint64_t pmode = zp->z_mode;
                uint64_t acl_obj;
                new_mode = (pmode & S_IFMT) | (vap->va_mode & ~S_IFMT);

                if (ZTOZSB(zp)->z_acl_mode == ZFS_ACL_RESTRICTED &&
                    !(zp->z_pflags & ZFS_ACL_TRIVIAL)) {
                        err = EPERM;
                        goto out;
                }

                if ((err = zfs_acl_chmod_setattr(zp, &aclp, new_mode)))
                        goto out;

                mutex_enter(&zp->z_lock);
                if (!zp->z_is_sa && ((acl_obj = zfs_external_acl(zp)) != 0)) {
                        /*
                         * Are we upgrading ACL from old V0 format
                         * to V1 format?
                         */
                        if (zfsvfs->z_version >= ZPL_VERSION_FUID &&
                            zfs_znode_acl_version(zp) ==
                            ZFS_ACL_VERSION_INITIAL) {
                                dmu_tx_hold_free(tx, acl_obj, 0,
                                    DMU_OBJECT_END);
                                dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                                    0, aclp->z_acl_bytes);
                        } else {
                                dmu_tx_hold_write(tx, acl_obj, 0,
                                    aclp->z_acl_bytes);
                        }
                } else if (!zp->z_is_sa && aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                        dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                            0, aclp->z_acl_bytes);
                }
                mutex_exit(&zp->z_lock);
                dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
        } else {
                if (((mask & ATTR_XVATTR) &&
                    XVA_ISSET_REQ(xvap, XAT_AV_SCANSTAMP)) ||
                    (projid != ZFS_INVALID_PROJID &&
                    !(zp->z_pflags & ZFS_PROJID)))
                        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
                else
                        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        }

        if (attrzp) {
                dmu_tx_hold_sa(tx, attrzp->z_sa_hdl, B_FALSE);
        }

        fuid_dirtied = zfsvfs->z_fuid_dirty;
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);

        zfs_sa_upgrade_txholds(tx, zp);

        err = dmu_tx_assign(tx, TXG_WAIT);
        if (err)
                goto out;

        count = 0;
        /*
         * Set each attribute requested.
         * We group settings according to the locks they need to acquire.
         *
         * Note: you cannot set ctime directly, although it will be
         * updated as a side-effect of calling this function.
         */

        if (projid != ZFS_INVALID_PROJID && !(zp->z_pflags & ZFS_PROJID)) {
                /*
                 * For the existed object that is upgraded from old system,
                 * its on-disk layout has no slot for the project ID attribute.
                 * But quota accounting logic needs to access related slots by
                 * offset directly. So we need to adjust old objects' layout
                 * to make the project ID to some unified and fixed offset.
                 */
                if (attrzp)
                        err = sa_add_projid(attrzp->z_sa_hdl, tx, projid);
                if (err == 0)
                        err = sa_add_projid(zp->z_sa_hdl, tx, projid);

                if (unlikely(err == EEXIST))
                        err = 0;
                else if (err != 0)
                        goto out;
                else
                        projid = ZFS_INVALID_PROJID;
        }

        if (mask & (ATTR_UID|ATTR_GID|ATTR_MODE))
                mutex_enter(&zp->z_acl_lock);
        mutex_enter(&zp->z_lock);

        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs), NULL,
            &zp->z_pflags, sizeof (zp->z_pflags));

        if (attrzp) {
                if (mask & (ATTR_UID|ATTR_GID|ATTR_MODE))
                        mutex_enter(&attrzp->z_acl_lock);
                mutex_enter(&attrzp->z_lock);
                SA_ADD_BULK_ATTR(xattr_bulk, xattr_count,
                    SA_ZPL_FLAGS(zfsvfs), NULL, &attrzp->z_pflags,
                    sizeof (attrzp->z_pflags));
                if (projid != ZFS_INVALID_PROJID) {
                        attrzp->z_projid = projid;
                        SA_ADD_BULK_ATTR(xattr_bulk, xattr_count,
                            SA_ZPL_PROJID(zfsvfs), NULL, &attrzp->z_projid,
                            sizeof (attrzp->z_projid));
                }
        }

        if (mask & (ATTR_UID|ATTR_GID)) {

                if (mask & ATTR_UID) {
                        ZTOI(zp)->i_uid = SUID_TO_KUID(new_kuid);
                        new_uid = zfs_uid_read(ZTOI(zp));
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_UID(zfsvfs), NULL,
                            &new_uid, sizeof (new_uid));
                        if (attrzp) {
                                SA_ADD_BULK_ATTR(xattr_bulk, xattr_count,
                                    SA_ZPL_UID(zfsvfs), NULL, &new_uid,
                                    sizeof (new_uid));
                                ZTOI(attrzp)->i_uid = SUID_TO_KUID(new_uid);
                        }
                }

                if (mask & ATTR_GID) {
                        ZTOI(zp)->i_gid = SGID_TO_KGID(new_kgid);
                        new_gid = zfs_gid_read(ZTOI(zp));
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_GID(zfsvfs),
                            NULL, &new_gid, sizeof (new_gid));
                        if (attrzp) {
                                SA_ADD_BULK_ATTR(xattr_bulk, xattr_count,
                                    SA_ZPL_GID(zfsvfs), NULL, &new_gid,
                                    sizeof (new_gid));
                                ZTOI(attrzp)->i_gid = SGID_TO_KGID(new_kgid);
                        }
                }
                if (!(mask & ATTR_MODE)) {
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MODE(zfsvfs),
                            NULL, &new_mode, sizeof (new_mode));
                        new_mode = zp->z_mode;
                }
                err = zfs_acl_chown_setattr(zp);
                ASSERT(err == 0);
                if (attrzp) {
                        err = zfs_acl_chown_setattr(attrzp);
                        ASSERT(err == 0);
                }
        }

        if (mask & ATTR_MODE) {
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MODE(zfsvfs), NULL,
                    &new_mode, sizeof (new_mode));
                zp->z_mode = ZTOI(zp)->i_mode = new_mode;
                ASSERT3P(aclp, !=, NULL);
                err = zfs_aclset_common(zp, aclp, cr, tx);
                ASSERT0(err);
                if (zp->z_acl_cached)
                        zfs_acl_free(zp->z_acl_cached);
                zp->z_acl_cached = aclp;
                aclp = NULL;
        }

        if ((mask & ATTR_ATIME) || zp->z_atime_dirty) {
                zp->z_atime_dirty = B_FALSE;
                ZFS_TIME_ENCODE(&ip->i_atime, atime);
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_ATIME(zfsvfs), NULL,
                    &atime, sizeof (atime));
        }

        if (mask & (ATTR_MTIME | ATTR_SIZE)) {
                ZFS_TIME_ENCODE(&vap->va_mtime, mtime);
                ZTOI(zp)->i_mtime = zpl_inode_timestamp_truncate(
                    vap->va_mtime, ZTOI(zp));

                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs), NULL,
                    mtime, sizeof (mtime));
        }

        if (mask & (ATTR_CTIME | ATTR_SIZE)) {
                ZFS_TIME_ENCODE(&vap->va_ctime, ctime);
                ZTOI(zp)->i_ctime = zpl_inode_timestamp_truncate(vap->va_ctime,
                    ZTOI(zp));
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
                    ctime, sizeof (ctime));
        }

        if (projid != ZFS_INVALID_PROJID) {
                zp->z_projid = projid;
                SA_ADD_BULK_ATTR(bulk, count,
                    SA_ZPL_PROJID(zfsvfs), NULL, &zp->z_projid,
                    sizeof (zp->z_projid));
        }

        if (attrzp && mask) {
                SA_ADD_BULK_ATTR(xattr_bulk, xattr_count,
                    SA_ZPL_CTIME(zfsvfs), NULL, &ctime,
                    sizeof (ctime));
        }

