Always validate checksums for Direct I/O reads

[zfs.git] / module / os / freebsd / zfs / zfs_dir.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) 2013, 2016 by Delphix. All rights reserved.
 * Copyright 2017 Nexenta Systems, Inc.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/resource.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/kmem.h>
#include <sys/uio.h>
#include <sys/cmn_err.h>
#include <sys/errno.h>
#include <sys/stat.h>
#include <sys/unistd.h>
#include <sys/sunddi.h>
#include <sys/random.h>
#include <sys/policy.h>
#include <sys/condvar.h>
#include <sys/callb.h>
#include <sys/smp.h>
#include <sys/zfs_dir.h>
#include <sys/zfs_acl.h>
#include <sys/fs/zfs.h>
#include <sys/zap.h>
#include <sys/dmu.h>
#include <sys/atomic.h>
#include <sys/zfs_ctldir.h>
#include <sys/zfs_fuid.h>
#include <sys/sa.h>
#include <sys/zfs_sa.h>
#include <sys/dmu_objset.h>
#include <sys/dsl_dir.h>

#include <sys/ccompat.h>

/*
 * zfs_match_find() is used by zfs_dirent_lookup() to perform zap lookups
 * of names after deciding which is the appropriate lookup interface.
 */
static int
zfs_match_find(zfsvfs_t *zfsvfs, znode_t *dzp, const char *name,
    matchtype_t mt, uint64_t *zoid)
{
        int error;

        if (zfsvfs->z_norm) {

                /*
                 * In the non-mixed case we only expect there would ever
                 * be one match, but we need to use the normalizing lookup.
                 */
                error = zap_lookup_norm(zfsvfs->z_os, dzp->z_id, name, 8, 1,
                    zoid, mt, NULL, 0, NULL);
        } else {
                error = zap_lookup(zfsvfs->z_os, dzp->z_id, name, 8, 1, zoid);
        }
        *zoid = ZFS_DIRENT_OBJ(*zoid);

        return (error);
}

/*
 * Look up a directory entry under a locked vnode.
 * dvp being locked gives us a guarantee that there are no concurrent
 * modification of the directory and, thus, if a node can be found in
 * the directory, then it must not be unlinked.
 *
 * Input arguments:
 *      dzp     - znode for directory
 *      name    - name of entry to lock
 *      flag    - ZNEW: if the entry already exists, fail with EEXIST.
 *                ZEXISTS: if the entry does not exist, fail with ENOENT.
 *                ZXATTR: we want dzp's xattr directory
 *
 * Output arguments:
 *      zpp     - pointer to the znode for the entry (NULL if there isn't one)
 *
 * Return value: 0 on success or errno on failure.
 *
 * NOTE: Always checks for, and rejects, '.' and '..'.
 */
int
zfs_dirent_lookup(znode_t *dzp, const char *name, znode_t **zpp, int flag)
{
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        znode_t         *zp;
        matchtype_t     mt = 0;
        uint64_t        zoid;
        int             error = 0;

        if (zfsvfs->z_replay == B_FALSE)
                ASSERT_VOP_LOCKED(ZTOV(dzp), __func__);

        *zpp = NULL;

        /*
         * Verify that we are not trying to lock '.', '..', or '.zfs'
         */
        if (name[0] == '.' &&
            (((name[1] == '\0') || (name[1] == '.' && name[2] == '\0')) ||
            (zfs_has_ctldir(dzp) && strcmp(name, ZFS_CTLDIR_NAME) == 0)))
                return (SET_ERROR(EEXIST));

        /*
         * Case sensitivity and normalization preferences are set when
         * the file system is created.  These are stored in the
         * zfsvfs->z_case and zfsvfs->z_norm fields.  These choices
         * affect how we perform zap lookups.
         *
         * When matching we may need to normalize & change case according to
         * FS settings.
         *
         * Note that a normalized match is necessary for a case insensitive
         * filesystem when the lookup request is not exact because normalization
         * can fold case independent of normalizing code point sequences.
         *
         * See the table above zfs_dropname().
         */
        if (zfsvfs->z_norm != 0) {
                mt = MT_NORMALIZE;

