diff options
Diffstat (limited to 'fs/super.c')
| -rw-r--r-- | fs/super.c | 652 |
1 files changed, 371 insertions, 281 deletions
diff --git a/fs/super.c b/fs/super.c index b142e71eb8df..c9c7223bc2a2 100644 --- a/fs/super.c +++ b/fs/super.c @@ -81,16 +81,13 @@ static inline void super_unlock_shared(struct super_block *sb) super_unlock(sb, false); } -static inline bool wait_born(struct super_block *sb) +static bool super_flags(const struct super_block *sb, unsigned int flags) { - unsigned int flags; - /* * Pairs with smp_store_release() in super_wake() and ensures - * that we see SB_BORN or SB_DYING after we're woken. + * that we see @flags after we're woken. */ - flags = smp_load_acquire(&sb->s_flags); - return flags & (SB_BORN | SB_DYING); + return smp_load_acquire(&sb->s_flags) & flags; } /** @@ -105,15 +102,21 @@ static inline bool wait_born(struct super_block *sb) * * The caller must have acquired a temporary reference on @sb->s_count. * - * Return: This returns true if SB_BORN was set, false if SB_DYING was - * set. The function acquires s_umount and returns with it held. + * Return: The function returns true if SB_BORN was set and with + * s_umount held. The function returns false if SB_DYING was + * set and without s_umount held. */ static __must_check bool super_lock(struct super_block *sb, bool excl) { - lockdep_assert_not_held(&sb->s_umount); -relock: + /* wait until the superblock is ready or dying */ + wait_var_event(&sb->s_flags, super_flags(sb, SB_BORN | SB_DYING)); + + /* Don't pointlessly acquire s_umount. */ + if (super_flags(sb, SB_DYING)) + return false; + __super_lock(sb, excl); /* @@ -121,32 +124,22 @@ relock: * @sb->s_root is NULL and @sb->s_active is 0. No one needs to * grab a reference to this. Tell them so. */ - if (sb->s_flags & SB_DYING) + if (sb->s_flags & SB_DYING) { + super_unlock(sb, excl); return false; + } - /* Has called ->get_tree() successfully. */ - if (sb->s_flags & SB_BORN) - return true; - - super_unlock(sb, excl); - - /* wait until the superblock is ready or dying */ - wait_var_event(&sb->s_flags, wait_born(sb)); - - /* - * Neither SB_BORN nor SB_DYING are ever unset so we never loop. - * Just reacquire @sb->s_umount for the caller. - */ - goto relock; + WARN_ON_ONCE(!(sb->s_flags & SB_BORN)); + return true; } -/* wait and acquire read-side of @sb->s_umount */ +/* wait and try to acquire read-side of @sb->s_umount */ static inline bool super_lock_shared(struct super_block *sb) { return super_lock(sb, false); } -/* wait and acquire write-side of @sb->s_umount */ +/* wait and try to acquire write-side of @sb->s_umount */ static inline bool super_lock_excl(struct super_block *sb) { return super_lock(sb, true); @@ -178,7 +171,7 @@ static void super_wake(struct super_block *sb, unsigned int flag) * One thing we have to be careful of with a per-sb shrinker is that we don't * drop the last active reference to the superblock from within the shrinker. * If that happens we could trigger unregistering the shrinker from within the - * shrinker path and that leads to deadlock on the shrinker_rwsem. Hence we + * shrinker path and that leads to deadlock on the shrinker_mutex. Hence we * take a passive reference to the superblock to avoid this from occurring. */ static unsigned long super_cache_scan(struct shrinker *shrink, @@ -191,7 +184,7 @@ static unsigned long super_cache_scan(struct shrinker *shrink, long dentries; long inodes; - sb = container_of(shrink, struct super_block, s_shrink); + sb = shrink->private_data; /* * Deadlock avoidance. We may hold various FS locks, and we don't want @@ -244,7 +237,7 @@ static unsigned long super_cache_count(struct shrinker *shrink, struct super_block *sb; long total_objects = 0; - sb = container_of(shrink, struct super_block, s_shrink); + sb = shrink->private_data; /* * We don't call super_trylock_shared() here as it is a scalability @@ -281,9 +274,11 @@ static void destroy_super_work(struct work_struct *work) { struct super_block *s = container_of(work, struct super_block, destroy_work); - int i; - - for (i = 0; i < SB_FREEZE_LEVELS; i++) + fsnotify_sb_free(s); + security_sb_free(s); + put_user_ns(s->s_user_ns); + kfree(s->s_subtype); + for (int i = 0; i < SB_FREEZE_LEVELS; i++) percpu_free_rwsem(&s->s_writers.rw_sem[i]); kfree(s); } @@ -303,10 +298,7 @@ static void destroy_unused_super(struct super_block *s) super_unlock_excl(s); list_lru_destroy(&s->s_dentry_lru); list_lru_destroy(&s->s_inode_lru); - security_sb_free(s); - put_user_ns(s->s_user_ns); - kfree(s->s_subtype); - free_prealloced_shrinker(&s->s_shrink); + shrinker_free(s->s_shrink); /* no delays needed */ destroy_super_work(&s->destroy_work); } @@ -323,7 +315,7 @@ static void destroy_unused_super(struct super_block *s) static struct super_block *alloc_super(struct file_system_type *type, int flags, struct user_namespace *user_ns) { - struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); + struct super_block *s = kzalloc(sizeof(struct super_block), GFP_KERNEL); static const struct super_operations default_op; int i; @@ -383,16 +375,19 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags, s->s_time_min = TIME64_MIN; s->s_time_max = TIME64_MAX; - s->s_shrink.seeks = DEFAULT_SEEKS; - s->s_shrink.scan_objects = super_cache_scan; - s->s_shrink.count_objects = super_cache_count; - s->s_shrink.batch = 1024; - s->s_shrink.flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE; - if (prealloc_shrinker(&s->s_shrink, "sb-%s", type->name)) + s->s_shrink = shrinker_alloc(SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE, + "sb-%s", type->name); + if (!s->s_shrink) goto fail; - if (list_lru_init_memcg(&s->s_dentry_lru, &s->s_shrink)) + + s->s_shrink->scan_objects = super_cache_scan; + s->s_shrink->count_objects = super_cache_count; + s->s_shrink->batch = 1024; + s->s_shrink->private_data = s; + + if (list_lru_init_memcg(&s->s_dentry_lru, s->s_shrink)) goto fail; - if (list_lru_init_memcg(&s->s_inode_lru, &s->s_shrink)) + if (list_lru_init_memcg(&s->s_inode_lru, s->s_shrink)) goto fail; return s; @@ -413,9 +408,6 @@ static void __put_super(struct super_block *s) WARN_ON(s->s_dentry_lru.node); WARN_ON(s->s_inode_lru.node); WARN_ON(!list_empty(&s->s_mounts)); - security_sb_free(s); - put_user_ns(s->s_user_ns); - kfree(s->s_subtype); call_rcu(&s->rcu, destroy_super_rcu); } } @@ -477,7 +469,7 @@ void deactivate_locked_super(struct super_block *s) { struct file_system_type *fs = s->s_type; if (atomic_dec_and_test(&s->s_active)) { - unregister_shrinker(&s->s_shrink); + shrinker_free(s->s_shrink); fs->kill_sb(s); kill_super_notify(s); @@ -518,48 +510,7 @@ void deactivate_super(struct super_block *s) EXPORT_SYMBOL(deactivate_super); /** - * grab_super - acquire an active reference - * @s: reference we are trying to make active - * - * Tries to acquire an active reference. grab_super() is used when we - * had just found a superblock in super_blocks or fs_type->fs_supers - * and want to turn it into a full-blown active reference. grab_super() - * is called with sb_lock held and drops it. Returns 1 in case of - * success, 0 if we had failed (superblock contents was already dead or - * dying when grab_super() had been called). Note that this is only - * called for superblocks not in rundown mode (== ones still on ->fs_supers - * of their type), so increment of ->s_count is OK here. - */ -static int grab_super(struct super_block *s) __releases(sb_lock) -{ - bool born; - - s->s_count++; - spin_unlock(&sb_lock); - born = super_lock_excl(s); - if (born && atomic_inc_not_zero(&s->s_active)) { - put_super(s); - return 1; - } - super_unlock_excl(s); - put_super(s); - return 0; -} - -static inline bool wait_dead(struct super_block *sb) -{ - unsigned int flags; - - /* - * Pairs with memory barrier in super_wake() and ensures - * that we see SB_DEAD after we're woken. - */ - flags = smp_load_acquire(&sb->s_flags); - return flags & SB_DEAD; -} - -/** - * grab_super_dead - acquire an active reference to a superblock + * grab_super - acquire an active reference to a superblock * @sb: superblock to acquire * * Acquire a temporary reference on a superblock and try to trade it for @@ -570,17 +521,21 @@ static inline bool wait_dead(struct super_block *sb) * Return: This returns true if an active reference could be acquired, * false if not. */ -static bool grab_super_dead(struct super_block *sb) +static bool grab_super(struct super_block *sb) { + bool locked; sb->s_count++; - if (grab_super(sb)) { - put_super(sb); - lockdep_assert_held(&sb->s_umount); - return true; + spin_unlock(&sb_lock); + locked = super_lock_excl(sb); + if (locked) { + if (atomic_inc_not_zero(&sb->s_active)) { + put_super(sb); + return true; + } + super_unlock_excl(sb); } - wait_var_event(&sb->s_flags, wait_dead(sb)); - lockdep_assert_not_held(&sb->s_umount); + wait_var_event(&sb->s_flags, super_flags(sb, SB_DEAD)); put_super(sb); return false; } @@ -666,7 +621,7 @@ void generic_shutdown_super(struct super_block *sb) sync_filesystem(sb); sb->s_flags &= ~SB_ACTIVE; - cgroup_writeback_umount(); + cgroup_writeback_umount(sb); /* Evict all inodes with zero refcount. */ evict_inodes(sb); @@ -678,12 +633,6 @@ void generic_shutdown_super(struct super_block *sb) fsnotify_sb_delete(sb); security_sb_delete(sb); - /* - * Now that all potentially-encrypted inodes have been evicted, - * the fscrypt keyring can be destroyed. - */ - fscrypt_destroy_keyring(sb); - if (sb->s_dio_done_wq) { destroy_workqueue(sb->s_dio_done_wq); sb->s_dio_done_wq = NULL; @@ -692,6 +641,12 @@ void generic_shutdown_super(struct super_block *sb) if (sop->put_super) sop->put_super(sb); + /* + * Now that all potentially-encrypted inodes have been evicted, + * the fscrypt keyring can be destroyed. + */ + fscrypt_destroy_keyring(sb); + if (CHECK_DATA_CORRUPTION(!list_empty(&sb->s_inodes), "VFS: Busy inodes after unmount of %s (%s)", sb->s_id, sb->s_type->name)) { @@ -829,7 +784,7 @@ retry: hlist_add_head(&s->s_instances, &s->s_type->fs_supers); spin_unlock(&sb_lock); get_filesystem(s->s_type); - register_shrinker_prepared(&s->s_shrink); + shrinker_register(s->s_shrink); return s; share_extant_sb: @@ -842,7 +797,7 @@ share_extant_sb: warnfc(fc, "reusing existing filesystem in another namespace not allowed"); return ERR_PTR(-EBUSY); } - if (!grab_super_dead(old)) + if (!grab_super(old)) goto retry; destroy_unused_super(s); return old; @@ -886,7 +841,7 @@ retry: destroy_unused_super(s); return ERR_PTR(-EBUSY); } - if (!grab_super_dead(old)) + if (!grab_super(old)) goto retry; destroy_unused_super(s); return old; @@ -912,7 +867,7 @@ retry: hlist_add_head(&s->s_instances, &type->fs_supers); spin_unlock(&sb_lock); get_filesystem(type); - register_shrinker_prepared(&s->s_shrink); + shrinker_register(s->s_shrink); return s; } EXPORT_SYMBOL(sget); @@ -938,8 +893,7 @@ static void __iterate_supers(void (*f)(struct super_block *)) spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { - /* Pairs with memory marrier in super_wake(). */ - if (smp_load_acquire(&sb->s_flags) & SB_DYING) + if (super_flags(sb, SB_DYING)) continue; sb->s_count++; spin_unlock(&sb_lock); @@ -969,15 +923,17 @@ void iterate_supers(void (*f)(struct super_block *, void *), void *arg) spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { - bool born; + bool locked; sb->s_count++; spin_unlock(&sb_lock); - born = super_lock_shared(sb); - if (born && sb->s_root) - f(sb, arg); - super_unlock_shared(sb); + locked = super_lock_shared(sb); + if (locked) { + if (sb->s_root) + f(sb, arg); + super_unlock_shared(sb); + } spin_lock(&sb_lock); if (p) @@ -1005,15 +961,17 @@ void iterate_supers_type(struct file_system_type *type, spin_lock(&sb_lock); hlist_for_each_entry(sb, &type->fs_supers, s_instances) { - bool born; + bool locked; sb->s_count++; spin_unlock(&sb_lock); - born = super_lock_shared(sb); - if (born && sb->s_root) - f(sb, arg); - super_unlock_shared(sb); + locked = super_lock_shared(sb); + if (locked) { + if (sb->s_root) + f(sb, arg); + super_unlock_shared(sb); + } spin_lock(&sb_lock); if (p) @@ -1027,34 +985,6 @@ void iterate_supers_type(struct file_system_type *type, EXPORT_SYMBOL(iterate_supers_type); -/** - * get_active_super - get an active reference to the superblock of a device - * @bdev: device to get the superblock for - * - * Scans the superblock list and finds the superblock of the file system - * mounted on the device given. Returns the superblock with an active - * reference or %NULL if none was found. - */ -struct super_block *get_active_super(struct block_device *bdev) -{ - struct super_block *sb; - - if (!bdev) - return NULL; - - spin_lock(&sb_lock); - list_for_each_entry(sb, &super_blocks, s_list) { - if (sb->s_bdev == bdev) { - if (!grab_super(sb)) - return