diff options
Diffstat (limited to 'module/zfs/zfs_ctldir.c')
| -rw-r--r-- | module/zfs/zfs_ctldir.c | 1159 |
1 files changed, 1159 insertions, 0 deletions
diff --git a/module/zfs/zfs_ctldir.c b/module/zfs/zfs_ctldir.c new file mode 100644 index 000000000..208fc3629 --- /dev/null +++ b/module/zfs/zfs_ctldir.c @@ -0,0 +1,1159 @@ +/* + * 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 2008 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +#pragma ident "%Z%%M% %I% %E% SMI" + +/* + * ZFS control directory (a.k.a. ".zfs") + * + * This directory provides a common location for all ZFS meta-objects. + * Currently, this is only the 'snapshot' directory, but this may expand in the + * future. The elements are built using the GFS primitives, 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 vnode. + * + * All mounts are handled automatically by the kernel, but unmounts are + * (currently) handled from user land. The main reason is that there is no + * reliable way to auto-unmount the filesystem when it's "no longer in use". + * When the user unmounts a filesystem, we call zfsctl_unmount(), which + * unmounts any snapshots within the snapshot directory. + * + * The '.zfs', '.zfs/snapshot', and all directories created under + * '.zfs/snapshot' (ie: '.zfs/snapshot/<snapname>') are all GFS nodes and + * share the same vfs_t as the head filesystem (what '.zfs' lives under). + * + * File systems mounted ontop of the GFS nodes '.zfs/snapshot/<snapname>' + * (ie: snapshots) are ZFS nodes and have their own unique vfs_t. + * However, vnodes within these mounted on file systems have their v_vfsp + * fields set to the head filesystem to make NFS happy (see + * zfsctl_snapdir_lookup()). We VFS_HOLD the head filesystem's vfs_t + * so that it cannot be freed until all snapshots have been unmounted. + */ + +#include <fs/fs_subr.h> +#include <sys/zfs_ctldir.h> +#include <sys/zfs_ioctl.h> +#include <sys/zfs_vfsops.h> +#include <sys/vfs_opreg.h> +#include <sys/gfs.h> +#include <sys/stat.h> +#include <sys/dmu.h> +#include <sys/dsl_deleg.h> +#include <sys/mount.h> +#include <sys/sunddi.h> + +#include "zfs_namecheck.h" + +typedef struct zfsctl_node { + gfs_dir_t zc_gfs_private; + uint64_t zc_id; + timestruc_t zc_cmtime; /* ctime and mtime, always the same */ +} zfsctl_node_t; + +typedef struct zfsctl_snapdir { + zfsctl_node_t sd_node; + kmutex_t sd_lock; + avl_tree_t sd_snaps; +} zfsctl_snapdir_t; + +typedef struct { + char *se_name; + vnode_t *se_root; + avl_node_t se_node; +} zfs_snapentry_t; + +static 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); +} + +vnodeops_t *zfsctl_ops_root; +vnodeops_t *zfsctl_ops_snapdir; +vnodeops_t *zfsctl_ops_snapshot; + +static const fs_operation_def_t zfsctl_tops_root[]; +static const fs_operation_def_t zfsctl_tops_snapdir[]; +static const fs_operation_def_t zfsctl_tops_snapshot[]; + +static vnode_t *zfsctl_mknode_snapdir(vnode_t *); +static vnode_t *zfsctl_snapshot_mknode(vnode_t *, uint64_t objset); +static int zfsctl_unmount_snap(zfs_snapentry_t *, int, cred_t *); + +static gfs_opsvec_t zfsctl_opsvec[] = { + { ".zfs", zfsctl_tops_root, &zfsctl_ops_root }, + { ".zfs/snapshot", zfsctl_tops_snapdir, &zfsctl_ops_snapdir }, + { ".zfs/snapshot/vnode", zfsctl_tops_snapshot, &zfsctl_ops_snapshot }, + { NULL } +}; + +/* + * Root directory elements. We have only a single static entry, 'snapshot'. + */ +static gfs_dirent_t zfsctl_root_entries[] = { + { "snapshot", zfsctl_mknode_snapdir, GFS_CACHE_VNODE }, + { NULL } +}; + +/* include . and .. in the calculation */ +#define NROOT_ENTRIES ((sizeof (zfsctl_root_entries) / \ + sizeof (gfs_dirent_t)) + 1) + + +/* + * Initialize the various GFS pieces we'll need to create and manipulate .zfs + * directories. This is called from the ZFS init routine, and initializes the + * vnode ops vectors that we'll be using. + */ +void +zfsctl_init(void) +{ + VERIFY(gfs_make_opsvec(zfsctl_opsvec) == 0); +} + +void +zfsctl_fini(void) +{ + /* + * Remove vfsctl vnode ops + */ + if (zfsctl_ops_root) + vn_freevnodeops(zfsctl_ops_root); + if (zfsctl_ops_snapdir) + vn_freevnodeops(zfsctl_ops_snapdir); + if (zfsctl_ops_snapshot) + vn_freevnodeops(zfsctl_ops_snapshot); + + zfsctl_ops_root = NULL; + zfsctl_ops_snapdir = NULL; + zfsctl_ops_snapshot = NULL; +} + +/* + * Return the inode number associated with the 'snapshot' directory. + */ +/* ARGSUSED */ +static ino64_t +zfsctl_root_inode_cb(vnode_t *vp, int index) +{ + ASSERT(index == 0); + return (ZFSCTL_INO_SNAPDIR); +} + +/* + * Create the '.zfs' directory. This directory is cached as part of the VFS + * structure. This results in a hold on the vfs_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. + */ +void +zfsctl_create(zfsvfs_t *zfsvfs) +{ + vnode_t *vp, *rvp; + zfsctl_node_t *zcp; + + ASSERT(zfsvfs->z_ctldir == NULL); + + vp = gfs_root_create(sizeof (zfsctl_node_t), zfsvfs->z_vfs, + zfsctl_ops_root, ZFSCTL_INO_ROOT, zfsctl_root_entries, + zfsctl_root_inode_cb, MAXNAMELEN, NULL, NULL); + zcp = vp->v_data; + zcp->zc_id = ZFSCTL_INO_ROOT; + + VERIFY(VFS_ROOT(zfsvfs->z_vfs, &rvp) == 0); + ZFS_TIME_DECODE(&zcp->zc_cmtime, VTOZ(rvp)->z_phys->zp_crtime); + VN_RELE(rvp); + + /* + * We're only faking the fact that we have a root of a filesystem for + * the sake of the GFS interfaces. Undo the flag manipulation it did + * for us. + */ + vp->v_flag &= ~(VROOT | VNOCACHE | VNOMAP | VNOSWAP | VNOMOUNT); + + zfsvfs->z_ctldir = vp; +} + +/* + * Destroy the '.zfs' directory. Only called when the filesystem is unmounted. + * There might still be more references if we were force unmounted, but only + * new zfs_inactive() calls can occur and they don't reference .zfs + */ +void +zfsctl_destroy(zfsvfs_t *zfsvfs) +{ + VN_RELE(zfsvfs->z_ctldir); + zfsvfs->z_ctldir = NULL; +} + +/* + * Given a root znode, retrieve the associated .zfs directory. + * Add a hold to the vnode and return it. + */ +vnode_t * +zfsctl_root(znode_t *zp) +{ + ASSERT(zfs_has_ctldir(zp)); + VN_HOLD(zp->z_zfsvfs->z_ctldir); + return (zp->z_zfsvfs->z_ctldir); +} + +/* + * Common open routine. Disallow any write access. + */ +/* ARGSUSED */ +static int +zfsctl_common_open(vnode_t **vpp, int flags, cred_t *cr, caller_context_t *ct) +{ + if (flags & FWRITE) + return (EACCES); + + return (0); +} + +/* + * Common close routine. Nothing to do here. + */ +/* ARGSUSED */ +static int +zfsctl_common_close(vnode_t *vpp, int flags, int count, offset_t off, + cred_t *cr, caller_context_t *ct) +{ + return (0); +} + +/* + * Common access routine. Disallow writes. + */ +/* ARGSUSED */ +static int +zfsctl_common_access(vnode_t *vp, int mode, int flags, cred_t *cr, + caller_context_t *ct) +{ + if (mode & VWRITE) + return (EACCES); + + return (0); +} + +/* + * Common getattr function. Fill in basic information. + */ +static void +zfsctl_common_getattr(vnode_t *vp, vattr_t *vap) +{ + zfsctl_node_t *zcp = vp->v_data; + timestruc_t now; + + vap->va_uid = 0; + vap->va_gid = 0; + vap->va_rdev = 0; + /* + * We are a purly virtual object, so we have