freebsd-dev/module/zfs/zfs_ctldir.c
Brian Behlendorf 6772fb679a Use dsl_dataset_snap_lookup()
Retire the dmu_snapshot_id() function which was introduced in the
initial .zfs control directory implementation.  There is already
an existing dsl_dataset_snap_lookup() which does exactly what we
need, and the dmu_snapshot_id() function as implemented is racy.

https://github.com/zfsonlinux/zfs/issues/1215#issuecomment-12579879

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1238
2013-01-25 15:07:40 -08:00

1003 lines
23 KiB
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 http://www.opensolaris.org/os/licensing.
* 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) 2011 Lawrence Livermore National Security, LLC.
* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
* LLNL-CODE-403049.
* Rewritten for Linux by:
* Rohan Puri <rohan.puri15@gmail.com>
* Brian Behlendorf <behlendorf1@llnl.gov>
*/
/*
* ZFS control directory (a.k.a. ".zfs")
*
* This directory provides a common location for all ZFS meta-objects.
* Currently, this is only the 'snapshot' and 'shares' directory, but this may
* expand in the future. The elements are built dynamically, as the hierarchy
* does not actually exist on disk.
*
* For 'snapshot', we don't want to have all snapshots always mounted, because
* this would take up a huge amount of space in /etc/mnttab. We have three
* types of objects:
*
* ctldir ------> snapshotdir -------> snapshot
* |
* |
* V
* mounted fs
*
* The 'snapshot' node contains just enough information to lookup '..' and act
* as a mountpoint for the snapshot. Whenever we lookup a specific snapshot, we
* perform an automount of the underlying filesystem and return the
* corresponding inode.
*
* All mounts are handled automatically by an user mode helper which invokes
* the mount mount procedure. Unmounts are handled by allowing the mount
* point to expire so the kernel may automatically unmount it.
*
* The '.zfs', '.zfs/snapshot', and all directories created under
* '.zfs/snapshot' (ie: '.zfs/snapshot/<snapname>') all share the same
* share the same zfs_sb_t as the head filesystem (what '.zfs' lives under).
*
* File systems mounted on top of the '.zfs/snapshot/<snapname>' paths
* (ie: snapshots) are complete ZFS filesystems and have their own unique
* zfs_sb_t. However, the fsid reported by these mounts will be the same
* as that used by the parent zfs_sb_t to make NFS happy.
*/
#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/pathname.h>
#include <sys/vfs.h>
#include <sys/vfs_opreg.h>
#include <sys/zfs_ctldir.h>
#include <sys/zfs_ioctl.h>
#include <sys/zfs_vfsops.h>
#include <sys/zfs_vnops.h>
#include <sys/stat.h>
#include <sys/dmu.h>
#include <sys/dsl_deleg.h>
#include <sys/mount.h>
#include <sys/zpl.h>
#include "zfs_namecheck.h"
/*
* Control Directory Tunables (.zfs)
*/
int zfs_expire_snapshot = ZFSCTL_EXPIRE_SNAPSHOT;
/*
* Dedicated task queue for unmounting snapshots.
*/
static taskq_t *zfs_expire_taskq;
static zfs_snapentry_t *
zfsctl_sep_alloc(void)
{
return kmem_zalloc(sizeof (zfs_snapentry_t), KM_SLEEP);
}
void
zfsctl_sep_free(zfs_snapentry_t *sep)
{
kmem_free(sep->se_name, MAXNAMELEN);
kmem_free(sep->se_path, PATH_MAX);
kmem_free(sep, sizeof (zfs_snapentry_t));
}
/*
* Attempt to expire an automounted snapshot, unmounts are attempted every
* 'zfs_expire_snapshot' seconds until they succeed. The work request is
* responsible for rescheduling itself and freeing the zfs_expire_snapshot_t.