        /*
         * Do this after setting timestamps to prevent timestamp
         * update from toggling bit
         */

        if (xoap && (mask & ATTR_XVATTR)) {

                /*
                 * restore trimmed off masks
                 * so that return masks can be set for caller.
                 */

                if (XVA_ISSET_REQ(tmpxvattr, XAT_APPENDONLY)) {
                        XVA_SET_REQ(xvap, XAT_APPENDONLY);
                }
                if (XVA_ISSET_REQ(tmpxvattr, XAT_NOUNLINK)) {
                        XVA_SET_REQ(xvap, XAT_NOUNLINK);
                }
                if (XVA_ISSET_REQ(tmpxvattr, XAT_IMMUTABLE)) {
                        XVA_SET_REQ(xvap, XAT_IMMUTABLE);
                }
                if (XVA_ISSET_REQ(tmpxvattr, XAT_NODUMP)) {
                        XVA_SET_REQ(xvap, XAT_NODUMP);
                }
                if (XVA_ISSET_REQ(tmpxvattr, XAT_AV_MODIFIED)) {
                        XVA_SET_REQ(xvap, XAT_AV_MODIFIED);
                }
                if (XVA_ISSET_REQ(tmpxvattr, XAT_AV_QUARANTINED)) {
                        XVA_SET_REQ(xvap, XAT_AV_QUARANTINED);
                }
                if (XVA_ISSET_REQ(tmpxvattr, XAT_PROJINHERIT)) {
                        XVA_SET_REQ(xvap, XAT_PROJINHERIT);
                }

                if (XVA_ISSET_REQ(xvap, XAT_AV_SCANSTAMP))
                        ASSERT(S_ISREG(ip->i_mode));

                zfs_xvattr_set(zp, xvap, tx);
        }

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);

        if (mask != 0)
                zfs_log_setattr(zilog, tx, TX_SETATTR, zp, vap, mask, fuidp);

        mutex_exit(&zp->z_lock);
        if (mask & (ATTR_UID|ATTR_GID|ATTR_MODE))
                mutex_exit(&zp->z_acl_lock);

        if (attrzp) {
                if (mask & (ATTR_UID|ATTR_GID|ATTR_MODE))
                        mutex_exit(&attrzp->z_acl_lock);
                mutex_exit(&attrzp->z_lock);
        }
out:
        if (err == 0 && xattr_count > 0) {
                err2 = sa_bulk_update(attrzp->z_sa_hdl, xattr_bulk,
                    xattr_count, tx);
                ASSERT(err2 == 0);
        }

        if (aclp)
                zfs_acl_free(aclp);

        if (fuidp) {
                zfs_fuid_info_free(fuidp);
                fuidp = NULL;
        }

        if (err) {
                dmu_tx_abort(tx);
                if (attrzp)
                        zrele(attrzp);
                if (err == ERESTART)
                        goto top;
        } else {
                if (count > 0)
                        err2 = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
                dmu_tx_commit(tx);
                if (attrzp) {
                        if (err2 == 0 && handle_eadir)
                                err2 = zfs_setattr_dir(attrzp);
                        zrele(attrzp);
                }
                zfs_znode_update_vfs(zp);
        }

out2:
        if (os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

out3:
        kmem_free(xattr_bulk, sizeof (sa_bulk_attr_t) * bulks);
        kmem_free(bulk, sizeof (sa_bulk_attr_t) * bulks);
        kmem_free(tmpxvattr, sizeof (xvattr_t));
        zfs_exit(zfsvfs, FTAG);
        return (err);
}

typedef struct zfs_zlock {
        krwlock_t       *zl_rwlock;     /* lock we acquired */
        znode_t         *zl_znode;      /* znode we held */
        struct zfs_zlock *zl_next;      /* next in list */
} zfs_zlock_t;

/*
 * Drop locks and release vnodes that were held by zfs_rename_lock().
 */
static void
zfs_rename_unlock(zfs_zlock_t **zlpp)
{
        zfs_zlock_t *zl;

        while ((zl = *zlpp) != NULL) {
                if (zl->zl_znode != NULL)
                        zfs_zrele_async(zl->zl_znode);
                rw_exit(zl->zl_rwlock);
                *zlpp = zl->zl_next;
                kmem_free(zl, sizeof (*zl));
        }
}

/*
 * Search back through the directory tree, using the ".." entries.
 * Lock each directory in the chain to prevent concurrent renames.
 * Fail any attempt to move a directory into one of its own descendants.
 * XXX - z_parent_lock can overlap with map or grow locks
 */
static int
zfs_rename_lock(znode_t *szp, znode_t *tdzp, znode_t *sdzp, zfs_zlock_t **zlpp)
{
        zfs_zlock_t     *zl;
        znode_t         *zp = tdzp;
        uint64_t        rootid = ZTOZSB(zp)->z_root;
        uint64_t        oidp = zp->z_id;
        krwlock_t       *rwlp = &szp->z_parent_lock;
        krw_t           rw = RW_WRITER;

        /*
         * First pass write-locks szp and compares to zp->z_id.
         * Later passes read-lock zp and compare to zp->z_parent.
         */
        do {
                if (!rw_tryenter(rwlp, rw)) {
                        /*
                         * Another thread is renaming in this path.
                         * Note that if we are a WRITER, we don't have any
                         * parent_locks held yet.
                         */
                        if (rw == RW_READER && zp->z_id > szp->z_id) {
                                /*
                                 * Drop our locks and restart
                                 */
                                zfs_rename_unlock(&zl);
                                *zlpp = NULL;
                                zp = tdzp;
                                oidp = zp->z_id;
                                rwlp = &szp->z_parent_lock;
                                rw = RW_WRITER;
                                continue;
                        } else {
                                /*
                                 * Wait for other thread to drop its locks
                                 */
                                rw_enter(rwlp, rw);
                        }
                }

                zl = kmem_alloc(sizeof (*zl), KM_SLEEP);
                zl->zl_rwlock = rwlp;
                zl->zl_znode = NULL;
                zl->zl_next = *zlpp;
                *zlpp = zl;

                if (oidp == szp->z_id)          /* We're a descendant of szp */
                        return (SET_ERROR(EINVAL));

                if (oidp == rootid)             /* We've hit the top */
                        return (0);

                if (rw == RW_READER) {          /* i.e. not the first pass */
                        int error = zfs_zget(ZTOZSB(zp), oidp, &zp);
                        if (error)
                                return (error);
                        zl->zl_znode = zp;
                }
                (void) sa_lookup(zp->z_sa_hdl, SA_ZPL_PARENT(ZTOZSB(zp)),
                    &oidp, sizeof (oidp));
                rwlp = &zp->z_parent_lock;
                rw = RW_READER;

