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author | Dave Chinner <dchinner@redhat.com> | 2013-01-21 12:53:55 (GMT) |
---|---|---|
committer | Ben Myers <bpm@sgi.com> | 2013-01-26 15:34:38 (GMT) |
commit | 3b19034d4f4554e39ca244fb28962bbf2ccba046 (patch) | |
tree | f37768d858c67d8e982d064d04fa2517914d6778 /fs/xfs/xfs_buf.c | |
parent | 4d559a3bcb7383f34334092af07e68fb60910684 (diff) | |
download | linux-3b19034d4f4554e39ca244fb28962bbf2ccba046.tar.xz |
xfs: fix shutdown hang on invalid inode during create
When the new inode verify in xfs_iread() fails, the create
transaction is aborted and a shutdown occurs. The subsequent unmount
then hangs in xfs_wait_buftarg() on a buffer that has an elevated
hold count. Debug showed that it was an AGI buffer getting stuck:
[ 22.576147] XFS (vdb): buffer 0x2/0x1, hold 0x2 stuck
[ 22.976213] XFS (vdb): buffer 0x2/0x1, hold 0x2 stuck
[ 23.376206] XFS (vdb): buffer 0x2/0x1, hold 0x2 stuck
[ 23.776325] XFS (vdb): buffer 0x2/0x1, hold 0x2 stuck
The trace of this buffer leading up to the shutdown (trimmed for
brevity) looks like:
xfs_buf_init: bno 0x2 nblks 0x1 hold 1 caller xfs_buf_get_map
xfs_buf_get: bno 0x2 len 0x200 hold 1 caller xfs_buf_read_map
xfs_buf_read: bno 0x2 len 0x200 hold 1 caller xfs_trans_read_buf_map
xfs_buf_iorequest: bno 0x2 nblks 0x1 hold 1 caller _xfs_buf_read
xfs_buf_hold: bno 0x2 nblks 0x1 hold 1 caller xfs_buf_iorequest
xfs_buf_rele: bno 0x2 nblks 0x1 hold 2 caller xfs_buf_iorequest
xfs_buf_iowait: bno 0x2 nblks 0x1 hold 1 caller _xfs_buf_read
xfs_buf_ioerror: bno 0x2 len 0x200 hold 1 caller xfs_buf_bio_end_io
xfs_buf_iodone: bno 0x2 nblks 0x1 hold 1 caller _xfs_buf_ioend
xfs_buf_iowait_done: bno 0x2 nblks 0x1 hold 1 caller _xfs_buf_read
xfs_buf_hold: bno 0x2 nblks 0x1 hold 1 caller xfs_buf_item_init
xfs_trans_read_buf: bno 0x2 len 0x200 hold 2 recur 0 refcount 1
xfs_trans_brelse: bno 0x2 len 0x200 hold 2 recur 0 refcount 1
xfs_buf_item_relse: bno 0x2 nblks 0x1 hold 2 caller xfs_trans_brelse
xfs_buf_rele: bno 0x2 nblks 0x1 hold 2 caller xfs_buf_item_relse
xfs_buf_unlock: bno 0x2 nblks 0x1 hold 1 caller xfs_trans_brelse
xfs_buf_rele: bno 0x2 nblks 0x1 hold 1 caller xfs_trans_brelse
xfs_buf_trylock: bno 0x2 nblks 0x1 hold 2 caller _xfs_buf_find
xfs_buf_find: bno 0x2 len 0x200 hold 2 caller xfs_buf_get_map
xfs_buf_get: bno 0x2 len 0x200 hold 2 caller xfs_buf_read_map
xfs_buf_read: bno 0x2 len 0x200 hold 2 caller xfs_trans_read_buf_map
xfs_buf_hold: bno 0x2 nblks 0x1 hold 2 caller xfs_buf_item_init
xfs_trans_read_buf: bno 0x2 len 0x200 hold 3 recur 0 refcount 1
xfs_trans_log_buf: bno 0x2 len 0x200 hold 3 recur 0 refcount 1
xfs_buf_item_unlock: bno 0x2 len 0x200 hold 3 flags DIRTY liflags ABORTED
xfs_buf_unlock: bno 0x2 nblks 0x1 hold 3 caller xfs_buf_item_unlock
xfs_buf_rele: bno 0x2 nblks 0x1 hold 3 caller xfs_buf_item_unlock
And that is the AGI buffer from cold cache read into memory to
transaction abort. You can see at transaction abort the bli is dirty
and only has a single reference. The item is not pinned, and it's
not in the AIL. Hence the only reference to it is this transaction.
The problem is that the xfs_buf_item_unlock() call is dropping the
last reference to the xfs_buf_log_item attached to the buffer (which
holds a reference to the buffer), but it is not freeing the
xfs_buf_log_item. Hence nothing will ever release the buffer, and
the unmount hangs waiting for this reference to go away.
The fix is simple - xfs_buf_item_unlock needs to detect the last
reference going away in this case and free the xfs_buf_log_item to
release the reference it holds on the buffer.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_buf.c')
-rw-r--r-- | fs/xfs/xfs_buf.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 689d726..fbbb9eb 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -1505,6 +1505,8 @@ restart: while (!list_empty(&btp->bt_lru)) { bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru); if (atomic_read(&bp->b_hold) > 1) { + trace_xfs_buf_wait_buftarg(bp, _RET_IP_); + list_move_tail(&bp->b_lru, &btp->bt_lru); spin_unlock(&btp->bt_lru_lock); delay(100); goto restart; |