diff options
Diffstat (limited to 'module/zfs/zfs_ctldir.c')
| -rw-r--r-- | module/zfs/zfs_ctldir.c | 736 |
1 files changed, 420 insertions, 316 deletions
diff --git a/module/zfs/zfs_ctldir.c b/module/zfs/zfs_ctldir.c index efa6cfa0a..f0aff7b45 100644 --- a/module/zfs/zfs_ctldir.c +++ b/module/zfs/zfs_ctldir.c @@ -88,6 +88,22 @@ #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 kmutex_t zfs_snapshot_lock; + +/* * Control Directory Tunables (.zfs) */ int zfs_expire_snapshot = ZFSCTL_EXPIRE_SNAPSHOT; @@ -97,45 +113,116 @@ int zfs_expire_snapshot = ZFSCTL_EXPIRE_SNAPSHOT; */ static taskq_t *zfs_expire_taskq; +typedef struct { + char *se_name; /* full snapshot name */ + char *se_path; /* full mount path */ + 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_sep_alloc(void) +zfsctl_snapshot_alloc(char *full_name, char *full_path, uint64_t objsetid, + struct dentry *root_dentry) { - return (kmem_zalloc(sizeof (zfs_snapentry_t), KM_SLEEP)); + 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_objsetid = objsetid; + se->se_root_dentry = root_dentry; + se->se_taskqid = -1; + + refcount_create(&se->se_refcount); + + return (se); } -void -zfsctl_sep_free(zfs_snapentry_t *sep) +/* + * Free a zfs_snapentry_t the called must ensure there are no active + * references. + */ +static void +zfsctl_snapshot_free(zfs_snapentry_t *se) { - kmem_free(sep->se_name, MAXNAMELEN); - kmem_free(sep->se_path, PATH_MAX); - kmem_free(sep, sizeof (zfs_snapentry_t)); + refcount_destroy(&se->se_refcount); + strfree(se->se_name); + strfree(se->se_path); + + kmem_free(se, 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. + * Hold a reference on the zfs_snapentry_t. */ static void -zfsctl_expire_snapshot(void *data) +zfsctl_snapshot_hold(zfs_snapentry_t *se) { - zfs_snapentry_t *sep = (zfs_snapentry_t *)data; - zfs_sb_t *zsb = ITOZSB(sep->se_inode); - int error; + 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); +} - 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); +/* + * 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(MUTEX_HELD(&zfs_snapshot_lock)); + refcount_add(&se->se_refcount, NULL); + avl_add(&zfs_snapshots_by_name, se); + avl_add(&zfs_snapshots_by_objsetid, se); } -int -snapentry_compare(const void *a, const void *b) +/* + * 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(MUTEX_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 *sa = a; - const zfs_snapentry_t *sb = b; - int ret = strcmp(sa->se_name, sb->se_name); + 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); @@ -145,12 +232,199 @@ snapentry_compare(const void *a, const void *b) 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_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(MUTEX_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(uint64_t objsetid) +{ + zfs_snapentry_t *se, search; + + ASSERT(MUTEX_HELD(&zfs_snapshot_lock)); + + 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(MUTEX_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; + uint64_t objsetid = se->se_objsetid; + + 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. + */ + mutex_enter(&zfs_snapshot_lock); + if ((se = zfsctl_snapshot_find_by_objsetid(objsetid)) != NULL) { + zfsctl_snapshot_unmount_delay_impl(se, zfs_expire_snapshot); + zfsctl_snapshot_rele(se); + } + mutex_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(MUTEX_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); + + se->se_taskqid = taskq_dispatch_delay(zfs_expire_taskq, + snapentry_expire, se, TQ_SLEEP, ddi_get_lbolt() + delay * HZ); + zfsctl_snapshot_hold(se); +} + +/* + * 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(uint64_t objsetid, int delay) +{ + zfs_snapentry_t *se; + int error = ENOENT; + + mutex_enter(&zfs_snapshot_lock); + if ((se = zfsctl_snapshot_find_by_objsetid(objsetid)) != NULL) { + zfsctl_snapshot_unmount_cancel(se); + zfsctl_snapshot_unmount_delay_impl(se, delay); + zfsctl_snapshot_rele(se); + error = 0; + } + mutex_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; + + mutex_enter(&zfs_snapshot_lock); + if ((se = zfsctl_snapshot_find_by_name(snapname)) != NULL) { + zfsctl_snapshot_rele(se); + ismounted = B_TRUE; + } + mutex_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) { @@ -250,24 +524,6 @@ zfsctl_inode_lookup(zfs_sb_t *zsb, uint64_t id, } /* - * Free zfsctl inode specific structures, currently there are none. - */ -void -zfsctl_inode_destroy(struct inode *ip) -{ -} - -/* - * 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 @@ -295,13 +551,27 @@ zfsctl_create(zfs_sb_t *zsb) } /* - * Destroy the '.zfs' directory. Only called when the filesystem is unmounted. + * 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) { - iput(zsb->z_ctldir); - zsb->z_ctldir = NULL; + if (zsb->z_issnap) { + zfs_snapentry_t *se; + uint64_t objsetid = dmu_objset_id(zsb->z_os); + + mutex_enter(&zfs_snapshot_lock); + if ((se = zfsctl_snapshot_find_by_objsetid(objsetid)) != NULL) { + zfsctl_snapshot_unmount_cancel(se); + zfsctl_snapshot_remove(se); + zfsctl_snapshot_rele(se); + } + mutex_exit(&zfs_snapshot_lock); + } else if (zsb->z_ctldir) { + iput(zsb->z_ctldir); + zsb->z_ctldir = NULL; + } } /* @@ -316,7 +586,6 @@ zfsctl_root(znode_t *zp) return (ZTOZSB(zp)->z_ctldir); } -/*ARGSUSED*/ int zfsctl_fid(struct inode *ip, fid_t *fidp) { @@ -349,31 +618,33 @@ zfsctl_fid(struct inode *ip, fid_t *fidp) return (0); } +/* + * Construct a full dataset name in full_name: "pool/dataset@snap_name" + */ static int -zfsctl_snapshot_zname(struct inode *ip, const char *name, int len, char *zname) +zfsctl_snapshot_name(zfs_sb_t *zsb, const char *snap_name, int len, + char *full_name) { - objset_t *os = ITOZSB(ip)->z_os; + objset_t *os = zsb->z_os; - if (zfs_component_namecheck(name, NULL, NULL) != 0) + if (zfs_component_namecheck(snap_name, NULL, NULL) != 0) return (SET_ERROR(EILSEQ)); - dmu_objset_name(os, zname); - if ((strlen(zname) + 1 + strlen(name)) >= len) + dmu_objset_name(os, full_name); + if ((strlen(full_name) + 1 + strlen(snap_name)) >= len) return (SET_ERROR(ENAMETOOLONG)); - (void) strcat(zname, "@"); - (void) strcat(zname, name); + (void) strcat(full_name, "@"); + (void) strcat(full_name, snap_name); return (0); } /* - * Gets the full dataset name that corresponds to the given snapshot name - * Example: - * zfsctl_snapshot_zname("snap1") -> "mypool/myfs@snap1" + * Returns full path in full_path: "/pool/dataset/.zfs/snapshot/snap_name/" */ static int -zfsctl_snapshot_zpath(struct path *path, int len, char *zpath) +zfsctl_snapshot_path(struct path *path, int len, char *full_path) { char *path_buffer, *path_ptr; int path_len, error = 0; @@ -392,8 +663,8 @@ zfsctl_snapshot_zpath(struct path *path, int len, char *zpath) goto out; } - memcpy(zpath, path_ptr, path_len); - zpath[path_len] = '\0'; + memcpy(full_path, path_ptr, path_len); + full_path[path_len] = '\0'; out: kmem_free(path_buffer, len); @@ -403,7 +674,6 @@ out: /* * 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) @@ -438,7 +708,6 @@ zfsctl_root_lookup(struct inode *dip, char *name, struct inode **ipp, * 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) @@ -457,49 +726,24 @@ zfsctl_snapdir_lookup(struct inode *dip, char *name, struct inode **ipp, *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 { + if (*ipp == NULL) error = SET_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 *snm, struct inode *tdip, char *tnm, cred_t *cr, int flags) { zfs_sb_t *zsb = ITOZSB(sdip); - zfs_snapentry_t search, *sep; - avl_index_t where; char *to, *from, *real, *fsname; int error; @@ -522,9 +766,9 @@ zfsctl_snapdir_rename(struct inode *sdip, char *snm, dmu_objset_name(zsb->z_os, fsname); - error = zfsctl_snapshot_zname(sdip, snm, MAXNAMELEN, from); + error = zfsctl_snapshot_name(ITOZSB(sdip), snm, MAXNAMELEN, from); if (error == 0) - error = zfsctl_snapshot_zname(tdip, tnm, MAXNAMELEN, to); + error = zfsctl_snapshot_name(ITOZSB(tdip), tnm, MAXNAMELEN, to); if (error == 0) error = zfs_secpolicy_rename_perms(from, to, cr); if (error != 0) @@ -546,19 +790,13 @@ zfsctl_snapdir_rename(struct inode *sdip, char *snm, goto out; } - mutex_enter(&zsb->z_ctldir_lock); + mutex_enter(&zfs_snapshot_lock); error = dsl_dataset_rename_snapshot(fsname, snm, tnm, B_FALSE); - if (error) - goto out_unlock; - - search.se_name = (char *)snm; - sep = avl_find(&zsb->z_ctldir_snaps, &search, &where); - if (sep) - zfsctl_rename_snap(zsb, sep, tnm); + if (error == 0) + (void) zfsctl_snapshot_rename(snm, tnm); -out_unlock: - mutex_exit(&zsb->z_ctldir_lock); + mutex_exit(&zfs_snapshot_lock); out: kmem_free(from, MAXNAMELEN); kmem_free(to, MAXNAMELEN); @@ -574,7 +812,6 @@ out: * 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) { @@ -597,13 +834,13 @@ zfsctl_snapdir_remove(struct inode *dip, char *name, cred_t *cr, int flags) } } - error = zfsctl_snapshot_zname(dip, name, MAXNAMELEN, snapname); + 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_unmount_snapshot(zsb, name, MNT_FORCE); + error = zfsctl_snapshot_unmount(snapname, MNT_FORCE); if ((error == 0) || (error == ENOENT)) error = dsl_destroy_snapshot(snapname, B_FALSE); out: @@ -619,7 +856,6 @@ out: * 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) @@ -656,36 +892,6 @@ out: } /* - * 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 @@ -697,18 +903,29 @@ zfsctl_snapdir_inactive(struct inode *ip) " 2>/dev/null; " \ "umount -t zfs -n %s'%s'" -static int -__zfsctl_unmount_snapshot(zfs_snapentry_t *sep, int flags) +int +zfsctl_snapshot_unmount(char *snapname, int flags) { char *argv[] = { "/bin/sh", "-c", NULL, NULL }; char *envp[] = { NULL }; + zfs_snapentry_t *se; int error; + mutex_enter(&zfs_snapshot_lock); + if ((se = zfsctl_snapshot_find_by_name(snapname)) == NULL) { + mutex_exit(&zfs_snapshot_lock); + return (ENOENT); + } + mutex_exit(&zfs_snapshot_lock); + argv[2] = kmem_asprintf(SET_UNMOUNT_CMD, - flags & MNT_FORCE ? "-f " : "", sep->se_path); + flags & MNT_FORCE ? "-f " : "", se->se_path); + zfsctl_snapshot_rele(se); + dprintf("unmount; path=%s\n", se->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 @@ -717,91 +934,10 @@ __zfsctl_unmount_snapshot(zfs_snapentry_t *sep, int flags) if (error) error = SET_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); - mutex_exit(&zsb->z_ctldir_lock); - - error = __zfsctl_unmount_snapshot(sep, flags); - - mutex_enter(&zsb->z_ctldir_lock); - if (error == EBUSY) - avl_add(&zsb->z_ctldir_snaps, sep); - else - zfsctl_sep_free(sep); - } else { - error = SET_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); - mutex_exit(&zsb->z_ctldir_lock); - - error = __zfsctl_unmount_snapshot(sep, flags); - - mutex_enter(&zsb->z_ctldir_lock); - 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 MOUNT_BUSY 0x80 /* Mount failed due to EBUSY (from mntent.h) */ - #define SET_MOUNT_CMD \ "exec 0</dev/null " \ " 1>/dev/null " \ @@ -809,32 +945,46 @@ zfsctl_unmount_snapshots(zfs_sb_t *zsb, int flags, int *count) "mount -t zfs -n '%s' '%s'" int -zfsctl_mount_snapshot(struct path *path, int flags) +zfsctl_snapshot_mount(struct path *path, int flags) { struct dentry *dentry = path->dentry; struct inode *ip = dentry->d_inode; - zfs_sb_t *zsb = ITOZSB(ip); + zfs_sb_t *zsb; + zfs_sb_t *snap_zsb; + zfs_snapentry_t *se; 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; + if (ip == NULL) + return (EISDIR); + + zsb = ITOZSB(ip); ZFS_ENTER(zsb); full_name = kmem_zalloc(MAXNAMELEN, KM_SLEEP); - full_path = kmem_zalloc(PATH_MAX, KM_SLEEP); + full_path = kmem_zalloc(MAXPATHLEN, KM_SLEEP); - error = zfsctl_snapshot_zname(ip, dname(dentry), MAXNAMELEN, full_name); + error = zfsctl_snapshot_name(zsb, dname(dentry), + MAXNAMELEN, full_name); if (error) goto error; - error = zfsctl_snapshot_zpath(path, PATH_MAX, full_path); + 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 = SET_ERROR(EISDIR); + 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 @@ -846,48 +996,37 @@ zfsctl_mount_snapshot(struct path *path, int flags) * 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 && !(error & MOUNT_BUSY << 8)) { - printk("ZFS: Unable to automount %s at %s: %d\n", - full_name, full_path, error); + cmn_err(CE_WARN, "Unable to automount %s/%s: %d", + full_path, full_name, error); error = SET_ERROR(EISDIR); goto error; } - error = 0; - 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. + * Follow down in to the mounted snapshot and set MNT_SHRINKABLE + * to identify this as an automounted filesystem. */ - 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); + zpl_follow_down_one(path); + snap_zsb = ITOZSB(path->dentry->d_inode); + dentry = path->dentry; + path->mnt->mnt_flags |= MNT_SHRINKABLE; + zpl_follow_up(path); + error = 0; - mutex_exit(&zsb->z_ctldir_lock); + mutex_enter(&zfs_snapshot_lock); + se = zfsctl_snapshot_alloc(full_name, full_path, + dmu_objset_id(snap_zsb->z_os), dentry); + zfsctl_snapshot_add(se); + zfsctl_snapshot_unmount_delay_impl(se, zfs_expire_snapshot); + mutex_exit(&zfs_snapshot_lock); error: - if (error) { - kmem_free(full_name, MAXNAMELEN); - kmem_free(full_path, PATH_MAX); - } + kmem_free(full_name, MAXNAMELEN); + kmem_free(full_path, MAXPATHLEN); ZFS_EXIT(zsb); @@ -895,82 +1034,35 @@ 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. + * Given the objset id of the snapshot return its zfs_sb_t as zsbp. */ -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; + zfs_snapentry_t *se; int error; - ASSERT(zsb->z_ctldir != NULL); - - mutex_enter(&zsb->z_ctldir_lock); - /* - * Verify that the snapshot is mounted. + * 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. */ - 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); - } + mutex_enter(&zfs_snapshot_lock); + if ((se = zfsctl_snapshot_find_by_objsetid(objsetid)) != NULL) { + *zsbp = ITOZSB(se->se_root_dentry->d_inode); + ASSERT3U(dmu_objset_id((*zsbp)->z_os), ==, objsetid); + zfsctl_snapshot_rele(se); + error = SET_ERROR(0); } else { - error = SET_ERROR(EINVAL); + error = SET_ERROR(ENOENT); } -out: - mutex_exit(&zsb->z_ctldir_lock); - ASSERT3S(error, >=, 0); + mutex_exit(&zfs_snapshot_lock); 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) @@ -1009,6 +1101,14 @@ zfsctl_shares_lookup(struct inode *dip, char *name, struct inode **ipp, 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)); + mutex_init(&zfs_snapshot_lock, NULL, MUTEX_DEFAULT, NULL); + zfs_expire_taskq = taskq_create("z_unmount", 1, defclsyspri, 1, 8, TASKQ_PREPOPULATE); } @@ -1021,6 +1121,10 @@ void zfsctl_fini(void) { taskq_destroy(zfs_expire_taskq); + + avl_destroy(&zfs_snapshots_by_name); + avl_destroy(&zfs_snapshots_by_objsetid); + mutex_destroy(&zfs_snapshot_lock); } module_param(zfs_expire_snapshot, int, 0644); |