        } while (zp->z_id != sdzp->z_id);

        return (0);
}

/*
 * Move an entry from the provided source directory to the target
 * directory.  Change the entry name as indicated.
 *
 *      IN:     sdzp    - Source directory containing the "old entry".
 *              snm     - Old entry name.
 *              tdzp    - Target directory to contain the "new entry".
 *              tnm     - New entry name.
 *              cr      - credentials of caller.
 *              flags   - case flags
 *
 *      RETURN: 0 on success, error code on failure.
 *
 * Timestamps:
 *      sdzp,tdzp - ctime|mtime updated
 */
int
zfs_rename(znode_t *sdzp, char *snm, znode_t *tdzp, char *tnm,
    cred_t *cr, int flags)
{
        znode_t         *szp, *tzp;
        zfsvfs_t        *zfsvfs = ZTOZSB(sdzp);
        zilog_t         *zilog;
        zfs_dirlock_t   *sdl, *tdl;
        dmu_tx_t        *tx;
        zfs_zlock_t     *zl;
        int             cmp, serr, terr;
        int             error = 0;
        int             zflg = 0;
        boolean_t       waited = B_FALSE;

        if (snm == NULL || tnm == NULL)
                return (SET_ERROR(EINVAL));

        if ((error = zfs_enter_verify_zp(zfsvfs, sdzp, FTAG)) != 0)
                return (error);
        zilog = zfsvfs->z_log;

        if ((error = zfs_verify_zp(tdzp)) != 0) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        /*
         * We check i_sb because snapshots and the ctldir must have different
         * super blocks.
         */
        if (ZTOI(tdzp)->i_sb != ZTOI(sdzp)->i_sb ||
            zfsctl_is_node(ZTOI(tdzp))) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EXDEV));
        }

        if (zfsvfs->z_utf8 && u8_validate(tnm,
            strlen(tnm), NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EILSEQ));
        }

        if (flags & FIGNORECASE)
                zflg |= ZCILOOK;

top:
        szp = NULL;
        tzp = NULL;
        zl = NULL;

        /*
         * This is to prevent the creation of links into attribute space
         * by renaming a linked file into/outof an attribute directory.
         * See the comment in zfs_link() for why this is considered bad.
         */
        if ((tdzp->z_pflags & ZFS_XATTR) != (sdzp->z_pflags & ZFS_XATTR)) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EINVAL));
        }

        /*
         * Lock source and target directory entries.  To prevent deadlock,
         * a lock ordering must be defined.  We lock the directory with
         * the smallest object id first, or if it's a tie, the one with
         * the lexically first name.
         */
        if (sdzp->z_id < tdzp->z_id) {
                cmp = -1;
        } else if (sdzp->z_id > tdzp->z_id) {
                cmp = 1;
        } else {
                /*
                 * First compare the two name arguments without
                 * considering any case folding.
                 */
                int nofold = (zfsvfs->z_norm & ~U8_TEXTPREP_TOUPPER);

                cmp = u8_strcmp(snm, tnm, 0, nofold, U8_UNICODE_LATEST, &error);
                ASSERT(error == 0 || !zfsvfs->z_utf8);
                if (cmp == 0) {
                        /*
                         * POSIX: "If the old argument and the new argument
                         * both refer to links to the same existing file,
                         * the rename() function shall return successfully
                         * and perform no other action."
                         */
                        zfs_exit(zfsvfs, FTAG);
                        return (0);
                }
                /*
                 * If the file system is case-folding, then we may
                 * have some more checking to do.  A case-folding file
                 * system is either supporting mixed case sensitivity
                 * access or is completely case-insensitive.  Note
                 * that the file system is always case preserving.
                 *
                 * In mixed sensitivity mode case sensitive behavior
                 * is the default.  FIGNORECASE must be used to
                 * explicitly request case insensitive behavior.
                 *
                 * If the source and target names provided differ only
                 * by case (e.g., a request to rename 'tim' to 'Tim'),
                 * we will treat this as a special case in the
                 * case-insensitive mode: as long as the source name
                 * is an exact match, we will allow this to proceed as
                 * a name-change request.
                 */
                if ((zfsvfs->z_case == ZFS_CASE_INSENSITIVE ||
                    (zfsvfs->z_case == ZFS_CASE_MIXED &&
                    flags & FIGNORECASE)) &&
                    u8_strcmp(snm, tnm, 0, zfsvfs->z_norm, U8_UNICODE_LATEST,
                    &error) == 0) {
                        /*
                         * case preserving rename request, require exact
                         * name matches
                         */
                        zflg |= ZCIEXACT;
                        zflg &= ~ZCILOOK;
                }
        }

        /*
         * If the source and destination directories are the same, we should
         * grab the z_name_lock of that directory only once.
         */
        if (sdzp == tdzp) {
                zflg |= ZHAVELOCK;
                rw_enter(&sdzp->z_name_lock, RW_READER);
        }

        if (cmp < 0) {
                serr = zfs_dirent_lock(&sdl, sdzp, snm, &szp,
                    ZEXISTS | zflg, NULL, NULL);
                terr = zfs_dirent_lock(&tdl,
                    tdzp, tnm, &tzp, ZRENAMING | zflg, NULL, NULL);
        } else {
                terr = zfs_dirent_lock(&tdl,
                    tdzp, tnm, &tzp, zflg, NULL, NULL);
                serr = zfs_dirent_lock(&sdl,
                    sdzp, snm, &szp, ZEXISTS | ZRENAMING | zflg,
                    NULL, NULL);
        }

        if (serr) {
                /*
                 * Source entry invalid or not there.
                 */
                if (!terr) {
                        zfs_dirent_unlock(tdl);
                        if (tzp)
                                zrele(tzp);
                }

                if (sdzp == tdzp)
                        rw_exit(&sdzp->z_name_lock);

                if (strcmp(snm, "..") == 0)
                        serr = EINVAL;
                zfs_exit(zfsvfs, FTAG);
                return (serr);
        }
        if (terr) {
                zfs_dirent_unlock(sdl);
                zrele(szp);

                if (sdzp == tdzp)
                        rw_exit(&sdzp->z_name_lock);

                if (strcmp(tnm, "..") == 0)
                        terr = EINVAL;
                zfs_exit(zfsvfs, FTAG);
                return (terr);
        }

        /*
         * If we are using project inheritance, means if the directory has
         * ZFS_PROJINHERIT set, then its descendant directories will inherit
         * not only the project ID, but also the ZFS_PROJINHERIT flag. Under
         * such case, we only allow renames into our tree when the project
         * IDs are the same.
         */
        if (tdzp->z_pflags & ZFS_PROJINHERIT &&
            tdzp->z_projid != szp->z_projid) {
                error = SET_ERROR(EXDEV);
                goto out;
        }

        /*
         * Must have write access at the source to remove the old entry
         * and write access at the target to create the new entry.
         * Note that if target and source are the same, this can be
         * done in a single check.
         */

        if ((error = zfs_zaccess_rename(sdzp, szp, tdzp, tzp, cr)))
                goto out;

        if (S_ISDIR(ZTOI(szp)->i_mode)) {
                /*
                 * Check to make sure rename is valid.
                 * Can't do a move like this: /usr/a/b to /usr/a/b/c/d
                 */
                if ((error = zfs_rename_lock(szp, tdzp, sdzp, &zl)))
                        goto out;
        }

        /*
         * Does target exist?
         */
        if (tzp) {
                /*
                 * Source and target must be the same type.
                 */
                if (S_ISDIR(ZTOI(szp)->i_mode)) {
                        if (!S_ISDIR(ZTOI(tzp)->i_mode)) {
                                error = SET_ERROR(ENOTDIR);
                                goto out;
                        }
                } else {
                        if (S_ISDIR(ZTOI(tzp)->i_mode)) {
                                error = SET_ERROR(EISDIR);
                                goto out;
                        }
                }
                /*
                 * POSIX dictates that when the source and target
                 * entries refer to the same file object, rename
                 * must do nothing and exit without error.
                 */
                if (szp->z_id == tzp->z_id) {
                        error = 0;
                        goto out;
                }
        }