*/
static void
zfsctl_expire_snapshot(void *data)
{
zfs_snapentry_t *sep = (zfs_snapentry_t *)data;
zfs_sb_t *zsb = ITOZSB(sep->se_inode);
int error;
error = zfsctl_unmount_snapshot(zsb, sep->se_name, MNT_EXPIRE);
if (error == EBUSY)
sep->se_taskqid = taskq_dispatch_delay(zfs_expire_taskq,
zfsctl_expire_snapshot, sep, TQ_SLEEP,
ddi_get_lbolt() + zfs_expire_snapshot * HZ);
}
int
snapentry_compare(const void *a, const void *b)
{
const zfs_snapentry_t *sa = a;
const zfs_snapentry_t *sb = b;
int ret = strcmp(sa->se_name, sb->se_name);
if (ret < 0)
return (-1);
else if (ret > 0)
return (1);
else
return (0);
}
boolean_t
zfsctl_is_node(struct inode *ip)
{
return (ITOZ(ip)->z_is_ctldir);
}
boolean_t
zfsctl_is_snapdir(struct inode *ip)
{
return (zfsctl_is_node(ip) && (ip->i_ino <= ZFSCTL_INO_SNAPDIRS));
}
/*
* Allocate a new inode with the passed id and ops.
*/
static struct inode *
zfsctl_inode_alloc(zfs_sb_t *zsb, uint64_t id,
const struct file_operations *fops, const struct inode_operations *ops)
{
struct timespec now = current_fs_time(zsb->z_sb);
struct inode *ip;
znode_t *zp;
ip = new_inode(zsb->z_sb);
if (ip == NULL)
return (NULL);
zp = ITOZ(ip);
ASSERT3P(zp->z_dirlocks, ==, NULL);
ASSERT3P(zp->z_acl_cached, ==, NULL);
ASSERT3P(zp->z_xattr_cached, ==, NULL);
zp->z_id = id;
zp->z_unlinked = 0;
zp->z_atime_dirty = 0;
zp->z_zn_prefetch = 0;
zp->z_moved = 0;
zp->z_sa_hdl = NULL;
zp->z_blksz = 0;
zp->z_seq = 0;
zp->z_mapcnt = 0;
zp->z_gen = 0;
zp->z_size = 0;
zp->z_atime[0] = 0;
zp->z_atime[1] = 0;
zp->z_links = 0;
zp->z_pflags = 0;
zp->z_uid = 0;
zp->z_gid = 0;
zp->z_mode = 0;
zp->z_sync_cnt = 0;
zp->z_is_zvol = B_FALSE;
zp->z_is_mapped = B_FALSE;
zp->z_is_ctldir = B_TRUE;
zp->z_is_sa = B_FALSE;
zp->z_is_stale = B_FALSE;
ip->i_ino = id;
ip->i_mode = (S_IFDIR | S_IRUGO | S_IXUGO);
ip->i_uid = 0;
ip->i_gid = 0;
ip->i_blkbits = SPA_MINBLOCKSHIFT;
ip->i_atime = now;
ip->i_mtime = now;
ip->i_ctime = now;
ip->i_fop = fops;
ip->i_op = ops;
if (insert_inode_locked(ip)) {
unlock_new_inode(ip);
iput(ip);
return (NULL);
}
mutex_enter(&zsb->z_znodes_lock);
list_insert_tail(&zsb->z_all_znodes, zp);
zsb->z_nr_znodes++;
membar_producer();
mutex_exit(&zsb->z_znodes_lock);
unlock_new_inode(ip);
return (ip);
}
/*
* Lookup the inode with given id, it will be allocated if needed.
*/
static struct inode *
zfsctl_inode_lookup(zfs_sb_t *zsb, uint64_t id,
const struct file_operations *fops, const struct inode_operations *ops)
{
struct inode *ip = NULL;
while (ip == NULL) {
ip = ilookup(zsb->z_sb, (unsigned long)id);
if (ip)
break;
/* May fail due to concurrent zfsctl_inode_alloc() */
ip = zfsctl_inode_alloc(zsb, id, fops, ops);
}
return (ip);
}
/*
* Free zfsctl inode specific structures, currently there are none.
*/
void
zfsctl_inode_destroy(struct inode *ip)
{
return;
}
/*
* An inode is being evicted from the cache.
*/
void
zfsctl_inode_inactive(struct inode *ip)
{
if (zfsctl_is_snapdir(ip))
zfsctl_snapdir_inactive(ip);
}
/*
* Create the '.zfs' directory. This directory is cached as part of the VFS
* structure. This results in a hold on the zfs_sb_t. The code in zfs_umount()
* therefore checks against a vfs_count of 2 instead of 1. This reference
* is removed when the ctldir is destroyed in the unmount. All other entities
* under the '.zfs' directory are created dynamically as needed.
