diff options
| -rw-r--r-- | fs/fs-writeback.c | 2 | ||||
| -rw-r--r-- | fs/super.c | 26 | ||||
| -rw-r--r-- | include/linux/fs.h | 1 |
3 files changed, 26 insertions, 3 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index f200e0b33ccc..fe1825d45f5a 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -423,7 +423,7 @@ restart: up_read(&sb->s_umount); } spin_lock(&sb_lock); - if (__put_super(sb)) + if (__put_super_and_need_restart(sb)) goto restart; } if (wbc->nr_to_write <= 0) diff --git a/fs/super.c b/fs/super.c index 38c23bf558d4..6f8960dbef68 100644 --- a/fs/super.c +++ b/fs/super.c @@ -116,6 +116,27 @@ int __put_super(struct super_block *sb) return ret; } +/* + * Drop a superblock's refcount. + * Returns non-zero if the superblock is about to be destroyed and + * at least is already removed from super_blocks list, so if we are + * making a loop through super blocks then we need to restart. + * The caller must hold sb_lock. + */ +int __put_super_and_need_restart(struct super_block *sb) +{ + /* check for race with generic_shutdown_super() */ + if (list_empty(&sb->s_list)) { + /* super block is removed, need to restart... */ + __put_super(sb); + return 1; + } + /* can't be the last, since s_list is still in use */ + sb->s_count--; + BUG_ON(sb->s_count == 0); + return 0; +} + /** * put_super - drop a temporary reference to superblock * @s: superblock in question @@ -229,7 +250,8 @@ void generic_shutdown_super(struct super_block *sb) unlock_super(sb); } spin_lock(&sb_lock); - list_del(&sb->s_list); + /* should be initialized for __put_super_and_need_restart() */ + list_del_init(&sb->s_list); list_del(&sb->s_instances); spin_unlock(&sb_lock); up_write(&sb->s_umount); @@ -282,7 +304,7 @@ retry: } s->s_type = type; strlcpy(s->s_id, type->name, sizeof(s->s_id)); - list_add(&s->s_list, super_blocks.prev); + list_add_tail(&s->s_list, &super_blocks); list_add(&s->s_instances, &type->fs_supers); spin_unlock(&sb_lock); get_filesystem(type); diff --git a/include/linux/fs.h b/include/linux/fs.h index 76f96659507a..5bb9738362d5 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1149,6 +1149,7 @@ struct super_block *sget(struct file_system_type *type, struct super_block *get_sb_pseudo(struct file_system_type *, char *, struct super_operations *ops, unsigned long); int __put_super(struct super_block *sb); +int __put_super_and_need_restart(struct super_block *sb); void unnamed_dev_init(void); /* Alas, no aliases. Too much hassle with bringing module.h everywhere */ |