/* * 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/module.h> #include <linux/slab.h> #include <linux/acct.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/cleancache.h> #include "internal.h" LIST_HEAD(super_blocks); DEFINE_SPINLOCK(sb_lock); /* * 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 * take a passive reference to the superblock to avoid this from occurring. */ static int prune_super(struct shrinker *shrink, struct shrink_control *sc) { struct super_block *sb; int fs_objects = 0; int total_objects; sb = container_of(shrink, struct super_block, s_shrink); /* * 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->nr_to_scan && !(sc->gfp_mask & __GFP_FS)) return -1; if (!grab_super_passive(sb)) return !sc->nr_to_scan ? 0 : -1; if (sb->s_op && sb->s_op->nr_cached_objects) fs_objects = sb->s_op->nr_cached_objects(sb); total_objects = sb->s_nr_dentry_unused + sb->s_nr_inodes_unused + fs_objects + 1; if (sc->nr_to_scan) { int dentries; int inodes; /* proportion the scan between the caches */ dentries = (sc->nr_to_scan * sb->s_nr_dentry_unused) / total_objects; inodes = (sc->nr_to_scan * sb->s_nr_inodes_unused) / total_objects; if (fs_objects) fs_objects = (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 */ prune_dcache_sb(sb, dentries); prune_icache_sb(sb, inodes); if (fs_objects && sb->s_op->free_cached_objects) { sb->s_op->free_cached_objects(sb, fs_objects); fs_objects = sb->s_op->nr_cached_objects(sb); } total_objects = sb->s_nr_dentry_unused + sb->s_nr_inodes_unused + fs_objects; } total_objects = (total_objects / 100) * sysctl_vfs_cache_pressure; drop_super(sb); return total_objects; } /** * alloc_super - create new superblock * @type: filesystem type superblock should belong to * * 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) { struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER); static const struct super_operations default_op; if (s) { if (security_sb_alloc(s)) { kfree(s); s = NULL; goto out; } #ifdef CONFIG_SMP s->s_files = alloc_percpu(struct list_head); if (!s->s_files) { security_sb_free(s); kfree(s); s = NULL; goto out; } else { int i; for_each_possible_cpu(i) INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i)); } #else INIT_LIST_HEAD(&s->s_files); #endif s->s_bdi = &default_backing_dev_info; INIT_HLIST_NODE(&s->s_instances); INIT_HLIST_BL_HEAD(&s->s_anon); INIT_LIST_HEAD(&s->s_inodes); INIT_LIST_HEAD(&s->s_dentry_lru); INIT_LIST_HEAD(&s->s_inode_lru); spin_lock_init(&s->s_inode_lru_lock); INIT_LIST_HEAD(&s->s_mounts); init_rwsem(&s->s_umount); mutex_init(&s->s_lock); lockdep_set_class(&s->s_umount, &type->s_umount_key); /* * The locking rules for s_lock are up to the * filesystem. For example ext3fs has different * lock ordering than usbfs: */ lockdep_set_class(&s->s_lock, &type->s_lock_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); 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); mutex_init(&s->s_dquot.dqio_mutex); mutex_init(&s->s_dquot.dqonoff_mutex); init_rwsem(&s->s_dquot.dqptr_sem); init_waitqueue_head(&s->s_wait_unfrozen); s->s_maxbytes = MAX_NON_LFS; s->s_op = &default_op; s->s_time_gran = 1000000000; s->cleancache_poolid = -1; s->s_shrink.seeks = DEFAULT_SEEKS; s->s_shrink.shrink = prune_super; s->s_shrink.batch = 1024; } out: return s; } /** * destroy_super - frees a superblock * @s: superblock to free * * Frees a superblock. */ static inline void destroy_super(struct super_block *s) { #ifdef CONFIG_SMP free_percpu(s->s_files); #endif security_sb_free(s); WARN_ON(!list_empty(&s->s_mounts)); kfree(s->s_subtype); kfree(s->s_options); kfree(s); } /* Superblock refcounting */ /* * Drop a superblock's refcount. The caller must hold sb_lock. */ static void __put_super(struct super_block *sb) { if (!