Expand PMF_FN_* macros.

[netbsd-mini2440.git] / sys / fs / tmpfs / tmpfs_subr.c

/*      $NetBSD: tmpfs_subr.c,v 1.55 2009/09/03 11:22:05 pooka Exp $    */

/*
 * Copyright (c) 2005, 2006, 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Julio M. Merino Vidal, developed as part of Google's Summer of Code
 * 2005 program.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Efficient memory file system supporting functions.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: tmpfs_subr.c,v 1.55 2009/09/03 11:22:05 pooka Exp $");

#include <sys/param.h>
#include <sys/dirent.h>
#include <sys/event.h>
#include <sys/kmem.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/systm.h>
#include <sys/swap.h>
#include <sys/vnode.h>
#include <sys/kauth.h>
#include <sys/proc.h>
#include <sys/atomic.h>

#include <uvm/uvm.h>

#include <miscfs/specfs/specdev.h>
#include <miscfs/genfs/genfs.h>
#include <fs/tmpfs/tmpfs.h>
#include <fs/tmpfs/tmpfs_fifoops.h>
#include <fs/tmpfs/tmpfs_specops.h>
#include <fs/tmpfs/tmpfs_vnops.h>

/* --------------------------------------------------------------------- */

/*
 * Allocates a new node of type 'type' inside the 'tmp' mount point, with
 * its owner set to 'uid', its group to 'gid' and its mode set to 'mode',
 * using the credentials of the process 'p'.
 *
 * If the node type is set to 'VDIR', then the parent parameter must point
 * to the parent directory of the node being created.  It may only be NULL
 * while allocating the root node.
 *
 * If the node type is set to 'VBLK' or 'VCHR', then the rdev parameter
 * specifies the device the node represents.
 *
 * If the node type is set to 'VLNK', then the parameter target specifies
 * the file name of the target file for the symbolic link that is being
 * created.
 *
 * Note that new nodes are retrieved from the available list if it has
 * items or, if it is empty, from the node pool as long as there is enough
 * space to create them.
 *
 * Returns zero on success or an appropriate error code on failure.
 */
int
tmpfs_alloc_node(struct tmpfs_mount *tmp, enum vtype type,
    uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *parent,
    char *target, dev_t rdev, struct tmpfs_node **node)
{
        struct tmpfs_node *nnode;

        /* If the root directory of the 'tmp' file system is not yet
         * allocated, this must be the request to do it. */
        KASSERT(IMPLIES(tmp->tm_root == NULL, parent == NULL && type == VDIR));

        KASSERT(IFF(type == VLNK, target != NULL));
        KASSERT(IFF(type == VBLK || type == VCHR, rdev != VNOVAL));

        KASSERT(uid != VNOVAL && gid != VNOVAL && mode != VNOVAL);

        nnode = NULL;
        if (atomic_inc_uint_nv(&tmp->tm_nodes_cnt) >= tmp->tm_nodes_max) {
                atomic_dec_uint(&tmp->tm_nodes_cnt);
                return ENOSPC;
        }

        nnode = (struct tmpfs_node *)TMPFS_POOL_GET(&tmp->tm_node_pool, 0);
        if (nnode == NULL) {
                atomic_dec_uint(&tmp->tm_nodes_cnt);
                return ENOSPC;
        }

        /*
         * XXX Where the pool is backed by a map larger than (4GB *
         * sizeof(*nnode)), this may produce duplicate inode numbers
         * for applications that do not understand 64-bit ino_t.
         */
        nnode->tn_id = (ino_t)((uintptr_t)nnode / sizeof(*nnode));
        nnode->tn_gen = arc4random();

        /* Generic initialization. */
        nnode->tn_type = type;
        nnode->tn_size = 0;
        nnode->tn_status = 0;
        nnode->tn_flags = 0;
        nnode->tn_links = 0;

        vfs_timestamp(&nnode->tn_atime);
        nnode->tn_birthtime = nnode->tn_atime;
        nnode->tn_ctime = nnode->tn_atime;
        nnode->tn_mtime = nnode->tn_atime;

        nnode->tn_uid = uid;
        nnode->tn_gid = gid;
        nnode->tn_mode = mode;
        nnode->tn_lockf = NULL;
        nnode->tn_vnode = NULL;

        /* Type-specific initialization. */
        switch (nnode->tn_type) {
        case VBLK:
        case VCHR:
                nnode->tn_spec.tn_dev.tn_rdev = rdev;
                break;

        case VDIR:
                TAILQ_INIT(&nnode->tn_spec.tn_dir.tn_dir);
                nnode->tn_spec.tn_dir.tn_parent =
                    (parent == NULL) ? nnode : parent;
                nnode->tn_spec.tn_dir.tn_readdir_lastn = 0;
                nnode->tn_spec.tn_dir.tn_readdir_lastp = NULL;
                nnode->tn_links++;
                break;

        case VFIFO:
                /* FALLTHROUGH */
        case VSOCK:
                break;

        case VLNK:
                KASSERT(strlen(target) < MAXPATHLEN);
                nnode->tn_size = strlen(target);
                nnode->tn_spec.tn_lnk.tn_link =
                    tmpfs_str_pool_get(&tmp->tm_str_pool, nnode->tn_size, 0);
                if (nnode->tn_spec.tn_lnk.tn_link == NULL) {
                        atomic_dec_uint(&tmp->tm_nodes_cnt);
                        TMPFS_POOL_PUT(&tmp->tm_node_pool, nnode);
                        return ENOSPC;
                }
                memcpy(nnode->tn_spec.tn_lnk.tn_link, target, nnode->tn_size);
                break;

