| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * linux/fs/super.c |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| * |
| * super.c contains code to handle: - mount structures |
| * - super-block tables |
| * - filesystem drivers list |
| * - mount system call |
| * - umount system call |
| * - ustat system call |
| * |
| * GK 2/5/95 - Changed to support mounting the root fs via NFS |
| * |
| * Added kerneld support: Jacques Gelinas and Bjorn Ekwall |
| * Added change_root: Werner Almesberger & Hans Lermen, Feb '96 |
| * Added options to /proc/mounts: |
| * Torbjörn Lindh (torbjorn.lindh@gopta.se), April 14, 1996. |
| * Added devfs support: Richard Gooch <rgooch@atnf.csiro.au>, 13-JAN-1998 |
| * Heavily rewritten for 'one fs - one tree' dcache architecture. AV, Mar 2000 |
| */ |
| |
| #include <linux/export.h> |
| #include <linux/slab.h> |
| #include <linux/blkdev.h> |
| #include <linux/mount.h> |
| #include <linux/security.h> |
| #include <linux/writeback.h> /* for the emergency remount stuff */ |
| #include <linux/idr.h> |
| #include <linux/mutex.h> |
| #include <linux/backing-dev.h> |
| #include <linux/rculist_bl.h> |
| #include <linux/fscrypt.h> |
| #include <linux/fsnotify.h> |
| #include <linux/lockdep.h> |
| #include <linux/user_namespace.h> |
| #include <linux/fs_context.h> |
| #include <uapi/linux/mount.h> |
| #include "internal.h" |
| |
| static int thaw_super_locked(struct super_block *sb, enum freeze_holder who); |
| |
| static LIST_HEAD(super_blocks); |
| static DEFINE_SPINLOCK(sb_lock); |
| |
| static char *sb_writers_name[SB_FREEZE_LEVELS] = { |
| "sb_writers", |
| "sb_pagefaults", |
| "sb_internal", |
| }; |
| |
| static inline void __super_lock(struct super_block *sb, bool excl) |
| { |
| if (excl) |
| down_write(&sb->s_umount); |
| else |
| down_read(&sb->s_umount); |
| } |
| |
| static inline void super_unlock(struct super_block *sb, bool excl) |
| { |
| if (excl) |
| up_write(&sb->s_umount); |
| else |
| up_read(&sb->s_umount); |
| } |
| |
| static inline void __super_lock_excl(struct super_block *sb) |
| { |
| __super_lock(sb, true); |
| } |
| |
| static inline void super_unlock_excl(struct super_block *sb) |
| { |
| super_unlock(sb, true); |
| } |
| |
| static inline void super_unlock_shared(struct super_block *sb) |
| { |
| super_unlock(sb, false); |
| } |
| |
| static bool super_flags(const struct super_block *sb, unsigned int flags) |
| { |
| /* |
| * Pairs with smp_store_release() in super_wake() and ensures |
| * that we see @flags after we're woken. |
| */ |
| return smp_load_acquire(&sb->s_flags) & flags; |
| } |
| |
| /** |
| * super_lock - wait for superblock to become ready and lock it |
| * @sb: superblock to wait for |
| * @excl: whether exclusive access is required |
| * |
| * If the superblock has neither passed through vfs_get_tree() or |
| * generic_shutdown_super() yet wait for it to happen. Either superblock |
| * creation will succeed and SB_BORN is set by vfs_get_tree() or we're |
| * woken and we'll see SB_DYING. |
| * |
| * The caller must have acquired a temporary reference on @sb->s_count. |
| * |
| * 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); |
| |
| /* 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); |
| |
| /* |
| * Has gone through generic_shutdown_super() in the meantime. |
| * @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) { |
| super_unlock(sb, excl); |
| return false; |
| } |
| |
| WARN_ON_ONCE(!(sb->s_flags & SB_BORN)); |
| return true; |
| } |
| |
| /* 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 try to acquire write-side of @sb->s_umount */ |
| static inline bool super_lock_excl(struct super_block *sb) |
| { |
| return super_lock(sb, true); |
| } |
| |
| /* wake waiters */ |
| #define SUPER_WAKE_FLAGS (SB_BORN | SB_DYING | SB_DEAD) |
| static void super_wake(struct super_block *sb, unsigned int flag) |
| { |
| WARN_ON_ONCE((flag & ~SUPER_WAKE_FLAGS)); |
| WARN_ON_ONCE(hweight32(flag & SUPER_WAKE_FLAGS) > 1); |
| |
| /* |
| * Pairs with smp_load_acquire() in super_lock() to make sure |
| * all initializations in the superblock are seen by the user |
| * seeing SB_BORN sent. |
| */ |
| smp_store_release(&sb->s_flags, sb->s_flags | flag); |
| /* |
| * Pairs with the barrier in prepare_to_wait_event() to make sure |
| * ___wait_var_event() either sees SB_BORN set or |
| * waitqueue_active() check in wake_up_var() sees the waiter. |
| */ |
| smp_mb(); |
| wake_up_var(&sb->s_flags); |
| } |
| |
| /* |
| * 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_mutex. Hence we |
| * take a passive reference to the superblock to avoid this from occurring. |
| */ |
| static unsigned long super_cache_scan(struct shrinker *shrink, |
| struct shrink_control *sc) |
| { |
| struct super_block *sb; |
| long fs_objects = 0; |
| long total_objects; |
| long freed = 0; |
| long dentries; |
| long inodes; |
| |
| sb = shrink->private_data; |
| |
| /* |
| * Deadlock avoidance. We may hold various FS locks, and we don't want |
| * to recurse into the FS that called us in clear_inode() and friends.. |
| */ |
| if (!(sc->gfp_mask & __GFP_FS)) |
| return SHRINK_STOP; |
| |
| if (!super_trylock_shared(sb)) |
| return SHRINK_STOP; |
| |
| if (sb->s_op->nr_cached_objects) |
| fs_objects = sb->s_op->nr_cached_objects(sb, sc); |
| |
| inodes = list_lru_shrink_count(&sb->s_inode_lru, sc); |
| dentries = list_lru_shrink_count(&sb->s_dentry_lru, sc); |
| total_objects = dentries + inodes + fs_objects + 1; |
| if (!total_objects) |
| total_objects = 1; |
| |
| /* proportion the scan between the caches */ |
| dentries = mult_frac(sc->nr_to_scan, dentries, total_objects); |
| inodes = mult_frac(sc->nr_to_scan, inodes, total_objects); |
| fs_objects = mult_frac(sc->nr_to_scan, fs_objects, total_objects); |
| |
| /* |
| * prune the dcache first as the icache is pinned by it, then |
| * prune the icache, followed by the filesystem specific caches |
| * |
| * Ensure that we always scan at least one object - memcg kmem |
| * accounting uses this to fully empty the caches. |
| */ |
| sc->nr_to_scan = dentries + 1; |
| freed = prune_dcache_sb(sb, sc); |
| sc->nr_to_scan = inodes + 1; |
| freed += prune_icache_sb(sb, sc); |
| |
| if (fs_objects) { |
| sc->nr_to_scan = fs_objects + 1; |
| freed += sb->s_op->free_cached_objects(sb, sc); |
| } |
| |
| super_unlock_shared(sb); |
| return freed; |
| } |
| |
| static unsigned long super_cache_count(struct shrinker *shrink, |
| struct shrink_control *sc) |
| { |
| struct super_block *sb; |
| long total_objects = 0; |
| |
| sb = shrink->private_data; |
| |
| /* |
| * We don't call super_trylock_shared() here as it is a scalability |
| * bottleneck, so we're exposed to partial setup state. The shrinker |