                /*
                 * Determine if the match needs to honor the case specified in
                 * lookup, and if so keep track of that so that during
                 * normalization we don't fold case.
                 */
                if (zfsvfs->z_case == ZFS_CASE_MIXED) {
                        mt |= MT_MATCH_CASE;
                }
        }

        /*
         * Only look in or update the DNLC if we are looking for the
         * name on a file system that does not require normalization
         * or case folding.  We can also look there if we happen to be
         * on a non-normalizing, mixed sensitivity file system IF we
         * are looking for the exact name.
         *
         * NB: we do not need to worry about this flag for ZFS_CASE_SENSITIVE
         * because in that case MT_EXACT and MT_FIRST should produce exactly
         * the same result.
         */

        if (dzp->z_unlinked && !(flag & ZXATTR))
                return (ENOENT);
        if (flag & ZXATTR) {
                error = sa_lookup(dzp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs), &zoid,
                    sizeof (zoid));
                if (error == 0)
                        error = (zoid == 0 ? ENOENT : 0);
        } else {
                error = zfs_match_find(zfsvfs, dzp, name, mt, &zoid);
        }
        if (error) {
                if (error != ENOENT || (flag & ZEXISTS)) {
                        return (error);
                }
        } else {
                if (flag & ZNEW) {
                        return (SET_ERROR(EEXIST));
                }
                error = zfs_zget(zfsvfs, zoid, &zp);
                if (error)
                        return (error);
                ASSERT(!zp->z_unlinked);
                *zpp = zp;
        }

        return (0);
}

static int
zfs_dd_lookup(znode_t *dzp, znode_t **zpp)
{
        zfsvfs_t *zfsvfs = dzp->z_zfsvfs;
        znode_t *zp;
        uint64_t parent;
        int error;

#ifdef ZFS_DEBUG
        if (zfsvfs->z_replay == B_FALSE)
                ASSERT_VOP_LOCKED(ZTOV(dzp), __func__);
#endif
        if (dzp->z_unlinked)
                return (ENOENT);

        if ((error = sa_lookup(dzp->z_sa_hdl,
            SA_ZPL_PARENT(zfsvfs), &parent, sizeof (parent))) != 0)
                return (error);

        error = zfs_zget(zfsvfs, parent, &zp);
        if (error == 0)
                *zpp = zp;
        return (error);
}

int
zfs_dirlook(znode_t *dzp, const char *name, znode_t **zpp)
{
        zfsvfs_t *zfsvfs __unused = dzp->z_zfsvfs;
        znode_t *zp = NULL;
        int error = 0;

#ifdef ZFS_DEBUG
        if (zfsvfs->z_replay == B_FALSE)
                ASSERT_VOP_LOCKED(ZTOV(dzp), __func__);
#endif
        if (dzp->z_unlinked)
                return (SET_ERROR(ENOENT));

        if (name[0] == 0 || (name[0] == '.' && name[1] == 0)) {
                *zpp = dzp;
        } else if (name[0] == '.' && name[1] == '.' && name[2] == 0) {
                error = zfs_dd_lookup(dzp, &zp);
                if (error == 0)
                        *zpp = zp;
        } else {
                error = zfs_dirent_lookup(dzp, name, &zp, ZEXISTS);
                if (error == 0) {
                        dzp->z_zn_prefetch = B_TRUE; /* enable prefetching */
                        *zpp = zp;
                }
        }
        return (error);
}

/*
 * unlinked Set (formerly known as the "delete queue") Error Handling
 *
 * When dealing with the unlinked set, we dmu_tx_hold_zap(), but we
 * don't specify the name of the entry that we will be manipulating.  We
 * also fib and say that we won't be adding any new entries to the
 * unlinked set, even though we might (this is to lower the minimum file
 * size that can be deleted in a full filesystem).  So on the small
 * chance that the nlink list is using a fat zap (ie. has more than
 * 2000 entries), we *may* not pre-read a block that's needed.
 * Therefore it is remotely possible for some of the assertions
 * regarding the unlinked set below to fail due to i/o error.  On a
 * nondebug system, this will result in the space being leaked.
 */
void
zfs_unlinked_add(znode_t *zp, dmu_tx_t *tx)
{
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;