        case VREG:
                nnode->tn_spec.tn_reg.tn_aobj =
                    uao_create(INT32_MAX - PAGE_SIZE, 0);
                nnode->tn_spec.tn_reg.tn_aobj_pages = 0;
                break;

        default:
                KASSERT(0);
        }

        mutex_init(&nnode->tn_vlock, MUTEX_DEFAULT, IPL_NONE);

        mutex_enter(&tmp->tm_lock);
        LIST_INSERT_HEAD(&tmp->tm_nodes, nnode, tn_entries);
        mutex_exit(&tmp->tm_lock);

        *node = nnode;
        return 0;
}

/* --------------------------------------------------------------------- */

/*
 * Destroys the node pointed to by node from the file system 'tmp'.
 * If the node does not belong to the given mount point, the results are
 * unpredicted.
 *
 * If the node references a directory; no entries are allowed because
 * their removal could need a recursive algorithm, something forbidden in
 * kernel space.  Furthermore, there is not need to provide such
 * functionality (recursive removal) because the only primitives offered
 * to the user are the removal of empty directories and the deletion of
 * individual files.
 *
 * Note that nodes are not really deleted; in fact, when a node has been
 * allocated, it cannot be deleted during the whole life of the file
 * system.  Instead, they are moved to the available list and remain there
 * until reused.
 */
void
tmpfs_free_node(struct tmpfs_mount *tmp, struct tmpfs_node *node)
{

        if (node->tn_type == VREG) {
                atomic_add_int(&tmp->tm_pages_used,
                    -node->tn_spec.tn_reg.tn_aobj_pages);
        }
        atomic_dec_uint(&tmp->tm_nodes_cnt);
        mutex_enter(&tmp->tm_lock);
        LIST_REMOVE(node, tn_entries);
        mutex_exit(&tmp->tm_lock);

        switch (node->tn_type) {
        case VLNK:
                tmpfs_str_pool_put(&tmp->tm_str_pool,
                    node->tn_spec.tn_lnk.tn_link, node->tn_size);
                break;

        case VREG:
                if (node->tn_spec.tn_reg.tn_aobj != NULL)
                        uao_detach(node->tn_spec.tn_reg.tn_aobj);
                break;

        default:
                break;
        }

        mutex_destroy(&node->tn_vlock);
        TMPFS_POOL_PUT(&tmp->tm_node_pool, node);
}

/* --------------------------------------------------------------------- */

/*
 * Allocates a new directory entry for the node node with a name of name.
 * The new directory entry is returned in *de.
 *
 * The link count of node is increased by one to reflect the new object
 * referencing it.  This takes care of notifying kqueue listeners about
 * this change.
 *
 * Returns zero on success or an appropriate error code on failure.
 */
int
tmpfs_alloc_dirent(struct tmpfs_mount *tmp, struct tmpfs_node *node,
    const char *name, uint16_t len, struct tmpfs_dirent **de)
{
        struct tmpfs_dirent *nde;

        nde = (struct tmpfs_dirent *)TMPFS_POOL_GET(&tmp->tm_dirent_pool, 0);
        if (nde == NULL)
                return ENOSPC;

        nde->td_name = tmpfs_str_pool_get(&tmp->tm_str_pool, len, 0);
        if (nde->td_name == NULL) {
                TMPFS_POOL_PUT(&tmp->tm_dirent_pool, nde);
                return ENOSPC;
        }
        nde->td_namelen = len;
        memcpy(nde->td_name, name, len);
        nde->td_node = node;

        node->tn_links++;
        if (node->tn_links > 1 && node->tn_vnode != NULL)
                VN_KNOTE(node->tn_vnode, NOTE_LINK);
        *de = nde;

        return 0;
}

/* --------------------------------------------------------------------- */

/*
 * Frees a directory entry.  It is the caller's responsibility to destroy
 * the node referenced by it if needed.
 *
 * The link count of node is decreased by one to reflect the removal of an
 * object that referenced it.  This only happens if 'node_exists' is true;
 * otherwise the function will not access the node referred to by the
 * directory entry, as it may already have been released from the outside.
 *
 * Interested parties (kqueue) are notified of the link count change; note
 * that this can include both the node pointed to by the directory entry
 * as well as its parent.
 */
void
tmpfs_free_dirent(struct tmpfs_mount *tmp, struct tmpfs_dirent *de,
    bool node_exists)
{
        if (node_exists) {
                struct tmpfs_node *node;

                node = de->td_node;

                KASSERT(node->tn_links > 0);
                node->tn_links--;
                if (node->tn_vnode != NULL)
                        VN_KNOTE(node->tn_vnode, node->tn_links == 0 ?
                            NOTE_DELETE : NOTE_LINK);
                if (node->tn_type == VDIR)
                        VN_KNOTE(node->tn_spec.tn_dir.tn_parent->tn_vnode,
                            NOTE_LINK);
        }

        tmpfs_str_pool_put(&tmp->tm_str_pool, de->td_name, de->td_namelen);
        TMPFS_POOL_PUT(&tmp->tm_dirent_pool, de);
}