| * rwsem does not protect filesystem operations backing |
| * list_lru_shrink_count() or s_op->nr_cached_objects(). Counts can |
| * change between super_cache_count and super_cache_scan, so we really |
| * don't need locks here. |
| * |
| * However, if we are currently mounting the superblock, the underlying |
| * filesystem might be in a state of partial construction and hence it |
| * is dangerous to access it. super_trylock_shared() uses a SB_BORN check |
| * to avoid this situation, so do the same here. The memory barrier is |
| * matched with the one in mount_fs() as we don't hold locks here. |
| */ |
| if (!(sb->s_flags & SB_BORN)) |
| return 0; |
| smp_rmb(); |
| |
| if (sb->s_op && sb->s_op->nr_cached_objects) |
| total_objects = sb->s_op->nr_cached_objects(sb, sc); |
| |
| total_objects += list_lru_shrink_count(&sb->s_dentry_lru, sc); |
| total_objects += list_lru_shrink_count(&sb->s_inode_lru, sc); |
| |
| if (!total_objects) |
| return SHRINK_EMPTY; |
| |
| total_objects = vfs_pressure_ratio(total_objects); |
| return total_objects; |
| } |
| |
| static void destroy_super_work(struct work_struct *work) |
| { |
| struct super_block *s = container_of(work, struct super_block, |
| destroy_work); |
| 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); |
| } |
| |
| static void destroy_super_rcu(struct rcu_head *head) |
| { |
| struct super_block *s = container_of(head, struct super_block, rcu); |
| INIT_WORK(&s->destroy_work, destroy_super_work); |
| schedule_work(&s->destroy_work); |
| } |
| |
| /* Free a superblock that has never been seen by anyone */ |
| static void destroy_unused_super(struct super_block *s) |
| { |
| if (!s) |
| return; |
| super_unlock_excl(s); |
| list_lru_destroy(&s->s_dentry_lru); |
| list_lru_destroy(&s->s_inode_lru); |
| shrinker_free(s->s_shrink); |
| /* no delays needed */ |
| destroy_super_work(&s->destroy_work); |
| } |
| |
| /** |
| * alloc_super - create new superblock |
| * @type: filesystem type superblock should belong to |
| * @flags: the mount flags |
| * @user_ns: User namespace for the super_block |
| * |
| * Allocates and initializes a new &struct super_block. alloc_super() |
| * returns a pointer new superblock or %NULL if allocation had failed. |
| */ |
| 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_KERNEL); |
| static const struct super_operations default_op; |
| int i; |
| |
| if (!s) |
| return NULL; |
| |
| INIT_LIST_HEAD(&s->s_mounts); |
| s->s_user_ns = get_user_ns(user_ns); |
| init_rwsem(&s->s_umount); |
| lockdep_set_class(&s->s_umount, &type->s_umount_key); |
| /* |
| * sget() can have s_umount recursion. |
| * |
| * When it cannot find a suitable sb, it allocates a new |
| * one (this one), and tries again to find a suitable old |
| * one. |
| * |
| * In case that succeeds, it will acquire the s_umount |
| * lock of the old one. Since these are clearly distrinct |
| * locks, and this object isn't exposed yet, there's no |
| * risk of deadlocks. |
| * |
| * Annotate this by putting this lock in a different |
| * subclass. |
| */ |
| down_write_nested(&s->s_umount, SINGLE_DEPTH_NESTING); |
| |
| if (security_sb_alloc(s)) |
| goto fail; |
| |
| for (i = 0; i < SB_FREEZE_LEVELS; i++) { |
| if (__percpu_init_rwsem(&s->s_writers.rw_sem[i], |
| sb_writers_name[i], |
| &type->s_writers_key[i])) |
| goto fail; |
| } |
| s->s_bdi = &noop_backing_dev_info; |
| s->s_flags = flags; |
| if (s->s_user_ns != &init_user_ns) |
| s->s_iflags |= SB_I_NODEV; |
| INIT_HLIST_NODE(&s->s_instances); |
| INIT_HLIST_BL_HEAD(&s->s_roots); |
| mutex_init(&s->s_sync_lock); |
| INIT_LIST_HEAD(&s->s_inodes); |
| spin_lock_init(&s->s_inode_list_lock); |
| INIT_LIST_HEAD(&s->s_inodes_wb); |
| spin_lock_init(&s->s_inode_wblist_lock); |
| |
| s->s_count = 1; |
| atomic_set(&s->s_active, 1); |
| mutex_init(&s->s_vfs_rename_mutex); |
| lockdep_set_class(&s->s_vfs_rename_mutex, &type->s_vfs_rename_key); |
| init_rwsem(&s->s_dquot.dqio_sem); |
| s->s_maxbytes = MAX_NON_LFS; |
| s->s_op = &default_op; |
| s->s_time_gran = 1000000000; |
| s->s_time_min = TIME64_MIN; |
| s->s_time_max = TIME64_MAX; |
| |
| s->s_shrink = shrinker_alloc(SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE, |
| "sb-%s", type->name); |
| if (!s->s_shrink) |
| goto fail; |
| |
| 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)) |
| goto fail; |
| return s; |
| |
| fail: |
| destroy_unused_super(s); |
| return NULL; |
| } |
| |
| /* Superblock refcounting */ |
| |
| /* |
| * Drop a superblock's refcount. The caller must hold sb_lock. |
| */ |
| static void __put_super(struct super_block *s) |
| { |
| if (!--s->s_count) { |
| list_del_init(&s->s_list); |
| WARN_ON(s->s_dentry_lru.node); |
| WARN_ON(s->s_inode_lru.node); |
| WARN_ON(!list_empty(&s->s_mounts)); |
| call_rcu(&s->rcu, destroy_super_rcu); |
| } |
| } |
| |
| /** |
| * put_super - drop a temporary reference to superblock |
| * @sb: superblock in question |
| * |
| * Drops a temporary reference, frees superblock if there's no |
| * references left. |
| */ |
| void put_super(struct super_block *sb) |
| { |
| spin_lock(&sb_lock); |
| __put_super(sb); |
| spin_unlock(&sb_lock); |
| } |
| |
| static void kill_super_notify(struct super_block *sb) |
| { |
| lockdep_assert_not_held(&sb->s_umount); |
| |
| /* already notified earlier */ |
| if (sb->s_flags & SB_DEAD) |
| return; |
| |
| /* |
| * Remove it from @fs_supers so it isn't found by new |
| * sget{_fc}() walkers anymore. Any concurrent mounter still |
| * managing to grab a temporary reference is guaranteed to |
| * already see SB_DYING and will wait until we notify them about |
| * SB_DEAD. |
| */ |
| spin_lock(&sb_lock); |
| hlist_del_init(&sb->s_instances); |
| spin_unlock(&sb_lock); |
| |
| /* |
| * Let concurrent mounts know that this thing is really dead. |
| * We don't need @sb->s_umount here as every concurrent caller |
| * will see SB_DYING and either discard the superblock or wait |
| * for SB_DEAD. |
| */ |
| super_wake(sb, SB_DEAD); |
| } |
| |
| /** |
| * deactivate_locked_super - drop an active reference to superblock |
| * @s: superblock to deactivate |
| * |
| * Drops an active reference to superblock, converting it into a temporary |
| * one if there is no other active references left. In that case we |
| * tell fs driver to shut it down and drop the temporary reference we |
| * had just acquired. |
| * |
| * Caller holds exclusive lock on superblock; that lock is released. |
| */ |
| void deactivate_locked_super(struct super_block *s) |
| { |
| struct file_system_type *fs = s->s_type; |
| if (atomic_dec_and_test(&s->s_active)) { |
| shrinker_free(s->s_shrink); |
| fs->kill_sb(s); |
| |
| kill_super_notify(s); |
| |
| /* |
| * Since list_lru_destroy() may sleep, we cannot call it from |