        ASSERT(zp->z_unlinked);
        ASSERT3U(zp->z_links, ==, 0);

        VERIFY0(zap_add_int(zfsvfs->z_os, zfsvfs->z_unlinkedobj, zp->z_id, tx));

        dataset_kstats_update_nunlinks_kstat(&zfsvfs->z_kstat, 1);
}

/*
 * Clean up any znodes that had no links when we either crashed or
 * (force) umounted the file system.
 */
void
zfs_unlinked_drain(zfsvfs_t *zfsvfs)
{
        zap_cursor_t    zc;
        zap_attribute_t *zap;
        dmu_object_info_t doi;
        znode_t         *zp;
        dmu_tx_t        *tx;
        int             error;

        /*
         * Iterate over the contents of the unlinked set.
         */
        zap = zap_attribute_alloc();
        for (zap_cursor_init(&zc, zfsvfs->z_os, zfsvfs->z_unlinkedobj);
            zap_cursor_retrieve(&zc, zap) == 0;
            zap_cursor_advance(&zc)) {

                /*
                 * See what kind of object we have in list
                 */

                error = dmu_object_info(zfsvfs->z_os,
                    zap->za_first_integer, &doi);
                if (error != 0)
                        continue;

                ASSERT((doi.doi_type == DMU_OT_PLAIN_FILE_CONTENTS) ||
                    (doi.doi_type == DMU_OT_DIRECTORY_CONTENTS));
                /*
                 * We need to re-mark these list entries for deletion,
                 * so we pull them back into core and set zp->z_unlinked.
                 */
                error = zfs_zget(zfsvfs, zap->za_first_integer, &zp);

                /*
                 * We may pick up znodes that are already marked for deletion.
                 * This could happen during the purge of an extended attribute
                 * directory.  All we need to do is skip over them, since they
                 * are already in the system marked z_unlinked.
                 */
                if (error != 0)
                        continue;

                vn_lock(ZTOV(zp), LK_EXCLUSIVE | LK_RETRY);

                /*
                 * Due to changes in zfs_rmnode we need to make sure the
                 * link count is set to zero here.
                 */
                if (zp->z_links != 0) {
                        tx = dmu_tx_create(zfsvfs->z_os);
                        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
                        error = dmu_tx_assign(tx, TXG_WAIT);
                        if (error != 0) {
                                dmu_tx_abort(tx);
                                vput(ZTOV(zp));
                                continue;
                        }
                        zp->z_links = 0;
                        VERIFY0(sa_update(zp->z_sa_hdl, SA_ZPL_LINKS(zfsvfs),
                            &zp->z_links, sizeof (zp->z_links), tx));
                        dmu_tx_commit(tx);
                }

                zp->z_unlinked = B_TRUE;
                vput(ZTOV(zp));
        }
        zap_cursor_fini(&zc);
        zap_attribute_free(zap);
}

/*
 * Delete the entire contents of a directory.  Return a count
 * of the number of entries that could not be deleted. If we encounter
 * an error, return a count of at least one so that the directory stays
 * in the unlinked set.
 *
 * NOTE: this function assumes that the directory is inactive,
 *      so there is no need to lock its entries before deletion.
 *      Also, it assumes the directory contents is *only* regular
 *      files.
 */
static int
zfs_purgedir(znode_t *dzp)
{
        zap_cursor_t    zc;
        zap_attribute_t *zap;
        znode_t         *xzp;
        dmu_tx_t        *tx;
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        int skipped = 0;
        int error;

        zap = zap_attribute_alloc();
        for (zap_cursor_init(&zc, zfsvfs->z_os, dzp->z_id);
            (error = zap_cursor_retrieve(&zc, zap)) == 0;
            zap_cursor_advance(&zc)) {
                error = zfs_zget(zfsvfs,
                    ZFS_DIRENT_OBJ(zap->za_first_integer), &xzp);
                if (error) {
                        skipped += 1;
                        continue;
                }

                vn_lock(ZTOV(xzp), LK_EXCLUSIVE | LK_RETRY);
                ASSERT((ZTOV(xzp)->v_type == VREG) ||
                    (ZTOV(xzp)->v_type == VLNK));