/* --------------------------------------------------------------------- */

/*
 * Allocates a new vnode for the node node or returns a new reference to
 * an existing one if the node had already a vnode referencing it.  The
 * resulting locked vnode is returned in *vpp.
 *
 * Returns zero on success or an appropriate error code on failure.
 */
int
tmpfs_alloc_vp(struct mount *mp, struct tmpfs_node *node, struct vnode **vpp)
{
        int error;
        struct vnode *vp;

        /* If there is already a vnode, then lock it. */
        for (;;) {
                mutex_enter(&node->tn_vlock);
                if ((vp = node->tn_vnode) != NULL) {
                        mutex_enter(&vp->v_interlock);
                        mutex_exit(&node->tn_vlock);
                        error = vget(vp, LK_EXCLUSIVE | LK_INTERLOCK);
                        if (error == ENOENT) {
                                /* vnode was reclaimed. */
                                continue;
                        }
                        *vpp = vp;
                        return error;
                }
                break;
        }

        /* Get a new vnode and associate it with our node. */
        error = getnewvnode(VT_TMPFS, mp, tmpfs_vnodeop_p, &vp);
        if (error != 0) {
                mutex_exit(&node->tn_vlock);
                return error;
        }

        error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        if (error != 0) {
                mutex_exit(&node->tn_vlock);
                ungetnewvnode(vp);
                return error;
        }

        vp->v_type = node->tn_type;

        /* Type-specific initialization. */
        switch (node->tn_type) {
        case VBLK:
                /* FALLTHROUGH */
        case VCHR:
                vp->v_op = tmpfs_specop_p;
                spec_node_init(vp, node->tn_spec.tn_dev.tn_rdev);
                break;

        case VDIR:
                vp->v_vflag |= node->tn_spec.tn_dir.tn_parent == node ?
                    VV_ROOT : 0;
                break;

        case VFIFO:
                vp->v_op = tmpfs_fifoop_p;
                break;

        case VLNK:
                /* FALLTHROUGH */
        case VREG:
                /* FALLTHROUGH */
        case VSOCK:
                break;

        default:
                KASSERT(0);
        }

        uvm_vnp_setsize(vp, node->tn_size);
        vp->v_data = node;
        node->tn_vnode = vp;
        mutex_exit(&node->tn_vlock);
        *vpp = vp;

        KASSERT(IFF(error == 0, *vpp != NULL && VOP_ISLOCKED(*vpp)));
        KASSERT(*vpp == node->tn_vnode);

        return error;
}

/* --------------------------------------------------------------------- */

/*
 * Destroys the association between the vnode vp and the node it
 * references.
 */
void
tmpfs_free_vp(struct vnode *vp)
{
        struct tmpfs_node *node;

        node = VP_TO_TMPFS_NODE(vp);

        mutex_enter(&node->tn_vlock);
        node->tn_vnode = NULL;
        mutex_exit(&node->tn_vlock);
        vp->v_data = NULL;
}

/* --------------------------------------------------------------------- */

/*
 * Allocates a new file of type 'type' and adds it to the parent directory
 * 'dvp'; this addition is done using the component name given in 'cnp'.
 * The ownership of the new file is automatically assigned based on the
 * credentials of the caller (through 'cnp'), the group is set based on
 * the parent directory and the mode is determined from the 'vap' argument.
 * If successful, *vpp holds a vnode to the newly created file and zero
 * is returned.  Otherwise *vpp is NULL and the function returns an
 * appropriate error code.
 */
int
tmpfs_alloc_file(struct vnode *dvp, struct vnode **vpp, struct vattr *vap,
    struct componentname *cnp, char *target)
{
        int error;
        struct tmpfs_dirent *de;
        struct tmpfs_mount *tmp;
        struct tmpfs_node *dnode;
        struct tmpfs_node *node;
        struct tmpfs_node *parent;

        KASSERT(VOP_ISLOCKED(dvp));
        KASSERT(cnp->cn_flags & HASBUF);

        tmp = VFS_TO_TMPFS(dvp->v_mount);
        dnode = VP_TO_TMPFS_DIR(dvp);
        *vpp = NULL;

        /* If the entry we are creating is a directory, we cannot overflow
         * the number of links of its parent, because it will get a new
         * link. */
        if (vap->va_type == VDIR) {
                /* Ensure that we do not overflow the maximum number of links
                 * imposed by the system. */
                KASSERT(dnode->tn_links <= LINK_MAX);
                if (dnode->tn_links == LINK_MAX) {
                        error = EMLINK;
                        goto out;
                }

                parent = dnode;
        } else
                parent = NULL;

        /* Allocate a node that represents the new file. */
        error = tmpfs_alloc_node(tmp, vap->va_type, kauth_cred_geteuid(cnp->cn_cred),
            dnode->tn_gid, vap->va_mode, parent, target, vap->va_rdev, &node);
        if (error != 0)
                goto out;

        /* Allocate a directory entry that points to the new file. */
        error = tmpfs_alloc_dirent(tmp, node, cnp->cn_nameptr, cnp->cn_namelen,
            &de);
        if (error != 0) {
                tmpfs_free_node(tmp, node);
                goto out;
        }

        /* Allocate a vnode for the new file. */
        error = tmpfs_alloc_vp(dvp->v_mount, node, vpp);
        if (error != 0) {
                tmpfs_free_dirent(tmp, de, true);
                tmpfs_free_node(tmp, node);
                goto out;
        }

