On 08/06/2011 04:35 AM, Liu Bo wrote:

When btrfs recovers from a crash, it may hit the oops below:

------------[ cut here ]------------
kernel BUG at fs/btrfs/inode.c:4580!
[...]
RIP: 0010:[<ffffffffa03df251>]  [<ffffffffa03df251>] btrfs_add_link+0x161/0x1c0 [btrfs]
[...]
Call Trace:
  [<ffffffffa03e7b31>] ? btrfs_inode_ref_index+0x31/0x80 [btrfs]
  [<ffffffffa04054e9>] add_inode_ref+0x319/0x3f0 [btrfs]
  [<ffffffffa0407087>] replay_one_buffer+0x2c7/0x390 [btrfs]
  [<ffffffffa040444a>] walk_down_log_tree+0x32a/0x480 [btrfs]
  [<ffffffffa0404695>] walk_log_tree+0xf5/0x240 [btrfs]
  [<ffffffffa0406cc0>] btrfs_recover_log_trees+0x250/0x350 [btrfs]
  [<ffffffffa0406dc0>] ? btrfs_recover_log_trees+0x350/0x350 [btrfs]
  [<ffffffffa03d18b2>] open_ctree+0x1442/0x17d0 [btrfs]
[...]

This comes from that while replaying an inode ref item, we forget to
check those old conflicting DIR_ITEM and DIR_INDEX items in fs/file tree,
then we will come to conflict corners which lead to BUG_ON().

Signed-off-by: Liu Bo<redacted>
---
  fs/btrfs/tree-log.c |   28 ++++++++++++++++++++++++----
  1 files changed, 24 insertions(+), 4 deletions(-)

This fixes the oops for me.  The bug was a regression in 2.6.39, I believe.

Tested-by: Andy Lutomirski <redacted>

--Andy