/* * 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 * Brian Behlendorf * Copyright (c) 2013 by Delphix. All rights reserved. */ /* * 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/') 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/' 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "zfs_namecheck.h" /* * Two AVL trees are maintained which contain all currently automounted * snapshots. Every automounted snapshots maps to a single zfs_snapentry_t * entry which MUST: * * - be attached to both trees, and * - be unique, no duplicate entries are allowed. * * The zfs_snapshots_by_name tree is indexed by the full dataset name * while the zfs_snapshots_by_objsetid tree is indexed by the unique * objsetid. This allows for fast lookups either by name or objsetid. */ static avl_tree_t zfs_snapshots_by_name; static avl_tree_t zfs_snapshots_by_objsetid; static krwlock_t zfs_snapshot_lock; /* * Control Directory Tunables (.zfs) */ int zfs_expire_snapshot = ZFSCTL_EXPIRE_SNAPSHOT; int zfs_admin_snapshot = 0; /* * Dedicated task queue for unmounting snapshots. */ static taskq_t *zfs_expire_taskq; typedef struct { char *se_name; /* full snapshot name */ char *se_path; /* full mount path */ spa_t *se_spa; /* pool spa */ uint64_t se_objsetid; /* snapshot objset id */ struct dentry *se_root_dentry; /* snapshot root dentry */ taskqid_t se_taskqid; /* scheduled unmount taskqid */ avl_node_t se_node_name; /* zfs_snapshots_by_name link */ avl_node_t se_node_objsetid; /* zfs_snapshots_by_objsetid link */ refcount_t se_refcount; /* reference count */ } zfs_snapentry_t; static void zfsctl_snapshot_unmount_delay_impl(zfs_snapentry_t *se, int delay); /* * Allocate a new zfs_snapentry_t being careful to make a copy of the * the snapshot name and provided mount point. No reference is taken. */ static zfs_snapentry_t * zfsctl_snapshot_alloc(char *full_name, char *full_path, spa_t *spa, uint64_t objsetid, struct dentry *root_dentry) { zfs_snapentry_t *se; se = kmem_zalloc(sizeof (zfs_snapentry_t), KM_SLEEP); se->se_name = strdup(full_name); se->se_path = strdup(full_path); se->se_spa = spa; se->se_objsetid = objsetid; se->se_root_dentry = root_dentry; se->se_taskqid = -1; refcount_create(&se->se_refcount); return (se); } /* * Free a zfs_snapentry_t the called must ensure there are no active * references. */ static void zfsctl_snapshot_free(zfs_snapentry_t *se) { refcount_destroy(&se->se_refcount); strfree(se->se_name); strfree(se->se_path); kmem_free(se, sizeof (zfs_snapentry_t)); } /* * Hold a reference on the zfs_snapentry_t. */ static void zfsctl_snapshot_hold(zfs_snapentry_t *se) { refcount_add(&se->se_refcount, NULL); } /* * Release a reference on the zfs_snapentry_t. When the number of * references drops to zero the structure will be freed. */ static void zfsctl_snapshot_rele(zfs_snapentry_t *se) { if (refcount_remove(&se->se_refcount, NULL) == 0) zfsctl_snapshot_free(se); } /* * Add a zfs_snapentry_t to both the zfs_snapshots_by_name and * zfs_snapshots_by_objsetid trees. While the zfs_snapentry_t is part * of the trees a reference is held. */ static void zfsctl_snapshot_add(zfs_snapentry_t *se) { ASSERT(RW_WRITE_HELD(&zfs_snapshot_lock)); refcount_add(&se->se_refcount, NULL); avl_add(&zfs_snapshots_by_name, se); avl_add(&zfs_snapshots_by_objsetid, se); } /* * Remove a zfs_snapentry_t from both the zfs_snapshots_by_name and * zfs_snapshots_by_objsetid trees. Upon removal a reference is dropped, * this can result in the structure being freed if that was the last * remaining reference. */ static void zfsctl_snapshot_remove(zfs_snapentry_t *se) { ASSERT(RW_WRITE_HELD(&zfs_snapshot_lock)); avl_remove(&zfs_snapshots_by_name, se); avl_remove(&zfs_snapshots_by_objsetid, se); zfsctl_snapshot_rele(se); } /* * Snapshot name comparison function for the zfs_snapshots_by_name. */ static int snapentry_compare_by_name(const void *a, const void *b) { const zfs_snapentry_t *se_a = a; const zfs_snapentry_t *se_b = b; int ret; ret = strcmp(se_a->se_name, se_b->se_name); if (ret < 0) return (-1); else if (ret > 0) return (1); else return (0); } /* * Snapshot name comparison function for the zfs_snapshots_by_objsetid. */ static int snapentry_compare_by_objsetid(const void *a, const void *b) { const zfs_snapentry_t *se_a = a; const zfs_snapentry_t *se_b = b; if (se_a->se_spa != se_b->se_spa) return ((ulong_t)se_a->se_spa < (ulong_t)se_b->se_spa ? -1 : 1); if (se_a->se_objsetid < se_b->se_objsetid) return (-1); else if (se_a->se_objsetid > se_b->se_objsetid) return (1); else return (0); } /* * Find a zfs_snapentry_t in zfs_snapshots_by_name. If the snapname * is found a pointer to the zfs_snapentry_t is returned and a reference * taken on the structure. The caller is responsible for dropping the * reference with zfsctl_snapshot_rele(). If the snapname is not found * NULL will be returned. */ static zfs_snapentry_t * zfsctl_snapshot_find_by_name(char *snapname) { zfs_snapentry_t *se, search; ASSERT(RW_LOCK_HELD(&zfs_snapshot_lock)); search.se_name = snapname; se = avl_find(&zfs_snapshots_by_name, &search, NULL); if (se) refcount_add(&se->se_refcount, NULL); return (se); } /* * Find a zfs_snapentry_t in zfs_snapshots_by_objsetid given the objset id * rather than the snapname. In all other respects it behaves the same * as zfsctl_snapshot_find_by_name(). */ static zfs_snapentry_t * zfsctl_snapshot_find_by_objsetid(spa_t *spa, uint64_t objsetid) { zfs_snapentry_t *se, search; ASSERT(RW_LOCK_HELD(&zfs_snapshot_lock)); search.se_spa = spa; search.se_objsetid = objsetid; se = avl_find(&zfs_snapshots_by_objsetid, &search, NULL); if (se) refcount_add(&se->se_refcount, NULL); return (se); } /* * Rename a zfs_snapentry_t in the zfs_snapshots_by_name. The structure is * removed, renamed, and added back to the new correct location in the tree. */ static int zfsctl_snapshot_rename(char *old_snapname, char *new_snapname) { zfs_snapentry_t *se; ASSERT(RW_WRITE_HELD(&zfs_snapshot_lock)); se = zfsctl_snapshot_find_by_name(old_snapname); if (se == NULL) return (ENOENT); zfsctl_snapshot_remove(se); strfree(se->se_name); se->se_name = strdup(new_snapname); zfsctl_snapshot_add(se); zfsctl_snapshot_rele(se); return (0); } /* * Delayed task responsible for unmounting an expired automounted snapshot. */ static void snapentry_expire(void *data) { zfs_snapentry_t *se = (zfs_snapentry_t *)data; spa_t *spa = se->se_spa; uint64_t objsetid = se->se_objsetid; if (zfs_expire_snapshot <= 0) { zfsctl_snapshot_rele(se); return; } se->se_taskqid = -1; (void) zfsctl_snapshot_unmount(se->se_name, MNT_EXPIRE); zfsctl_snapshot_rele(se); /* * Reschedule the unmount if the zfs_snapentry_t wasn't removed. * This can occur when the snapshot is busy. */ rw_enter(&zfs_snapshot_lock, RW_READER); if ((se = zfsctl_snapshot_find_by_objsetid(spa, objsetid)) != NULL) { zfsctl_snapshot_unmount_delay_impl(se, zfs_expire_snapshot); zfsctl_snapshot_rele(se); } rw_exit(&zfs_snapshot_lock); } /* * Cancel an automatic unmount of a snapname. This callback is responsible * for dropping the reference on the zfs_snapentry_t which was taken when * during dispatch. */ static void zfsctl_snapshot_unmount_cancel(zfs_snapentry_t *se) { ASSERT(RW_LOCK_HELD(&zfs_snapshot_lock)); if (taskq_cancel_id(zfs_expire_taskq, se->se_taskqid) == 