X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=blobdiff_plain;f=fs%2Fsuper.c;h=3f56a269a4f4e30c4c31feb0b73b05064cc974b9;hp=ab3d672db0deae0a84a01bc1938cd967cc27e79f;hb=22712200e175e0df5c7f9edfe6c6bf5c94c23b83;hpb=5a791ea4fa4495f7136679cb5366f6544148e613 diff --git a/fs/super.c b/fs/super.c index ab3d672db0de..3f56a269a4f4 100644 --- a/fs/super.c +++ b/fs/super.c @@ -38,6 +38,69 @@ 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 -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 @@ -77,6 +140,8 @@ static struct super_block *alloc_super(struct file_system_type *type) 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_rwsem(&s->s_umount); mutex_init(&s->s_lock); lockdep_set_class(&s->s_umount, &type->s_umount_key); @@ -114,6 +179,10 @@ static struct super_block *alloc_super(struct file_system_type *type) 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; @@ -181,6 +250,10 @@ void deactivate_locked_super(struct super_block *s) 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. @@ -240,18 +313,49 @@ static int grab_super(struct super_block *s) __releases(sb_lock) 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 (list_empty(&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) + 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) { - get_fs_excl(); mutex_lock(&sb->s_lock); } void unlock_super(struct super_block * sb) { - put_fs_excl(); mutex_unlock(&sb->s_lock); } @@ -276,11 +380,9 @@ 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); - get_fs_excl(); sb->s_flags &= ~MS_ACTIVE; fsnotify_unmount_inodes(&sb->s_inodes); @@ -295,7 +397,6 @@ void generic_shutdown_super(struct super_block *sb) "Self-destruct in 5 seconds. Have a nice day...\n", sb->s_id); } - put_fs_excl(); } spin_lock(&sb_lock); /* should be initialized for __put_super_and_need_restart() */ @@ -364,6 +465,7 @@ retry: list_add(&s->s_instances, &type->fs_supers); spin_unlock(&sb_lock); get_filesystem(type); + register_shrinker(&s->s_shrink); return s; } @@ -451,6 +553,42 @@ void iterate_supers(void (*f)(struct super_block *, void *), void *arg) 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); + list_for_each_entry(sb, &type->fs_supers, s_instances) { + sb->s_count++; + spin_unlock(&sb_lock); + + down_read(&sb->s_umount); + if (sb->s_root) + 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 @@ -657,7 +795,7 @@ 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 set_anon_super(struct super_block *s, void *data) +int get_anon_bdev(dev_t *p) { int dev; int error; @@ -684,24 +822,38 @@ int set_anon_super(struct super_block *s, void *data) spin_unlock(&unnamed_dev_lock); return -EMFILE; } - s->s_dev = MKDEV(0, dev & MINORMASK); - s->s_bdi = &noop_backing_dev_info; + *p = MKDEV(0, dev & MINORMASK); return 0; } +EXPORT_SYMBOL(get_anon_bdev); -EXPORT_SYMBOL(set_anon_super); - -void kill_anon_super(struct super_block *sb) +void free_anon_bdev(dev_t dev) { - int slot = MINOR(sb->s_dev); - - generic_shutdown_super(sb); + 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);