        /* Now that all required items are allocated, we can proceed to
         * insert the new node into the directory, an operation that
         * cannot fail. */
        tmpfs_dir_attach(dvp, de);
        if (vap->va_type == VDIR) {
                VN_KNOTE(dvp, NOTE_LINK);
                dnode->tn_links++;
                KASSERT(dnode->tn_links <= LINK_MAX);
        }

out:
        if (error != 0 || !(cnp->cn_flags & SAVESTART))
                PNBUF_PUT(cnp->cn_pnbuf);
        vput(dvp);

        KASSERT(IFF(error == 0, *vpp != NULL));

        return error;
}

/* --------------------------------------------------------------------- */

/*
 * Attaches the directory entry de to the directory represented by vp.
 * Note that this does not change the link count of the node pointed by
 * the directory entry, as this is done by tmpfs_alloc_dirent.
 *
 * As the "parent" directory changes, interested parties are notified of
 * a write to it.
 */
void
tmpfs_dir_attach(struct vnode *vp, struct tmpfs_dirent *de)
{
        struct tmpfs_node *dnode;

        dnode = VP_TO_TMPFS_DIR(vp);

        TAILQ_INSERT_TAIL(&dnode->tn_spec.tn_dir.tn_dir, de, td_entries);
        dnode->tn_size += sizeof(struct tmpfs_dirent);
        dnode->tn_status |= TMPFS_NODE_ACCESSED | TMPFS_NODE_CHANGED | \
            TMPFS_NODE_MODIFIED;
        uvm_vnp_setsize(vp, dnode->tn_size);

        VN_KNOTE(vp, NOTE_WRITE);
}

/* --------------------------------------------------------------------- */

/*
 * Detaches the directory entry de from the directory represented by vp.
 * Note that this does not change the link count of the node pointed by
 * the directory entry, as this is done by tmpfs_free_dirent.
 *
 * As the "parent" directory changes, interested parties are notified of
 * a write to it.
 */
void
tmpfs_dir_detach(struct vnode *vp, struct tmpfs_dirent *de)
{
        struct tmpfs_node *dnode;

        KASSERT(VOP_ISLOCKED(vp));

        dnode = VP_TO_TMPFS_DIR(vp);

        if (dnode->tn_spec.tn_dir.tn_readdir_lastp == de) {
                dnode->tn_spec.tn_dir.tn_readdir_lastn = 0;
                dnode->tn_spec.tn_dir.tn_readdir_lastp = NULL;
        }

        TAILQ_REMOVE(&dnode->tn_spec.tn_dir.tn_dir, de, td_entries);
        dnode->tn_size -= sizeof(struct tmpfs_dirent);
        dnode->tn_status |= TMPFS_NODE_ACCESSED | TMPFS_NODE_CHANGED | \
            TMPFS_NODE_MODIFIED;
        uvm_vnp_setsize(vp, dnode->tn_size);

        VN_KNOTE(vp, NOTE_WRITE);
}

/* --------------------------------------------------------------------- */

/*
 * Looks for a directory entry in the directory represented by node.
 * 'cnp' describes the name of the entry to look for.  Note that the .
 * and .. components are not allowed as they do not physically exist
 * within directories.
 *
 * Returns a pointer to the entry when found, otherwise NULL.
 */
struct tmpfs_dirent *
tmpfs_dir_lookup(struct tmpfs_node *node, struct componentname *cnp)
{
        struct tmpfs_dirent *de;

        KASSERT(VOP_ISLOCKED(node->tn_vnode));
        KASSERT(IMPLIES(cnp->cn_namelen == 1, cnp->cn_nameptr[0] != '.'));
        KASSERT(IMPLIES(cnp->cn_namelen == 2, !(cnp->cn_nameptr[0] == '.' &&
            cnp->cn_nameptr[1] == '.')));
        TMPFS_VALIDATE_DIR(node);

        node->tn_status |= TMPFS_NODE_ACCESSED;

        TAILQ_FOREACH(de, &node->tn_spec.tn_dir.tn_dir, td_entries) {
                KASSERT(cnp->cn_namelen < 0xffff);
                if (de->td_namelen == (uint16_t)cnp->cn_namelen &&
                    memcmp(de->td_name, cnp->cn_nameptr, de->td_namelen) == 0) {
                        break;
                }
        }

        return de;
}

/* --------------------------------------------------------------------- */

/*
 * Helper function for tmpfs_readdir.  Creates a '.' entry for the given
 * directory and returns it in the uio space.  The function returns 0
 * on success, -1 if there was not enough space in the uio structure to
 * hold the directory entry or an appropriate error code if another
 * error happens.
 */
int
tmpfs_dir_getdotdent(struct tmpfs_node *node, struct uio *uio)
{
        int error;
        struct dirent *dentp;