0) { se->se_taskqid = -1; zfsctl_snapshot_rele(se); } } /* * Dispatch the unmount task for delayed handling with a hold protecting it. */ static void zfsctl_snapshot_unmount_delay_impl(zfs_snapentry_t *se, int delay) { ASSERT3S(se->se_taskqid, ==, -1); if (delay <= 0) return; zfsctl_snapshot_hold(se); se->se_taskqid = taskq_dispatch_delay(zfs_expire_taskq, snapentry_expire, se, TQ_SLEEP, ddi_get_lbolt() + delay * HZ); } /* * Schedule an automatic unmount of objset id to occur in delay seconds from * now. Any previous delayed unmount will be cancelled in favor of the * updated deadline. A reference is taken by zfsctl_snapshot_find_by_name() * and held until the outstanding task is handled or cancelled. */ int zfsctl_snapshot_unmount_delay(spa_t *spa, uint64_t objsetid, int delay) { zfs_snapentry_t *se; int error = ENOENT; rw_enter(&zfs_snapshot_lock, RW_READER); if ((se = zfsctl_snapshot_find_by_objsetid(spa, objsetid)) != NULL) { zfsctl_snapshot_unmount_cancel(se); zfsctl_snapshot_unmount_delay_impl(se, delay); zfsctl_snapshot_rele(se); error = 0; } rw_exit(&zfs_snapshot_lock); return (error); } /* * Check if snapname is currently mounted. Returned non-zero when mounted * and zero when unmounted. */ static boolean_t zfsctl_snapshot_ismounted(char *snapname) { zfs_snapentry_t *se; boolean_t ismounted = B_FALSE; rw_enter(&zfs_snapshot_lock, RW_READER); if ((se = zfsctl_snapshot_find_by_name(snapname)) != NULL) { zfsctl_snapshot_rele(se); ismounted = B_TRUE; } rw_exit(&zfs_snapshot_lock); return (ismounted); } /* * Check if the given inode is a part of the virtual .zfs directory. */ boolean_t zfsctl_is_node(struct inode *ip) { return (ITOZ(ip)->z_is_ctldir); } /* * Check if the given inode is a .zfs/snapshots/snapname directory. */ 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_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 = SUID_TO_KUID(0); ip->i_gid = SGID_TO_KGID(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); } /* * 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 (SET_ERROR(ENOENT)); return (0); #else return (SET_ERROR(EOPNOTSUPP)); #endif /* CONFIG_64BIT */ } /* * Destroy the '.zfs' directory or remove a snapshot from zfs_snapshots_by_name. * Only called when the filesystem is unmounted. */ void zfsctl_destroy(zfs_sb_t *zsb) { if (zsb->z_issnap) { zfs_snapentry_t *se; spa_t *spa = zsb->z_os->os_spa; uint64_t objsetid = dmu_objset_id(zsb->z_os); rw_enter(&zfs_snapshot_lock, RW_WRITER); if ((se = zfsctl_snapshot_find_by_objsetid(spa, objsetid)) != NULL) { zfsctl_snapshot_unmount_cancel(se); zfsctl_snapshot_remove(se); zfsctl_snapshot_rele(se); } rw_exit(&zfs_snapshot_lock); } else if (zsb->z_ctldir) { 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); } /* * Generate a long fid which includes the root object and objset of a * snapshot but not the generation number. For the root object the * generation number is ignored when zero to avoid needing to open * the dataset when generating fids for the snapshot names. */ static int zfsctl_snapdir_fid(struct inode *ip, fid_t *fidp) { zfs_sb_t *zsb = ITOZSB(ip); zfid_short_t *zfid = (zfid_short_t *)fidp; zfid_long_t *zlfid = (zfid_long_t *)fidp; uint32_t gen = 0; uint64_t object; uint64_t objsetid; int i; object = zsb->z_root; objsetid = ZFSCTL_INO_SNAPDIRS - ip->i_ino; zfid->zf_len = LONG_FID_LEN; for (i = 0; i < sizeof (zfid->zf_object); i++) zfid->zf_object[i] = (uint8_t)(object >> (8 * i)); for (i = 0; i < sizeof (zfid->zf_gen); i++) zfid->zf_gen[i] = (uint8_t)(gen >> (8 * i)); for (i = 0; i < sizeof (zlfid->zf_setid); i++) zlfid->zf_setid[i] = (uint8_t)(objsetid >> (8 * i)); for (i = 0; i < sizeof (zlfid->zf_setgen); i++) zlfid->zf_setgen[i] = 0; return (0); } /* * Generate an appropriate fid for an entry in the .zfs directory. */ 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 (SET_ERROR(ENOSPC)); } if (zfsctl_is_snapdir(ip)) { ZFS_EXIT(zsb); return (zfsctl_snapdir_fid(ip, fidp)); } 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); } /* * Construct a full dataset name in full_name: "pool/dataset@snap_name" */ static int zfsctl_snapshot_name(zfs_sb_t *zsb, const char *snap_name, int len, char *full_name) { objset_t *os = zsb->z_os; if (zfs_component_namecheck(snap_name, NULL, NULL) != 0) return (SET_ERROR(EILSEQ)); dmu_objset_name(os, full_name); if ((strlen(full_name) + 1 + strlen(snap_name)) >= len) return (SET_ERROR(ENAMETOOLONG)); (void) strcat(full_name, "@"); (void) strcat(full_name, snap_name); return (0); } /* * Returns full path in full_path: "/pool/dataset/.zfs/snapshot/snap_name/" */ static int zfsctl_snapshot_path(struct path *path, int len, char *full_path) { 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 = SET_ERROR(EFAULT); goto out; } memcpy(full_path, path_ptr, path_len); full_path[path_len] = '\0'; out: kmem_free(path_buffer, len); return (error); } /* * Returns full path in full_path: "/pool/dataset/.zfs/snapshot/snap_name/" */ static int zfsctl_snapshot_path_objset(zfs_sb_t *zsb, uint64_t objsetid, int path_len, char *full_path) { objset_t *os = zsb->z_os; fstrans_cookie_t cookie; char *snapname; boolean_t case_conflict; uint64_t id, pos = 0; int error = 0; if (zsb->z_mntopts->z_mntpoint == NULL) return (ENOENT); cookie = spl_fstrans_mark(); snapname = kmem_alloc(MAXNAMELEN, KM_SLEEP); while (error == 0) { dsl_pool_config_enter(dmu_objset_pool(os), FTAG); error = dmu_snapshot_list_next(zsb->z_os, MAXNAMELEN, snapname, &id, &pos, &case_conflict); dsl_pool_config_exit(dmu_objset_pool(os), FTAG); if (error) goto out; if (id == objsetid) break; } memset(full_path, 0, path_len); snprintf(full_path, path_len - 1, "%s/.zfs/snapshot/%s", zsb->z_mntopts->z_mntpoint, snapname); out: kmem_free(snapname, MAXNAMELEN); spl_fstrans_unmark(cookie); return (error); } /* * Special case the handling of "..". */ 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 = SET_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. */ 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 == NULL) error = SET_ERROR(ENOENT); ZFS_EXIT(zsb); return (error); } /* * 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. */ int zfsctl_snapdir_rename(struct inode *sdip, char *snm, struct inode *tdip, char *tnm, cred_t *cr, int flags) { zfs_sb_t *zsb = ITOZSB(sdip); char *to, *from, *real, *fsname; int error; if (!zfs_admin_snapshot) return (EACCES); ZFS_ENTER(zsb); to = kmem_alloc(MAXNAMELEN, KM_SLEEP); from = kmem_alloc(MAXNAMELEN, KM_SLEEP); real = kmem_alloc(MAXNAMELEN, KM_SLEEP); fsname = kmem_alloc(MAXNAMELEN, KM_SLEEP); if (zsb->z_case == ZFS_CASE_INSENSITIVE) { error = dmu_snapshot_realname(zsb->z_os, snm, real, MAXNAMELEN, NULL); if (error == 0) { snm = real; } else if (error != ENOTSUP) { goto out; } } dmu_objset_name(zsb->z_os, fsname); error = zfsctl_snapshot_name(ITOZSB(sdip), snm, MAXNAMELEN, from); if (error == 0) error = zfsctl_snapshot_name(ITOZSB(tdip), tnm, MAXNAMELEN, to); if (error == 0) error = zfs_secpolicy_rename_perms(from, to, cr); if (error != 0) goto out; /* * Cannot move snapshots out of the snapdir. */ if (sdip != tdip) { error = SET_ERROR(EINVAL); goto out; } /* * No-op when names are identical. */ if (strcmp(snm, tnm) == 0) { error = 0; goto out; } rw_enter(&zfs_snapshot_lock, RW_WRITER); error = dsl_dataset_rename_snapshot(fsname, snm, tnm, B_FALSE); if (error == 0) (void) zfsctl_snapshot_rename(snm, tnm); rw_exit(&zfs_snapshot_lock); out: kmem_free(from, MAXNAMELEN); kmem_free(to, MAXNAMELEN); kmem_free(real, MAXNAMELEN); kmem_free(fsname, MAXNAMELEN); ZFS_EXIT(zsb); return (error); } /* * Removing a directory under '.zfs/snapshot' will automatically trigger * the removal of the snapshot with the given name. */ 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; if (!zfs_admin_snapshot) return (EACCES); 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_name(ITOZSB(dip), name, MAXNAMELEN, snapname); if (error == 0) error = zfs_secpolicy_destroy_perms(snapname, cr); if (error != 0) goto out; error = zfsctl_snapshot_unmount(snapname, MNT_FORCE); if ((error == 0) || (error == ENOENT)) error = dsl_destroy_snapshot(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. */ 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; if (!zfs_admin_snapshot) return (EACCES); dsname = kmem_alloc(MAXNAMELEN, KM_SLEEP); if (zfs_component_namecheck(dirname, NULL, NULL) != 0) { error = SET_ERROR(EILSEQ); goto out; } dmu_objset_name(zsb->z_os, dsname); error = zfs_secpolicy_snapshot_perms(dsname, cr); if (error != 0) goto out; if (error == 0) { error = dmu_objset_snapshot_one(dsname, dirname); if (error != 0) goto out; error = zfsctl_snapdir_lookup(dip, dirname, ipp, 0, cr, NULL, NULL); } out: kmem_free(dsname, MAXNAMELEN); return (error); } /* * 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 " \ " 2>/dev/null; " \ "umount -t zfs -n %s'%s'" int zfsctl_snapshot_unmount(char *snapname, int flags) { char *argv[] = { "/bin/sh", "-c", NULL, NULL }; char *envp[] = { NULL }; zfs_snapentry_t *se; int error; rw_enter(&zfs_snapshot_lock, RW_READER); if ((se = zfsctl_snapshot_find_by_name(snapname)) == NULL) { rw_exit(&zfs_snapshot_lock); return (ENOENT); } rw_exit(&zfs_snapshot_lock); argv[2] = kmem_asprintf(SET_UNMOUNT_CMD, flags & MNT_FORCE ? "-f " : "", se->se_path); dprintf("unmount; path=%s\n", se->se_path); error = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC); strfree(argv[2]); zfsctl_snapshot_rele(se); /* * 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 = SET_ERROR(EBUSY); return (error); } #define MOUNT_BUSY 0x80 /* Mount failed due to EBUSY (from mntent.h) */ #define SET_MOUNT_CMD \ "exec 0/dev/null " \ " 2>/dev/null; " \ "mount -t zfs -n '%s' '%s'" int zfsctl_snapshot_mount(struct path *path, int flags) { struct dentry *dentry = path->dentry; struct inode *ip = dentry->d_inode; zfs_sb_t *zsb; zfs_sb_t *snap_zsb; zfs_snapentry_t *se; char *full_name, *full_path; char *argv[] = { "/bin/sh", "-c", NULL, NULL }; char *envp[] = { NULL }; int error; struct path spath; if (ip == NULL) return (EISDIR); zsb = ITOZSB(ip); ZFS_ENTER(zsb); full_name = kmem_zalloc(MAXNAMELEN, KM_SLEEP); full_path = kmem_zalloc(MAXPATHLEN, KM_SLEEP); error = zfsctl_snapshot_name(zsb, dname(dentry), MAXNAMELEN, full_name); if (error) goto error; error = zfsctl_snapshot_path(path, MAXPATHLEN, full_path); if (error) goto error; /* * Multiple concurrent automounts of a snapshot are never allowed. * The snapshot may be manually mounted as many times as desired. */ if (zfsctl_snapshot_ismounted(full_name)) { error = 0; 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. * * If the user mode helper happens to return EBUSY, a concurrent * mount is already in progress in which case the error is ignored. * Take note that if the program was executed successfully the return * value from call_usermodehelper() will be (exitcode << 8 + signal). */ dprintf("mount; name=%s path=%s\n", full_name, full_path); 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) { if (!