| * put_super(), where we hold the sb_lock. Therefore we destroy |
| * the lru lists right now. |
| */ |
| list_lru_destroy(&s->s_dentry_lru); |
| list_lru_destroy(&s->s_inode_lru); |
| |
| put_filesystem(fs); |
| put_super(s); |
| } else { |
| super_unlock_excl(s); |
| } |
| } |
| |
| EXPORT_SYMBOL(deactivate_locked_super); |
| |
| /** |
| * deactivate_super - drop an active reference to superblock |
| * @s: superblock to deactivate |
| * |
| * Variant of deactivate_locked_super(), except that superblock is *not* |
| * locked by caller. If we are going to drop the final active reference, |
| * lock will be acquired prior to that. |
| */ |
| void deactivate_super(struct super_block *s) |
| { |
| if (!atomic_add_unless(&s->s_active, -1, 1)) { |
| __super_lock_excl(s); |
| deactivate_locked_super(s); |
| } |
| } |
| |
| EXPORT_SYMBOL(deactivate_super); |
| |
| /** |
| * 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 |
| * an active reference. This is used in sget{_fc}() to wait for a |
| * superblock to either become SB_BORN or for it to pass through |
| * sb->kill() and be marked as SB_DEAD. |
| * |
| * Return: This returns true if an active reference could be acquired, |
| * false if not. |
| */ |
| static bool grab_super(struct super_block *sb) |
| { |
| bool locked; |
| |
| sb->s_count++; |
| 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, super_flags(sb, SB_DEAD)); |
| put_super(sb); |
| return false; |
| } |
| |
| /* |
| * super_trylock_shared - try to grab ->s_umount shared |
| * @sb: reference we are trying to grab |
| * |
| * Try to prevent fs shutdown. This is used in places where we |
| * cannot take an active reference but we need to ensure that the |
| * filesystem is not shut down while we are working on it. It returns |
| * false if we cannot acquire s_umount or if we lose the race and |
| * filesystem already got into shutdown, and returns true with the s_umount |
| * lock held in read mode in case of success. On successful return, |
| * the caller must drop the s_umount lock when done. |
| * |
| * Note that unlike get_super() et.al. this one does *not* bump ->s_count. |
| * The reason why it's safe is that we are OK with doing trylock instead |
| * of down_read(). There's a couple of places that are OK with that, but |
| * it's very much not a general-purpose interface. |
| */ |
| bool super_trylock_shared(struct super_block *sb) |
| { |
| if (down_read_trylock(&sb->s_umount)) { |
| if (!(sb->s_flags & SB_DYING) && sb->s_root && |
| (sb->s_flags & SB_BORN)) |
| return true; |
| super_unlock_shared(sb); |
| } |
| |
| return false; |
| } |
| |
| /** |
| * retire_super - prevents superblock from being reused |
| * @sb: superblock to retire |
| * |
| * The function marks superblock to be ignored in superblock test, which |
| * prevents it from being reused for any new mounts. If the superblock has |
| * a private bdi, it also unregisters it, but doesn't reduce the refcount |
| * of the superblock to prevent potential races. The refcount is reduced |
| * by generic_shutdown_super(). The function can not be called |
| * concurrently with generic_shutdown_super(). It is safe to call the |
| * function multiple times, subsequent calls have no effect. |
| * |
| * The marker will affect the re-use only for block-device-based |
| * superblocks. Other superblocks will still get marked if this function |
| * is used, but that will not affect their reusability. |
| */ |
| void retire_super(struct super_block *sb) |
| { |
| WARN_ON(!sb->s_bdev); |
| __super_lock_excl(sb); |
| if (sb->s_iflags & SB_I_PERSB_BDI) { |
| bdi_unregister(sb->s_bdi); |
| sb->s_iflags &= ~SB_I_PERSB_BDI; |
| } |
| sb->s_iflags |= SB_I_RETIRED; |
| super_unlock_excl(sb); |
| } |
| EXPORT_SYMBOL(retire_super); |
| |
| /** |
| * generic_shutdown_super - common helper for ->kill_sb() |
| * @sb: superblock to kill |
| * |
| * generic_shutdown_super() does all fs-independent work on superblock |
| * shutdown. Typical ->kill_sb() should pick all fs-specific objects |
| * that need destruction out of superblock, call generic_shutdown_super() |
| * and release aforementioned objects. Note: dentries and inodes _are_ |
| * taken care of and do not need specific handling. |
| * |
| * Upon calling this function, the filesystem may no longer alter or |
| * rearrange the set of dentries belonging to this super_block, nor may it |
| * change the attachments of dentries to inodes. |
| */ |
| void generic_shutdown_super(struct super_block *sb) |
| { |
| const struct super_operations *sop = sb->s_op; |
| |
| if (sb->s_root) { |
| shrink_dcache_for_umount(sb); |
| sync_filesystem(sb); |
| sb->s_flags &= ~SB_ACTIVE; |
| |
| cgroup_writeback_umount(); |
| |
| /* Evict all inodes with zero refcount. */ |
| evict_inodes(sb); |
| |
| /* |
| * Clean up and evict any inodes that still have references due |
| * to fsnotify or the security policy. |
| */ |
| fsnotify_sb_delete(sb); |
| security_sb_delete(sb); |
| |
| if (sb->s_dio_done_wq) { |
| destroy_workqueue(sb->s_dio_done_wq); |
| sb->s_dio_done_wq = NULL; |
| } |
| |
| 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)) { |
| /* |
| * Adding a proper bailout path here would be hard, but |
| * we can at least make it more likely that a later |
| * iput_final() or such crashes cleanly. |
| */ |
| struct inode *inode; |
| |
| spin_lock(&sb->s_inode_list_lock); |
| list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { |
| inode->i_op = VFS_PTR_POISON; |
| inode->i_sb = VFS_PTR_POISON; |
| inode->i_mapping = VFS_PTR_POISON; |
| } |
| spin_unlock(&sb->s_inode_list_lock); |
| } |
| } |
| /* |
| * Broadcast to everyone that grabbed a temporary reference to this |
| * superblock before we removed it from @fs_supers that the superblock |
| * is dying. Every walker of @fs_supers outside of sget{_fc}() will now |
| * discard this superblock and treat it as dead. |
| * |
| * We leave the superblock on @fs_supers so it can be found by |
| * sget{_fc}() until we passed sb->kill_sb(). |
| */ |
| super_wake(sb, SB_DYING); |
| super_unlock_excl(sb); |
| if (sb->s_bdi != &noop_backing_dev_info) { |
| if (sb->s_iflags & SB_I_PERSB_BDI) |
| bdi_unregister(sb->s_bdi); |
| bdi_put(sb->s_bdi); |
| sb->s_bdi = &noop_backing_dev_info; |
| } |
| } |
| |
| EXPORT_SYMBOL(generic_shutdown_super); |
| |
| bool mount_capable(struct fs_context *fc) |
| { |
| if (!(fc->fs_type->fs_flags & FS_USERNS_MOUNT)) |
| return capable(CAP_SYS_ADMIN); |
| else |
| return ns_capable(fc->user_ns, CAP_SYS_ADMIN); |
| } |
| |
| /** |
| * sget_fc - Find or create a superblock |
| * @fc: Filesystem context. |
| * @test: Comparison callback |
| * @set: Setup callback |
| * |
| * Create a new superblock or find an existing one. |
| * |
| * The @test callback is used to find a matching existing superblock. |