NULL; - super_unlock_excl(sb); - return sb; - } - } - spin_unlock(&sb_lock); - return NULL; -} - struct super_block *user_get_super(dev_t dev, bool excl) { struct super_block *sb; @@ -1062,15 +992,17 @@ struct super_block *user_get_super(dev_t dev, bool excl) spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { if (sb->s_dev == dev) { - bool born; + bool locked; sb->s_count++; spin_unlock(&sb_lock); /* still alive? */ - born = super_lock(sb, excl); - if (born && sb->s_root) - return sb; - super_unlock(sb, excl); + locked = super_lock(sb, excl); + if (locked) { + if (sb->s_root) + return sb; + super_unlock(sb, excl); + } /* nope, got unmounted */ spin_lock(&sb_lock); __put_super(sb); @@ -1181,9 +1113,9 @@ cancel_readonly: static void do_emergency_remount_callback(struct super_block *sb) { - bool born = super_lock_excl(sb); + bool locked = super_lock_excl(sb); - if (born && sb->s_root && sb->s_bdev && !sb_rdonly(sb)) { + if (locked && sb->s_root && sb->s_bdev && !sb_rdonly(sb)) { struct fs_context *fc; fc = fs_context_for_reconfigure(sb->s_root, @@ -1194,7 +1126,8 @@ static void do_emergency_remount_callback(struct super_block *sb) put_fs_context(fc); } } - super_unlock_excl(sb); + if (locked) + super_unlock_excl(sb); } static void do_emergency_remount(struct work_struct *work) @@ -1217,16 +1150,17 @@ void emergency_remount(void) static void do_thaw_all_callback(struct super_block *sb) { - bool born = super_lock_excl(sb); + bool locked = super_lock_excl(sb); - if (born && sb->s_root) { + if (locked && sb->s_root) { if (IS_ENABLED(CONFIG_BLOCK)) - while (sb->s_bdev && !thaw_bdev(sb->s_bdev)) + while (sb->s_bdev && !bdev_thaw(sb->s_bdev)) pr_warn("Emergency Thaw on %pg\n", sb->s_bdev); thaw_super_locked(sb, FREEZE_HOLDER_USERSPACE); - } else { - super_unlock_excl(sb); + return; } + if (locked) + super_unlock_excl(sb); } static void do_thaw_all(struct work_struct *work) @@ -1430,32 +1364,54 @@ EXPORT_SYMBOL(sget_dev); #ifdef CONFIG_BLOCK /* - * Lock a super block that the callers holds a reference to. + * Lock the superblock that is holder of the bdev. Returns the superblock + * pointer if we successfully locked the superblock and it is alive. Otherwise + * we return NULL and just unlock bdev->bd_holder_lock. * - * The caller needs to ensure that the super_block isn't being freed while - * calling this function, e.g. by holding a lock over the call to this function - * and the place that clears the pointer to the superblock used by this function - * before freeing the superblock. + * The function must be called with bdev->bd_holder_lock and releases it. */ -static bool super_lock_shared_active(struct super_block *sb) +static struct super_block *bdev_super_lock(struct block_device *bdev, bool excl) + __releases(&bdev->bd_holder_lock) { - bool born = super_lock_shared(sb); + struct super_block *sb = bdev->bd_holder; + bool locked; - if (!born || !sb->s_root || !(sb->s_flags & SB_ACTIVE)) { - super_unlock_shared(sb); - return false; + lockdep_assert_held(&bdev->bd_holder_lock); + lockdep_assert_not_held(&sb->s_umount); + lockdep_assert_not_held(&bdev->bd_disk->open_mutex); + + /* Make sure sb doesn't go away from under us */ + spin_lock(&sb_lock); + sb->s_count++; + spin_unlock(&sb_lock); + + mutex_unlock(&bdev->bd_holder_lock); + + locked = super_lock(sb, excl); + + /* + * If the superblock wasn't already SB_DYING then we hold + * s_umount and can safely drop our temporary reference. + */ + put_super(sb); + + if (!locked) + return NULL; + + if (!sb->s_root || !(sb->s_flags & SB_ACTIVE)) { + super_unlock(sb, excl); + return NULL; } - return true; + + return sb; } static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise) { - struct super_block *sb = bdev->bd_holder; - - /* bd_holder_lock ensures that the sb isn't freed */ - lockdep_assert_held(&bdev->bd_holder_lock); + struct super_block *sb; - if (!super_lock_shared_active(sb)) + sb = bdev_super_lock(bdev, false); + if (!sb) return; if (!surprise) @@ -1470,19 +1426,121 @@ static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise) static void fs_bdev_sync(struct block_device *bdev) { - struct super_block *sb = bdev->bd_holder; - - lockdep_assert_held(&bdev->bd_holder_lock); + struct super_block *sb; - if (!super_lock_shared_active(sb)) + sb = bdev_super_lock(bdev, false); + if (!sb) return; + sync_filesystem(sb); super_unlock_shared(sb); } +static struct super_block *get_bdev_super(struct block_device *bdev) +{ + bool active = false; + struct super_block *sb; + + sb = bdev_super_lock(bdev, true); + if (sb) { + active = atomic_inc_not_zero(&sb->s_active); + super_unlock_excl(sb); + } + if (!active) + return NULL; + return sb; +} + +/** + * fs_bdev_freeze - freeze owning filesystem of block device + * @bdev: block device + * + * Freeze the filesystem that owns this block device if it is still + * active. + * + * A filesystem that owns multiple block devices may be frozen from each + * block device and won't be unfrozen until all block devices are + * unfrozen. Each block device can only freeze the filesystem once as we + * nest freezes for block devices in the block layer. + * + * Return: If the freeze was successful zero is returned. If the freeze + * failed a negative error code is returned. + */ +static int fs_bdev_freeze(struct block_device *bdev) +{ + struct super_block *sb; + int error = 0; + + lockdep_assert_held(&bdev->bd_fsfreeze_mutex); + + sb = get_bdev_super(bdev); + if (!sb) + return -EINVAL; + + if (sb->s_op->freeze_super) + error = sb->s_op->freeze_super(sb, + FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE); + else + error = freeze_super(sb, + FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE); + if (!error) + error = sync_blockdev(bdev); + deactivate_super(sb); + return error; +} + +/** + * fs_bdev_thaw - thaw owning filesystem of block device + * @bdev: block device + * + * Thaw the filesystem that owns this block device. + * + * A filesystem that owns multiple block devices may be frozen from each + * block device and won't be unfrozen until all block devices are + * unfrozen. Each block device can only freeze the filesystem once as we + * nest freezes for block devices in the block layer. + * + * Return: If the thaw was successful zero is returned. If the thaw + * failed a negative error code is returned. If this function + * returns zero it doesn't mean that the filesystem is unfrozen + * as it may have been frozen multiple times (kernel may hold a + * freeze or might be frozen from other block devices). + */ +static int fs_bdev_thaw(struct block_device *bdev) +{ + struct super_block *sb; + int error; + + lockdep_assert_held(&bdev->bd_fsfreeze_mutex); + + /* + * The block device may have been frozen before it was claimed by a + * filesystem. Concurrently another process might try to mount that + * frozen block device and has temporarily claimed the block device for + * that purpose causing a concurrent fs_bdev_thaw() to end up here. The + * mounter is already about to abort mounting because they still saw an + * elevanted bdev->bd_fsfreeze_count so get_bdev_super() will return + * NULL in that case. + */ + sb = get_bdev_super(bdev); + if (!sb) + return -EINVAL; + + if (sb->s_op->thaw_super) + error = sb->s_op->thaw_super(sb, + FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE); + else + error = thaw_super(sb, + FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE); + deactivate_super(sb); + return error; +} + const struct blk_holder_ops fs_holder_ops = { .mark_dead = fs_bdev_mark_dead, .sync = fs_bdev_sync, + .freeze = fs_bdev_freeze, + .thaw = fs_bdev_thaw, }; EXPORT_SYMBOL_GPL(fs_holder_ops); @@ -1490,16 +1548,16 @@ int setup_bdev_super(struct super_block *sb, int sb_flags, struct fs_context *fc) { blk_mode_t mode = sb_open_mode(sb_flags); - struct bdev_handle *bdev_handle; + struct file *bdev_file; struct block_device *bdev; - bdev_handle = bdev_open_by_dev(sb->s_dev, mode, sb, &fs_holder_ops); - if (IS_ERR(bdev_handle)) { + bdev_file = bdev_file_open_by_dev(sb->s_dev, mode, sb, &fs_holder_ops); + if (IS_ERR(bdev_file)) { if (fc) errorf(fc, "%s: Can't open blockdev", fc->source); - return PTR_ERR(bdev_handle); + return PTR_ERR(bdev_file); } - bdev = bdev_handle->bdev; + bdev = file_bdev(bdev_file); /* * This really should be in blkdev_get_by_dev, but right now can't due @@ -1507,36 +1565,30 @@ int setup_bdev_super(struct super_block *sb, int sb_flags, * writable from userspace even for a read-only