diff options
| -rw-r--r-- | fs/btrfs/ctree.h | 10 | ||||
| -rw-r--r-- | fs/btrfs/super.c | 4 |
2 files changed, 14 insertions, 0 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 169baa817d96..d8e539fe5544 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1304,6 +1304,16 @@ struct btrfs_fs_info { * so it is also safe. */ u64 max_inline; + /* + * Protected by ->chunk_mutex and sb->s_umount. + * + * The reason that we use two lock to protect it is because only + * remount and mount operations can change it and these two operations + * are under sb->s_umount, but the read side (chunk allocation) can not + * acquire sb->s_umount or the deadlock would happen. So we use two + * locks to protect it. On the write side, we must acquire two locks, + * and on the read side, we just need acquire one of them. + */ u64 alloc_start; struct btrfs_transaction *running_transaction; wait_queue_head_t transaction_throttle; diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 6846ededfe95..eda330df45a4 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -519,7 +519,9 @@ int btrfs_parse_options(struct btrfs_root *root, char *options) case Opt_alloc_start: num = match_strdup(&args[0]); if (num) { + mutex_lock(&info->chunk_mutex); info->alloc_start = memparse(num, NULL); + mutex_unlock(&info->chunk_mutex); kfree(num); printk(KERN_INFO "btrfs: allocations start at %llu\n", @@ -1289,7 +1291,9 @@ restore: fs_info->mount_opt = old_opts; fs_info->compress_type = old_compress_type; fs_info->max_inline = old_max_inline; + mutex_lock(&fs_info->chunk_mutex); fs_info->alloc_start = old_alloc_start; + mutex_unlock(&fs_info->chunk_mutex); btrfs_resize_thread_pool(fs_info, old_thread_pool_size, fs_info->thread_pool_size); fs_info->metadata_ratio = old_metadata_ratio; |