no + * blocksize or allocated blocks. + */ + vap->va_blksize = 0; + vap->va_nblocks = 0; + vap->va_seq = 0; + vap->va_fsid = vp->v_vfsp->vfs_dev; + vap->va_mode = S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | + S_IROTH | S_IXOTH; + vap->va_type = VDIR; + /* + * We live in the now (for atime). + */ + gethrestime(&now); + vap->va_atime = now; + vap->va_mtime = vap->va_ctime = zcp->zc_cmtime; +} + +/*ARGSUSED*/ +static int +zfsctl_common_fid(vnode_t *vp, fid_t *fidp, caller_context_t *ct) +{ + zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data; + zfsctl_node_t *zcp = vp->v_data; + uint64_t object = zcp->zc_id; + zfid_short_t *zfid; + int i; + + ZFS_ENTER(zfsvfs); + + if (fidp->fid_len < SHORT_FID_LEN) { + fidp->fid_len = SHORT_FID_LEN; + ZFS_EXIT(zfsvfs); + 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(zfsvfs); + return (0); +} + +/* + * .zfs inode namespace + * + * We need to generate unique inode numbers for all files and directories + * within the .zfs pseudo-filesystem. We use the following scheme: + * + * ENTRY ZFSCTL_INODE + * .zfs 1 + * .zfs/snapshot 2 + * .zfs/snapshot/<snap> objectid(snap) + */ + +#define ZFSCTL_INO_SNAP(id) (id) + +/* + * Get root directory attributes. + */ +/* ARGSUSED */ +static int +zfsctl_root_getattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr, + caller_context_t *ct) +{ + zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data; + + ZFS_ENTER(zfsvfs); + vap->va_nodeid = ZFSCTL_INO_ROOT; + vap->va_nlink = vap->va_size = NROOT_ENTRIES; + + zfsctl_common_getattr(vp, vap); + ZFS_EXIT(zfsvfs); + + return (0); +} + +/* + * Special case the handling of "..". + */ +/* ARGSUSED */ +int +zfsctl_root_lookup(vnode_t *dvp, char *nm, vnode_t **vpp, pathname_t *pnp, + int flags, vnode_t *rdir, cred_t *cr, caller_context_t *ct, + int *direntflags, pathname_t *realpnp) +{ + zfsvfs_t *zfsvfs = dvp->v_vfsp->vfs_data; + int err; + + /* + * No extended attributes allowed under .zfs + */ + if (flags & LOOKUP_XATTR) + return (EINVAL); + + ZFS_ENTER(zfsvfs); + + if (strcmp(nm, "..") == 0) { + err = VFS_ROOT(dvp->v_vfsp, vpp); + } else { + err = gfs_vop_lookup(dvp, nm, vpp, pnp, flags, rdir, + cr, ct, direntflags, realpnp); + } + + ZFS_EXIT(zfsvfs); + + return (err); +} + +static const fs_operation_def_t zfsctl_tops_root[] = { + { VOPNAME_OPEN, { .vop_open = zfsctl_common_open } }, + { VOPNAME_CLOSE, { .vop_close = zfsctl_common_close } }, + { VOPNAME_IOCTL, { .error = fs_inval } }, + { VOPNAME_GETATTR, { .vop_getattr = zfsctl_root_getattr } }, + { VOPNAME_ACCESS, { .vop_access = zfsctl_common_access } }, + { VOPNAME_READDIR, { .vop_readdir = gfs_vop_readdir } }, + { VOPNAME_LOOKUP, { .vop_lookup = zfsctl_root_lookup } }, + { VOPNAME_SEEK, { .vop_seek = fs_seek } }, + { VOPNAME_INACTIVE, { .vop_inactive = gfs_vop_inactive } }, + { VOPNAME_FID, { .vop_fid = zfsctl_common_fid } }, + { NULL } +}; + +static int +zfsctl_snapshot_zname(vnode_t *vp, const char *name, int len, char *zname) +{ + objset_t *os = ((zfsvfs_t *)((vp)->v_vfsp->vfs_data))->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_unmount_snap(zfs_snapentry_t *sep, int fflags, cred_t *cr) +{ + vnode_t *svp = sep->se_root; + int error; + + ASSERT(vn_ismntpt(svp)); + + /* this will be dropped by dounmount() */ + if ((error = vn_vfswlock(svp)) != 0) + return (error); + + VN_HOLD(svp); + error = dounmount(vn_mountedvfs(svp), fflags, cr); + if (error) { + VN_RELE(svp); + return (error); + } + VFS_RELE(svp->v_vfsp); + /* + * We can't use