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_sa(tx, szp->z_sa_hdl, B_FALSE);
        dmu_tx_hold_sa(tx, sdzp->z_sa_hdl, B_FALSE);
        dmu_tx_hold_zap(tx, sdzp->z_id, FALSE, snm);
        dmu_tx_hold_zap(tx, tdzp->z_id, TRUE, tnm);
        if (sdzp != tdzp) {
                dmu_tx_hold_sa(tx, tdzp->z_sa_hdl, B_FALSE);
                zfs_sa_upgrade_txholds(tx, tdzp);
        }
        if (tzp) {
                dmu_tx_hold_sa(tx, tzp->z_sa_hdl, B_FALSE);
                zfs_sa_upgrade_txholds(tx, tzp);
        }

        zfs_sa_upgrade_txholds(tx, szp);
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
        error = dmu_tx_assign(tx, (waited ? TXG_NOTHROTTLE : 0) | TXG_NOWAIT);
        if (error) {
                if (zl != NULL)
                        zfs_rename_unlock(&zl);
                zfs_dirent_unlock(sdl);
                zfs_dirent_unlock(tdl);

                if (sdzp == tdzp)
                        rw_exit(&sdzp->z_name_lock);

                if (error == ERESTART) {
                        waited = B_TRUE;
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        zrele(szp);
                        if (tzp)
                                zrele(tzp);
                        goto top;
                }
                dmu_tx_abort(tx);
                zrele(szp);
                if (tzp)
                        zrele(tzp);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        if (tzp)        /* Attempt to remove the existing target */
                error = zfs_link_destroy(tdl, tzp, tx, zflg, NULL);

        if (error == 0) {
                error = zfs_link_create(tdl, szp, tx, ZRENAMING);
                if (error == 0) {
                        szp->z_pflags |= ZFS_AV_MODIFIED;
                        if (tdzp->z_pflags & ZFS_PROJINHERIT)
                                szp->z_pflags |= ZFS_PROJINHERIT;

                        error = sa_update(szp->z_sa_hdl, SA_ZPL_FLAGS(zfsvfs),
                            (void *)&szp->z_pflags, sizeof (uint64_t), tx);
                        ASSERT0(error);

                        error = zfs_link_destroy(sdl, szp, tx, ZRENAMING, NULL);
                        if (error == 0) {
                                zfs_log_rename(zilog, tx, TX_RENAME |
                                    (flags & FIGNORECASE ? TX_CI : 0), sdzp,
                                    sdl->dl_name, tdzp, tdl->dl_name, szp);
                        } else {
                                /*
                                 * At this point, we have successfully created
                                 * the target name, but have failed to remove
                                 * the source name.  Since the create was done
                                 * with the ZRENAMING flag, there are
                                 * complications; for one, the link count is
                                 * wrong.  The easiest way to deal with this
                                 * is to remove the newly created target, and
                                 * return the original error.  This must
                                 * succeed; fortunately, it is very unlikely to
                                 * fail, since we just created it.
                                 */
                                VERIFY3U(zfs_link_destroy(tdl, szp, tx,
                                    ZRENAMING, NULL), ==, 0);
                        }
                } else {
                        /*
                         * If we had removed the existing target, subsequent
                         * call to zfs_link_create() to add back the same entry
                         * but, the new dnode (szp) should not fail.
                         */
                        ASSERT(tzp == NULL);
                }
        }

        dmu_tx_commit(tx);
out:
        if (zl != NULL)
                zfs_rename_unlock(&zl);

        zfs_dirent_unlock(sdl);
        zfs_dirent_unlock(tdl);

        zfs_znode_update_vfs(sdzp);
        if (sdzp == tdzp)
                rw_exit(&sdzp->z_name_lock);

        if (sdzp != tdzp)
                zfs_znode_update_vfs(tdzp);

        zfs_znode_update_vfs(szp);
        zrele(szp);
        if (tzp) {
                zfs_znode_update_vfs(tzp);
                zrele(tzp);
        }

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        zfs_exit(zfsvfs, FTAG);
        return (error);
}

/*
 * Insert the indicated symbolic reference entry into the directory.
 *
 *      IN:     dzp     - Directory to contain new symbolic link.
 *              name    - Name of directory entry in dip.
 *              vap     - Attributes of new entry.
 *              link    - Name for new symlink entry.
 *              cr      - credentials of caller.
 *              flags   - case flags
 *
 *      OUT:    zpp     - Znode for new symbolic link.
 *
 *      RETURN: 0 on success, error code on failure.
 *
 * Timestamps:
 *      dip - ctime|mtime updated
 */
int
zfs_symlink(znode_t *dzp, char *name, vattr_t *vap, char *link,
    znode_t **zpp, cred_t *cr, int flags)
{
        znode_t         *zp;
        zfs_dirlock_t   *dl;
        dmu_tx_t        *tx;
        zfsvfs_t        *zfsvfs = ZTOZSB(dzp);
        zilog_t         *zilog;
        uint64_t        len = strlen(link);
        int             error;
        int             zflg = ZNEW;
        zfs_acl_ids_t   acl_ids;
        boolean_t       fuid_dirtied;
        uint64_t        txtype = TX_SYMLINK;
        boolean_t       waited = B_FALSE;

        ASSERT(S_ISLNK(vap->va_mode));

        if (name == NULL)
                return (SET_ERROR(EINVAL));

        if ((error = zfs_enter_verify_zp(zfsvfs, dzp, FTAG)) != 0)
                return (error);
        zilog = zfsvfs->z_log;

        if (zfsvfs->z_utf8 && u8_validate(name, strlen(name),
            NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EILSEQ));
        }
        if (flags & FIGNORECASE)
                zflg |= ZCILOOK;

        if (len > MAXPATHLEN) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(ENAMETOOLONG));
        }

        if ((error = zfs_acl_ids_create(dzp, 0,
            vap, cr, NULL, &acl_ids)) != 0) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }
top:
        *zpp = NULL;

        /*
         * Attempt to lock directory; fail if entry already exists.
         */
        error = zfs_dirent_lock(&dl, dzp, name, &zp, zflg, NULL, NULL);
        if (error) {
                zfs_acl_ids_free(&acl_ids);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        if ((error = zfs_zaccess(dzp, ACE_ADD_FILE, 0, B_FALSE, cr))) {
                zfs_acl_ids_free(&acl_ids);
                zfs_dirent_unlock(dl);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        if (zfs_acl_ids_overquota(zfsvfs, &acl_ids, ZFS_DEFAULT_PROJID)) {
                zfs_acl_ids_free(&acl_ids);
                zfs_dirent_unlock(dl);
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EDQUOT));
        }
        tx = dmu_tx_create(zfsvfs->z_os);
        fuid_dirtied = zfsvfs->z_fuid_dirty;
        dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0, MAX(1, len));
        dmu_tx_hold_zap(tx, dzp->z_id, TRUE, name);
        dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
            ZFS_SA_BASE_ATTR_SIZE + len);
        dmu_tx_hold_sa(tx, dzp->z_sa_hdl, B_FALSE);
        if (!zfsvfs->z_use_sa && acl_ids.z_aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0,
                    acl_ids.z_aclp->z_acl_bytes);
        }
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);
        error = dmu_tx_assign(tx, (waited ? TXG_NOTHROTTLE : 0) | TXG_NOWAIT);
        if (error) {
                zfs_dirent_unlock(dl);
                if (error == ERESTART) {
                        waited = B_TRUE;
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                zfs_acl_ids_free(&acl_ids);
                dmu_tx_abort(tx);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        /*
         * Create a new object for the symlink.
         * for version 4 ZPL datasets the symlink will be an SA attribute
         */
        zfs_mknode(dzp, vap, tx, cr, 0, &zp, &acl_ids);