--sb->s_count) { list_del_init(&sb->s_list); destroy_super(sb); } } /** * put_super - drop a temporary reference to superblock * @sb: superblock in question * * Drops a temporary reference, frees superblock if there's no * references left. */ static void put_super(struct super_block *sb) { spin_lock(&sb_lock); __put_super(sb); spin_unlock(&sb_lock); } /** * deactivate_locked_super - drop an active reference to superblock * @s: superblock to deactivate * * Drops an active reference to superblock, converting it into a temprory * 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)) { cleancache_flush_fs(s); fs->kill_sb(s); /* caches are now gone, we can safely kill the shrinker now */ unregister_shrinker(&s->s_shrink); /* * We need to call rcu_barrier so all the delayed rcu free * inodes are flushed before we release the fs module. */ rcu_barrier(); put_filesystem(fs); put_super(s); } else { up_write(&s->s_umount); } } 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)) { down_write(&s->s_umount); deactivate_locked_super(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). */ static int grab_super(struct super_block *s) __releases(sb_lock) { if (atomic_inc_not_zero(&s->s_active)) { spin_unlock(&sb_lock); return 1; } /* it's going away */ s->s_count++; spin_unlock(&sb_lock); /* wait for it to die */ down_write(&s->s_umount); up_write(&s->s_umount); put_super(s); return 0; } /* * grab_super_passive - acquire a passive reference * @s: reference we are trying to grab * * Tries to acquire a passive reference. This is used in places where we * cannot take an active reference but we need to ensure that the * superblock does not go away while we are working on it. It returns * false if a reference was not gained, and returns true with the s_umount * lock held in read mode if a reference is gained. On successful return, * the caller must drop the s_umount lock and the passive reference when * done. */ bool grab_super_passive(struct super_block *sb) { spin_lock(&sb_lock); if (hlist_unhashed(&sb->s_instances)) { spin_unlock(&sb_lock); return false; } sb->s_count++; spin_unlock(&sb_lock); if (down_read_trylock(&sb->s_umount)) { if (sb->s_root && (sb->s_flags & MS_BORN)) return true; up_read(&sb->s_umount); } put_super(sb); return false; } /* * Superblock locking. We really ought to get rid of these two. */ void lock_super(struct super_block * sb) { mutex_lock(&sb->s_lock); } void unlock_super(struct super_block * sb) { mutex_unlock(&sb->s_lock); } EXPORT_SYMBOL(lock_super); EXPORT_SYMBOL(unlock_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 &= ~MS_ACTIVE; fsnotify_unmount_inodes(&sb->s_inodes); evict_inodes(sb); if (sop->put_super) sop->put_super(sb); if (!list_empty(&sb->s_inodes)) { printk("VFS: Busy inodes after unmount of %s. " "Self-destruct in 5 seconds. Have a nice day...\n", sb->s_id); } } spin_lock(&sb_lock); /* should be initialized for __put_super_and_need_restart() */ hlist_del_init(&sb->s_instances); spin_unlock(&sb_lock); up_write(&sb->s_umount); } EXPORT_SYMBOL(generic_shutdown_super); /** * sget - find or create a superblock * @type: filesystem type superblock should belong to * @test: comparison callback * @set: setup callback * @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 *), void *data) { struct super_block *s = NULL; struct hlist_node *node; struct super_block *old; int err; retry: spin_lock(&sb_lock); if (test) { hlist_for_each_entry(old, node, &type->fs_supers, s_instances) { if (!test(old, data)) continue; if (!grab_super(old)) goto retry; if (s) { up_write(&s->s_umount); destroy_super(s); s = NULL; } down_write(&old->s_umount); if (unlikely(!(old->s_flags & MS_BORN))) { deactivate_locked_super(old); goto retry; } return old; } } if (!s) { spin_unlock(&sb_lock); s = alloc_super(type); if (!s) return ERR_PTR(-ENOMEM); goto retry; } err = set(s, data); if (err) { spin_unlock(&sb_lock); up_write(&s->s_umount); destroy_super(s); return ERR_PTR(err); } s->s_type = type; strlcpy(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); register_shrinker(&s->s_shrink); return s; } EXPORT_SYMBOL(sget); void drop_super(struct super_block *sb) { up_read(&sb->s_umount); put_super(sb); } EXPORT_SYMBOL(drop_super); /** * sync_supers - helper for periodic superblock writeback * * Call the write_super method if present on all dirty superblocks in * the system. This is for the periodic writeback used by most older * filesystems. For data integrity superblock writeback use * sync_filesystems() instead. * * Note: check the dirty flag before waiting, so we don't * hold up the sync while mounting a device. (The newly * mounted device won't need syncing.) */ void sync_supers(void) { struct super_block *sb, *p = NULL; spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; if (sb->s_op->write_super && sb->s_dirt) { sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); if (sb->s_root && sb->s_dirt && (sb->s_flags & MS_BORN)) sb->s_op->write_super(sb); up_read(&sb->s_umount); 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) { if (hlist_unhashed(&sb->s_instances)) continue; sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); if (sb->s_root && (sb->s_flags & MS_BORN)) f(sb, arg); up_read(&sb->s_umount); 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; struct hlist_node *node; spin_lock(&sb_lock); hlist_for_each_entry(sb, node, &type->fs_supers, s_instances) { sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); if (sb->s_root && (sb->s_flags & MS_BORN)) f(sb, arg); up_read(&sb->s_umount); 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); /** * get_super - get 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. %NULL is returned if no match is found. */ struct super_block *get_super(struct block_device *bdev) { struct super_block *sb; if (!bdev) return NULL; spin_lock(&sb_lock); rescan: list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; if (sb->s_bdev == bdev) { sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); /* still alive? */ if (sb->s_root && (sb->s_flags & MS_BORN)) return sb; up_read(&sb->s_umount); /* nope, got unmounted */ spin_lock(&sb_lock); __put_super(sb); goto rescan; } } spin_unlock(&sb_lock); return NULL; } EXPORT_SYMBOL(get_super); /** * 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; restart: spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; if (sb->s_bdev == bdev) { if (grab_super(sb)) /* drops sb_lock */ return sb; else goto restart; } } spin_unlock(&sb_lock); return NULL; } struct super_block *user_get_super(dev_t dev) { struct super_block *sb; spin_lock(&sb_lock); rescan: list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; if (sb->s_dev == dev) { sb->s_count++; spin_unlock(&sb_lock); down_read(&sb->s_umount); /* still alive? */ if (sb->s_root && (sb->s_flags & MS_BORN)) return sb; up_read(&sb->s_umount); /* nope, got unmounted */ spin_lock(&sb_lock); __put_super(sb); goto rescan; } } spin_unlock(&sb_lock); return NULL; } /** * do_remount_sb - asks filesystem to change mount options. * @sb: superblock in question * @flags: numeric part of options * @data: the rest of options * @force: whether or not to force the change * * Alters the mount options of a mounted file system. */ int do_remount_sb(struct super_block *sb, int flags, void *data, int force) { int retval; int remount_ro; if (sb->s_frozen != SB_UNFROZEN) return -EBUSY; #ifdef CONFIG_BLOCK if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev)) return -EACCES; #endif if (flags & MS_RDONLY) acct_auto_close(sb); shrink_dcache_sb(sb); sync_filesystem(sb); remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY); /* If we are remounting RDONLY and current sb is read/write, make sure there are no rw files opened */ if (remount_ro) { if (force) { mark_files_ro(sb); } else { retval = sb_prepare_remount_readonly(sb); if (retval) return retval; } } if (sb->s_op->remount_fs) { retval = sb->s_op->remount_fs(sb, &flags, data); 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); } } sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK); /* Needs to be ordered wrt mnt_is_readonly() */ smp_wmb(); sb->s_readonly_remount = 0; /* * 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->s_readonly_remount = 0; return retval; } static void do_emergency_remount(struct work_struct *work) { struct super_block *sb, *p = NULL; spin_lock(&sb_lock); list_for_each_entry(sb, &super_blocks, s_list) { if (hlist_unhashed(&sb->s_instances)) continue; sb->s_count++; spin_unlock(&sb_lock); down_write(&sb->s_umount); if (sb->s_root && sb->s_bdev && (sb->s_flags & MS_BORN) && !