        TMPFS_VALIDATE_DIR(node);
        KASSERT(uio->uio_offset == TMPFS_DIRCOOKIE_DOT);

        dentp = kmem_alloc(sizeof(struct dirent), KM_SLEEP);

        dentp->d_fileno = node->tn_id;
        dentp->d_type = DT_DIR;
        dentp->d_namlen = 1;
        dentp->d_name[0] = '.';
        dentp->d_name[1] = '\0';
        dentp->d_reclen = _DIRENT_SIZE(dentp);

        if (dentp->d_reclen > uio->uio_resid)
                error = -1;
        else {
                error = uiomove(dentp, dentp->d_reclen, uio);
                if (error == 0)
                        uio->uio_offset = TMPFS_DIRCOOKIE_DOTDOT;
        }

        node->tn_status |= TMPFS_NODE_ACCESSED;

        kmem_free(dentp, sizeof(struct dirent));
        return error;
}

/* --------------------------------------------------------------------- */

/*
 * Helper function for tmpfs_readdir.  Creates a '..' entry for the given
 * directory and returns it in the uio space.  The function returns 0
 * on success, -1 if there was not enough space in the uio structure to
 * hold the directory entry or an appropriate error code if another
 * error happens.
 */
int
tmpfs_dir_getdotdotdent(struct tmpfs_node *node, struct uio *uio)
{
        int error;
        struct dirent *dentp;

        TMPFS_VALIDATE_DIR(node);
        KASSERT(uio->uio_offset == TMPFS_DIRCOOKIE_DOTDOT);

        dentp = kmem_alloc(sizeof(struct dirent), KM_SLEEP);

        dentp->d_fileno = node->tn_spec.tn_dir.tn_parent->tn_id;
        dentp->d_type = DT_DIR;
        dentp->d_namlen = 2;
        dentp->d_name[0] = '.';
        dentp->d_name[1] = '.';
        dentp->d_name[2] = '\0';
        dentp->d_reclen = _DIRENT_SIZE(dentp);

        if (dentp->d_reclen > uio->uio_resid)
                error = -1;
        else {
                error = uiomove(dentp, dentp->d_reclen, uio);
                if (error == 0) {
                        struct tmpfs_dirent *de;

                        de = TAILQ_FIRST(&node->tn_spec.tn_dir.tn_dir);
                        if (de == NULL)
                                uio->uio_offset = TMPFS_DIRCOOKIE_EOF;
                        else
                                uio->uio_offset = tmpfs_dircookie(de);
                }
        }

        node->tn_status |= TMPFS_NODE_ACCESSED;

        kmem_free(dentp, sizeof(struct dirent));
        return error;
}

/* --------------------------------------------------------------------- */

/*
 * Lookup a directory entry by its associated cookie.
 */
struct tmpfs_dirent *
tmpfs_dir_lookupbycookie(struct tmpfs_node *node, off_t cookie)
{
        struct tmpfs_dirent *de;

        KASSERT(VOP_ISLOCKED(node->tn_vnode));

        if (cookie == node->tn_spec.tn_dir.tn_readdir_lastn &&
            node->tn_spec.tn_dir.tn_readdir_lastp != NULL) {
                return node->tn_spec.tn_dir.tn_readdir_lastp;
        }

        TAILQ_FOREACH(de, &node->tn_spec.tn_dir.tn_dir, td_entries) {
                if (tmpfs_dircookie(de) == cookie) {
                        break;
                }
        }

        return de;
}

/* --------------------------------------------------------------------- */

/*
 * Helper function for tmpfs_readdir.  Returns as much directory entries
 * as can fit in the uio space.  The read starts at uio->uio_offset.
 * The function returns 0 on success, -1 if there was not enough space
 * in the uio structure to hold the directory entry or an appropriate
 * error code if another error happens.
 */
int
tmpfs_dir_getdents(struct tmpfs_node *node, struct uio *uio, off_t *cntp)
{
        int error;
        off_t startcookie;
        struct dirent *dentp;
        struct tmpfs_dirent *de;

        KASSERT(VOP_ISLOCKED(node->tn_vnode));
        TMPFS_VALIDATE_DIR(node);

        /* Locate the first directory entry we have to return.  We have cached
         * the last readdir in the node, so use those values if appropriate.
         * Otherwise do a linear scan to find the requested entry. */
        startcookie = uio->uio_offset;
        KASSERT(startcookie != TMPFS_DIRCOOKIE_DOT);
        KASSERT(startcookie != TMPFS_DIRCOOKIE_DOTDOT);
        if (startcookie == TMPFS_DIRCOOKIE_EOF) {
                return 0;
        } else {
                de = tmpfs_dir_lookupbycookie(node, startcookie);
        }
        if (de == NULL) {
                return EINVAL;
        }

        dentp = kmem_alloc(sizeof(struct dirent), KM_SLEEP);

        /* Read as much entries as possible; i.e., until we reach the end of
         * the directory or we exhaust uio space. */
        do {
                /* Create a dirent structure representing the current
                 * tmpfs_node and fill it. */
                dentp->d_fileno = de->td_node->tn_id;
                switch (de->td_node->tn_type) {
                case VBLK:
                        dentp->d_type = DT_BLK;
                        break;

                case VCHR:
                        dentp->d_type = DT_CHR;
                        break;

                case VDIR:
                        dentp->d_type = DT_DIR;
                        break;

                case VFIFO:
                        dentp->d_type = DT_FIFO;
                        break;

                case VLNK:
                        dentp->d_type = DT_LNK;
                        break;

                case VREG:
                        dentp->d_type = DT_REG;
                        break;

                case VSOCK:
                        dentp->d_type = DT_SOCK;
                        break;

                default:
                        KASSERT(0);
                }
                dentp->d_namlen = de->td_namelen;
                KASSERT(de->td_namelen < sizeof(dentp->d_name));
                (void)memcpy(dentp->d_name, de->td_name, de->td_namelen);
                dentp->d_name[de->td_namelen] = '\0';
                dentp->d_reclen = _DIRENT_SIZE(dentp);