*
* Because the dynamically created '.zfs' directory entries assume the use
* of 64-bit inode numbers this support must be disabled on 32-bit systems.
*/
int
zfsctl_create(zfs_sb_t *zsb)
{
#if defined(CONFIG_64BIT)
ASSERT(zsb->z_ctldir == NULL);
zsb->z_ctldir = zfsctl_inode_alloc(zsb, ZFSCTL_INO_ROOT,
&zpl_fops_root, &zpl_ops_root);
if (zsb->z_ctldir == NULL)
return (ENOENT);
return (0);
#else
return (EOPNOTSUPP);
#endif /* CONFIG_64BIT */
}
/*
* Destroy the '.zfs' directory. Only called when the filesystem is unmounted.
*/
void
zfsctl_destroy(zfs_sb_t *zsb)
{
iput(zsb->z_ctldir);
zsb->z_ctldir = NULL;
}
/*
* Given a root znode, retrieve the associated .zfs directory.
* Add a hold to the vnode and return it.
*/
struct inode *
zfsctl_root(znode_t *zp)
{
ASSERT(zfs_has_ctldir(zp));
igrab(ZTOZSB(zp)->z_ctldir);
return (ZTOZSB(zp)->z_ctldir);
}
/*ARGSUSED*/
int
zfsctl_fid(struct inode *ip, fid_t *fidp)
{
znode_t *zp = ITOZ(ip);
zfs_sb_t *zsb = ITOZSB(ip);
uint64_t object = zp->z_id;
zfid_short_t *zfid;
int i;
ZFS_ENTER(zsb);
if (fidp->fid_len < SHORT_FID_LEN) {
fidp->fid_len = SHORT_FID_LEN;
ZFS_EXIT(zsb);
return (ENOSPC);
}
zfid = (zfid_short_t *)fidp;
zfid->zf_len = SHORT_FID_LEN;
for (i = 0; i < sizeof (zfid->zf_object); i++)
zfid->zf_object[i] = (uint8_t)(object >> (8 * i));
/* .zfs znodes always have a generation number of 0 */
for (i = 0; i < sizeof (zfid->zf_gen); i++)
zfid->zf_gen[i] = 0;
ZFS_EXIT(zsb);
return (0);
}
static int
zfsctl_snapshot_zname(struct inode *ip, const char *name, int len, char *zname)
{
objset_t *os = ITOZSB(ip)->z_os;
if (snapshot_namecheck(name, NULL, NULL) != 0)
return (EILSEQ);
dmu_objset_name(os, zname);
if ((strlen(zname) + 1 + strlen(name)) >= len)
return (ENAMETOOLONG);
(void) strcat(zname, "@");
(void) strcat(zname, name);
return (0);
}
static int
zfsctl_snapshot_zpath(struct path *path, int len, char *zpath)
{
char *path_buffer, *path_ptr;
int path_len, error = 0;
path_buffer = kmem_alloc(len, KM_SLEEP);
path_ptr = d_path(path, path_buffer, len);
if (IS_ERR(path_ptr)) {
error = -PTR_ERR(path_ptr);
goto out;
}
path_len = path_buffer + len - 1 - path_ptr;
if (path_len > len) {
error = EFAULT;
goto out;
}
memcpy(zpath, path_ptr, path_len);
zpath[path_len] = '\0';
out:
kmem_free(path_buffer, len);
return (error);
}
/*
* Special case the handling of "..".
*/
/* ARGSUSED */
int
zfsctl_root_lookup(struct inode *dip, char *name, struct inode **ipp,
int flags, cred_t *cr, int *direntflags, pathname_t *realpnp)
{
zfs_sb_t *zsb = ITOZSB(dip);
int error = 0;
ZFS_ENTER(zsb);
if (strcmp(name, "..") == 0) {
*ipp = dip->i_sb->s_root->d_inode;
} else if (strcmp(name, ZFS_SNAPDIR_NAME) == 0) {
*ipp = zfsctl_inode_lookup(zsb, ZFSCTL_INO_SNAPDIR,
&zpl_fops_snapdir, &zpl_ops_snapdir);
} else if (strcmp(name, ZFS_SHAREDIR_NAME) == 0) {
*ipp = zfsctl_inode_lookup(zsb, ZFSCTL_INO_SHARES,
&zpl_fops_shares, &zpl_ops_shares);
} else {
*ipp = NULL;
}
if (*ipp == NULL)
error = ENOENT;
ZFS_EXIT(zsb);
return (error);
}
/*
* Lookup entry point for the 'snapshot' directory. Try to open the
* snapshot if it exist, creating the pseudo filesystem inode as necessary.