VN_RELE(), as that will try to invoke + * zfsctl_snapdir_inactive(), which would cause us to destroy + * the sd_lock mutex held by our caller. + */ + ASSERT(svp->v_count == 1); + gfs_vop_inactive(svp, cr, NULL); + + kmem_free(sep->se_name, strlen(sep->se_name) + 1); + kmem_free(sep, sizeof (zfs_snapentry_t)); + + return (0); +} + +static void +zfsctl_rename_snap(zfsctl_snapdir_t *sdp, zfs_snapentry_t *sep, const char *nm) +{ + avl_index_t where; + vfs_t *vfsp; + refstr_t *pathref; + char newpath[MAXNAMELEN]; + char *tail; + + ASSERT(MUTEX_HELD(&sdp->sd_lock)); + ASSERT(sep != NULL); + + vfsp = vn_mountedvfs(sep->se_root); + ASSERT(vfsp != NULL); + + vfs_lock_wait(vfsp); + + /* + * Change the name in the AVL tree. + */ + avl_remove(&sdp->sd_snaps, sep); + kmem_free(sep->se_name, strlen(sep->se_name) + 1); + sep->se_name = kmem_alloc(strlen(nm) + 1, KM_SLEEP); + (void) strcpy(sep->se_name, nm); + VERIFY(avl_find(&sdp->sd_snaps, sep, &where) == NULL); + avl_insert(&sdp->sd_snaps, sep, where); + + /* + * Change the current mountpoint info: + * - update the tail of the mntpoint path + * - update the tail of the resource path + */ + pathref = vfs_getmntpoint(vfsp); + (void) strncpy(newpath, refstr_value(pathref), sizeof (newpath)); + VERIFY((tail = strrchr(newpath, '/')) != NULL); + *(tail+1) = '\0'; + ASSERT3U(strlen(newpath) + strlen(nm), <, sizeof (newpath)); + (void) strcat(newpath, nm); + refstr_rele(pathref); + vfs_setmntpoint(vfsp, newpath); + + pathref = vfs_getresource(vfsp); + (void) strncpy(newpath, refstr_value(pathref), sizeof (newpath)); + VERIFY((tail = strrchr(newpath, '@')) != NULL); + *(tail+1) = '\0'; + ASSERT3U(strlen(newpath) + strlen(nm), <, sizeof (newpath)); + (void) strcat(newpath, nm); + refstr_rele(pathref); + vfs_setresource(vfsp, newpath); + + vfs_unlock(vfsp); +} + +/*ARGSUSED*/ +static int +zfsctl_snapdir_rename(vnode_t *sdvp, char *snm, vnode_t *tdvp, char *tnm, + cred_t *cr, caller_context_t *ct, int flags) +{ + zfsctl_snapdir_t *sdp = sdvp->v_data; + zfs_snapentry_t search, *sep; + zfsvfs_t *zfsvfs; + avl_index_t where; + char from[MAXNAMELEN], to[MAXNAMELEN]; + char real[MAXNAMELEN]; + int err; + + zfsvfs = sdvp->v_vfsp->vfs_data; + ZFS_ENTER(zfsvfs); + + if ((flags & FIGNORECASE) || zfsvfs->z_case == ZFS_CASE_INSENSITIVE) { + err = dmu_snapshot_realname(zfsvfs->z_os, snm, real, + MAXNAMELEN, NULL); + if (err == 0) { + snm = real; + } else if (err != ENOTSUP) { + ZFS_EXIT(zfsvfs); + return (err); + } + } + + ZFS_EXIT(zfsvfs); + + err = zfsctl_snapshot_zname(sdvp, snm, MAXNAMELEN, from); + if (!err) + err = zfsctl_snapshot_zname(tdvp, tnm, MAXNAMELEN, to); + if (!err) + err = zfs_secpolicy_rename_perms(from, to, cr); + if (err) + return (err); + + /* + * Cannot move snapshots out of the snapdir. + */ + if (sdvp != tdvp) + return (EINVAL); + + if (strcmp(snm, tnm) == 0) + return (0); + + mutex_enter(&sdp->sd_lock); + + search.se_name = (char *)snm; + if ((sep = avl_find(&sdp->sd_snaps, &search, &where)) == NULL) { + mutex_exit(&sdp->sd_lock); + return (ENOENT); + } + + err = dmu_objset_rename(from, to, B_FALSE); + if (err == 0) + zfsctl_rename_snap(sdp, sep, tnm); + + mutex_exit(&sdp->sd_lock); + + return (err); +} + +/* ARGSUSED */ +static int +zfsctl_snapdir_remove(vnode_t *dvp, char *name, vnode_t *cwd, cred_t *cr, + caller_context_t *ct, int flags) +{ + zfsctl_snapdir_t *sdp = dvp->v_data; + zfs_snapentry_t *sep; + zfs_snapentry_t search; + zfsvfs_t *zfsvfs; + char snapname[MAXNAMELEN]; + char real[MAXNAMELEN]; + int