                /* Stop reading if the directory entry we are treating is
                 * bigger than the amount of data that can be returned. */
                if (dentp->d_reclen > uio->uio_resid) {
                        error = -1;
                        break;
                }

                /* Copy the new dirent structure into the output buffer and
                 * advance pointers. */
                error = uiomove(dentp, dentp->d_reclen, uio);

                (*cntp)++;
                de = TAILQ_NEXT(de, td_entries);
        } while (error == 0 && uio->uio_resid > 0 && de != NULL);

        /* Update the offset and cache. */
        if (de == NULL) {
                uio->uio_offset = TMPFS_DIRCOOKIE_EOF;
                node->tn_spec.tn_dir.tn_readdir_lastn = 0;
                node->tn_spec.tn_dir.tn_readdir_lastp = NULL;
        } else {
                node->tn_spec.tn_dir.tn_readdir_lastn = uio->uio_offset =
                    tmpfs_dircookie(de);
                node->tn_spec.tn_dir.tn_readdir_lastp = de;
        }

        node->tn_status |= TMPFS_NODE_ACCESSED;

        kmem_free(dentp, sizeof(struct dirent));
        return error;
}

/* --------------------------------------------------------------------- */

/*
 * Resizes the aobj associated to the regular file pointed to by vp to
 * the size newsize.  'vp' must point to a vnode that represents a regular
 * file.  'newsize' must be positive.
 *
 * If the file is extended, the appropriate kevent is raised.  This does
 * not rise a write event though because resizing is not the same as
 * writing.
 *
 * Returns zero on success or an appropriate error code on failure.
 */
int
tmpfs_reg_resize(struct vnode *vp, off_t newsize)
{
        int error;
        unsigned int newpages, oldpages;
        struct tmpfs_mount *tmp;
        struct tmpfs_node *node;
        off_t oldsize;

        KASSERT(vp->v_type == VREG);
        KASSERT(newsize >= 0);

        node = VP_TO_TMPFS_NODE(vp);
        tmp = VFS_TO_TMPFS(vp->v_mount);

        /* Convert the old and new sizes to the number of pages needed to
         * store them.  It may happen that we do not need to do anything
         * because the last allocated page can accommodate the change on
         * its own. */
        oldsize = node->tn_size;
        oldpages = round_page(oldsize) / PAGE_SIZE;
        KASSERT(oldpages == node->tn_spec.tn_reg.tn_aobj_pages);
        newpages = round_page(newsize) / PAGE_SIZE;

        if (newpages > oldpages &&
            (ssize_t)(newpages - oldpages) > TMPFS_PAGES_AVAIL(tmp)) {
                error = ENOSPC;
                goto out;
        }
        atomic_add_int(&tmp->tm_pages_used, newpages - oldpages);

        if (newsize < oldsize) {
                int zerolen = MIN(round_page(newsize), node->tn_size) - newsize;

                /*
                 * zero out the truncated part of the last page.
                 */

                uvm_vnp_zerorange(vp, newsize, zerolen);
        }

        node->tn_spec.tn_reg.tn_aobj_pages = newpages;
        node->tn_size = newsize;
        uvm_vnp_setsize(vp, newsize);

        /*
         * free "backing store"
         */

        if (newpages < oldpages) {
                struct uvm_object *uobj;

                uobj = node->tn_spec.tn_reg.tn_aobj;

                mutex_enter(&uobj->vmobjlock);
                uao_dropswap_range(uobj, newpages, oldpages);
                mutex_exit(&uobj->vmobjlock);
        }

        error = 0;

        if (newsize > oldsize)
                VN_KNOTE(vp, NOTE_EXTEND);

out:
        return error;
}

/* --------------------------------------------------------------------- */

/*
 * Returns information about the number of available memory pages,
 * including physical and virtual ones.
 *
 * If 'total' is true, the value returned is the total amount of memory
 * pages configured for the system (either in use or free).
 * If it is FALSE, the value returned is the amount of free memory pages.
 *
 * Remember to remove TMPFS_PAGES_RESERVED from the returned value to avoid
 * excessive memory usage.
 *
 */
size_t
tmpfs_mem_info(bool total)
{
        size_t size;

        size = 0;
        size += uvmexp.swpgavail;
        if (!total) {
                size -= uvmexp.swpgonly;
        }
        size += uvmexp.free;
        size += uvmexp.filepages;
        if (size > uvmexp.wired) {
                size -= uvmexp.wired;
        } else {
                size = 0;
        }

        return size;
}

/* --------------------------------------------------------------------- */

/*
 * Change flags of the given vnode.
 * Caller should execute tmpfs_update on vp after a successful execution.
 * The vnode must be locked on entry and remain locked on exit.
 */
int
tmpfs_chflags(struct vnode *vp, int flags, kauth_cred_t cred, struct lwp *l)
{
        int error;
        struct tmpfs_node *node;
        kauth_action_t action = KAUTH_VNODE_WRITE_FLAGS;
        int fs_decision = 0;

        KASSERT(VOP_ISLOCKED(vp));

        node = VP_TO_TMPFS_NODE(vp);