* Perform a mount of the associated dataset on top of the inode.
*/
/* ARGSUSED */
int
zfsctl_snapdir_lookup(struct inode *dip, char *name, struct inode **ipp,
int flags, cred_t *cr, int *direntflags, pathname_t *realpnp)
{
zfs_sb_t *zsb = ITOZSB(dip);
uint64_t id;
int error;
ZFS_ENTER(zsb);
error = dmu_snapshot_lookup(zsb->z_os, name, &id);
if (error) {
ZFS_EXIT(zsb);
return (error);
}
*ipp = zfsctl_inode_lookup(zsb, ZFSCTL_INO_SNAPDIRS - id,
&simple_dir_operations, &simple_dir_inode_operations);
if (*ipp) {
#ifdef HAVE_AUTOMOUNT
(*ipp)->i_flags |= S_AUTOMOUNT;
#endif /* HAVE_AUTOMOUNT */
} else {
error = ENOENT;
}
ZFS_EXIT(zsb);
return (error);
}
static void
zfsctl_rename_snap(zfs_sb_t *zsb, zfs_snapentry_t *sep, const char *name)
{
avl_index_t where;
ASSERT(MUTEX_HELD(&zsb->z_ctldir_lock));
ASSERT(sep != NULL);
/*
* Change the name in the AVL tree.
*/
avl_remove(&zsb->z_ctldir_snaps, sep);
(void) strcpy(sep->se_name, name);
VERIFY(avl_find(&zsb->z_ctldir_snaps, sep, &where) == NULL);
avl_insert(&zsb->z_ctldir_snaps, sep, where);
}
/*
* Renaming a directory under '.zfs/snapshot' will automatically trigger
* a rename of the snapshot to the new given name. The rename is confined
* to the '.zfs/snapshot' directory snapshots cannot be moved elsewhere.
*/
/*ARGSUSED*/
int
zfsctl_snapdir_rename(struct inode *sdip, char *sname,
struct inode *tdip, char *tname, cred_t *cr, int flags)
{
zfs_sb_t *zsb = ITOZSB(sdip);
zfs_snapentry_t search, *sep;
avl_index_t where;
char *to, *from, *real;
int error;
ZFS_ENTER(zsb);
to = kmem_alloc(MAXNAMELEN, KM_SLEEP);
from = kmem_alloc(MAXNAMELEN, KM_SLEEP);
real = kmem_alloc(MAXNAMELEN, KM_SLEEP);
if (zsb->z_case == ZFS_CASE_INSENSITIVE) {
error = dmu_snapshot_realname(zsb->z_os, sname, real,
MAXNAMELEN, NULL);
if (error == 0) {
sname = real;
} else if (error != ENOTSUP) {
goto out;
}
}
error = zfsctl_snapshot_zname(sdip, sname, MAXNAMELEN, from);
if (!error)
error = zfsctl_snapshot_zname(tdip, tname, MAXNAMELEN, to);
if (!error)
error = zfs_secpolicy_rename_perms(from, to, cr);
if (error)
goto out;
/*
* Cannot move snapshots out of the snapdir.
*/
if (sdip != tdip) {
error = EINVAL;
goto out;
}
/*
* No-op when names are identical.
*/
if (strcmp(sname, tname) == 0) {
error = 0;
goto out;
}
mutex_enter(&zsb->z_ctldir_lock);
error = dmu_objset_rename(from, to, B_FALSE);
if (error)
goto out_unlock;
search.se_name = (char *)sname;
sep = avl_find(&zsb->z_ctldir_snaps, &search, &where);
if (sep)
zfsctl_rename_snap(zsb, sep, tname);
out_unlock:
mutex_exit(&zsb->z_ctldir_lock);
out:
kmem_free(from, MAXNAMELEN);
kmem_free(to, MAXNAMELEN);
kmem_free(real, MAXNAMELEN);
ZFS_EXIT(zsb);
return (error);
}
/*
* Removing a directory under '.zfs/snapshot' will automatically trigger
* the removal of the snapshot with the given name.