                tx = dmu_tx_create(zfsvfs->z_os);
                dmu_tx_hold_sa(tx, dzp->z_sa_hdl, B_FALSE);
                dmu_tx_hold_zap(tx, dzp->z_id, FALSE, zap->za_name);
                dmu_tx_hold_sa(tx, xzp->z_sa_hdl, B_FALSE);
                dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
                /* Is this really needed ? */
                zfs_sa_upgrade_txholds(tx, xzp);
                dmu_tx_mark_netfree(tx);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        dmu_tx_abort(tx);
                        vput(ZTOV(xzp));
                        skipped += 1;
                        continue;
                }

                error = zfs_link_destroy(dzp, zap->za_name, xzp, tx, 0, NULL);
                if (error)
                        skipped += 1;
                dmu_tx_commit(tx);

                vput(ZTOV(xzp));
        }
        zap_cursor_fini(&zc);
        zap_attribute_free(zap);
        if (error != ENOENT)
                skipped += 1;
        return (skipped);
}

extern taskq_t *zfsvfs_taskq;

void
zfs_rmnode(znode_t *zp)
{
        zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
        objset_t        *os = zfsvfs->z_os;
        dmu_tx_t        *tx;
        uint64_t        z_id = zp->z_id;
        uint64_t        acl_obj;
        uint64_t        xattr_obj;
        uint64_t        count;
        int             error;

        ASSERT3U(zp->z_links, ==, 0);
        if (zfsvfs->z_replay == B_FALSE)
                ASSERT_VOP_ELOCKED(ZTOV(zp), __func__);

        /*
         * If this is an attribute directory, purge its contents.
         */
        if (ZTOV(zp) != NULL && ZTOV(zp)->v_type == VDIR &&
            (zp->z_pflags & ZFS_XATTR)) {
                if (zfs_purgedir(zp) != 0) {
                        /*
                         * Not enough space to delete some xattrs.
                         * Leave it in the unlinked set.
                         */
                        ZFS_OBJ_HOLD_ENTER(zfsvfs, z_id);
                        zfs_znode_dmu_fini(zp);
                        zfs_znode_free(zp);
                        ZFS_OBJ_HOLD_EXIT(zfsvfs, z_id);
                        return;
                }
        } else {
                /*
                 * Free up all the data in the file.  We don't do this for
                 * XATTR directories because we need truncate and remove to be
                 * in the same tx, like in zfs_znode_delete(). Otherwise, if
                 * we crash here we'll end up with an inconsistent truncated
                 * zap object in the delete queue.  Note a truncated file is
                 * harmless since it only contains user data.
                 */
                error = dmu_free_long_range(os, zp->z_id, 0, DMU_OBJECT_END);
                if (error) {
                        /*
                         * Not enough space or we were interrupted by unmount.
                         * Leave the file in the unlinked set.
                         */
                        ZFS_OBJ_HOLD_ENTER(zfsvfs, z_id);
                        zfs_znode_dmu_fini(zp);
                        zfs_znode_free(zp);
                        ZFS_OBJ_HOLD_EXIT(zfsvfs, z_id);
                        return;
                }
        }

        /*
         * If the file has extended attributes, we're going to unlink
         * the xattr dir.
         */
        error = sa_lookup(zp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs),
            &xattr_obj, sizeof (xattr_obj));
        if (error)
                xattr_obj = 0;

        acl_obj = zfs_external_acl(zp);

        /*
         * Set up the final transaction.
         */
        tx = dmu_tx_create(os);
        dmu_tx_hold_free(tx, zp->z_id, 0, DMU_OBJECT_END);
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
        if (xattr_obj)
                dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, TRUE, NULL);
        if (acl_obj)
                dmu_tx_hold_free(tx, acl_obj, 0, DMU_OBJECT_END);

        zfs_sa_upgrade_txholds(tx, zp);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                /*
                 * Not enough space to delete the file.  Leave it in the
                 * unlinked set, leaking it until the fs is remounted (at
                 * which point we'll call zfs_unlinked_drain() to process it).
                 */
                dmu_tx_abort(tx);
                ZFS_OBJ_HOLD_ENTER(zfsvfs, z_id);
                zfs_znode_dmu_fini(zp);
                zfs_znode_free(zp);
                ZFS_OBJ_HOLD_EXIT(zfsvfs, z_id);
                return;
        }

