From c00869f1ae6a8fa49802d5e60d843b7051a112ec Mon Sep 17 00:00:00 2001 From: Miao Xie Date: Wed, 25 Sep 2013 21:47:44 +0800 Subject: Btrfs: fix oops caused by the space balance and dead roots When doing space balance and subvolume destroy at the same time, we met the following oops: kernel BUG at fs/btrfs/relocation.c:2247! RIP: 0010: [] prepare_to_merge+0x154/0x1f0 [btrfs] Call Trace: [] relocate_block_group+0x466/0x4e6 [btrfs] [] btrfs_relocate_block_group+0x143/0x275 [btrfs] [] btrfs_relocate_chunk.isra.27+0x5c/0x5a2 [btrfs] [] ? btrfs_item_key_to_cpu+0x15/0x31 [btrfs] [] ? btrfs_get_token_64+0x7e/0xcd [btrfs] [] ? btrfs_tree_read_unlock_blocking+0xb2/0xb7 [btrfs] [] btrfs_balance+0x9c7/0xb6f [btrfs] [] btrfs_ioctl_balance+0x234/0x2ac [btrfs] [] btrfs_ioctl+0xd87/0x1ef9 [btrfs] [] ? path_openat+0x234/0x4db [] ? __do_page_fault+0x31d/0x391 [] ? vma_link+0x74/0x94 [] vfs_ioctl+0x1d/0x39 [] do_vfs_ioctl+0x32d/0x3e2 [] SyS_ioctl+0x57/0x83 [] ? do_page_fault+0xe/0x10 [] system_call_fastpath+0x16/0x1b It is because we returned the error number if the reference of the root was 0 when doing space relocation. It was not right here, because though the root was dead(refs == 0), but the space it held still need be relocated, or we could not remove the block group. So in this case, we should return the root no matter it is dead or not. Signed-off-by: Miao Xie Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'fs/btrfs/disk-io.c') diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 4ae17ed13b32..62176ad89846 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1561,8 +1561,9 @@ int btrfs_insert_fs_root(struct btrfs_fs_info *fs_info, return ret; } -struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info, - struct btrfs_key *location) +struct btrfs_root *btrfs_get_fs_root(struct btrfs_fs_info *fs_info, + struct btrfs_key *location, + bool check_ref) { struct btrfs_root *root; int ret; @@ -1586,7 +1587,7 @@ struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info, again: root = btrfs_lookup_fs_root(fs_info, location->objectid); if (root) { - if (btrfs_root_refs(&root->root_item) == 0) + if (check_ref && btrfs_root_refs(&root->root_item) == 0) return ERR_PTR(-ENOENT); return root; } @@ -1595,7 +1596,7 @@ again: if (IS_ERR(root)) return root; - if (btrfs_root_refs(&root->root_item) == 0) { + if (check_ref && btrfs_root_refs(&root->root_item) == 0) { ret = -ENOENT; goto fail; } -- cgit v1.2.2