(error & MOUNT_BUSY << 8)) { cmn_err(CE_WARN, "Unable to automount %s/%s: %d", full_path, full_name, error); error = SET_ERROR(EISDIR); } else { /* * EBUSY, this could mean a concurrent mount, or the * snapshot has already been mounted at completely * different place. We return 0 so VFS will retry. For * the latter case the VFS will retry several times * and return ELOOP, which is probably not a very good * behavior. */ error = 0; } goto error; } /* * Follow down in to the mounted snapshot and set MNT_SHRINKABLE * to identify this as an automounted filesystem. */ spath = *path; path_get(&spath); if (zpl_follow_down_one(&spath)) { snap_zsb = ITOZSB(spath.dentry->d_inode); snap_zsb->z_parent = zsb; dentry = spath.dentry; spath.mnt->mnt_flags |= MNT_SHRINKABLE; rw_enter(&zfs_snapshot_lock, RW_WRITER); se = zfsctl_snapshot_alloc(full_name, full_path, snap_zsb->z_os->os_spa, dmu_objset_id(snap_zsb->z_os), dentry); zfsctl_snapshot_add(se); zfsctl_snapshot_unmount_delay_impl(se, zfs_expire_snapshot); rw_exit(&zfs_snapshot_lock); } path_put(&spath); error: kmem_free(full_name, MAXNAMELEN); kmem_free(full_path, MAXPATHLEN); ZFS_EXIT(zsb); return (error); } /* * Given the objset id of the snapshot return its zfs_sb_t as zsbp. */ int zfsctl_lookup_objset(struct super_block *sb, uint64_t objsetid, zfs_sb_t **zsbp) { zfs_snapentry_t *se; int error; spa_t *spa = ((zfs_sb_t *)(sb->s_fs_info))->z_os->os_spa; /* * Verify that the snapshot is mounted then 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 zfs_snapshot_lock to prevent the race. */ rw_enter(&zfs_snapshot_lock, RW_READER); if ((se = zfsctl_snapshot_find_by_objsetid(spa, objsetid)) != NULL) { zfs_sb_t *zsb; zsb = ITOZSB(se->se_root_dentry->d_inode); ASSERT3U(dmu_objset_id(zsb->z_os), ==, objsetid); if (time_after(jiffies, zsb->z_snap_defer_time + MAX(zfs_expire_snapshot * HZ / 2, HZ))) { zsb->z_snap_defer_time = jiffies; zfsctl_snapshot_unmount_cancel(se); zfsctl_snapshot_unmount_delay_impl(se, zfs_expire_snapshot); } *zsbp = zsb; zfsctl_snapshot_rele(se); error = SET_ERROR(0); } else { error = SET_ERROR(ENOENT); } rw_exit(&zfs_snapshot_lock); /* * Automount the snapshot given the objset id by constructing the * full mount point and performing a traversal. */ if (error == ENOENT) { struct path path; char *mnt; mnt = kmem_alloc(MAXPATHLEN, KM_SLEEP); error = zfsctl_snapshot_path_objset(sb->s_fs_info, objsetid, MAXPATHLEN, mnt); if (error) { kmem_free(mnt, MAXPATHLEN); return (SET_ERROR(error)); } error = kern_path(mnt, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &path); if (error == 0) { *zsbp = ITOZSB(path.dentry->d_inode); path_put(&path); } kmem_free(mnt, MAXPATHLEN); } return (error); } 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 (SET_ERROR(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) { avl_create(&zfs_snapshots_by_name, snapentry_compare_by_name, sizeof (zfs_snapentry_t), offsetof(zfs_snapentry_t, se_node_name)); avl_create(&zfs_snapshots_by_objsetid, snapentry_compare_by_objsetid, sizeof (zfs_snapentry_t), offsetof(zfs_snapentry_t, se_node_objsetid)); rw_init(&zfs_snapshot_lock, NULL, RW_DEFAULT, NULL); zfs_expire_taskq = taskq_create("z_unmount", 1, defclsyspri, 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); avl_destroy(&zfs_snapshots_by_name); avl_destroy(&zfs_snapshots_by_objsetid); rw_destroy(&zfs_snapshot_lock); } module_param(zfs_admin_snapshot, int, 0644); MODULE_PARM_DESC(zfs_admin_snapshot, "Enable mkdir/rmdir/mv in .zfs/snapshot"); module_param(zfs_expire_snapshot, int, 0644); MODULE_PARM_DESC(zfs_expire_snapshot, "Seconds to expire .zfs/snapshot");