block device. */ if ((mode & BLK_OPEN_WRITE) && bdev_read_only(bdev)) { - bdev_release(bdev_handle); + bdev_fput(bdev_file); return -EACCES; } /* - * Until SB_BORN flag is set, there can be no active superblock - * references and thus no filesystem freezing. get_active_super() will - * just loop waiting for SB_BORN so even freeze_bdev() cannot proceed. - * - * It is enough to check bdev was not frozen before we set s_bdev. + * It is enough to check bdev was not frozen before we set + * s_bdev as freezing will wait until SB_BORN is set. */ - mutex_lock(&bdev->bd_fsfreeze_mutex); - if (bdev->bd_fsfreeze_count > 0) { - mutex_unlock(&bdev->bd_fsfreeze_mutex); + if (atomic_read(&bdev->bd_fsfreeze_count) > 0) { if (fc) warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev); - bdev_release(bdev_handle); + bdev_fput(bdev_file); return -EBUSY; } spin_lock(&sb_lock); - sb->s_bdev_handle = bdev_handle; + sb->s_bdev_file = bdev_file; sb->s_bdev = bdev; sb->s_bdi = bdi_get(bdev->bd_disk->bdi); if (bdev_stable_writes(bdev)) sb->s_iflags |= SB_I_STABLE_WRITES; spin_unlock(&sb_lock); - mutex_unlock(&bdev->bd_fsfreeze_mutex); snprintf(sb->s_id, sizeof(sb->s_id), "%pg", bdev); - shrinker_debugfs_rename(&sb->s_shrink, "sb-%s:%s", sb->s_type->name, + shrinker_debugfs_rename(sb->s_shrink, "sb-%s:%s", sb->s_type->name, sb->s_id); sb_set_blocksize(sb, block_size(bdev)); return 0; @@ -1544,13 +1596,14 @@ int setup_bdev_super(struct super_block *sb, int sb_flags, EXPORT_SYMBOL_GPL(setup_bdev_super); /** - * get_tree_bdev - Get a superblock based on a single block device + * get_tree_bdev_flags - Get a superblock based on a single block device * @fc: The filesystem context holding the parameters * @fill_super: Helper to initialise a new superblock + * @flags: GET_TREE_BDEV_* flags */ -int get_tree_bdev(struct fs_context *fc, - int (*fill_super)(struct super_block *, - struct fs_context *)) +int get_tree_bdev_flags(struct fs_context *fc, + int (*fill_super)(struct super_block *sb, + struct fs_context *fc), unsigned int flags) { struct super_block *s; int error = 0; @@ -1561,10 +1614,10 @@ int get_tree_bdev(struct fs_context *fc, error = lookup_bdev(fc->source, &dev); if (error) { - errorf(fc, "%s: Can't lookup blockdev", fc->source); + if (!(flags & GET_TREE_BDEV_QUIET_LOOKUP)) + errorf(fc, "%s: Can't lookup blockdev", fc->source); return error; } - fc->sb_flags |= SB_NOSEC; s = sget_dev(fc, dev); if (IS_ERR(s)) @@ -1578,15 +1631,7 @@ int get_tree_bdev(struct fs_context *fc, return -EBUSY; } } else { - /* - * We drop s_umount here because we need to open the bdev and - * bdev->open_mutex ranks above s_umount (blkdev_put() -> - * bdev_mark_dead()). It is safe because we have active sb - * reference and SB_BORN is not set yet. - */ - super_unlock_excl(s); error = setup_bdev_super(s, fc->sb_flags, fc); - __super_lock_excl(s); if (!error) error = fill_super(s, fc); if (error) { @@ -1600,6 +1645,19 @@ int get_tree_bdev(struct fs_context *fc, fc->root = dget(s->s_root); return 0; } +EXPORT_SYMBOL_GPL(get_tree_bdev_flags); + +/** + * get_tree_bdev - Get a superblock based on a single block device + * @fc: The filesystem context holding the parameters + * @fill_super: Helper to initialise a new superblock + */ +int get_tree_bdev(struct fs_context *fc, + int (*fill_super)(struct super_block *, + struct fs_context *)) +{ + return get_tree_bdev_flags(fc, fill_super, 0); +} EXPORT_SYMBOL(get_tree_bdev); static int test_bdev_super(struct super_block *s, void *data) @@ -1630,15 +1688,7 @@ struct dentry *mount_bdev(struct file_system_type *fs_type, return ERR_PTR(-EBUSY); } } else { - /* - * We drop s_umount here because we need to open the bdev and - * bdev->open_mutex ranks above s_umount (blkdev_put() -> - * bdev_mark_dead()). It is safe because we have active sb - * reference and SB_BORN is not set yet. - */ - super_unlock_excl(s); error = setup_bdev_super(s, flags, NULL); - __super_lock_excl(s); if (!error) error = fill_super(s, data, flags & SB_SILENT ? 