| * Whether or not the requested parameters in @fc are taken into account |
| * is specific to the @test callback that is used. They may even be |
| * completely ignored. |
| * |
| * If an extant superblock is matched, it will be returned unless: |
| * |
| * (1) the namespace the filesystem context @fc and the extant |
| * superblock's namespace differ |
| * |
| * (2) the filesystem context @fc has requested that reusing an extant |
| * superblock is not allowed |
| * |
| * In both cases EBUSY will be returned. |
| * |
| * If no match is made, a new superblock will be allocated and basic |
| * initialisation will be performed (s_type, s_fs_info and s_id will be |
| * set and the @set callback will be invoked), the superblock will be |
| * published and it will be returned in a partially constructed state |
| * with SB_BORN and SB_ACTIVE as yet unset. |
| * |
| * Return: On success, an extant or newly created superblock is |
| * returned. On failure an error pointer is returned. |
| */ |
| struct super_block *sget_fc(struct fs_context *fc, |
| int (*test)(struct super_block *, struct fs_context *), |
| int (*set)(struct super_block *, struct fs_context *)) |
| { |
| struct super_block *s = NULL; |
| struct super_block *old; |
| struct user_namespace *user_ns = fc->global ? &init_user_ns : fc->user_ns; |
| int err; |
| |
| retry: |
| spin_lock(&sb_lock); |
| if (test) { |
| hlist_for_each_entry(old, &fc->fs_type->fs_supers, s_instances) { |
| if (test(old, fc)) |
| goto share_extant_sb; |
| } |
| } |
| if (!s) { |
| spin_unlock(&sb_lock); |
| s = alloc_super(fc->fs_type, fc->sb_flags, user_ns); |
| if (!s) |
| return ERR_PTR(-ENOMEM); |
| goto retry; |
| } |
| |
| s->s_fs_info = fc->s_fs_info; |
| err = set(s, fc); |
| if (err) { |
| s->s_fs_info = NULL; |
| spin_unlock(&sb_lock); |
| destroy_unused_super(s); |
| return ERR_PTR(err); |
| } |
| fc->s_fs_info = NULL; |
| s->s_type = fc->fs_type; |
| s->s_iflags |= fc->s_iflags; |
| strscpy(s->s_id, s->s_type->name, sizeof(s->s_id)); |
| /* |
| * Make the superblock visible on @super_blocks and @fs_supers. |
| * It's in a nascent state and users should wait on SB_BORN or |
| * SB_DYING to be set. |
| */ |
| list_add_tail(&s->s_list, &super_blocks); |
| hlist_add_head(&s->s_instances, &s->s_type->fs_supers); |
| spin_unlock(&sb_lock); |
| get_filesystem(s->s_type); |
| shrinker_register(s->s_shrink); |
| return s; |
| |
| share_extant_sb: |
| if (user_ns != old->s_user_ns || fc->exclusive) { |
| spin_unlock(&sb_lock); |
| destroy_unused_super(s); |
| if (fc->exclusive) |
| warnfc(fc, "reusing existing filesystem not allowed"); |
| else |
| warnfc(fc, "reusing existing filesystem in another namespace not allowed"); |
| return ERR_PTR(-EBUSY); |
| } |
| if (!grab_super(old)) |
| goto retry; |
| destroy_unused_super(s); |
| return old; |
| } |
| EXPORT_SYMBOL(sget_fc); |
| |
| /** |
| * sget - find or create a superblock |
| * @type: filesystem type superblock should belong to |
| * @test: comparison callback |
| * @set: setup callback |
| * @flags: mount flags |
| * @data: argument to each of them |
| */ |
| struct super_block *sget(struct file_system_type *type, |
| int (*test)(struct super_block *,void *), |
| int (*set)(struct super_block *,void *), |
| int flags, |
| void *data) |
| { |
| struct user_namespace *user_ns = current_user_ns(); |
| struct super_block *s = NULL; |
| struct super_block *old; |
| int err; |
| |
| /* We don't yet pass the user namespace of the parent |
| * mount through to here so always use &init_user_ns |
| * until that changes. |
| */ |
| if (flags & SB_SUBMOUNT) |
| user_ns = &init_user_ns; |
| |
| retry: |
| spin_lock(&sb_lock); |
| if (test) { |
| hlist_for_each_entry(old, &type->fs_supers, s_instances) { |
| if (!test(old, data)) |
| continue; |
| if (user_ns != old->s_user_ns) { |
| spin_unlock(&sb_lock); |
| destroy_unused_super(s); |
| return ERR_PTR(-EBUSY); |
| } |
| if (!grab_super(old)) |
| goto retry; |
| destroy_unused_super(s); |
| return old; |
| } |
| } |
| if (!s) { |
| spin_unlock(&sb_lock); |
| s = alloc_super(type, (flags & ~SB_SUBMOUNT), user_ns); |
| if (!s) |
| return ERR_PTR(-ENOMEM); |
| goto retry; |
| } |
| |
| err = set(s, data); |
| if (err) { |
| spin_unlock(&sb_lock); |
| destroy_unused_super(s); |
| return ERR_PTR(err); |
| } |
| s->s_type = type; |
| strscpy(s->s_id, type->name, sizeof(s->s_id)); |
| list_add_tail(&s->s_list, &super_blocks); |
| hlist_add_head(&s->s_instances, &type->fs_supers); |
| spin_unlock(&sb_lock); |
| get_filesystem(type); |
| shrinker_register(s->s_shrink); |
| return s; |
| } |
| EXPORT_SYMBOL(sget); |
| |
| void drop_super(struct super_block *sb) |
| { |
| super_unlock_shared(sb); |
| put_super(sb); |
| } |
| |
| EXPORT_SYMBOL(drop_super); |
| |
| void drop_super_exclusive(struct super_block *sb) |
| { |
| super_unlock_excl(sb); |
| put_super(sb); |
| } |
| EXPORT_SYMBOL(drop_super_exclusive); |
| |
| static void __iterate_supers(void (*f)(struct super_block *)) |
| { |
| struct super_block *sb, *p = NULL; |
| |
| spin_lock(&sb_lock); |
| list_for_each_entry(sb, &super_blocks, s_list) { |
| if (super_flags(sb, SB_DYING)) |
| continue; |
| sb->s_count++; |
| spin_unlock(&sb_lock); |
| |
| f(sb); |
| |
| spin_lock(&sb_lock); |
| if (p) |
| __put_super(p); |
| p = sb; |
| } |
| if (p) |
| __put_super(p); |
| spin_unlock(&sb_lock); |
| } |
| /** |
| * iterate_supers - call function for all active superblocks |
| * @f: function to call |
| * @arg: argument to pass to it |
| * |
| * Scans the superblock list and calls given function, passing it |
| * locked superblock and given argument. |
| */ |
| void iterate_supers(void (*f)(struct super_block *, void *), void *arg) |
| { |
| struct super_block *sb, *p = NULL; |
| |
| spin_lock(&sb_lock); |
| list_for_each_entry(sb, &super_blocks, s_list) { |
| bool locked; |
| |
| sb->s_count++; |
| spin_unlock(&sb_lock); |
| |
| locked = super_lock_shared(sb); |
| if (locked) { |
| if (sb->s_root) |
| f(sb, arg); |
| super_unlock_shared(sb); |
| } |
| |
| spin_lock(&sb_lock); |
| if (p) |
| __put_super(p); |
| p = sb; |
| } |
| if (p) |
| __put_super(p); |
| spin_unlock(&sb_lock); |
| } |
| |
| /** |
| * iterate_supers_type - call function for superblocks of given type |
| * @type: fs type |
| * @f: function to call |
| * @arg: argument to pass to it |
| * |
| * Scans the superblock list and calls given function, passing it |
| * locked superblock and given argument. |
| */ |
| void iterate_supers_type(struct file_system_type *type, |
| void (*f)(struct super_block *, void *), void *arg) |
| { |
| struct super_block *sb, *p = NULL; |
| |
| spin_lock(&sb_lock); |
| hlist_for_each_entry(sb, &type->fs_supers, s_instances) { |
| bool locked; |