*/
/* ARGSUSED */
int
zfsctl_snapdir_remove(struct inode *dip, char *name, cred_t *cr, int flags)
{
zfs_sb_t *zsb = ITOZSB(dip);
char *snapname, *real;
int error;
ZFS_ENTER(zsb);
snapname = kmem_alloc(MAXNAMELEN, KM_SLEEP);
real = kmem_alloc(MAXNAMELEN, KM_SLEEP);
if (zsb->z_case == ZFS_CASE_INSENSITIVE) {
error = dmu_snapshot_realname(zsb->z_os, name, real,
MAXNAMELEN, NULL);
if (error == 0) {
name = real;
} else if (error != ENOTSUP) {
goto out;
}
}
error = zfsctl_snapshot_zname(dip, name, MAXNAMELEN, snapname);
if (!error)
error = zfs_secpolicy_destroy_perms(snapname, cr);
if (error)
goto out;
error = zfsctl_unmount_snapshot(zsb, name, MNT_FORCE);
if ((error == 0) || (error == ENOENT))
error = dmu_objset_destroy(snapname, B_FALSE);
out:
kmem_free(snapname, MAXNAMELEN);
kmem_free(real, MAXNAMELEN);
ZFS_EXIT(zsb);
return (error);
}
/*
* Creating a directory under '.zfs/snapshot' will automatically trigger
* the creation of a new snapshot with the given name.
*/
/* ARGSUSED */
int
zfsctl_snapdir_mkdir(struct inode *dip, char *dirname, vattr_t *vap,
struct inode **ipp, cred_t *cr, int flags)
{
zfs_sb_t *zsb = ITOZSB(dip);
char *dsname;
int error;
dsname = kmem_alloc(MAXNAMELEN, KM_SLEEP);
if (snapshot_namecheck(dirname, NULL, NULL) != 0) {
error = EILSEQ;
goto out;
}
dmu_objset_name(zsb->z_os, dsname);
error = zfs_secpolicy_snapshot_perms(dsname, cr);
if (error)
goto out;
if (error == 0) {
error = dmu_objset_snapshot(dsname, dirname,
NULL, NULL, B_FALSE, B_FALSE, -1);
if (error)
goto out;
error = zfsctl_snapdir_lookup(dip, dirname, ipp,
0, cr, NULL, NULL);
}
out:
kmem_free(dsname, MAXNAMELEN);
return (error);
}
/*
* When a .zfs/snapshot/<snapshot> inode is evicted they must be removed
* from the snapshot list. This will normally happen as part of the auto
* unmount, however in the case of a manual snapshot unmount this will be
* the only notification we receive.
*/
void
zfsctl_snapdir_inactive(struct inode *ip)
{
zfs_sb_t *zsb = ITOZSB(ip);
zfs_snapentry_t *sep, *next;
mutex_enter(&zsb->z_ctldir_lock);
sep = avl_first(&zsb->z_ctldir_snaps);
while (sep != NULL) {
next = AVL_NEXT(&zsb->z_ctldir_snaps, sep);
if (sep->se_inode == ip) {
avl_remove(&zsb->z_ctldir_snaps, sep);
taskq_cancel_id(zfs_expire_taskq, sep->se_taskqid);
zfsctl_sep_free(sep);
break;
}
sep = next;
}
mutex_exit(&zsb->z_ctldir_lock);
}
/*
* Attempt to unmount a snapshot by making a call to user space.
* There is no assurance that this can or will succeed, is just a
* best effort. In the case where it does fail, perhaps because
* it's in use, the unmount will fail harmlessly.
*/
#define SET_UNMOUNT_CMD \
"exec 0</dev/null " \
" 1>/dev/null " \
" 2>/dev/null; " \
"umount -t zfs -n %s'%s'"
static int
__zfsctl_unmount_snapshot(zfs_snapentry_t *sep, int flags)
{
char *argv[] = { "/bin/sh", "-c", NULL, NULL };
char *envp[] = { NULL };
int error;
argv[2] = kmem_asprintf(SET_UNMOUNT_CMD,
flags & MNT_FORCE ? "-f " : "", sep->se_path);
error = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
strfree(argv[2]);
/*
* The umount system utility will return 256 on error. We must
* assume this error is because the file system is busy so it is
* converted to the more sensible EBUSY.