1 : 0); if (error) { @@ -1660,7 +1710,7 @@ void kill_block_super(struct super_block *sb) generic_shutdown_super(sb); if (bdev) { sync_blockdev(bdev); - bdev_release(sb->s_bdev_handle); + bdev_fput(sb->s_bdev_file); } } @@ -1766,8 +1816,8 @@ int vfs_get_tree(struct fs_context *fc) return error; if (!fc->root) { - pr_err("Filesystem %s get_tree() didn't set fc->root\n", - fc->fs_type->name); + pr_err("Filesystem %s get_tree() didn't set fc->root, returned %i\n", + fc->fs_type->name, error); /* We don't know what the locking state of the superblock is - * if there is a superblock. */ @@ -1869,7 +1919,7 @@ static void lockdep_sb_freeze_release(struct super_block *sb) int level; for (level = SB_FREEZE_LEVELS - 1; level >= 0; level--) - percpu_rwsem_release(sb->s_writers.rw_sem + level, 0, _THIS_IP_); + percpu_rwsem_release(sb->s_writers.rw_sem + level, _THIS_IP_); } /* @@ -1907,6 +1957,47 @@ static int wait_for_partially_frozen(struct super_block *sb) return ret; } +#define FREEZE_HOLDERS (FREEZE_HOLDER_KERNEL | FREEZE_HOLDER_USERSPACE) +#define FREEZE_FLAGS (FREEZE_HOLDERS | FREEZE_MAY_NEST) + +static inline int freeze_inc(struct super_block *sb, enum freeze_holder who) +{ + WARN_ON_ONCE((who & ~FREEZE_FLAGS)); + WARN_ON_ONCE(hweight32(who & FREEZE_HOLDERS) > 1); + + if (who & FREEZE_HOLDER_KERNEL) + ++sb->s_writers.freeze_kcount; + if (who & FREEZE_HOLDER_USERSPACE) + ++sb->s_writers.freeze_ucount; + return sb->s_writers.freeze_kcount + sb->s_writers.freeze_ucount; +} + +static inline int freeze_dec(struct super_block *sb, enum freeze_holder who) +{ + WARN_ON_ONCE((who & ~FREEZE_FLAGS)); + WARN_ON_ONCE(hweight32(who & FREEZE_HOLDERS) > 1); + + if ((who & FREEZE_HOLDER_KERNEL) && sb->s_writers.freeze_kcount) + --sb->s_writers.freeze_kcount; + if ((who & FREEZE_HOLDER_USERSPACE) && sb->s_writers.freeze_ucount) + --sb->s_writers.freeze_ucount; + return sb->s_writers.freeze_kcount + sb->s_writers.freeze_ucount; +} + +static inline bool may_freeze(struct super_block *sb, enum freeze_holder who) +{ + WARN_ON_ONCE((who & ~FREEZE_FLAGS)); + WARN_ON_ONCE(hweight32(who & FREEZE_HOLDERS) > 1); + + if (who & FREEZE_HOLDER_KERNEL) + return (who & FREEZE_MAY_NEST) || + sb->s_writers.freeze_kcount == 0; + if (who & FREEZE_HOLDER_USERSPACE) + return (who & FREEZE_MAY_NEST) || + sb->s_writers.freeze_ucount == 0; + return false; +} + /** * freeze_super - lock the filesystem and force it into a consistent state * @sb: the super to lock @@ -1919,6 +2010,7 @@ static int wait_for_partially_frozen(struct super_block *sb) * @who should be: * * %FREEZE_HOLDER_USERSPACE if userspace wants to freeze the fs; * * %FREEZE_HOLDER_KERNEL if the kernel wants to freeze the fs. + * * %FREEZE_MAY_NEST whether nesting freeze and thaw requests is allowed. * * The @who argument distinguishes between the kernel and userspace trying to * freeze the filesystem. Although there cannot be multiple kernel freezes or @@ -1926,6 +2018,13 @@ static int wait_for_partially_frozen(struct super_block *sb) * userspace can both hold a filesystem frozen. The filesystem remains frozen * until there are no kernel or userspace freezes in effect. * + * A filesystem may hold multiple devices and thus a filesystems may be + * frozen through the block layer via multiple block devices. In this + * case the request is marked as being allowed to nest by passing + * FREEZE_MAY_NEST. The filesystem remains frozen until all block + * devices are unfrozen. If multiple freezes are attempted without + * FREEZE_MAY_NEST -EBUSY will be returned. + * * During this function, sb->s_writers.frozen goes through these values: * * SB_UNFROZEN: File system is normal, all writes progress as usual. @@ -1950,31 +2049,29 @@ static int wait_for_partially_frozen(struct super_block *sb) * mostly auxiliary for filesystems to verify they do not modify frozen fs. * * sb->s_writers.frozen is protected by sb->s_umount. + * + * Return: If the freeze was successful zero is returned. If the freeze + * failed a negative error code is returned. */ int freeze_super(struct super_block *sb, enum freeze_holder who) { int ret; + if (!super_lock_excl(sb)) { + WARN_ON_ONCE("Dying superblock while freezing!"); + return -EINVAL; + } atomic_inc(&sb->s_active); - if (!super_lock_excl(sb)) - WARN(1, "Dying superblock while freezing!"); retry: if (sb->s_writers.frozen == SB_FREEZE_COMPLETE) { - if (sb->s_writers.freeze_holders & who) { - deactivate_locked_super(sb); - return -EBUSY; - } - - WARN_ON(sb->s_writers.freeze_holders == 0); - - /* - * Someone else already holds this type of freeze; share the - * freeze and assign the active ref to the freeze. - */ - sb->s_writers.freeze_holders |= who; - super_unlock_excl(sb); - return 0; + if (may_freeze(sb, who)) + ret = !!WARN_ON_ONCE(freeze_inc(sb, who) == 1); + else + ret = -EBUSY; + /* All freezers share a single active reference. */ + deactivate_locked_super(sb); + return ret; } if (sb->s_writers.frozen != SB_UNFROZEN) { @@ -1987,14 +2084,9 @@ retry: goto retry; } - if (!