        /*
         * FreeBSD's implementation of zfs_zget requires a vnode to back it.
         * This means that we could end up calling into getnewvnode while
         * calling zfs_rmnode as a result of a prior call to getnewvnode
         * trying to clear vnodes out of the cache. If this repeats we can
         * recurse enough that we overflow our stack. To avoid this, we
         * avoid calling zfs_zget on the xattr znode and instead simply add
         * it to the unlinked set and schedule a call to zfs_unlinked_drain.
         */
        if (xattr_obj) {
                /* Add extended attribute directory to the unlinked set. */
                VERIFY3U(0, ==,
                    zap_add_int(os, zfsvfs->z_unlinkedobj, xattr_obj, tx));
        }

        mutex_enter(&os->os_dsl_dataset->ds_dir->dd_activity_lock);

        /* Remove this znode from the unlinked set */
        VERIFY3U(0, ==,
            zap_remove_int(os, zfsvfs->z_unlinkedobj, zp->z_id, tx));

        if (zap_count(os, zfsvfs->z_unlinkedobj, &count) == 0 && count == 0) {
                cv_broadcast(&os->os_dsl_dataset->ds_dir->dd_activity_cv);
        }

        mutex_exit(&os->os_dsl_dataset->ds_dir->dd_activity_lock);

        dataset_kstats_update_nunlinked_kstat(&zfsvfs->z_kstat, 1);

        zfs_znode_delete(zp, tx);
        zfs_znode_free(zp);

        dmu_tx_commit(tx);

        if (xattr_obj) {
                /*
                 * We're using the FreeBSD taskqueue API here instead of
                 * the Solaris taskq API since the FreeBSD API allows for a
                 * task to be enqueued multiple times but executed once.
                 */
                taskqueue_enqueue(zfsvfs_taskq->tq_queue,
                    &zfsvfs->z_unlinked_drain_task);
        }
}

static uint64_t
zfs_dirent(znode_t *zp, uint64_t mode)
{
        uint64_t de = zp->z_id;

        if (zp->z_zfsvfs->z_version >= ZPL_VERSION_DIRENT_TYPE)
                de |= IFTODT(mode) << 60;
        return (de);
}

/*
 * Link zp into dzp.  Can only fail if zp has been unlinked.
 */
int
zfs_link_create(znode_t *dzp, const char *name, znode_t *zp, dmu_tx_t *tx,
    int flag)
{
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        vnode_t *vp = ZTOV(zp);
        uint64_t value;
        int zp_is_dir = (vp->v_type == VDIR);
        sa_bulk_attr_t bulk[5];
        uint64_t mtime[2], ctime[2];
        int count = 0;
        int error;

        if (zfsvfs->z_replay == B_FALSE) {
                ASSERT_VOP_ELOCKED(ZTOV(dzp), __func__);
                ASSERT_VOP_ELOCKED(ZTOV(zp), __func__);
        }
        if (zp_is_dir) {
                if (dzp->z_links >= ZFS_LINK_MAX)
                        return (SET_ERROR(EMLINK));
        }
        if (!(flag & ZRENAMING)) {
                if (zp->z_unlinked) {   /* no new links to unlinked zp */
                        ASSERT(!(flag & (ZNEW | ZEXISTS)));
                        return (SET_ERROR(ENOENT));
                }
                if (zp->z_links >= ZFS_LINK_MAX - zp_is_dir) {
                        return (SET_ERROR(EMLINK));
                }
                zp->z_links++;
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zfsvfs), NULL,
                    &zp->z_links, sizeof (zp->z_links));

        } else {
                ASSERT(!zp->z_unlinked);
        }
        value = zfs_dirent(zp, zp->z_mode);
        error = zap_add(zp->z_zfsvfs->z_os, dzp->z_id, name,
            8, 1, &value, tx);

        /*
         * zap_add could fail to add the entry if it exceeds the capacity of the
         * leaf-block and zap_leaf_split() failed to help.
         * The caller of this routine is responsible for failing the transaction
         * which will rollback the SA updates done above.
         */
        if (error != 0) {
                if (!(flag & ZRENAMING) && !(flag & ZNEW))
                        zp->z_links--;
                return (error);
        }