err; + + zfsvfs = dvp->v_vfsp->vfs_data; + ZFS_ENTER(zfsvfs); + + if ((flags & FIGNORECASE) || zfsvfs->z_case == ZFS_CASE_INSENSITIVE) { + + err = dmu_snapshot_realname(zfsvfs->z_os, name, real, + MAXNAMELEN, NULL); + if (err == 0) { + name = real; + } else if (err != ENOTSUP) { + ZFS_EXIT(zfsvfs); + return (err); + } + } + + ZFS_EXIT(zfsvfs); + + err = zfsctl_snapshot_zname(dvp, name, MAXNAMELEN, snapname); + if (!err) + err = zfs_secpolicy_destroy_perms(snapname, cr); + if (err) + return (err); + + mutex_enter(&sdp->sd_lock); + + search.se_name = name; + sep = avl_find(&sdp->sd_snaps, &search, NULL); + if (sep) { + avl_remove(&sdp->sd_snaps, sep); + err = zfsctl_unmount_snap(sep, MS_FORCE, cr); + if (err) + avl_add(&sdp->sd_snaps, sep); + else + err = dmu_objset_destroy(snapname); + } else { + err = ENOENT; + } + + mutex_exit(&sdp->sd_lock); + + return (err); +} + +/* + * This creates a snapshot under '.zfs/snapshot'. + */ +/* ARGSUSED */ +static int +zfsctl_snapdir_mkdir(vnode_t *dvp, char *dirname, vattr_t *vap, vnode_t **vpp, + cred_t *cr, caller_context_t *cc, int flags, vsecattr_t *vsecp) +{ + zfsvfs_t *zfsvfs = dvp->v_vfsp->vfs_data; + char name[MAXNAMELEN]; + int err; + static enum symfollow follow = NO_FOLLOW; + static enum uio_seg seg = UIO_SYSSPACE; + + if (snapshot_namecheck(dirname, NULL, NULL) != 0) + return (EILSEQ); + + dmu_objset_name(zfsvfs->z_os, name); + + *vpp = NULL; + + err = zfs_secpolicy_snapshot_perms(name, cr); + if (err) + return (err); + + if (err == 0) { + err = dmu_objset_snapshot(name, dirname, B_FALSE); + if (err) + return (err); + err = lookupnameat(dirname, seg, follow, NULL, vpp, dvp); + } + + return (err); +} + +/* + * Lookup entry point for the 'snapshot' directory. Try to open the + * snapshot if it exist, creating the pseudo filesystem vnode as necessary. + * Perform a mount of the associated dataset on top of the vnode. + */ +/* ARGSUSED */ +static int +zfsctl_snapdir_lookup(vnode_t *dvp, char *nm, vnode_t **vpp, pathname_t *pnp, + int flags, vnode_t *rdir, cred_t *cr, caller_context_t *ct, + int *direntflags, pathname_t *realpnp) +{ + zfsctl_snapdir_t *sdp = dvp->v_data; + objset_t *snap; + char snapname[MAXNAMELEN]; + char real[MAXNAMELEN]; + char *mountpoint; + zfs_snapentry_t *sep, search; + struct mounta margs; + vfs_t *vfsp; + size_t mountpoint_len; + avl_index_t where; + zfsvfs_t *zfsvfs = dvp->v_vfsp->vfs_data; + int err; + + /* + * No extended attributes allowed under .zfs + */ + if (flags & LOOKUP_XATTR) + return (EINVAL); + + ASSERT(dvp->v_type == VDIR); + + if (gfs_lookup_dot(vpp, dvp, zfsvfs->z_ctldir, nm) == 0) + return (0); + + /* + * If we get a recursive call, that means we got called + * from the domount() code while it was trying to look up the + * spec (which looks like a local path for zfs). We need to + * add some flag to domount() to tell it not to do this lookup. + */ + if (MUTEX_HELD(&sdp->sd_lock)) + return (ENOENT); + + ZFS_ENTER(zfsvfs); + + if (flags & FIGNORECASE) { + boolean_t conflict = B_FALSE; + + err = dmu_snapshot_realname(zfsvfs->z_os, nm, real, + MAXNAMELEN, &conflict); + if (err == 0) { + nm = real; + } else if (err != ENOTSUP) { + ZFS_EXIT(zfsvfs); + return (err); + } + if (realpnp) + (void) strlcpy(realpnp->pn_buf, nm, + realpnp->pn_bufsize); + if (conflict && direntflags) + *direntflags = ED_CASE_CONFLICT; + } + + mutex_enter(&sdp->sd_lock); + search.se_name = (char *)nm; + if ((sep = avl_find(&sdp->sd_snaps, &search, &where)) != NULL) { + *vpp = sep->se_root; + VN_HOLD(*vpp); + err = traverse(vpp); + if (err) { + VN_RELE(*vpp); + *vpp = NULL; + } else if (*vpp == sep->se_root) { + /* + * The snapshot was unmounted behind our backs, + * try to remount it. + */ + goto domount; + } else { + /* + * VROOT was set during the traverse call. We need + * to clear it since we're pretending to be part + * of our parent's vfs. + */ + (*vpp)->v_flag &= ~VROOT; + } + mutex_exit(&sdp->sd_lock); + ZFS_EXIT(zfsvfs); + return (err); + } + + /* + * The requested snapshot is not currently mounted, look it up. + */ + err = zfsctl_snapshot_zname(dvp, nm, MAXNAMELEN, snapname); + if (err) { + mutex_exit(&sdp->sd_lock); + ZFS_EXIT(zfsvfs); + /* + * handle "ls *" or "?" in a graceful manner, + * forcing EILSEQ to ENOENT. + * Since shell ultimately passes "*" or "?" as name to lookup + */ + return (err == EILSEQ ? ENOENT : err); + } + if (dmu_objset_open(snapname, DMU_OST_ZFS, + DS_MODE_USER | DS_MODE_READONLY, &snap) != 0) { + mutex_exit(&sdp->sd_lock); + ZFS_EXIT(zfsvfs); + return (ENOENT); + } + + sep = kmem_alloc(sizeof (zfs_snapentry_t), KM_SLEEP); + sep->se_name = kmem_alloc(strlen(nm) + 1, KM_SLEEP); + (void) strcpy(sep->se_name, nm); + *vpp = sep->se_root = zfsctl_snapshot_mknode(dvp, dmu_objset_id(snap)); + avl_insert(&sdp->sd_snaps, sep, where); + + dmu_objset_close(snap); +domount: + mountpoint_len = strlen(refstr_value(dvp->v_vfsp->vfs_mntpt)) + + strlen("/.zfs/snapshot/") + strlen(nm) + 1; + mountpoint = kmem_alloc(mountpoint_len, KM_SLEEP); + (void) snprintf(mountpoint, mountpoint_len, "%s/.zfs/snapshot/%s", + refstr_value(dvp->v_vfsp->vfs_mntpt), nm); + + margs.spec = snapname; + margs.dir = mountpoint; + margs.flags = MS_SYSSPACE | MS_NOMNTTAB; + margs.fstype = "zfs"; + margs.dataptr = NULL; + margs.datalen = 0; + margs.optptr = NULL; + margs.optlen = 0; + + err = domount("zfs", &margs, *vpp, kcred, &vfsp); + kmem_free(mountpoint, mountpoint_len); + + if (err == 0) { + /* + * Return the mounted root rather than the covered mount point. + * Takes the GFS vnode at .zfs/snapshot/<snapname> and returns + * the ZFS vnode mounted on top of the GFS node. This ZFS + * vnode is the root the newly created vfsp. + */ + VFS_RELE(vfsp); + err = traverse(vpp); + } + + if (err == 0) { + /* + * Fix up the root vnode mounted on .zfs/snapshot/<snapname>. + * + * This is where we lie about our v_vfsp in order to + * make .zfs/snapshot/<snapname> accessible over NFS + * without requiring manual mounts of <snapname>. + */ + ASSERT(VTOZ(*vpp)->z_zfsvfs != zfsvfs); + VTOZ(*vpp)->z_zfsvfs->z_parent = zfsvfs; + (*vpp)->v_vfsp = zfsvfs->z_vfs; + (*vpp)->v_flag &= ~VROOT; + } + mutex_exit(&sdp->sd_lock); + ZFS_EXIT(zfsvfs); + + /* + * If we had an error, drop our hold on the vnode and + * zfsctl_snapshot_inactive() will clean up. + */ + if (err) { + VN_RELE(*vpp); + *vpp = NULL; + } + return (err); +} + +/* ARGSUSED */ +static int +zfsctl_snapdir_readdir_cb(vnode_t *vp, void *dp, int *eofp, + offset_t *offp, offset_t *nextp, void *data, int flags) +{ + zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data; + char snapname[MAXNAMELEN]; + uint64_t id, cookie; + boolean_t case_conflict; + int error; + + ZFS_ENTER(zfsvfs); + + cookie = *offp; + error = dmu_snapshot_list_next(zfsvfs->z_os, MAXNAMELEN, snapname, &id, + &cookie, &case_conflict); + if (error) { + ZFS_EXIT(zfsvfs); + if (error == ENOENT) { + *eofp = 1; + return (0); + } + return (error); + } + + if (flags & V_RDDIR_ENTFLAGS) { + edirent_t *eodp = dp; + + (void) strcpy(eodp->ed_name, snapname); + eodp->ed_ino = ZFSCTL_INO_SNAP(id); + eodp->ed_eflags = case_conflict ? ED_CASE_CONFLICT : 0; + } else { + struct dirent64 *odp = dp; + + (void) strcpy(odp->d_name, snapname); + odp->d_ino = ZFSCTL_INO_SNAP(id); + } + *nextp = cookie; + + ZFS_EXIT(zfsvfs); + + return (0); +} + +/* + * pvp is the '.zfs' directory (zfsctl_node_t). + * Creates vp, which is '.zfs/snapshot' (zfsctl_snapdir_t). + * + * This function is the callback to create a GFS vnode for '.zfs/snapshot' + * when a lookup is performed on .zfs for "snapshot". + */ +vnode_t * +zfsctl_mknode_snapdir(vnode_t *pvp) +{ + vnode_t *vp; + zfsctl_snapdir_t *sdp; + + vp = gfs_dir_create(sizeof (zfsctl_snapdir_t), pvp, + zfsctl_ops_snapdir, NULL, NULL, MAXNAMELEN, + zfsctl_snapdir_readdir_cb, NULL); + sdp = vp->v_data; + sdp->sd_node.zc_id = ZFSCTL_INO_SNAPDIR; + sdp->sd_node.zc_cmtime = ((zfsctl_node_t *)pvp->v_data)->zc_cmtime; + mutex_init(&sdp->sd_lock, NULL, MUTEX_DEFAULT, NULL); + avl_create(&sdp->sd_snaps, snapentry_compare, + sizeof (zfs_snapentry_t), offsetof(zfs_snapentry_t, se_node)); + return (vp); +} + +/* ARGSUSED */ +static int +zfsctl_snapdir_getattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr, + caller_context_t *ct) +{ + zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data; + zfsctl_snapdir_t *sdp = vp->v_data; + + ZFS_ENTER(zfsvfs); + zfsctl_common_getattr(vp, vap); + vap->va_nodeid = gfs_file_inode(vp); + vap->va_nlink = vap->va_size = avl_numnodes(&sdp->sd_snaps) + 2; + ZFS_EXIT(zfsvfs); + + return (0); +} + +/* ARGSUSED */ +static void +zfsctl_snapdir_inactive(vnode_t *vp, cred_t *cr, caller_context_t *ct) +{ + zfsctl_snapdir_t *sdp = vp->v_data; + void *private; + + private = gfs_dir_inactive(vp); + if (private != NULL) { + ASSERT(avl_numnodes(&sdp->sd_snaps) == 0); + mutex_destroy(&sdp->sd_lock); + avl_destroy(&sdp->sd_snaps); + kmem_free(private, sizeof (zfsctl_snapdir_t)); + } +} + +static const fs_operation_def_t zfsctl_tops_snapdir[] = { + { VOPNAME_OPEN, { .vop_open = zfsctl_common_open } }, + { VOPNAME_CLOSE, { .vop_close = zfsctl_common_close } }, + { VOPNAME_IOCTL, { .error = fs_inval } }, + { VOPNAME_GETATTR, { .vop_getattr = zfsctl_snapdir_getattr } }, + { VOPNAME_ACCESS, { .vop_access = zfsctl_common_access } }, + { VOPNAME_RENAME, { .vop_rename = zfsctl_snapdir_rename } }, + { VOPNAME_RMDIR, { .vop_rmdir = zfsctl_snapdir_remove } }, + { VOPNAME_MKDIR, { .vop_mkdir = zfsctl_snapdir_mkdir } }, + { VOPNAME_READDIR, { .vop_readdir = gfs_vop_readdir } }, + { VOPNAME_LOOKUP, { .vop_lookup = zfsctl_snapdir_lookup } }, + { VOPNAME_SEEK, { .vop_seek = fs_seek } }, + { VOPNAME_INACTIVE, { .vop_inactive = zfsctl_snapdir_inactive } }, + { VOPNAME_FID, { .vop_fid = zfsctl_common_fid } }, + { NULL } +}; + +/* + * pvp is the GFS vnode '.zfs/snapshot'. + * + * This creates a GFS node under '.zfs/snapshot' representing each + * snapshot. This newly created GFS node is what we mount snapshot + * vfs_t's ontop of. + */ +static vnode_t * +zfsctl_snapshot_mknode(vnode_t *pvp, uint64_t objset) +{ + vnode_t *vp; + zfsctl_node_t *zcp; + + vp = gfs_dir_create(sizeof (zfsctl_node_t), pvp, + zfsctl_ops_snapshot, NULL, NULL, MAXNAMELEN, NULL, NULL); + zcp = vp->v_data; + zcp->zc_id = objset; + VFS_HOLD(vp->v_vfsp); + + return (vp); +} + +static void +zfsctl_snapshot_inactive(vnode_t *vp, cred_t *cr, caller_context_t *ct) +{ + zfsctl_snapdir_t *sdp; + zfs_snapentry_t *sep, *next; + vnode_t *dvp; + + VERIFY(gfs_dir_lookup(vp, "..", &dvp, cr, 