*/
if (error)
error = EBUSY;
/*
* This was the result of a manual unmount, cancel the delayed work
* to prevent zfsctl_expire_snapshot() from attempting a unmount.
*/
if ((error == 0) && !(flags & MNT_EXPIRE))
taskq_cancel_id(zfs_expire_taskq, sep->se_taskqid);
return (error);
}
int
zfsctl_unmount_snapshot(zfs_sb_t *zsb, char *name, int flags)
{
zfs_snapentry_t search;
zfs_snapentry_t *sep;
int error = 0;
mutex_enter(&zsb->z_ctldir_lock);
search.se_name = name;
sep = avl_find(&zsb->z_ctldir_snaps, &search, NULL);
if (sep) {
avl_remove(&zsb->z_ctldir_snaps, sep);
error = __zfsctl_unmount_snapshot(sep, flags);
if (error == EBUSY)
avl_add(&zsb->z_ctldir_snaps, sep);
else
zfsctl_sep_free(sep);
} else {
error = ENOENT;
}
mutex_exit(&zsb->z_ctldir_lock);
ASSERT3S(error, >=, 0);
return (error);
}
/*
* Traverse all mounted snapshots and attempt to unmount them. This
* is best effort, on failure EEXIST is returned and count will be set
* to the number of file snapshots which could not be unmounted.
*/
int
zfsctl_unmount_snapshots(zfs_sb_t *zsb, int flags, int *count)
{
zfs_snapentry_t *sep, *next;
int error = 0;
*count = 0;
ASSERT(zsb->z_ctldir != NULL);
mutex_enter(&zsb->z_ctldir_lock);
sep = avl_first(&zsb->z_ctldir_snaps);
while (sep != NULL) {
next = AVL_NEXT(&zsb->z_ctldir_snaps, sep);
avl_remove(&zsb->z_ctldir_snaps, sep);
error = __zfsctl_unmount_snapshot(sep, flags);
if (error == EBUSY) {
avl_add(&zsb->z_ctldir_snaps, sep);
(*count)++;
} else {
zfsctl_sep_free(sep);
}
sep = next;
}
mutex_exit(&zsb->z_ctldir_lock);
return ((*count > 0) ? EEXIST : 0);
}
#define SET_MOUNT_CMD \
"exec 0</dev/null " \
" 1>/dev/null " \
" 2>/dev/null; " \
"mount -t zfs -n '%s' '%s'"
int
zfsctl_mount_snapshot(struct path *path, int flags)
{
struct dentry *dentry = path->dentry;
struct inode *ip = dentry->d_inode;
zfs_sb_t *zsb = ITOZSB(ip);
char *full_name, *full_path;
zfs_snapentry_t *sep;
zfs_snapentry_t search;
char *argv[] = { "/bin/sh", "-c", NULL, NULL };
char *envp[] = { NULL };
int error;
ZFS_ENTER(zsb);
full_name = kmem_zalloc(MAXNAMELEN, KM_SLEEP);
full_path = kmem_zalloc(PATH_MAX, KM_SLEEP);
error = zfsctl_snapshot_zname(ip, dname(dentry), MAXNAMELEN, full_name);
if (error)
goto error;
error = zfsctl_snapshot_zpath(path, PATH_MAX, full_path);
if (error)
goto error;
/*
* Attempt to mount the snapshot from user space. Normally this
* would be done using the vfs_kern_mount() function, however that
* function is marked GPL-only and cannot be used. On error we
* careful to log the real error to the console and return EISDIR
* to safely abort the automount. This should be very rare.
*/
argv[2] = kmem_asprintf(SET_MOUNT_CMD, full_name, full_path);
error = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
strfree(argv[2]);
if (error) {
printk("ZFS: Unable to automount %s at %s: %d\n",
full_name, full_path, error);
error = EISDIR;
goto error;
}
mutex_enter(&zsb->z_ctldir_lock);
/*
* Ensure a previous entry does not exist, if it does safely remove
* it any cancel the outstanding expiration. This can occur when a
* snapshot is manually unmounted and then an automount is triggered.