        /* Disallow this operation if the file system is mounted read-only. */
        if (vp->v_mount->mnt_flag & MNT_RDONLY)
                return EROFS;

        if (kauth_cred_geteuid(cred) != node->tn_uid)
                fs_decision = EACCES;

        /*
         * If the new flags have non-user flags that are different than
         * those on the node, we need special permission to change them.
         */
        if ((flags & SF_SETTABLE) != (node->tn_flags & SF_SETTABLE)) {
                action |= KAUTH_VNODE_WRITE_SYSFLAGS;
                if (!fs_decision)
                        fs_decision = EPERM;
        }

        /*
         * Indicate that this node's flags have system attributes in them if
         * that's the case.
         */
        if (node->tn_flags & (SF_IMMUTABLE | SF_APPEND)) {
                action |= KAUTH_VNODE_HAS_SYSFLAGS;
        }

        error = kauth_authorize_vnode(cred, action, vp, NULL, fs_decision);
        if (error)
                return error;

        /*
         * Set the flags. If we're not setting non-user flags, be careful not
         * to overwrite them.
         *
         * XXX: Can't we always assign here? if the system flags are different,
         *      the code above should catch attempts to change them without
         *      proper permissions, and if we're here it means it's okay to
         *      change them...
         */
        if (action & KAUTH_VNODE_WRITE_SYSFLAGS) {
                node->tn_flags = flags;
        } else {
                /* Clear all user-settable flags and re-set them. */
                node->tn_flags &= SF_SETTABLE;
                node->tn_flags |= (flags & UF_SETTABLE);
        }

        node->tn_status |= TMPFS_NODE_CHANGED;
        VN_KNOTE(vp, NOTE_ATTRIB);

        KASSERT(VOP_ISLOCKED(vp));

        return 0;
}

/* --------------------------------------------------------------------- */

/*
 * Change access mode on the given vnode.
 * Caller should execute tmpfs_update on vp after a successful execution.
 * The vnode must be locked on entry and remain locked on exit.
 */
int
tmpfs_chmod(struct vnode *vp, mode_t mode, kauth_cred_t cred, struct lwp *l)
{
        int error;
        struct tmpfs_node *node;

        KASSERT(VOP_ISLOCKED(vp));

        node = VP_TO_TMPFS_NODE(vp);

        /* Disallow this operation if the file system is mounted read-only. */
        if (vp->v_mount->mnt_flag & MNT_RDONLY)
                return EROFS;

        /* Immutable or append-only files cannot be modified, either. */
        if (node->tn_flags & (IMMUTABLE | APPEND))
                return EPERM;

        error = genfs_can_chmod(vp, cred, node->tn_uid, node->tn_gid,
            mode);

        error = kauth_authorize_vnode(cred, KAUTH_VNODE_WRITE_SECURITY, vp,
            NULL, error);
        if (error)
                return (error);

        node->tn_mode = (mode & ALLPERMS);

        node->tn_status |= TMPFS_NODE_CHANGED;
        VN_KNOTE(vp, NOTE_ATTRIB);

        KASSERT(VOP_ISLOCKED(vp));

        return 0;
}

/* --------------------------------------------------------------------- */

/*
 * Change ownership of the given vnode.  At least one of uid or gid must
 * be different than VNOVAL.  If one is set to that value, the attribute
 * is unchanged.
 * Caller should execute tmpfs_update on vp after a successful execution.
 * The vnode must be locked on entry and remain locked on exit.
 */
int
tmpfs_chown(struct vnode *vp, uid_t uid, gid_t gid, kauth_cred_t cred,
    struct lwp *l)
{
        int error;
        struct tmpfs_node *node;

        KASSERT(VOP_ISLOCKED(vp));

        node = VP_TO_TMPFS_NODE(vp);

        /* Assign default values if they are unknown. */
        KASSERT(uid != VNOVAL || gid != VNOVAL);
        if (uid == VNOVAL)
                uid = node->tn_uid;
        if (gid == VNOVAL)
                gid = node->tn_gid;
        KASSERT(uid != VNOVAL && gid != VNOVAL);

        /* Disallow this operation if the file system is mounted read-only. */
        if (vp->v_mount->mnt_flag & MNT_RDONLY)
                return EROFS;

        /* Immutable or append-only files cannot be modified, either. */
        if (node->tn_flags & (IMMUTABLE | APPEND))
                return EPERM;

        error = genfs_can_chown(vp, cred, node->tn_uid, node->tn_gid, uid,
            gid);

        error = kauth_authorize_vnode(cred, KAUTH_VNODE_CHANGE_OWNERSHIP, vp,
            NULL, error);
        if (error)
                return (error);

        node->tn_uid = uid;
        node->tn_gid = gid;

        node->tn_status |= TMPFS_NODE_CHANGED;
        VN_KNOTE(vp, NOTE_ATTRIB);

        KASSERT(VOP_ISLOCKED(vp));

        return 0;
}

/* --------------------------------------------------------------------- */

/*
 * Change size of the given vnode.
 * Caller should execute tmpfs_update on vp after a successful execution.
 * The vnode must be locked on entry and remain locked on exit.
 */
int
tmpfs_chsize(struct vnode *vp, u_quad_t size, kauth_cred_t cred,
    struct lwp *l)
{
        int error;
        struct tmpfs_node *node;

        KASSERT(VOP_ISLOCKED(vp));

        node = VP_TO_TMPFS_NODE(vp);