(sb->s_flags & SB_BORN)) { - super_unlock_excl(sb); - return 0; /* sic - it's "nothing to do" */ - } - if (sb_rdonly(sb)) { /* Nothing to do really... */ - sb->s_writers.freeze_holders |= who; + WARN_ON_ONCE(freeze_inc(sb, who) > 1); sb->s_writers.frozen = SB_FREEZE_COMPLETE; wake_up_var(&sb->s_writers.frozen); super_unlock_excl(sb); @@ -2005,8 +2097,7 @@ retry: /* Release s_umount to preserve sb_start_write -> s_umount ordering */ super_unlock_excl(sb); sb_wait_write(sb, SB_FREEZE_WRITE); - if (!super_lock_excl(sb)) - WARN(1, "Dying superblock while freezing!"); + __super_lock_excl(sb); /* Now we go and block page faults... */ sb->s_writers.frozen = SB_FREEZE_PAGEFAULT; @@ -2042,7 +2133,7 @@ retry: * For debugging purposes so that fs can warn if it sees write activity * when frozen is set to SB_FREEZE_COMPLETE, and for thaw_super(). */ - sb->s_writers.freeze_holders |= who; + WARN_ON_ONCE(freeze_inc(sb, who) > 1); sb->s_writers.frozen = SB_FREEZE_COMPLETE; wake_up_var(&sb->s_writers.frozen); lockdep_sb_freeze_release(sb); @@ -2059,34 +2150,22 @@ EXPORT_SYMBOL(freeze_super); */ static int thaw_super_locked(struct super_block *sb, enum freeze_holder who) { - int error; + int error = -EINVAL; - if (sb->s_writers.frozen == SB_FREEZE_COMPLETE) { - if (!(sb->s_writers.freeze_holders & who)) { - super_unlock_excl(sb); - return -EINVAL; - } + if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) + goto out_unlock; - /* - * Freeze is shared with someone else. Release our hold and - * drop the active ref that freeze_super assigned to the - * freezer. - */ - if (sb->s_writers.freeze_holders & ~who) { - sb->s_writers.freeze_holders &= ~who; - deactivate_locked_super(sb); - return 0; - } - } else { - super_unlock_excl(sb); - return -EINVAL; - } + /* + * All freezers share a single active reference. + * So just unlock in case there are any left. + */ + if (freeze_dec(sb, who)) + goto out_unlock; if (sb_rdonly(sb)) { - sb->s_writers.freeze_holders &= ~who; sb->s_writers.frozen = SB_UNFROZEN; wake_up_var(&sb->s_writers.frozen); - goto out; + goto out_deactivate; } lockdep_sb_freeze_acquire(sb); @@ -2094,20 +2173,23 @@ static int thaw_super_locked(struct super_block *sb, enum freeze_holder who) if (sb->s_op->unfreeze_fs) { error = sb->s_op->unfreeze_fs(sb); if (error) { - printk(KERN_ERR "VFS:Filesystem thaw failed\n"); + pr_err("VFS: Filesystem thaw failed\n"); + freeze_inc(sb, who); lockdep_sb_freeze_release(sb); - super_unlock_excl(sb); - return error; + goto out_unlock; } } - sb->s_writers.freeze_holders &= ~who; sb->s_writers.frozen = SB_UNFROZEN; wake_up_var(&sb->s_writers.frozen); sb_freeze_unlock(sb, SB_FREEZE_FS); -out: +out_deactivate: deactivate_locked_super(sb); return 0; + +out_unlock: + super_unlock_excl(sb); + return error; } /** @@ -2121,11 +2203,18 @@ out: * @who should be: * * %FREEZE_HOLDER_USERSPACE if userspace wants to thaw the fs; * * %FREEZE_HOLDER_KERNEL if the kernel wants to thaw the fs. + * * %FREEZE_MAY_NEST whether nesting freeze and thaw requests is allowed + * + * A filesystem may hold multiple devices and thus a filesystems may + * have been frozen through the block layer via multiple block devices. + * The filesystem remains frozen until all block devices are unfrozen. */ int thaw_super(struct super_block *sb, enum freeze_holder who) { - if (!super_lock_excl(sb)) - WARN(1, "Dying superblock while thawing!"); + if (!super_lock_excl(sb)) { + WARN_ON_ONCE("Dying superblock while thawing!"); + return -EINVAL; + } return thaw_super_locked(sb, who); } EXPORT_SYMBOL(thaw_super); @@ -2153,3 +2242,4 @@ int sb_init_dio_done_wq(struct super_block *sb) destroy_workqueue(wq); return 0; } +EXPORT_SYMBOL_GPL(sb_init_dio_done_wq); |