| |
| sb->s_count++; |
| spin_unlock(&sb_lock); |
| |
| locked = super_lock_shared(sb); |
| if (locked) { |
| if (sb->s_root) |
| f(sb, arg); |
| super_unlock_shared(sb); |
| } |
| |
| spin_lock(&sb_lock); |
| if (p) |
| __put_super(p); |
| p = sb; |
| } |
| if (p) |
| __put_super(p); |
| spin_unlock(&sb_lock); |
| } |
| |
| EXPORT_SYMBOL(iterate_supers_type); |
| |
| struct super_block *user_get_super(dev_t dev, bool excl) |
| { |
| struct super_block *sb; |
| |
| spin_lock(&sb_lock); |
| list_for_each_entry(sb, &super_blocks, s_list) { |
| if (sb->s_dev == dev) { |
| bool locked; |
| |
| sb->s_count++; |
| spin_unlock(&sb_lock); |
| /* still alive? */ |
| 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); |
| break; |
| } |
| } |
| spin_unlock(&sb_lock); |
| return NULL; |
| } |
| |
| /** |
| * reconfigure_super - asks filesystem to change superblock parameters |
| * @fc: The superblock and configuration |
| * |
| * Alters the configuration parameters of a live superblock. |
| */ |
| int reconfigure_super(struct fs_context *fc) |
| { |
| struct super_block *sb = fc->root->d_sb; |
| int retval; |
| bool remount_ro = false; |
| bool remount_rw = false; |
| bool force = fc->sb_flags & SB_FORCE; |
| |
| if (fc->sb_flags_mask & ~MS_RMT_MASK) |
| return -EINVAL; |
| if (sb->s_writers.frozen != SB_UNFROZEN) |
| return -EBUSY; |
| |
| retval = security_sb_remount(sb, fc->security); |
| if (retval) |
| return retval; |
| |
| if (fc->sb_flags_mask & SB_RDONLY) { |
| #ifdef CONFIG_BLOCK |
| if (!(fc->sb_flags & SB_RDONLY) && sb->s_bdev && |
| bdev_read_only(sb->s_bdev)) |
| return -EACCES; |
| #endif |
| remount_rw = !(fc->sb_flags & SB_RDONLY) && sb_rdonly(sb); |
| remount_ro = (fc->sb_flags & SB_RDONLY) && !sb_rdonly(sb); |
| } |
| |
| if (remount_ro) { |
| if (!hlist_empty(&sb->s_pins)) { |
| super_unlock_excl(sb); |
| group_pin_kill(&sb->s_pins); |
| __super_lock_excl(sb); |
| if (!sb->s_root) |
| return 0; |
| if (sb->s_writers.frozen != SB_UNFROZEN) |
| return -EBUSY; |
| remount_ro = !sb_rdonly(sb); |
| } |
| } |
| shrink_dcache_sb(sb); |
| |
| /* If we are reconfiguring to RDONLY and current sb is read/write, |
| * make sure there are no files open for writing. |
| */ |
| if (remount_ro) { |
| if (force) { |
| sb_start_ro_state_change(sb); |
| } else { |
| retval = sb_prepare_remount_readonly(sb); |
| if (retval) |
| return retval; |
| } |
| } else if (remount_rw) { |
| /* |
| * Protect filesystem's reconfigure code from writes from |
| * userspace until reconfigure finishes. |
| */ |
| sb_start_ro_state_change(sb); |
| } |
| |
| if (fc->ops->reconfigure) { |
| retval = fc->ops->reconfigure(fc); |
| if (retval) { |
| if (!force) |
| goto cancel_readonly; |
| /* If forced remount, go ahead despite any errors */ |
| WARN(1, "forced remount of a %s fs returned %i\n", |
| sb->s_type->name, retval); |
| } |
| } |
| |
| WRITE_ONCE(sb->s_flags, ((sb->s_flags & ~fc->sb_flags_mask) | |
| (fc->sb_flags & fc->sb_flags_mask))); |
| sb_end_ro_state_change(sb); |
| |
| /* |
| * Some filesystems modify their metadata via some other path than the |
| * bdev buffer cache (eg. use a private mapping, or directories in |
| * pagecache, etc). Also file data modifications go via their own |
| * mappings. So If we try to mount readonly then copy the filesystem |
| * from bdev, we could get stale data, so invalidate it to give a best |
| * effort at coherency. |
| */ |
| if (remount_ro && sb->s_bdev) |
| invalidate_bdev(sb->s_bdev); |
| return 0; |
| |
| cancel_readonly: |
| sb_end_ro_state_change(sb); |
| return retval; |
| } |
| |
| static void do_emergency_remount_callback(struct super_block *sb) |
| { |
| bool locked = super_lock_excl(sb); |
| |
| if (locked && sb->s_root && sb->s_bdev && !sb_rdonly(sb)) { |
| struct fs_context *fc; |
| |
| fc = fs_context_for_reconfigure(sb->s_root, |
| SB_RDONLY | SB_FORCE, SB_RDONLY); |
| if (!IS_ERR(fc)) { |
| if (parse_monolithic_mount_data(fc, NULL) == 0) |
| (void)reconfigure_super(fc); |
| put_fs_context(fc); |
| } |
| } |
| if (locked) |
| super_unlock_excl(sb); |
| } |
| |
| static void do_emergency_remount(struct work_struct *work) |
| { |
| __iterate_supers(do_emergency_remount_callback); |
| kfree(work); |
| printk("Emergency Remount complete\n"); |
| } |
| |
| void emergency_remount(void) |
| { |
| struct work_struct *work; |
| |
| work = kmalloc(sizeof(*work), GFP_ATOMIC); |
| if (work) { |
| INIT_WORK(work, do_emergency_remount); |
| schedule_work(work); |
| } |
| } |
| |
| static void do_thaw_all_callback(struct super_block *sb) |
| { |
| bool locked = super_lock_excl(sb); |
| |
| if (locked && sb->s_root) { |
| if (IS_ENABLED(CONFIG_BLOCK)) |
| 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); |
| return; |
| } |
| if (locked) |
| super_unlock_excl(sb); |
| } |
| |
| static void do_thaw_all(struct work_struct *work) |
| { |
| __iterate_supers(do_thaw_all_callback); |
| kfree(work); |
| printk(KERN_WARNING "Emergency Thaw complete\n"); |
| } |
| |
| /** |
| * emergency_thaw_all -- forcibly thaw every frozen filesystem |
| * |
| * Used for emergency unfreeze of all filesystems via SysRq |
| */ |
| void emergency_thaw_all(void) |
| { |
| struct work_struct *work; |
| |
| work = kmalloc(sizeof(*work), GFP_ATOMIC); |
| if (work) { |
| INIT_WORK(work, do_thaw_all); |
| schedule_work(work); |
| } |
| } |
| |
| static DEFINE_IDA(unnamed_dev_ida); |
| |
| /** |
| * get_anon_bdev - Allocate a block device for filesystems which don't have one. |
| * @p: Pointer to a dev_t. |
| * |
| * Filesystems which don't use real block devices can call this function |
| * to allocate a virtual block device. |
| * |
| * Context: Any context. Frequently called while holding sb_lock. |
| * Return: 0 on success, -EMFILE if there are no anonymous bdevs left |
| * or -ENOMEM if memory allocation failed. |
| */ |
| int get_anon_bdev(dev_t *p) |
| { |
| int dev; |
| |
| /* |
| * Many userspace utilities consider an FSID of 0 invalid. |
| * Always return at least 1 from get_anon_bdev. |
| */ |
| dev = ida_alloc_range(&unnamed_dev_ida, 1, (1 << MINORBITS) - 1, |
| GFP_ATOMIC); |
| if (dev == -ENOSPC) |
| dev = -EMFILE; |
| if (dev < 0) |
| return dev; |
| |
| *p = MKDEV(0, dev); |
| return 0; |
| } |
| EXPORT_SYMBOL(get_anon_bdev); |
| |
| void free_anon_bdev(dev_t dev) |
| { |
| ida_free(&unnamed_dev_ida, MINOR(dev)); |
| } |
| EXPORT_SYMBOL(free_anon_bdev); |
| |
| int set_anon_super(struct super_block *s, void *data) |
| { |
| return get_anon_bdev(&s->s_dev); |
| } |
| EXPORT_SYMBOL(set_anon_super); |
| |
| void kill_anon_super(struct super_block *sb) |
| { |
| dev_t dev = sb->s_dev; |
| generic_shutdown_super(sb); |
| kill_super_notify(sb); |
| free_anon_bdev(dev); |
| } |
| EXPORT_SYMBOL(kill_anon_super); |
| |