        /* Decide whether this is a valid operation based on the file type. */
        error = 0;
        switch (vp->v_type) {
        case VDIR:
                return EISDIR;

        case VREG:
                if (vp->v_mount->mnt_flag & MNT_RDONLY)
                        return EROFS;
                break;

        case VBLK:
                /* FALLTHROUGH */
        case VCHR:
                /* FALLTHROUGH */
        case VFIFO:
                /* Allow modifications of special files even if in the file
                 * system is mounted read-only (we are not modifying the
                 * files themselves, but the objects they represent). */
                return 0;

        default:
                /* Anything else is unsupported. */
                return EOPNOTSUPP;
        }

        /* Immutable or append-only files cannot be modified, either. */
        if (node->tn_flags & (IMMUTABLE | APPEND))
                return EPERM;

        error = tmpfs_truncate(vp, size);
        /* tmpfs_truncate will raise the NOTE_EXTEND and NOTE_ATTRIB kevents
         * for us, as will update tn_status; no need to do that here. */

        KASSERT(VOP_ISLOCKED(vp));

        return error;
}

/* --------------------------------------------------------------------- */

/*
 * Change access and modification times of the given vnode.
 * Caller should execute tmpfs_update on vp after a successful execution.
 * The vnode must be locked on entry and remain locked on exit.
 */
int
tmpfs_chtimes(struct vnode *vp, const struct timespec *atime,
    const struct timespec *mtime, const struct timespec *btime,
    int vaflags, kauth_cred_t cred, struct lwp *l)
{
        int error;
        struct tmpfs_node *node;

        KASSERT(VOP_ISLOCKED(vp));

        node = VP_TO_TMPFS_NODE(vp);

        /* Disallow this operation if the file system is mounted read-only. */
        if (vp->v_mount->mnt_flag & MNT_RDONLY)
                return EROFS;

        /* Immutable or append-only files cannot be modified, either. */
        if (node->tn_flags & (IMMUTABLE | APPEND))
                return EPERM;

        error = genfs_can_chtimes(vp, vaflags, node->tn_uid, cred);

        error = kauth_authorize_vnode(cred, KAUTH_VNODE_WRITE_TIMES, vp, NULL,
            error);
        if (error)
                return (error);

        if (atime->tv_sec != VNOVAL && atime->tv_nsec != VNOVAL)
                node->tn_status |= TMPFS_NODE_ACCESSED;

        if (mtime->tv_sec != VNOVAL && mtime->tv_nsec != VNOVAL)
                node->tn_status |= TMPFS_NODE_MODIFIED;

        if (btime->tv_sec == VNOVAL && btime->tv_nsec == VNOVAL)
                btime = NULL;

        tmpfs_update(vp, atime, mtime, btime, 0);
        VN_KNOTE(vp, NOTE_ATTRIB);

        KASSERT(VOP_ISLOCKED(vp));

        return 0;
}

/* --------------------------------------------------------------------- */

/* Sync timestamps */
void
tmpfs_itimes(struct vnode *vp, const struct timespec *acc,
    const struct timespec *mod, const struct timespec *birth)
{
        struct tmpfs_node *node;
        struct timespec nowtm;

        node = VP_TO_TMPFS_NODE(vp);

        if ((node->tn_status & (TMPFS_NODE_ACCESSED | TMPFS_NODE_MODIFIED |
            TMPFS_NODE_CHANGED)) == 0)
                return;

        if (birth != NULL) {
                node->tn_birthtime = *birth;
        }
        vfs_timestamp(&nowtm);

        if (node->tn_status & TMPFS_NODE_ACCESSED) {
                node->tn_atime = acc ? *acc : nowtm;
        }
        if (node->tn_status & TMPFS_NODE_MODIFIED) {
                node->tn_mtime = mod ? *mod : nowtm;
        }
        if (node->tn_status & TMPFS_NODE_CHANGED) {
                node->tn_ctime = nowtm;
        }

        node->tn_status &=
            ~(TMPFS_NODE_ACCESSED | TMPFS_NODE_MODIFIED | TMPFS_NODE_CHANGED);
}

/* --------------------------------------------------------------------- */

void
tmpfs_update(struct vnode *vp, const struct timespec *acc,
    const struct timespec *mod, const struct timespec *birth, int flags)
{

        struct tmpfs_node *node;

        KASSERT(VOP_ISLOCKED(vp));

        node = VP_TO_TMPFS_NODE(vp);

#if 0
        if (flags & UPDATE_CLOSE)
                ; /* XXX Need to do anything special? */
#endif

        tmpfs_itimes(vp, acc, mod, birth);

        KASSERT(VOP_ISLOCKED(vp));
}

/* --------------------------------------------------------------------- */

int
tmpfs_truncate(struct vnode *vp, off_t length)
{
        bool extended;
        int error;
        struct tmpfs_node *node;

        node = VP_TO_TMPFS_NODE(vp);
        extended = length > node->tn_size;

        if (length < 0) {
                error = EINVAL;
                goto out;
        }

        if (node->tn_size == length) {
                error = 0;
                goto out;
        }

        error = tmpfs_reg_resize(vp, length);
        if (error == 0)
                node->tn_status |= TMPFS_NODE_CHANGED | TMPFS_NODE_MODIFIED;

out:
        tmpfs_update(vp, NULL, NULL, NULL, 0);

        return error;
}