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);

        mutex_enter(&zp->z_lock);
        if (zp->z_is_sa)
                error = sa_update(zp->z_sa_hdl, SA_ZPL_SYMLINK(zfsvfs),
                    link, len, tx);
        else
                zfs_sa_symlink(zp, link, len, tx);
        mutex_exit(&zp->z_lock);

        zp->z_size = len;
        (void) sa_update(zp->z_sa_hdl, SA_ZPL_SIZE(zfsvfs),
            &zp->z_size, sizeof (zp->z_size), tx);
        /*
         * Insert the new object into the directory.
         */
        error = zfs_link_create(dl, zp, tx, ZNEW);
        if (error != 0) {
                zfs_znode_delete(zp, tx);
                remove_inode_hash(ZTOI(zp));
        } else {
                if (flags & FIGNORECASE)
                        txtype |= TX_CI;
                zfs_log_symlink(zilog, tx, txtype, dzp, zp, name, link);

                zfs_znode_update_vfs(dzp);
                zfs_znode_update_vfs(zp);
        }

        zfs_acl_ids_free(&acl_ids);

        dmu_tx_commit(tx);

        zfs_dirent_unlock(dl);

        if (error == 0) {
                *zpp = zp;

                if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                        zil_commit(zilog, 0);
        } else {
                zrele(zp);
        }

        zfs_exit(zfsvfs, FTAG);
        return (error);
}

/*
 * Return, in the buffer contained in the provided uio structure,
 * the symbolic path referred to by ip.
 *
 *      IN:     ip      - inode of symbolic link
 *              uio     - structure to contain the link path.
 *              cr      - credentials of caller.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      ip - atime updated
 */
int
zfs_readlink(struct inode *ip, zfs_uio_t *uio, cred_t *cr)
{
        (void) cr;
        znode_t         *zp = ITOZ(ip);
        zfsvfs_t        *zfsvfs = ITOZSB(ip);
        int             error;

        if ((error = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (error);

        mutex_enter(&zp->z_lock);
        if (zp->z_is_sa)
                error = sa_lookup_uio(zp->z_sa_hdl,
                    SA_ZPL_SYMLINK(zfsvfs), uio);
        else
                error = zfs_sa_readlink(zp, uio);
        mutex_exit(&zp->z_lock);

        zfs_exit(zfsvfs, FTAG);
        return (error);
}

/*
 * Insert a new entry into directory tdzp referencing szp.
 *
 *      IN:     tdzp    - Directory to contain new entry.
 *              szp     - znode of new entry.
 *              name    - name of new entry.
 *              cr      - credentials of caller.
 *              flags   - case flags.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      tdzp - ctime|mtime updated
 *       szp - ctime updated
 */
int
zfs_link(znode_t *tdzp, znode_t *szp, char *name, cred_t *cr,
    int flags)
{
        struct inode *sip = ZTOI(szp);
        znode_t         *tzp;
        zfsvfs_t        *zfsvfs = ZTOZSB(tdzp);
        zilog_t         *zilog;
        zfs_dirlock_t   *dl;
        dmu_tx_t        *tx;
        int             error;
        int             zf = ZNEW;
        uint64_t        parent;
        uid_t           owner;
        boolean_t       waited = B_FALSE;
        boolean_t       is_tmpfile = 0;
        uint64_t        txg;
#ifdef HAVE_TMPFILE
        is_tmpfile = (sip->i_nlink == 0 && (sip->i_state & I_LINKABLE));
#endif
        ASSERT(S_ISDIR(ZTOI(tdzp)->i_mode));

        if (name == NULL)
                return (SET_ERROR(EINVAL));

        if ((error = zfs_enter_verify_zp(zfsvfs, tdzp, FTAG)) != 0)
                return (error);
        zilog = zfsvfs->z_log;

        /*
         * POSIX dictates that we return EPERM here.
         * Better choices include ENOTSUP or EISDIR.
         */
        if (S_ISDIR(sip->i_mode)) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EPERM));
        }

        if ((error = zfs_verify_zp(szp)) != 0) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        /*
         * If we are using project inheritance, means if the directory has
         * ZFS_PROJINHERIT set, then its descendant directories will inherit
         * not only the project ID, but also the ZFS_PROJINHERIT flag. Under
         * such case, we only allow hard link creation in our tree when the
         * project IDs are the same.
         */
        if (tdzp->z_pflags & ZFS_PROJINHERIT &&
            tdzp->z_projid != szp->z_projid) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EXDEV));
        }

        /*
         * We check i_sb because snapshots and the ctldir must have different
         * super blocks.
         */
        if (sip->i_sb != ZTOI(tdzp)->i_sb || zfsctl_is_node(sip)) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EXDEV));
        }

        /* Prevent links to .zfs/shares files */

        if ((error = sa_lookup(szp->z_sa_hdl, SA_ZPL_PARENT(zfsvfs),
            &parent, sizeof (uint64_t))) != 0) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }
        if (parent == zfsvfs->z_shares_dir) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EPERM));
        }

        if (zfsvfs->z_utf8 && u8_validate(name,
            strlen(name), NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EILSEQ));
        }
        if (flags & FIGNORECASE)
                zf |= ZCILOOK;

        /*
         * We do not support links between attributes and non-attributes
         * because of the potential security risk of creating links
         * into "normal" file space in order to circumvent restrictions
         * imposed in attribute space.
         */
        if ((szp->z_pflags & ZFS_XATTR) != (tdzp->z_pflags & ZFS_XATTR)) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EINVAL));
        }

        owner = zfs_fuid_map_id(zfsvfs, KUID_TO_SUID(sip->i_uid),
            cr, ZFS_OWNER);
        if (owner != crgetuid(cr) && secpolicy_basic_link(cr) != 0) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EPERM));
        }

        if ((error = zfs_zaccess(tdzp, ACE_ADD_FILE, 0, B_FALSE, cr))) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

top:
        /*
         * Attempt to lock directory; fail if entry already exists.
         */
        error = zfs_dirent_lock(&dl, tdzp, name, &tzp, zf, NULL, NULL);
        if (error) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_sa(tx, szp->z_sa_hdl, B_FALSE);
        dmu_tx_hold_zap(tx, tdzp->z_id, TRUE, name);
        if (is_tmpfile)
                dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);

        zfs_sa_upgrade_txholds(tx, szp);
        zfs_sa_upgrade_txholds(tx, tdzp);
        error = dmu_tx_assign(tx, (waited ? TXG_NOTHROTTLE : 0) | TXG_NOWAIT);
        if (error) {
                zfs_dirent_unlock(dl);
                if (error == ERESTART) {
                        waited = B_TRUE;
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                dmu_tx_abort(tx);
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }
        /* unmark z_unlinked so zfs_link_create will not reject */
        if (is_tmpfile)
                szp->z_unlinked = B_FALSE;
        error = zfs_link_create(dl, szp, tx, 0);