| void kill_litter_super(struct super_block *sb) |
| { |
| if (sb->s_root) |
| d_genocide(sb->s_root); |
| kill_anon_super(sb); |
| } |
| EXPORT_SYMBOL(kill_litter_super); |
| |
| int set_anon_super_fc(struct super_block *sb, struct fs_context *fc) |
| { |
| return set_anon_super(sb, NULL); |
| } |
| EXPORT_SYMBOL(set_anon_super_fc); |
| |
| static int test_keyed_super(struct super_block *sb, struct fs_context *fc) |
| { |
| return sb->s_fs_info == fc->s_fs_info; |
| } |
| |
| static int test_single_super(struct super_block *s, struct fs_context *fc) |
| { |
| return 1; |
| } |
| |
| static int vfs_get_super(struct fs_context *fc, |
| int (*test)(struct super_block *, struct fs_context *), |
| int (*fill_super)(struct super_block *sb, |
| struct fs_context *fc)) |
| { |
| struct super_block *sb; |
| int err; |
| |
| sb = sget_fc(fc, test, set_anon_super_fc); |
| if (IS_ERR(sb)) |
| return PTR_ERR(sb); |
| |
| if (!sb->s_root) { |
| err = fill_super(sb, fc); |
| if (err) |
| goto error; |
| |
| sb->s_flags |= SB_ACTIVE; |
| } |
| |
| fc->root = dget(sb->s_root); |
| return 0; |
| |
| error: |
| deactivate_locked_super(sb); |
| return err; |
| } |
| |
| int get_tree_nodev(struct fs_context *fc, |
| int (*fill_super)(struct super_block *sb, |
| struct fs_context *fc)) |
| { |
| return vfs_get_super(fc, NULL, fill_super); |
| } |
| EXPORT_SYMBOL(get_tree_nodev); |
| |
| int get_tree_single(struct fs_context *fc, |
| int (*fill_super)(struct super_block *sb, |
| struct fs_context *fc)) |
| { |
| return vfs_get_super(fc, test_single_super, fill_super); |
| } |
| EXPORT_SYMBOL(get_tree_single); |
| |
| int get_tree_keyed(struct fs_context *fc, |
| int (*fill_super)(struct super_block *sb, |
| struct fs_context *fc), |
| void *key) |
| { |
| fc->s_fs_info = key; |
| return vfs_get_super(fc, test_keyed_super, fill_super); |
| } |
| EXPORT_SYMBOL(get_tree_keyed); |
| |
| static int set_bdev_super(struct super_block *s, void *data) |
| { |
| s->s_dev = *(dev_t *)data; |
| return 0; |
| } |
| |
| static int super_s_dev_set(struct super_block *s, struct fs_context *fc) |
| { |
| return set_bdev_super(s, fc->sget_key); |
| } |
| |
| static int super_s_dev_test(struct super_block *s, struct fs_context *fc) |
| { |
| return !(s->s_iflags & SB_I_RETIRED) && |
| s->s_dev == *(dev_t *)fc->sget_key; |
| } |
| |
| /** |
| * sget_dev - Find or create a superblock by device number |
| * @fc: Filesystem context. |
| * @dev: device number |
| * |
| * Find or create a superblock using the provided device number that |
| * will be stored in fc->sget_key. |
| * |
| * If an extant superblock is matched, then that will be returned with |
| * an elevated reference count that the caller must transfer or discard. |
| * |
| * If no match is made, a new superblock will be allocated and basic |
| * initialisation will be performed (s_type, s_fs_info, s_id, s_dev will |
| * be set). The superblock will be published and it will be returned in |
| * a partially constructed state with SB_BORN and SB_ACTIVE as yet |
| * unset. |
| * |
| * Return: an existing or newly created superblock on success, an error |
| * pointer on failure. |
| */ |
| struct super_block *sget_dev(struct fs_context *fc, dev_t dev) |
| { |
| fc->sget_key = &dev; |
| return sget_fc(fc, super_s_dev_test, super_s_dev_set); |
| } |
| EXPORT_SYMBOL(sget_dev); |
| |
| #ifdef CONFIG_BLOCK |
| /* |
| * 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 function must be called with bdev->bd_holder_lock and releases it. |
| */ |
| static struct super_block *bdev_super_lock(struct block_device *bdev, bool excl) |
| __releases(&bdev->bd_holder_lock) |
| { |
| struct super_block *sb = bdev->bd_holder; |
| bool locked; |
| |
| 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 sb; |
| } |
| |
| static void fs_bdev_mark_dead(struct block_device *bdev, bool surprise) |
| { |
| struct super_block *sb; |
| |
| sb = bdev_super_lock(bdev, false); |
| if (!sb) |
| return; |
| |
| if (!surprise) |
| sync_filesystem(sb); |
| shrink_dcache_sb(sb); |
| invalidate_inodes(sb); |
| if (sb->s_op->shutdown) |
| sb->s_op->shutdown(sb); |
| |
| super_unlock_shared(sb); |
| } |
| |
| static void fs_bdev_sync(struct block_device *bdev) |
| { |
| struct super_block *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); |
| |
| sb = get_bdev_super(bdev); |
| if (WARN_ON_ONCE(!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); |
| |
| 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 file *bdev_file; |
| struct block_device *bdev; |
| |
| 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_file); |
| } |
| bdev = file_bdev(bdev_file); |
| |
| /* |
| * This really should be in blkdev_get_by_dev, but right now can't due |
| * to legacy issues that require us to allow opening a block device node |
| * writable from userspace even for a read-only block device. |
| */ |
| if ((mode & BLK_OPEN_WRITE) && bdev_read_only(bdev)) { |
| bdev_fput(bdev_file); |
| return -EACCES; |
| } |
| |
| /* |
| * It is enough to check bdev was not frozen before we set |
| * s_bdev as freezing will wait until SB_BORN is set. |
| */ |
| if (atomic_read(&bdev->bd_fsfreeze_count) > 0) { |
| if (fc) |
| warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev); |
| bdev_fput(bdev_file); |
| return -EBUSY; |
| } |
| spin_lock(&sb_lock); |
| 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); |
| |
| snprintf(sb->s_id, sizeof(sb->s_id), "%pg", bdev); |
| 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; |
| } |
| EXPORT_SYMBOL_GPL(setup_bdev_super); |
| |
| /** |
| * 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 *)) |
| { |
| struct super_block *s; |
| int error = 0; |
| dev_t dev; |
| |
| if (!fc->source) |
| return invalf(fc, "No source specified"); |
| |
| error = lookup_bdev(fc->source, &dev); |
| if (error) { |
| 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)) |
| return PTR_ERR(s); |
| |
| if (s->s_root) { |
| /* Don't summarily change the RO/RW state. */ |
| if ((fc->sb_flags ^ s->s_flags) & SB_RDONLY) { |
| warnf(fc, "%pg: Can't mount, would change RO state", s->s_bdev); |
| deactivate_locked_super(s); |
| return -EBUSY; |
| } |
| } else { |
| error = setup_bdev_super(s, fc->sb_flags, fc); |
| if (!error) |
| error = fill_super(s, fc); |
| if (error) { |
| deactivate_locked_super(s); |
| return error; |
| } |
| s->s_flags |= SB_ACTIVE; |
| } |
| |
| BUG_ON(fc->root); |
| fc->root = dget(s->s_root); |
| return 0; |
| } |
| EXPORT_SYMBOL(get_tree_bdev); |
| |
| static int test_bdev_super(struct super_block *s, void *data) |
| { |
| return !(s->s_iflags & SB_I_RETIRED) && s->s_dev == *(dev_t *)data; |
| } |
| |
| struct dentry *mount_bdev(struct file_system_type *fs_type, |
| int flags, const char *dev_name, void *data, |