(sb->s_flags & MS_RDONLY)) { /* * What lock protects sb->s_flags?? */ do_remount_sb(sb, MS_RDONLY, NULL, 1); } up_write(&sb->s_umount); spin_lock(&sb_lock); if (p) __put_super(p); p = sb; } if (p) __put_super(p); spin_unlock(&sb_lock); 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); } } /* * Unnamed block devices are dummy devices used by virtual * filesystems which don't use real block-devices. -- jrs */ static DEFINE_IDA(unnamed_dev_ida); static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */ static int unnamed_dev_start = 0; /* don't bother trying below it */ int get_anon_bdev(dev_t *p) { int dev; int error; retry: if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0) return -ENOMEM; spin_lock(&unnamed_dev_lock); error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev); if (!error) unnamed_dev_start = dev + 1; spin_unlock(&unnamed_dev_lock); if (error == -EAGAIN) /* We raced and lost with another CPU. */ goto retry; else if (error) return -EAGAIN; if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) { spin_lock(&unnamed_dev_lock); ida_remove(&unnamed_dev_ida, dev); if (unnamed_dev_start > dev) unnamed_dev_start = dev; spin_unlock(&unnamed_dev_lock); return -EMFILE; } *p = MKDEV(0, dev & MINORMASK); return 0; } EXPORT_SYMBOL(get_anon_bdev); void free_anon_bdev(dev_t dev) { int slot = MINOR(dev); spin_lock(&unnamed_dev_lock); ida_remove(&unnamed_dev_ida, slot); if (slot < unnamed_dev_start) unnamed_dev_start = slot; spin_unlock(&unnamed_dev_lock); } EXPORT_SYMBOL(free_anon_bdev); int set_anon_super(struct super_block *s, void *data) { int error = get_anon_bdev(&s->s_dev); if (!error) s->s_bdi = &noop_backing_dev_info; return error; } EXPORT_SYMBOL(set_anon_super); void kill_anon_super(struct super_block *sb) { dev_t dev = sb->s_dev; generic_shutdown_super(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); static int ns_test_super(struct super_block *sb, void *data) { return sb->s_fs_info == data; } static int ns_set_super(struct super_block *sb, void *data) { sb->s_fs_info = data; return set_anon_super(sb, NULL); } struct dentry *mount_ns(struct file_system_type *fs_type, int flags, void *data, int (*fill_super)(struct super_block *, void *, int)) { struct super_block *sb; sb = sget(fs_type, ns_test_super, ns_set_super, data); if (IS_ERR(sb)) return ERR_CAST(sb); if (!sb->s_root) { int err; sb->s_flags = flags; err = fill_super(sb, data, flags & MS_SILENT ? 1 : 0); if (err) { deactivate_locked_super(sb); return ERR_PTR(err); } sb->s_flags |= MS_ACTIVE; } return dget(sb->s_root); } EXPORT_SYMBOL(mount_ns); #ifdef CONFIG_BLOCK static int set_bdev_super(struct super_block *s, void *data) { s->s_bdev = data; s->s_dev = s->s_bdev->bd_dev; /* * We set the bdi here to the queue backing, file systems can * overwrite this in ->fill_super() */ s->s_bdi = &bdev_get_queue(s->s_bdev)->backing_dev_info; return 0; } static int test_bdev_super(struct super_block *s, void *data) { return (void *)s->s_bdev == 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 block_device *bdev; struct super_block *s; fmode_t mode = FMODE_READ | FMODE_EXCL; int error = 0; if (!(flags & MS_RDONLY)) mode |= FMODE_WRITE; bdev = blkdev_get_by_path(dev_name, mode, fs_type); if (IS_ERR(bdev)) return ERR_CAST(bdev); /* * once the super is inserted into the list by sget, s_umount * will protect the lockfs code from trying to start a snapshot * while we are mounting */ mutex_lock(&bdev->bd_fsfreeze_mutex); if (bdev->bd_fsfreeze_count > 0) { mutex_unlock(&bdev->bd_fsfreeze_mutex); error = -EBUSY; goto error_bdev; } s = sget(fs_type, test_bdev_super, set_bdev_super, bdev); mutex_unlock(&bdev->bd_fsfreeze_mutex); if (IS_ERR(s)) goto error_s; if (s->s_root) { if ((flags ^ s->s_flags) & MS_RDONLY) { deactivate_locked_super(s); error = -EBUSY; goto error_bdev; } /* * s_umount nests inside bd_mutex during * __invalidate_device(). blkdev_put() acquires * bd_mutex and can't be called under s_umount. Drop * s_umount temporarily. This is safe as we're * holding an active