        if (error == 0) {
                uint64_t txtype = TX_LINK;
                /*
                 * tmpfile is created to be in z_unlinkedobj, so remove it.
                 * Also, we don't log in ZIL, because all previous file
                 * operation on the tmpfile are ignored by ZIL. Instead we
                 * always wait for txg to sync to make sure all previous
                 * operation are sync safe.
                 */
                if (is_tmpfile) {
                        VERIFY(zap_remove_int(zfsvfs->z_os,
                            zfsvfs->z_unlinkedobj, szp->z_id, tx) == 0);
                } else {
                        if (flags & FIGNORECASE)
                                txtype |= TX_CI;
                        zfs_log_link(zilog, tx, txtype, tdzp, szp, name);
                }
        } else if (is_tmpfile) {
                /* restore z_unlinked since when linking failed */
                szp->z_unlinked = B_TRUE;
        }
        txg = dmu_tx_get_txg(tx);
        dmu_tx_commit(tx);

        zfs_dirent_unlock(dl);

        if (!is_tmpfile && zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        if (is_tmpfile && zfsvfs->z_os->os_sync != ZFS_SYNC_DISABLED)
                txg_wait_synced(dmu_objset_pool(zfsvfs->z_os), txg);

        zfs_znode_update_vfs(tdzp);
        zfs_znode_update_vfs(szp);
        zfs_exit(zfsvfs, FTAG);
        return (error);
}

static void
zfs_putpage_sync_commit_cb(void *arg)
{
        struct page *pp = arg;

        ClearPageError(pp);
        end_page_writeback(pp);
}

static void
zfs_putpage_async_commit_cb(void *arg)
{
        struct page *pp = arg;
        znode_t *zp = ITOZ(pp->mapping->host);

        ClearPageError(pp);
        end_page_writeback(pp);
        atomic_dec_32(&zp->z_async_writes_cnt);
}

/*
 * Push a page out to disk, once the page is on stable storage the
 * registered commit callback will be run as notification of completion.
 *
 *      IN:     ip       - page mapped for inode.
 *              pp       - page to push (page is locked)
 *              wbc      - writeback control data
 *              for_sync - does the caller intend to wait synchronously for the
 *                         page writeback to complete?
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      ip - ctime|mtime updated
 */
int
zfs_putpage(struct inode *ip, struct page *pp, struct writeback_control *wbc,
    boolean_t for_sync)
{
        znode_t         *zp = ITOZ(ip);
        zfsvfs_t        *zfsvfs = ITOZSB(ip);
        loff_t          offset;
        loff_t          pgoff;
        unsigned int    pglen;
        dmu_tx_t        *tx;
        caddr_t         va;
        int             err = 0;
        uint64_t        mtime[2], ctime[2];
        sa_bulk_attr_t  bulk[3];
        int             cnt = 0;
        struct address_space *mapping;

        if ((err = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (err);

        ASSERT(PageLocked(pp));

        pgoff = page_offset(pp);        /* Page byte-offset in file */
        offset = i_size_read(ip);       /* File length in bytes */
        pglen = MIN(PAGE_SIZE,          /* Page length in bytes */
            P2ROUNDUP(offset, PAGE_SIZE)-pgoff);

        /* Page is beyond end of file */
        if (pgoff >= offset) {
                unlock_page(pp);
                zfs_exit(zfsvfs, FTAG);
                return (0);
        }

        /* Truncate page length to end of file */
        if (pgoff + pglen > offset)
                pglen = offset - pgoff;

#if 0
        /*
         * FIXME: Allow mmap writes past its quota.  The correct fix
         * is to register a page_mkwrite() handler to count the page
         * against its quota when it is about to be dirtied.
         */
        if (zfs_id_overblockquota(zfsvfs, DMU_USERUSED_OBJECT,
            KUID_TO_SUID(ip->i_uid)) ||
            zfs_id_overblockquota(zfsvfs, DMU_GROUPUSED_OBJECT,
            KGID_TO_SGID(ip->i_gid)) ||
            (zp->z_projid != ZFS_DEFAULT_PROJID &&
            zfs_id_overblockquota(zfsvfs, DMU_PROJECTUSED_OBJECT,
            zp->z_projid))) {
                err = EDQUOT;
        }
#endif

        /*
         * The ordering here is critical and must adhere to the following
         * rules in order to avoid deadlocking in either zfs_read() or
         * zfs_free_range() due to a lock inversion.
         *
         * 1) The page must be unlocked prior to acquiring the range lock.
         *    This is critical because zfs_read() calls find_lock_page()
         *    which may block on the page lock while holding the range lock.
         *
         * 2) Before setting or clearing write back on a page the range lock
         *    must be held in order to prevent a lock inversion with the
         *    zfs_free_range() function.
         *
         * This presents a problem because upon entering this function the
         * page lock is already held.  To safely acquire the range lock the
         * page lock must be dropped.  This creates a window where another
         * process could truncate, invalidate, dirty, or write out the page.
         *
         * Therefore, after successfully reacquiring the range and page locks
         * the current page state is checked.  In the common case everything
         * will be as is expected and it can be written out.  However, if
         * the page state has changed it must be handled accordingly.
         */
        mapping = pp->mapping;
        redirty_page_for_writepage(wbc, pp);
        unlock_page(pp);

        zfs_locked_range_t *lr = zfs_rangelock_enter(&zp->z_rangelock,
            pgoff, pglen, RL_WRITER);
        lock_page(pp);

        /* Page mapping changed or it was no longer dirty, we're done */
        if (unlikely((mapping != pp->mapping) || !PageDirty(pp))) {
                unlock_page(pp);
                zfs_rangelock_exit(lr);
                zfs_exit(zfsvfs, FTAG);
                return (0);
        }

        /* Another process started write block if required */
        if (PageWriteback(pp)) {
                unlock_page(pp);
                zfs_rangelock_exit(lr);

                if (wbc->sync_mode != WB_SYNC_NONE) {
                        /*
                         * Speed up any non-sync page writebacks since
                         * they may take several seconds to complete.
                         * Refer to the comment in zpl_fsync() (when
                         * HAVE_FSYNC_RANGE is defined) for details.
                         */
                        if (atomic_load_32(&zp->z_async_writes_cnt) > 0) {
                                zil_commit(zfsvfs->z_log, zp->z_id);
                        }

                        if (PageWriteback(pp))
#ifdef HAVE_PAGEMAP_FOLIO_WAIT_BIT
                                folio_wait_bit(page_folio(pp), PG_writeback);
#else
                                wait_on_page_bit(pp, PG_writeback);
#endif
                }

                zfs_exit(zfsvfs, FTAG);
                return (0);
        }

        /* Clear the dirty flag the required locks are held */
        if (!clear_page_dirty_for_io(pp)) {
                unlock_page(pp);
                zfs_rangelock_exit(lr);
                zfs_exit(zfsvfs, FTAG);
                return (0);
        }

        /*
         * Counterpart for redirty_page_for_writepage() above.  This page
         * was in fact not skipped and should not be counted as if it were.
         */
        wbc->pages_skipped--;
        if (!for_sync)
                atomic_inc_32(&zp->z_async_writes_cnt);
        set_page_writeback(pp);
        unlock_page(pp);

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_write(tx, zp->z_id, pgoff, pglen);
        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        zfs_sa_upgrade_txholds(tx, zp);

        err = dmu_tx_assign(tx, TXG_NOWAIT);
        if (err != 0) {
                if (err == ERESTART)
                        dmu_tx_wait(tx);

                dmu_tx_abort(tx);
#ifdef HAVE_VFS_FILEMAP_DIRTY_FOLIO
                filemap_dirty_folio(page_mapping(pp), page_folio(pp));
#else
                __set_page_dirty_nobuffers(pp);
#endif
                ClearPageError(pp);
                end_page_writeback(pp);
                if (!for_sync)
                        atomic_dec_32(&zp->z_async_writes_cnt);
                zfs_rangelock_exit(lr);
                zfs_exit(zfsvfs, FTAG);
                return (err);
        }

        va = kmap(pp);
        ASSERT3U(pglen, <=, PAGE_SIZE);
        dmu_write(zfsvfs->z_os, zp->z_id, pgoff, pglen, va, tx);
        kunmap(pp);