        /*
         * If we added a longname activate the SPA_FEATURE_LONGNAME.
         */
        if (strlen(name) >= ZAP_MAXNAMELEN) {
                dsl_dataset_t *ds = dmu_objset_ds(zfsvfs->z_os);
                ds->ds_feature_activation[SPA_FEATURE_LONGNAME] =
                    (void *)B_TRUE;
        }

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

        if (!(flag & ZNEW)) {
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
                    ctime, sizeof (ctime));
                zfs_tstamp_update_setup(zp, STATE_CHANGED, mtime,
                    ctime);
        }
        error = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
        ASSERT0(error);

        dzp->z_size++;
        dzp->z_links += zp_is_dir;
        count = 0;
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_SIZE(zfsvfs), NULL,
            &dzp->z_size, sizeof (dzp->z_size));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zfsvfs), NULL,
            &dzp->z_links, sizeof (dzp->z_links));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs), NULL,
            mtime, sizeof (mtime));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
            ctime, sizeof (ctime));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs), NULL,
            &dzp->z_pflags, sizeof (dzp->z_pflags));
        zfs_tstamp_update_setup(dzp, CONTENT_MODIFIED, mtime, ctime);
        error = sa_bulk_update(dzp->z_sa_hdl, bulk, count, tx);
        ASSERT0(error);
        return (0);
}

/*
 * The match type in the code for this function should conform to:
 *
 * ------------------------------------------------------------------------
 * fs type  | z_norm      | lookup type | match type
 * ---------|-------------|-------------|----------------------------------
 * CS !norm | 0           |           0 | 0 (exact)
 * CS  norm | formX       |           0 | MT_NORMALIZE
 * CI !norm | upper       |   !ZCIEXACT | MT_NORMALIZE
 * CI !norm | upper       |    ZCIEXACT | MT_NORMALIZE | MT_MATCH_CASE
 * CI  norm | upper|formX |   !ZCIEXACT | MT_NORMALIZE
 * CI  norm | upper|formX |    ZCIEXACT | MT_NORMALIZE | MT_MATCH_CASE
 * CM !norm | upper       |    !ZCILOOK | MT_NORMALIZE | MT_MATCH_CASE
 * CM !norm | upper       |     ZCILOOK | MT_NORMALIZE
 * CM  norm | upper|formX |    !ZCILOOK | MT_NORMALIZE | MT_MATCH_CASE
 * CM  norm | upper|formX |     ZCILOOK | MT_NORMALIZE
 *
 * Abbreviations:
 *    CS = Case Sensitive, CI = Case Insensitive, CM = Case Mixed
 *    upper = case folding set by fs type on creation (U8_TEXTPREP_TOUPPER)
 *    formX = unicode normalization form set on fs creation
 */
static int
zfs_dropname(znode_t *dzp, const char *name, znode_t *zp, dmu_tx_t *tx,
    int flag)
{
        int error;

        if (zp->z_zfsvfs->z_norm) {
                matchtype_t mt = MT_NORMALIZE;

                if (zp->z_zfsvfs->z_case == ZFS_CASE_MIXED) {
                        mt |= MT_MATCH_CASE;
                }

                error = zap_remove_norm(zp->z_zfsvfs->z_os, dzp->z_id,
                    name, mt, tx);
        } else {
                error = zap_remove(zp->z_zfsvfs->z_os, dzp->z_id, name, tx);
        }

        return (error);
}

/*
 * Unlink zp from dzp, and mark zp for deletion if this was the last link.
 * Can fail if zp is a mount point (EBUSY) or a non-empty directory (EEXIST).
 * If 'unlinkedp' is NULL, we put unlinked znodes on the unlinked list.
 * If it's non-NULL, we use it to indicate whether the znode needs deletion,
 * and it's the caller's job to do it.
 */
int
zfs_link_destroy(znode_t *dzp, const char *name, znode_t *zp, dmu_tx_t *tx,
    int flag, boolean_t *unlinkedp)
{
        zfsvfs_t *zfsvfs = dzp->z_zfsvfs;
        vnode_t *vp = ZTOV(zp);
        int zp_is_dir = (vp->v_type == VDIR);
        boolean_t unlinked = B_FALSE;
        sa_bulk_attr_t bulk[5];
        uint64_t mtime[2], ctime[2];
        int count = 0;
        int error;