| int (*fill_super)(struct super_block *, void *, int)) |
| { |
| struct super_block *s; |
| int error; |
| dev_t dev; |
| |
| error = lookup_bdev(dev_name, &dev); |
| if (error) |
| return ERR_PTR(error); |
| |
| flags |= SB_NOSEC; |
| s = sget(fs_type, test_bdev_super, set_bdev_super, flags, &dev); |
| if (IS_ERR(s)) |
| return ERR_CAST(s); |
| |
| if (s->s_root) { |
| if ((flags ^ s->s_flags) & SB_RDONLY) { |
| deactivate_locked_super(s); |
| return ERR_PTR(-EBUSY); |
| } |
| } else { |
| error = setup_bdev_super(s, flags, NULL); |
| if (!error) |
| error = fill_super(s, data, flags & SB_SILENT ? 1 : 0); |
| if (error) { |
| deactivate_locked_super(s); |
| return ERR_PTR(error); |
| } |
| |
| s->s_flags |= SB_ACTIVE; |
| } |
| |
| return dget(s->s_root); |
| } |
| EXPORT_SYMBOL(mount_bdev); |
| |
| void kill_block_super(struct super_block *sb) |
| { |
| struct block_device *bdev = sb->s_bdev; |
| |
| generic_shutdown_super(sb); |
| if (bdev) { |
| sync_blockdev(bdev); |
| bdev_fput(sb->s_bdev_file); |
| } |
| } |
| |
| EXPORT_SYMBOL(kill_block_super); |
| #endif |
| |
| struct dentry *mount_nodev(struct file_system_type *fs_type, |
| int flags, void *data, |
| int (*fill_super)(struct super_block *, void *, int)) |
| { |
| int error; |
| struct super_block *s = sget(fs_type, NULL, set_anon_super, flags, NULL); |
| |
| if (IS_ERR(s)) |
| return ERR_CAST(s); |
| |
| error = fill_super(s, data, flags & SB_SILENT ? 1 : 0); |
| if (error) { |
| deactivate_locked_super(s); |
| return ERR_PTR(error); |
| } |
| s->s_flags |= SB_ACTIVE; |
| return dget(s->s_root); |
| } |
| EXPORT_SYMBOL(mount_nodev); |
| |
| int reconfigure_single(struct super_block *s, |
| int flags, void *data) |
| { |
| struct fs_context *fc; |
| int ret; |
| |
| /* The caller really need to be passing fc down into mount_single(), |
| * then a chunk of this can be removed. [Bollocks -- AV] |
| * Better yet, reconfiguration shouldn't happen, but rather the second |
| * mount should be rejected if the parameters are not compatible. |
| */ |
| fc = fs_context_for_reconfigure(s->s_root, flags, MS_RMT_MASK); |
| if (IS_ERR(fc)) |
| return PTR_ERR(fc); |
| |
| ret = parse_monolithic_mount_data(fc, data); |
| if (ret < 0) |
| goto out; |
| |
| ret = reconfigure_super(fc); |
| out: |
| put_fs_context(fc); |
| return ret; |
| } |
| |
| static int compare_single(struct super_block *s, void *p) |
| { |
| return 1; |
| } |
| |
| struct dentry *mount_single(struct file_system_type *fs_type, |
| int flags, void *data, |
| int (*fill_super)(struct super_block *, void *, int)) |
| { |
| struct super_block *s; |
| int error; |
| |
| s = sget(fs_type, compare_single, set_anon_super, flags, NULL); |
| if (IS_ERR(s)) |
| return ERR_CAST(s); |
| if (!s->s_root) { |
| error = fill_super(s, data, flags & SB_SILENT ? 1 : 0); |
| if (!error) |
| s->s_flags |= SB_ACTIVE; |
| } else { |
| error = reconfigure_single(s, flags, data); |
| } |
| if (unlikely(error)) { |
| deactivate_locked_super(s); |
| return ERR_PTR(error); |
| } |
| return dget(s->s_root); |
| } |
| EXPORT_SYMBOL(mount_single); |
| |
| /** |
| * vfs_get_tree - Get the mountable root |
| * @fc: The superblock configuration context. |
| * |
| * The filesystem is invoked to get or create a superblock which can then later |
| * be used for mounting. The filesystem places a pointer to the root to be |
| * used for mounting in @fc->root. |
| */ |
| int vfs_get_tree(struct fs_context *fc) |
| { |
| struct super_block *sb; |
| int error; |
| |
| if (fc->root) |
| return -EBUSY; |
| |
| /* Get the mountable root in fc->root, with a ref on the root and a ref |
| * on the superblock. |
| */ |
| error = fc->ops->get_tree(fc); |
| if (error < 0) |
| return error; |
| |
| if (!fc->root) { |
| pr_err("Filesystem %s get_tree() didn't set fc->root\n", |
| fc->fs_type->name); |
| /* We don't know what the locking state of the superblock is - |
| * if there is a superblock. |
| */ |
| BUG(); |
| } |
| |
| sb = fc->root->d_sb; |
| WARN_ON(!sb->s_bdi); |
| |
| /* |
| * super_wake() contains a memory barrier which also care of |
| * ordering for super_cache_count(). We place it before setting |
| * SB_BORN as the data dependency between the two functions is |
| * the superblock structure contents that we just set up, not |
| * the SB_BORN flag. |
| */ |
| super_wake(sb, SB_BORN); |
| |
| error = security_sb_set_mnt_opts(sb, fc->security, 0, NULL); |
| if (unlikely(error)) { |
| fc_drop_locked(fc); |
| return error; |
| } |
| |
| /* |
| * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE |
| * but s_maxbytes was an unsigned long long for many releases. Throw |
| * this warning for a little while to try and catch filesystems that |
| * violate this rule. |
| */ |
| WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to " |
| "negative value (%lld)\n", fc->fs_type->name, sb->s_maxbytes); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(vfs_get_tree); |
| |
| /* |
| * Setup private BDI for given superblock. It gets automatically cleaned up |
| * in generic_shutdown_super(). |
| */ |
| int super_setup_bdi_name(struct super_block *sb, char *fmt, ...) |
| { |
| struct backing_dev_info *bdi; |
| int err; |
| va_list args; |
| |
| bdi = bdi_alloc(NUMA_NO_NODE); |
| if (!bdi) |
| return -ENOMEM; |
| |
| va_start(args, fmt); |
| err = bdi_register_va(bdi, fmt, args); |
| va_end(args); |
| if (err) { |
| bdi_put(bdi); |
| return err; |
| } |
| WARN_ON(sb->s_bdi != &noop_backing_dev_info); |
| sb->s_bdi = bdi; |
| sb->s_iflags |= SB_I_PERSB_BDI; |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(super_setup_bdi_name); |
| |
| /* |
| * Setup private BDI for given superblock. I gets automatically cleaned up |
| * in generic_shutdown_super(). |
| */ |
| int super_setup_bdi(struct super_block *sb) |
| { |
| static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0); |
| |
| return super_setup_bdi_name(sb, "%.28s-%ld", sb->s_type->name, |
| atomic_long_inc_return(&bdi_seq)); |
| } |
| EXPORT_SYMBOL(super_setup_bdi); |
| |
| /** |
| * sb_wait_write - wait until all writers to given file system finish |
| * @sb: the super for which we wait |
| * @level: type of writers we wait for (normal vs page fault) |
| * |
| * This function waits until there are no writers of given type to given file |
| * system. |
| */ |
| static void sb_wait_write(struct super_block *sb, int level) |
| { |
| percpu_down_write(sb->s_writers.rw_sem + level-1); |
| } |
| |
| /* |
| * We are going to return to userspace and forget about these locks, the |
| * ownership goes to the caller of thaw_super() which does unlock(). |
| */ |
| 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_); |
| } |
| |
| /* |
| * Tell lockdep we are holding these locks before we call ->unfreeze_fs(sb). |
