diff options
3 files changed, 47 insertions, 10 deletions
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c index beb6401..d2bd7ad 100644 --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c @@ -955,11 +955,22 @@ zfsvfs_setup(zfsvfs_t *zfsvfs, boolean_t mounting) return (0); } +extern krwlock_t zfsvfs_lock; /* in zfs_znode.c */ + void zfsvfs_free(zfsvfs_t *zfsvfs) { int i; + /* + * This is a barrier to prevent the filesystem from going away in + * zfs_znode_move() until we can safely ensure that the filesystem is + * not unmounted. We consider the filesystem valid before the barrier + * and invalid after the barrier. + */ + rw_enter(&zfsvfs_lock, RW_READER); + rw_exit(&zfsvfs_lock); + zfs_fuid_destroy(zfsvfs); mutex_destroy(&zfsvfs->z_znodes_lock); diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c index 9292880..8ba0843 100644 --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c @@ -201,6 +201,12 @@ zfs_close(vnode_t *vp, int flag, int count, offset_t offset, cred_t *cr, znode_t *zp = VTOZ(vp); zfsvfs_t *zfsvfs = zp->z_zfsvfs; + /* + * Clean up any locks held by this process on the vp. + */ + cleanlocks(vp, ddi_get_pid(), 0); + cleanshares(vp, ddi_get_pid()); + ZFS_ENTER(zfsvfs); ZFS_VERIFY_ZP(zp); @@ -208,12 +214,6 @@ zfs_close(vnode_t *vp, int flag, int count, offset_t offset, cred_t *cr, if ((flag & (FSYNC | FDSYNC)) && (count == 1)) atomic_dec_32(&zp->z_sync_cnt); - /* - * Clean up any locks held by this process on the vp. - */ - cleanlocks(vp, ddi_get_pid(), 0); - cleanshares(vp, ddi_get_pid()); - if (!zfs_has_ctldir(zp) && zp->z_zfsvfs->z_vscan && ZTOV(zp)->v_type == VREG && !(zp->z_phys->zp_flags & ZFS_AV_QUARANTINED) && diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c index 740302a..7b50f24 100644 --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_znode.c @@ -87,6 +87,12 @@ SYSCTL_INT(_debug_sizeof, OID_AUTO, znode, CTLFLAG_RD, 0, sizeof(znode_t), * (such as VFS logic) that will not compile easily in userland. */ #ifdef _KERNEL +/* + * Needed to close a small window in zfs_znode_move() that allows the zfsvfs to + * be freed before it can be safely accessed. + */ +krwlock_t zfsvfs_lock; + static kmem_cache_t *znode_cache = NULL; /*ARGSUSED*/ @@ -198,8 +204,9 @@ zfs_znode_cache_destructor(void *buf, void *arg) #ifdef ZNODE_STATS static struct { uint64_t zms_zfsvfs_invalid; + uint64_t zms_zfsvfs_recheck1; uint64_t zms_zfsvfs_unmounted; - uint64_t zms_zfsvfs_recheck_invalid; + uint64_t zms_zfsvfs_recheck2; uint64_t zms_obj_held; uint64_t zms_vnode_locked; uint64_t zms_not_only_dnlc; @@ -274,15 +281,32 @@ zfs_znode_move(void *buf, void *newbuf, size_t size, void *arg) } /* - * Ensure that the filesystem is not unmounted during the move. - * This is the equivalent to ZFS_ENTER(). + * Close a small window in which it's possible that the filesystem could + * be unmounted and freed, and zfsvfs, though valid in the previous + * statement, could point to unrelated memory by the time we try to + * prevent the filesystem from being unmounted. + */ + rw_enter(&zfsvfs_lock, RW_WRITER); + if (zfsvfs != ozp->z_zfsvfs) { + rw_exit(&zfsvfs_lock); + ZNODE_STAT_ADD(znode_move_stats.zms_zfsvfs_recheck1); + return (KMEM_CBRC_DONT_KNOW); + } + + /* + * If the znode is still valid, then so is the file system. We know that + * no valid file system can be freed while we hold zfsvfs_lock, so we + * can safely ensure that the filesystem is not and will not be + * unmounted. The next statement is equivalent to ZFS_ENTER(). */ rrw_enter(&zfsvfs->z_teardown_lock, RW_READER, FTAG); if (zfsvfs->z_unmounted) { ZFS_EXIT(zfsvfs); + rw_exit(&zfsvfs_lock); ZNODE_STAT_ADD(znode_move_stats.zms_zfsvfs_unmounted); return (KMEM_CBRC_DONT_KNOW); } + rw_exit(&zfsvfs_lock); mutex_enter(&zfsvfs->z_znodes_lock); /* @@ -292,7 +316,7 @@ zfs_znode_move(void *buf, void *newbuf, size_t size, void *arg) if (zfsvfs != ozp->z_zfsvfs) { mutex_exit(&zfsvfs->z_znodes_lock); ZFS_EXIT(zfsvfs); - ZNODE_STAT_ADD(znode_move_stats.zms_zfsvfs_recheck_invalid); + ZNODE_STAT_ADD(znode_move_stats.zms_zfsvfs_recheck2); return (KMEM_CBRC_DONT_KNOW); } @@ -349,6 +373,7 @@ zfs_znode_init(void) /* * Initialize zcache */ + rw_init(&zfsvfs_lock, NULL, RW_DEFAULT, NULL); ASSERT(znode_cache == NULL); znode_cache = kmem_cache_create("zfs_znode_cache", sizeof (znode_t), 0, /* zfs_znode_cache_constructor */ NULL, @@ -367,6 +392,7 @@ zfs_znode_fini(void) if (znode_cache) kmem_cache_destroy(znode_cache); znode_cache = NULL; + rw_destroy(&zfsvfs_lock); } int |