*/
search.se_name = full_name;
sep = avl_find(&zsb->z_ctldir_snaps, &search, NULL);
if (sep) {
avl_remove(&zsb->z_ctldir_snaps, sep);
taskq_cancel_id(zfs_expire_taskq, sep->se_taskqid);
zfsctl_sep_free(sep);
}
sep = zfsctl_sep_alloc();
sep->se_name = full_name;
sep->se_path = full_path;
sep->se_inode = ip;
avl_add(&zsb->z_ctldir_snaps, sep);
sep->se_taskqid = taskq_dispatch_delay(zfs_expire_taskq,
zfsctl_expire_snapshot, sep, TQ_SLEEP,
ddi_get_lbolt() + zfs_expire_snapshot * HZ);
mutex_exit(&zsb->z_ctldir_lock);
error:
if (error) {
kmem_free(full_name, MAXNAMELEN);
kmem_free(full_path, PATH_MAX);
}
ZFS_EXIT(zsb);
return (error);
}
/*
* Check if this super block has a matching objset id.
*/
static int
zfsctl_test_super(struct super_block *sb, void *objsetidp)
{
zfs_sb_t *zsb = sb->s_fs_info;
uint64_t objsetid = *(uint64_t *)objsetidp;
return (dmu_objset_id(zsb->z_os) == objsetid);
}
/*
* Prevent a new super block from being allocated if an existing one
* could not be located. We only want to preform a lookup operation.
*/
static int
zfsctl_set_super(struct super_block *sb, void *objsetidp)
{
return (-EEXIST);
}
int
zfsctl_lookup_objset(struct super_block *sb, uint64_t objsetid, zfs_sb_t **zsbp)
{
zfs_sb_t *zsb = sb->s_fs_info;
struct super_block *sbp;
zfs_snapentry_t *sep;
uint64_t id;
int error;
ASSERT(zsb->z_ctldir != NULL);
mutex_enter(&zsb->z_ctldir_lock);
/*
* Verify that the snapshot is mounted.
*/
sep = avl_first(&zsb->z_ctldir_snaps);
while (sep != NULL) {
error = dmu_snapshot_lookup(zsb->z_os, sep->se_name, &id);
if (error)
goto out;
if (id == objsetid)
break;
sep = AVL_NEXT(&zsb->z_ctldir_snaps, sep);
}
if (sep != NULL) {
/*
* Lookup the mounted root rather than the covered mount
* point. This may fail if the snapshot has just been
* unmounted by an unrelated user space process. This
* race cannot occur to an expired mount point because
* we hold the zsb->z_ctldir_lock to prevent the race.
*/
sbp = zpl_sget(&zpl_fs_type, zfsctl_test_super,
zfsctl_set_super, 0, &id);
if (IS_ERR(sbp)) {
error = -PTR_ERR(sbp);
} else {
*zsbp = sbp->s_fs_info;
deactivate_super(sbp);
}
} else {
error = EINVAL;
}
out:
mutex_exit(&zsb->z_ctldir_lock);
ASSERT3S(error, >=, 0);
return (error);
}
/* ARGSUSED */
int
zfsctl_shares_lookup(struct inode *dip, char *name, struct inode **ipp,
int flags, cred_t *cr, int *direntflags, pathname_t *realpnp)
{
zfs_sb_t *zsb = ITOZSB(dip);
struct inode *ip;
znode_t *dzp;
int error;
ZFS_ENTER(zsb);
if (zsb->z_shares_dir == 0) {
ZFS_EXIT(zsb);
return (ENOTSUP);
}
error = zfs_zget(zsb, zsb->z_shares_dir, &dzp);
if (error) {
ZFS_EXIT(zsb);
return (error);
}
error = zfs_lookup(ZTOI(dzp), name, &ip, 0, cr, NULL, NULL);
iput(ZTOI(dzp));
ZFS_EXIT(zsb);
return (error);
}
/*
* Initialize the various pieces we'll need to create and manipulate .zfs
* directories. Currently this is unused but available.
*/
void
zfsctl_init(void)
{
zfs_expire_taskq = taskq_create("z_unmount", 1, maxclsyspri,
1, 8, TASKQ_PREPOPULATE);
}
/*
* Cleanup the various pieces we needed for .zfs directories. In particular
* ensure the expiry timer is canceled safely.
*/
void
zfsctl_fini(void)
{
taskq_destroy(zfs_expire_taskq);
}
module_param(zfs_expire_snapshot, int, 0644);
MODULE_PARM_DESC(zfs_expire_snapshot, "Seconds to expire .zfs/snapshot");