reference. */ up_write(&s->s_umount); blkdev_put(bdev, mode); down_write(&s->s_umount); } else { char b[BDEVNAME_SIZE]; s->s_flags = flags | MS_NOSEC; s->s_mode = mode; strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id)); sb_set_blocksize(s, block_size(bdev)); error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); if (error) { deactivate_locked_super(s); goto error; } s->s_flags |= MS_ACTIVE; bdev->bd_super = s; } return dget(s->s_root); error_s: error = PTR_ERR(s); error_bdev: blkdev_put(bdev, mode); error: return ERR_PTR(error); } EXPORT_SYMBOL(mount_bdev); void kill_block_super(struct super_block *sb) { struct block_device *bdev = sb->s_bdev; fmode_t mode = sb->s_mode; bdev->bd_super = NULL; generic_shutdown_super(sb); sync_blockdev(bdev); WARN_ON_ONCE(!(mode & FMODE_EXCL)); blkdev_put(bdev, mode | FMODE_EXCL); } 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, NULL); if (IS_ERR(s)) return ERR_CAST(s); s->s_flags = flags; error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); if (error) { deactivate_locked_super(s); return ERR_PTR(error); } s->s_flags |= MS_ACTIVE; return dget(s->s_root); } EXPORT_SYMBOL(mount_nodev); 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, NULL); if (IS_ERR(s)) return ERR_CAST(s); if (!s->s_root) { s->s_flags = flags; error = fill_super(s, data, flags & MS_SILENT ? 1 : 0); if (error) { deactivate_locked_super(s); return ERR_PTR(error); } s->s_flags |= MS_ACTIVE; } else { do_remount_sb(s, flags, data, 0); } return dget(s->s_root); } EXPORT_SYMBOL(mount_single); struct dentry * mount_fs(struct file_system_type *type, int flags, const char *name, void *data) { struct dentry *root; struct super_block *sb; char *secdata = NULL; int error = -ENOMEM; if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) { secdata = alloc_secdata(); if (!secdata) goto out; error = security_sb_copy_data(data, secdata); if (error) goto out_free_secdata; } root = type->mount(type, flags, name, data); if (IS_ERR(root)) { error = PTR_ERR(root); goto out_free_secdata; } sb = root->d_sb; BUG_ON(!sb); WARN_ON(!sb->s_bdi); WARN_ON(sb->s_bdi == &default_backing_dev_info); sb->s_flags |= MS_BORN; error = security_sb_kern_mount(sb, flags, secdata); if (error) goto out_sb; /* * 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", type->name, sb->s_maxbytes); up_write(&sb->s_umount); free_secdata(secdata); return root; out_sb: dput(root); deactivate_locked_super(sb); out_free_secdata: free_secdata(secdata); out: return ERR_PTR(error); } /** * freeze_super - lock the filesystem and force it into a consistent state * @sb: the super to lock * * 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 will return * -EBUSY. */ int freeze_super(struct super_block *sb) { int ret; atomic_inc(&sb->s_active); down_write(&sb->s_umount); if (sb->s_frozen) { deactivate_locked_super(sb); return -EBUSY; } if (!(sb->s_flags & MS_BORN)) { up_write(&sb->s_umount); return 0; /* sic - it's "nothing to do" */ } if (sb->s_flags & MS_RDONLY) { sb->s_frozen = SB_FREEZE_TRANS; smp_wmb(); up_write(&sb->s_umount); return 0; } sb->s_frozen = SB_FREEZE_WRITE; smp_wmb(); sync_filesystem(sb); sb->s_frozen = SB_FREEZE_TRANS; smp_wmb(); sync_blockdev(sb->s_bdev); 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_frozen = SB_UNFROZEN; deactivate_locked_super(sb); return ret; } } up_write(&sb->s_umount); return 0; } EXPORT_SYMBOL(freeze_super); /** * thaw_super -- unlock filesystem * @sb: the super to thaw * * Unlocks the filesystem and marks it writeable again after freeze_super(). */ int thaw_super(struct super_block *sb) { int error; down_write(&sb->s_umount); if (sb->s_frozen == SB_UNFROZEN) { up_write(&sb->s_umount); return -EINVAL; } if (sb->s_flags & MS_RDONLY) goto out; if (sb->s_op->unfreeze_fs) { error = sb->s_op->unfreeze_fs(sb); if (error) { printk(KERN_ERR "VFS:Filesystem thaw failed\n"); sb->s_frozen = SB_FREEZE_TRANS; up_write(&sb->s_umount); return error; } } out: sb->s_frozen = SB_UNFROZEN; smp_wmb(); wake_up(&sb->s_wait_unfrozen); deactivate_locked_super(sb); return 0; } EXPORT_SYMBOL(thaw_super);