        SA_ADD_BULK_ATTR(bulk, cnt, SA_ZPL_MTIME(zfsvfs), NULL, &mtime, 16);
        SA_ADD_BULK_ATTR(bulk, cnt, SA_ZPL_CTIME(zfsvfs), NULL, &ctime, 16);
        SA_ADD_BULK_ATTR(bulk, cnt, SA_ZPL_FLAGS(zfsvfs), NULL,
            &zp->z_pflags, 8);

        /* Preserve the mtime and ctime provided by the inode */
        ZFS_TIME_ENCODE(&ip->i_mtime, mtime);
        ZFS_TIME_ENCODE(&ip->i_ctime, ctime);
        zp->z_atime_dirty = B_FALSE;
        zp->z_seq++;

        err = sa_bulk_update(zp->z_sa_hdl, bulk, cnt, tx);

        zfs_log_write(zfsvfs->z_log, tx, TX_WRITE, zp, pgoff, pglen, 0,
            for_sync ? zfs_putpage_sync_commit_cb :
            zfs_putpage_async_commit_cb, pp);

        dmu_tx_commit(tx);

        zfs_rangelock_exit(lr);

        if (wbc->sync_mode != WB_SYNC_NONE) {
                /*
                 * Note that this is rarely called under writepages(), because
                 * writepages() normally handles the entire commit for
                 * performance reasons.
                 */
                zil_commit(zfsvfs->z_log, zp->z_id);
        } else if (!for_sync && atomic_load_32(&zp->z_sync_writes_cnt) > 0) {
                /*
                 * If the caller does not intend to wait synchronously
                 * for this page writeback to complete and there are active
                 * synchronous calls on this file, do a commit so that
                 * the latter don't accidentally end up waiting for
                 * our writeback to complete. Refer to the comment in
                 * zpl_fsync() (when HAVE_FSYNC_RANGE is defined) for details.
                 */
                zil_commit(zfsvfs->z_log, zp->z_id);
        }

        dataset_kstats_update_write_kstats(&zfsvfs->z_kstat, pglen);

        zfs_exit(zfsvfs, FTAG);
        return (err);
}

/*
 * Update the system attributes when the inode has been dirtied.  For the
 * moment we only update the mode, atime, mtime, and ctime.
 */
int
zfs_dirty_inode(struct inode *ip, int flags)
{
        znode_t         *zp = ITOZ(ip);
        zfsvfs_t        *zfsvfs = ITOZSB(ip);
        dmu_tx_t        *tx;
        uint64_t        mode, atime[2], mtime[2], ctime[2];
        sa_bulk_attr_t  bulk[4];
        int             error = 0;
        int             cnt = 0;

        if (zfs_is_readonly(zfsvfs) || dmu_objset_is_snapshot(zfsvfs->z_os))
                return (0);

        if ((error = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (error);

#ifdef I_DIRTY_TIME
        /*
         * This is the lazytime semantic introduced in Linux 4.0
         * This flag will only be called from update_time when lazytime is set.
         * (Note, I_DIRTY_SYNC will also set if not lazytime)
         * Fortunately mtime and ctime are managed within ZFS itself, so we
         * only need to dirty atime.
         */
        if (flags == I_DIRTY_TIME) {
                zp->z_atime_dirty = B_TRUE;
                goto out;
        }
#endif

        tx = dmu_tx_create(zfsvfs->z_os);

        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        zfs_sa_upgrade_txholds(tx, zp);

        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                goto out;
        }

        mutex_enter(&zp->z_lock);
        zp->z_atime_dirty = B_FALSE;

        SA_ADD_BULK_ATTR(bulk, cnt, SA_ZPL_MODE(zfsvfs), NULL, &mode, 8);
        SA_ADD_BULK_ATTR(bulk, cnt, SA_ZPL_ATIME(zfsvfs), NULL, &atime, 16);
        SA_ADD_BULK_ATTR(bulk, cnt, SA_ZPL_MTIME(zfsvfs), NULL, &mtime, 16);
        SA_ADD_BULK_ATTR(bulk, cnt, SA_ZPL_CTIME(zfsvfs), NULL, &ctime, 16);

        /* Preserve the mode, mtime and ctime provided by the inode */
        ZFS_TIME_ENCODE(&ip->i_atime, atime);
        ZFS_TIME_ENCODE(&ip->i_mtime, mtime);
        ZFS_TIME_ENCODE(&ip->i_ctime, ctime);
        mode = ip->i_mode;

        zp->z_mode = mode;

        error = sa_bulk_update(zp->z_sa_hdl, bulk, cnt, tx);
        mutex_exit(&zp->z_lock);

        dmu_tx_commit(tx);
out:
        zfs_exit(zfsvfs, FTAG);
        return (error);
}

void
zfs_inactive(struct inode *ip)
{
        znode_t *zp = ITOZ(ip);
        zfsvfs_t *zfsvfs = ITOZSB(ip);
        uint64_t atime[2];
        int error;
        int need_unlock = 0;

        /* Only read lock if we haven't already write locked, e.g. rollback */
        if (!RW_WRITE_HELD(&zfsvfs->z_teardown_inactive_lock)) {
                need_unlock = 1;
                rw_enter(&zfsvfs->z_teardown_inactive_lock, RW_READER);
        }
        if (zp->z_sa_hdl == NULL) {
                if (need_unlock)
                        rw_exit(&zfsvfs->z_teardown_inactive_lock);
                return;
        }

        if (zp->z_atime_dirty && zp->z_unlinked == B_FALSE) {
                dmu_tx_t *tx = dmu_tx_create(zfsvfs->z_os);

                dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
                zfs_sa_upgrade_txholds(tx, zp);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        dmu_tx_abort(tx);
                } else {
                        ZFS_TIME_ENCODE(&ip->i_atime, atime);
                        mutex_enter(&zp->z_lock);
                        (void) sa_update(zp->z_sa_hdl, SA_ZPL_ATIME(zfsvfs),
                            (void *)&atime, sizeof (atime), tx);
                        zp->z_atime_dirty = B_FALSE;
                        mutex_exit(&zp->z_lock);
                        dmu_tx_commit(tx);
                }
        }

        zfs_zinactive(zp);
        if (need_unlock)
                rw_exit(&zfsvfs->z_teardown_inactive_lock);
}

/*
 * Fill pages with data from the disk.
 */
static int
zfs_fillpage(struct inode *ip, struct page *pl[], int nr_pages)
{
        znode_t *zp = ITOZ(ip);
        zfsvfs_t *zfsvfs = ITOZSB(ip);
        objset_t *os;
        struct page *cur_pp;
        u_offset_t io_off, total;
        size_t io_len;
        loff_t i_size;
        unsigned page_idx;
        int err;

        os = zfsvfs->z_os;
        io_len = nr_pages << PAGE_SHIFT;
        i_size = i_size_read(ip);
        io_off = page_offset(pl[0]);

        if (io_off + io_len > i_size)
                io_len = i_size - io_off;