        if (zfsvfs->z_replay == B_FALSE) {
                ASSERT_VOP_ELOCKED(ZTOV(dzp), __func__);
                ASSERT_VOP_ELOCKED(ZTOV(zp), __func__);
        }
        if (!(flag & ZRENAMING)) {

                if (zp_is_dir && !zfs_dirempty(zp))
                        return (SET_ERROR(ENOTEMPTY));

                /*
                 * If we get here, we are going to try to remove the object.
                 * First try removing the name from the directory; if that
                 * fails, return the error.
                 */
                error = zfs_dropname(dzp, name, zp, tx, flag);
                if (error != 0) {
                        return (error);
                }

                if (zp->z_links <= zp_is_dir) {
                        zfs_panic_recover("zfs: link count on vnode %p is %u, "
                            "should be at least %u", zp->z_vnode,
                            (int)zp->z_links,
                            zp_is_dir + 1);
                        zp->z_links = zp_is_dir + 1;
                }
                if (--zp->z_links == zp_is_dir) {
                        zp->z_unlinked = B_TRUE;
                        zp->z_links = 0;
                        unlinked = B_TRUE;
                } else {
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs),
                            NULL, &ctime, sizeof (ctime));
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs),
                            NULL, &zp->z_pflags, sizeof (zp->z_pflags));
                        zfs_tstamp_update_setup(zp, STATE_CHANGED, mtime,
                            ctime);
                }
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zfsvfs),
                    NULL, &zp->z_links, sizeof (zp->z_links));
                error = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
                count = 0;
                ASSERT0(error);
        } else {
                ASSERT(!zp->z_unlinked);
                error = zfs_dropname(dzp, name, zp, tx, flag);
                if (error != 0)
                        return (error);
        }

        dzp->z_size--;          /* one dirent removed */
        dzp->z_links -= zp_is_dir;      /* ".." link from zp */
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zfsvfs),
            NULL, &dzp->z_links, sizeof (dzp->z_links));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_SIZE(zfsvfs),
            NULL, &dzp->z_size, sizeof (dzp->z_size));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs),
            NULL, ctime, sizeof (ctime));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs),
            NULL, mtime, sizeof (mtime));
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs),
            NULL, &dzp->z_pflags, sizeof (dzp->z_pflags));
        zfs_tstamp_update_setup(dzp, CONTENT_MODIFIED, mtime, ctime);
        error = sa_bulk_update(dzp->z_sa_hdl, bulk, count, tx);
        ASSERT0(error);

        if (unlinkedp != NULL)
                *unlinkedp = unlinked;
        else if (unlinked)
                zfs_unlinked_add(zp, tx);

        return (0);
}

/*
 * Indicate whether the directory is empty.
 */
boolean_t
zfs_dirempty(znode_t *dzp)
{
        return (dzp->z_size == 2);
}

int
zfs_make_xattrdir(znode_t *zp, vattr_t *vap, znode_t **xvpp, cred_t *cr)
{
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        znode_t *xzp;
        dmu_tx_t *tx;
        int error;
        zfs_acl_ids_t acl_ids;
        boolean_t fuid_dirtied;
        uint64_t parent __maybe_unused;

        *xvpp = NULL;

        if ((error = zfs_acl_ids_create(zp, IS_XATTR, vap, cr, NULL,
            &acl_ids, NULL)) != 0)
                return (error);
        if (zfs_acl_ids_overquota(zfsvfs, &acl_ids, 0)) {
                zfs_acl_ids_free(&acl_ids);
                return (SET_ERROR(EDQUOT));
        }

        getnewvnode_reserve();

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
            ZFS_SA_BASE_ATTR_SIZE);
        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
        dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
        fuid_dirtied = zfsvfs->z_fuid_dirty;
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                zfs_acl_ids_free(&acl_ids);
                dmu_tx_abort(tx);
                getnewvnode_drop_reserve();
                return (error);
        }
        zfs_mknode(zp, vap, tx, cr, IS_XATTR, &xzp, &acl_ids);