0, NULL, NULL) == 0); + sdp = dvp->v_data; + + mutex_enter(&sdp->sd_lock); + + if (vp->v_count > 1) { + mutex_exit(&sdp->sd_lock); + return; + } + ASSERT(!vn_ismntpt(vp)); + + sep = avl_first(&sdp->sd_snaps); + while (sep != NULL) { + next = AVL_NEXT(&sdp->sd_snaps, sep); + + if (sep->se_root == vp) { + avl_remove(&sdp->sd_snaps, sep); + kmem_free(sep->se_name, strlen(sep->se_name) + 1); + kmem_free(sep, sizeof (zfs_snapentry_t)); + break; + } + sep = next; + } + ASSERT(sep != NULL); + + mutex_exit(&sdp->sd_lock); + VN_RELE(dvp); + VFS_RELE(vp->v_vfsp); + + /* + * Dispose of the vnode for the snapshot mount point. + * This is safe to do because once this entry has been removed + * from the AVL tree, it can't be found again, so cannot become + * "active". If we lookup the same name again we will end up + * creating a new vnode. + */ + gfs_vop_inactive(vp, cr, ct); +} + + +/* + * These VP's should never see the light of day. They should always + * be covered. + */ +static const fs_operation_def_t zfsctl_tops_snapshot[] = { + VOPNAME_INACTIVE, { .vop_inactive = zfsctl_snapshot_inactive }, + NULL, NULL +}; + +int +zfsctl_lookup_objset(vfs_t *vfsp, uint64_t objsetid, zfsvfs_t **zfsvfsp) +{ + zfsvfs_t *zfsvfs = vfsp->vfs_data; + vnode_t *dvp, *vp; + zfsctl_snapdir_t *sdp; + zfsctl_node_t *zcp; + zfs_snapentry_t *sep; + int error; + + ASSERT(zfsvfs->z_ctldir != NULL); + error = zfsctl_root_lookup(zfsvfs->z_ctldir, "snapshot", &dvp, + NULL, 0, NULL, kcred, NULL, NULL, NULL); + if (error != 0) + return (error); + sdp = dvp->v_data; + + mutex_enter(&sdp->sd_lock); + sep = avl_first(&sdp->sd_snaps); + while (sep != NULL) { + vp = sep->se_root; + zcp = vp->v_data; + if (zcp->zc_id == objsetid) + break; + + sep = AVL_NEXT(&sdp->sd_snaps, sep); + } + + if (sep != NULL) { + VN_HOLD(vp); + /* + * Return the mounted root rather than the covered mount point. + * Takes the GFS vnode at .zfs/snapshot/<snapshot objsetid> + * and returns the ZFS vnode mounted on top of the GFS node. + * This ZFS vnode is the root of the vfs for objset 'objsetid'. + */ + error = traverse(&vp); + if (error == 0) { + if (vp == sep->se_root) + error = EINVAL; + else + *zfsvfsp = VTOZ(vp)->z_zfsvfs; + } + mutex_exit(&sdp->sd_lock); + VN_RELE(vp); + } else { + error = EINVAL; + mutex_exit(&sdp->sd_lock); + } + + VN_RELE(dvp); + + return (error); +} + +/* + * Unmount any snapshots for the given filesystem. This is called from + * zfs_umount() - if we have a ctldir, then go through and unmount all the + * snapshots. + */ +int +zfsctl_umount_snapshots(vfs_t *vfsp, int fflags, cred_t *cr) +{ + zfsvfs_t *zfsvfs = vfsp->vfs_data; + vnode_t *dvp; + zfsctl_snapdir_t *sdp; + zfs_snapentry_t *sep, *next; + int error; + + ASSERT(zfsvfs->z_ctldir != NULL); + error = zfsctl_root_lookup(zfsvfs->z_ctldir, "snapshot", &dvp, + NULL, 0, NULL, cr, NULL, NULL, NULL); + if (error != 0) + return (error); + sdp = dvp->v_data; + + mutex_enter(&sdp->sd_lock); + + sep = avl_first(&sdp->sd_snaps); + while (sep != NULL) { + next = AVL_NEXT(&sdp->sd_snaps, sep); + + /* + * If this snapshot is not mounted, then it must + * have just been unmounted by somebody else, and + * will be cleaned up by zfsctl_snapdir_inactive(). + */ + if (vn_ismntpt(sep->se_root)) { + avl_remove(&sdp->sd_snaps, sep); + error = zfsctl_unmount_snap(sep, fflags, cr); + if (error) { + avl_add(&sdp->sd_snaps, sep); + break; + } + } + sep = next; + } + + mutex_exit(&sdp->sd_lock); + VN_RELE(dvp); + + return (error); +} |