        /*
         * Iterate over list of pages and read each page individually.
         */
        page_idx = 0;
        for (total = io_off + io_len; io_off < total; io_off += PAGESIZE) {
                caddr_t va;

                cur_pp = pl[page_idx++];
                va = kmap(cur_pp);
                err = dmu_read(os, zp->z_id, io_off, PAGESIZE, va,
                    DMU_READ_PREFETCH);
                kunmap(cur_pp);
                if (err) {
                        /* convert checksum errors into IO errors */
                        if (err == ECKSUM)
                                err = SET_ERROR(EIO);
                        return (err);
                }
        }

        return (0);
}

/*
 * Uses zfs_fillpage to read data from the file and fill the pages.
 *
 *      IN:     ip       - inode of file to get data from.
 *              pl       - list of pages to read
 *              nr_pages - number of pages to read
 *
 *      RETURN: 0 on success, error code on failure.
 *
 * Timestamps:
 *      vp - atime updated
 */
int
zfs_getpage(struct inode *ip, struct page *pl[], int nr_pages)
{
        znode_t  *zp  = ITOZ(ip);
        zfsvfs_t *zfsvfs = ITOZSB(ip);
        int      err;

        if (pl == NULL)
                return (0);

        if ((err = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (err);

        err = zfs_fillpage(ip, pl, nr_pages);

        dataset_kstats_update_read_kstats(&zfsvfs->z_kstat, nr_pages*PAGESIZE);

        zfs_exit(zfsvfs, FTAG);
        return (err);
}

/*
 * Check ZFS specific permissions to memory map a section of a file.
 *
 *      IN:     ip      - inode of the file to mmap
 *              off     - file offset
 *              addrp   - start address in memory region
 *              len     - length of memory region
 *              vm_flags- address flags
 *
 *      RETURN: 0 if success
 *              error code if failure
 */
int
zfs_map(struct inode *ip, offset_t off, caddr_t *addrp, size_t len,
    unsigned long vm_flags)
{
        (void) addrp;
        znode_t  *zp = ITOZ(ip);
        zfsvfs_t *zfsvfs = ITOZSB(ip);
        int error;

        if ((error = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (error);

        if ((vm_flags & VM_WRITE) && (zp->z_pflags &
            (ZFS_IMMUTABLE | ZFS_READONLY | ZFS_APPENDONLY))) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EPERM));
        }

        if ((vm_flags & (VM_READ | VM_EXEC)) &&
            (zp->z_pflags & ZFS_AV_QUARANTINED)) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EACCES));
        }

        if (off < 0 || len > MAXOFFSET_T - off) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(ENXIO));
        }

        zfs_exit(zfsvfs, FTAG);
        return (0);
}

/*
 * Free or allocate space in a file.  Currently, this function only
 * supports the `F_FREESP' command.  However, this command is somewhat
 * misnamed, as its functionality includes the ability to allocate as
 * well as free space.
 *
 *      IN:     zp      - znode of file to free data in.
 *              cmd     - action to take (only F_FREESP supported).
 *              bfp     - section of file to free/alloc.
 *              flag    - current file open mode flags.
 *              offset  - current file offset.
 *              cr      - credentials of caller.
 *
 *      RETURN: 0 on success, error code on failure.
 *
 * Timestamps:
 *      zp - ctime|mtime updated
 */
int
zfs_space(znode_t *zp, int cmd, flock64_t *bfp, int flag,
    offset_t offset, cred_t *cr)
{
        (void) offset;
        zfsvfs_t        *zfsvfs = ZTOZSB(zp);
        uint64_t        off, len;
        int             error;

        if ((error = zfs_enter_verify_zp(zfsvfs, zp, FTAG)) != 0)
                return (error);

        if (cmd != F_FREESP) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EINVAL));
        }

        /*
         * Callers might not be able to detect properly that we are read-only,
         * so check it explicitly here.
         */
        if (zfs_is_readonly(zfsvfs)) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EROFS));
        }

        if (bfp->l_len < 0) {
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(EINVAL));
        }

        /*
         * Permissions aren't checked on Solaris because on this OS
         * zfs_space() can only be called with an opened file handle.
         * On Linux we can get here through truncate_range() which
         * operates directly on inodes, so we need to check access rights.
         */
        if ((error = zfs_zaccess(zp, ACE_WRITE_DATA, 0, B_FALSE, cr))) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        off = bfp->l_start;
        len = bfp->l_len; /* 0 means from off to end of file */

        error = zfs_freesp(zp, off, len, flag, TRUE);

        zfs_exit(zfsvfs, FTAG);
        return (error);
}

int
zfs_fid(struct inode *ip, fid_t *fidp)
{
        znode_t         *zp = ITOZ(ip);
        zfsvfs_t        *zfsvfs = ITOZSB(ip);
        uint32_t        gen;
        uint64_t        gen64;
        uint64_t        object = zp->z_id;
        zfid_short_t    *zfid;
        int             size, i, error;

        if ((error = zfs_enter(zfsvfs, FTAG)) != 0)
                return (error);

        if (fidp->fid_len < SHORT_FID_LEN) {
                fidp->fid_len = SHORT_FID_LEN;
                zfs_exit(zfsvfs, FTAG);
                return (SET_ERROR(ENOSPC));
        }

        if ((error = zfs_verify_zp(zp)) != 0) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        if ((error = sa_lookup(zp->z_sa_hdl, SA_ZPL_GEN(zfsvfs),
            &gen64, sizeof (uint64_t))) != 0) {
                zfs_exit(zfsvfs, FTAG);
                return (error);
        }

        gen = (uint32_t)gen64;

        size = SHORT_FID_LEN;

        zfid = (zfid_short_t *)fidp;

        zfid->zf_len = size;

        for (i = 0; i < sizeof (zfid->zf_object); i++)
                zfid->zf_object[i] = (uint8_t)(object >> (8 * i));

        /* Must have a non-zero generation number to distinguish from .zfs */
        if (gen == 0)
                gen = 1;
        for (i = 0; i < sizeof (zfid->zf_gen); i++)
                zfid->zf_gen[i] = (uint8_t)(gen >> (8 * i));

        zfs_exit(zfsvfs, FTAG);
        return (0);
}

#if defined(_KERNEL)
EXPORT_SYMBOL(zfs_open);
EXPORT_SYMBOL(zfs_close);
EXPORT_SYMBOL(zfs_lookup);
EXPORT_SYMBOL(zfs_create);
EXPORT_SYMBOL(zfs_tmpfile);
EXPORT_SYMBOL(zfs_remove);
EXPORT_SYMBOL(zfs_mkdir);
EXPORT_SYMBOL(zfs_rmdir);
EXPORT_SYMBOL(zfs_readdir);
EXPORT_SYMBOL(zfs_getattr_fast);
EXPORT_SYMBOL(zfs_setattr);
EXPORT_SYMBOL(zfs_rename);
EXPORT_SYMBOL(zfs_symlink);
EXPORT_SYMBOL(zfs_readlink);
EXPORT_SYMBOL(zfs_link);
EXPORT_SYMBOL(zfs_inactive);
EXPORT_SYMBOL(zfs_space);
EXPORT_SYMBOL(zfs_fid);
EXPORT_SYMBOL(zfs_getpage);
EXPORT_SYMBOL(zfs_putpage);
EXPORT_SYMBOL(zfs_dirty_inode);
EXPORT_SYMBOL(zfs_map);

/* CSTYLED */
module_param(zfs_delete_blocks, ulong, 0644);
MODULE_PARM_DESC(zfs_delete_blocks, "Delete files larger than N blocks async");

#endif