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);

        ASSERT0(sa_lookup(xzp->z_sa_hdl, SA_ZPL_PARENT(zfsvfs), &parent,
            sizeof (parent)));
        ASSERT3U(parent, ==, zp->z_id);

        VERIFY0(sa_update(zp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs), &xzp->z_id,
            sizeof (xzp->z_id), tx));

        zfs_log_create(zfsvfs->z_log, tx, TX_MKXATTR, zp, xzp, "", NULL,
            acl_ids.z_fuidp, vap);

        zfs_acl_ids_free(&acl_ids);
        dmu_tx_commit(tx);

        getnewvnode_drop_reserve();

        *xvpp = xzp;

        return (0);
}

/*
 * Return a znode for the extended attribute directory for zp.
 * ** If the directory does not already exist, it is created **
 *
 *      IN:     zp      - znode to obtain attribute directory from
 *              cr      - credentials of caller
 *              flags   - flags from the VOP_LOOKUP call
 *
 *      OUT:    xzpp    - pointer to extended attribute znode
 *
 *      RETURN: 0 on success
 *              error number on failure
 */
int
zfs_get_xattrdir(znode_t *zp, znode_t **xzpp, cred_t *cr, int flags)
{
        zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
        znode_t         *xzp;
        vattr_t         va;
        int             error;
top:
        error = zfs_dirent_lookup(zp, "", &xzp, ZXATTR);
        if (error)
                return (error);

        if (xzp != NULL) {
                *xzpp = xzp;
                return (0);
        }


        if (!(flags & CREATE_XATTR_DIR))
                return (SET_ERROR(ENOATTR));

        if (zfsvfs->z_vfs->vfs_flag & VFS_RDONLY) {
                return (SET_ERROR(EROFS));
        }

        /*
         * The ability to 'create' files in an attribute
         * directory comes from the write_xattr permission on the base file.
         *
         * The ability to 'search' an attribute directory requires
         * read_xattr permission on the base file.
         *
         * Once in a directory the ability to read/write attributes
         * is controlled by the permissions on the attribute file.
         */
        va.va_mask = AT_MODE | AT_UID | AT_GID;
        va.va_type = VDIR;
        va.va_mode = S_IFDIR | S_ISVTX | 0777;
        zfs_fuid_map_ids(zp, cr, &va.va_uid, &va.va_gid);

        error = zfs_make_xattrdir(zp, &va, xzpp, cr);

        if (error == ERESTART) {
                /* NB: we already did dmu_tx_wait() if necessary */
                goto top;
        }
        if (error == 0)
                VOP_UNLOCK(ZTOV(*xzpp));

        return (error);
}

/*
 * Decide whether it is okay to remove within a sticky directory.
 *
 * In sticky directories, write access is not sufficient;
 * you can remove entries from a directory only if:
 *
 *      you own the directory,
 *      you own the entry,
 *      the entry is a plain file and you have write access,
 *      or you are privileged (checked in secpolicy...).
 *
 * The function returns 0 if remove access is granted.
 */
int
zfs_sticky_remove_access(znode_t *zdp, znode_t *zp, cred_t *cr)
{
        uid_t           uid;
        uid_t           downer;
        uid_t           fowner;
        zfsvfs_t        *zfsvfs = zdp->z_zfsvfs;

        if (zdp->z_zfsvfs->z_replay)
                return (0);

        if ((zdp->z_mode & S_ISVTX) == 0)
                return (0);

        downer = zfs_fuid_map_id(zfsvfs, zdp->z_uid, cr, ZFS_OWNER);
        fowner = zfs_fuid_map_id(zfsvfs, zp->z_uid, cr, ZFS_OWNER);

        if ((uid = crgetuid(cr)) == downer || uid == fowner ||
            (ZTOV(zp)->v_type == VREG &&
            zfs_zaccess(zp, ACE_WRITE_DATA, 0, B_FALSE, cr, NULL) == 0))
                return (0);
        else
                return (secpolicy_vnode_remove(ZTOV(zp), cr));
}