| */ |
| static void lockdep_sb_freeze_acquire(struct super_block *sb) |
| { |
| int level; |
| |
| for (level = 0; level < SB_FREEZE_LEVELS; ++level) |
| percpu_rwsem_acquire(sb->s_writers.rw_sem + level, 0, _THIS_IP_); |
| } |
| |
| static void sb_freeze_unlock(struct super_block *sb, int level) |
| { |
| for (level--; level >= 0; level--) |
| percpu_up_write(sb->s_writers.rw_sem + level); |
| } |
| |
| static int wait_for_partially_frozen(struct super_block *sb) |
| { |
| int ret = 0; |
| |
| do { |
| unsigned short old = sb->s_writers.frozen; |
| |
| up_write(&sb->s_umount); |
| ret = wait_var_event_killable(&sb->s_writers.frozen, |
| sb->s_writers.frozen != old); |
| down_write(&sb->s_umount); |
| } while (ret == 0 && |
| sb->s_writers.frozen != SB_UNFROZEN && |
| sb->s_writers.frozen != SB_FREEZE_COMPLETE); |
| |
| 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 |
| * @who: context that wants to freeze |
| * |
| * Syncs the super to make sure the filesystem is consistent and calls the fs's |
| * freeze_fs. Subsequent calls to this without first thawing the fs may return |
| * -EBUSY. |
| * |
| * @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 |
| * multiple userspace freezes in effect at any given time, the kernel and |
| * 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. |
| * |
| * SB_FREEZE_WRITE: The file system is in the process of being frozen. New |
| * writes should be blocked, though page faults are still allowed. We wait for |
| * all writes to complete and then proceed to the next stage. |
| * |
| * SB_FREEZE_PAGEFAULT: Freezing continues. Now also page faults are blocked |
| * but internal fs threads can still modify the filesystem (although they |
| * should not dirty new pages or inodes), writeback can run etc. After waiting |
| * for all running page faults we sync the filesystem which will clean all |
| * dirty pages and inodes (no new dirty pages or inodes can be created when |
| * sync is running). |
| * |
| * SB_FREEZE_FS: The file system is frozen. Now all internal sources of fs |
| * modification are blocked (e.g. XFS preallocation truncation on inode |
| * reclaim). This is usually implemented by blocking new transactions for |
| * filesystems that have them and need this additional guard. After all |
| * internal writers are finished we call ->freeze_fs() to finish filesystem |
| * freezing. Then we transition to SB_FREEZE_COMPLETE state. This state is |
| * 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); |
| |
| retry: |
| if (sb->s_writers.frozen == SB_FREEZE_COMPLETE) { |
| 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) { |
| ret = wait_for_partially_frozen(sb); |
| if (ret) { |
| deactivate_locked_super(sb); |
| return ret; |
| } |
| |
| goto retry; |
| } |
| |
| if (sb_rdonly(sb)) { |
| /* Nothing to do really... */ |
| 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); |
| return 0; |
| } |
| |
| sb->s_writers.frozen = SB_FREEZE_WRITE; |
| /* Release s_umount to preserve sb_start_write -> s_umount ordering */ |
| super_unlock_excl(sb); |
| sb_wait_write(sb, SB_FREEZE_WRITE); |
| __super_lock_excl(sb); |
| |
| /* Now we go and block page faults... */ |
| sb->s_writers.frozen = SB_FREEZE_PAGEFAULT; |
| sb_wait_write(sb, SB_FREEZE_PAGEFAULT); |
| |
| /* All writers are done so after syncing there won't be dirty data */ |
| ret = sync_filesystem(sb); |
| if (ret) { |
| sb->s_writers.frozen = SB_UNFROZEN; |
| sb_freeze_unlock(sb, SB_FREEZE_PAGEFAULT); |
| wake_up_var(&sb->s_writers.frozen); |
| deactivate_locked_super(sb); |
| return ret; |
| } |
| |
| /* Now wait for internal filesystem counter */ |
| sb->s_writers.frozen = SB_FREEZE_FS; |
| sb_wait_write(sb, SB_FREEZE_FS); |
| |
| if (sb->s_op->freeze_fs) { |
| ret = sb->s_op->freeze_fs(sb); |
| if (ret) { |
| printk(KERN_ERR |
| "VFS:Filesystem freeze failed\n"); |
| sb->s_writers.frozen = SB_UNFROZEN; |
| sb_freeze_unlock(sb, SB_FREEZE_FS); |
| wake_up_var(&sb->s_writers.frozen); |
| deactivate_locked_super(sb); |
| return ret; |
| } |
| } |
| /* |
| * 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(). |
| */ |
| 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); |
| super_unlock_excl(sb); |
| return 0; |
| } |
| EXPORT_SYMBOL(freeze_super); |
| |
| /* |
| * Undoes the effect of a freeze_super_locked call. If the filesystem is |
| * frozen both by userspace and the kernel, a thaw call from either source |
| * removes that state without releasing the other state or unlocking the |
| * filesystem. |
| */ |
| static int thaw_super_locked(struct super_block *sb, enum freeze_holder who) |
| { |
| int error = -EINVAL; |
| |
| if (sb->s_writers.frozen != SB_FREEZE_COMPLETE) |
| goto out_unlock; |
| |
| /* |
| * 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.frozen = SB_UNFROZEN; |
| wake_up_var(&sb->s_writers.frozen); |
| goto out_deactivate; |
| } |
| |
| lockdep_sb_freeze_acquire(sb); |
| |
| if (sb->s_op->unfreeze_fs) { |
| error = sb->s_op->unfreeze_fs(sb); |
| if (error) { |
| pr_err("VFS: Filesystem thaw failed\n"); |
| freeze_inc(sb, who); |
| lockdep_sb_freeze_release(sb); |
| goto out_unlock; |
| } |
| } |
| |
| sb->s_writers.frozen = SB_UNFROZEN; |
| wake_up_var(&sb->s_writers.frozen); |
| sb_freeze_unlock(sb, SB_FREEZE_FS); |
| out_deactivate: |
| deactivate_locked_super(sb); |
| return 0; |
| |
| out_unlock: |
| super_unlock_excl(sb); |
| return error; |
| } |
| |
| /** |
| * thaw_super -- unlock filesystem |
| * @sb: the super to thaw |
| * @who: context that wants to freeze |
| * |
| * Unlocks the filesystem and marks it writeable again after freeze_super() |
| * if there are no remaining freezes on the filesystem. |
| * |
| * @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_ON_ONCE("Dying superblock while thawing!"); |
| return -EINVAL; |
| } |
| return thaw_super_locked(sb, who); |
| } |
| EXPORT_SYMBOL(thaw_super); |
| |
| /* |
| * Create workqueue for deferred direct IO completions. We allocate the |
| * workqueue when it's first needed. This avoids creating workqueue for |
| * filesystems that don't need it and also allows us to create the workqueue |
| * late enough so the we can include s_id in the name of the workqueue. |
| */ |
| int sb_init_dio_done_wq(struct super_block *sb) |
| { |
| struct workqueue_struct *old; |
| struct workqueue_struct *wq = alloc_workqueue("dio/%s", |
| WQ_MEM_RECLAIM, 0, |
| sb->s_id); |
| if (!wq) |
| return -ENOMEM; |
| /* |
| * This has to be atomic as more DIOs can race to create the workqueue |
| */ |
| old = cmpxchg(&sb->s_dio_done_wq, NULL, wq); |
| /* Someone created workqueue before us? Free ours... */ |
| if (old) |
| destroy_workqueue(wq); |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(sb_init_dio_done_wq); |