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authorDave Chinner <dchinner@redhat.com>2013-01-21 23:53:55 +1100
committerBen Myers <bpm@sgi.com>2013-01-28 12:51:12 -0600
commit9f87832a82923943aaab38b8d53658af134bbfa4 (patch)
treea777e8186956f3018347710cfa03313bb6f3fd4f /fs
parentf2a459565b02b60408f3f2e5ca992a031319712b (diff)
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')
-rw-r--r--fs/xfs/xfs_buf.c2
-rw-r--r--fs/xfs/xfs_buf_item.c12
-rw-r--r--fs/xfs/xfs_trace.h1
3 files changed, 13 insertions, 2 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 689d72655ea6..fbbb9eb92e32 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;
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 77b09750e92c..3f9949fee391 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -652,7 +652,10 @@ xfs_buf_item_unlock(
/*
* If the buf item isn't tracking any data, free it, otherwise drop the
- * reference we hold to it.
+ * reference we hold to it. If we are aborting the transaction, this may
+ * be the only reference to the buf item, so we free it anyway
+ * regardless of whether it is dirty or not. A dirty abort implies a
+ * shutdown, anyway.
*/
clean = 1;
for (i = 0; i < bip->bli_format_count; i++) {
@@ -664,7 +667,12 @@ xfs_buf_item_unlock(
}
if (clean)
xfs_buf_item_relse(bp);
- else
+ else if (aborted) {
+ if (atomic_dec_and_test(&bip->bli_refcount)) {
+ ASSERT(XFS_FORCED_SHUTDOWN(lip->li_mountp));
+ xfs_buf_item_relse(bp);
+ }
+ } else
atomic_dec(&bip->bli_refcount);
if (!hold)
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 2e137d4a85ae..16a812977eab 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -341,6 +341,7 @@ DEFINE_BUF_EVENT(xfs_buf_item_relse);
DEFINE_BUF_EVENT(xfs_buf_item_iodone);
DEFINE_BUF_EVENT(xfs_buf_item_iodone_async);
DEFINE_BUF_EVENT(xfs_buf_error_relse);
+DEFINE_BUF_EVENT(xfs_buf_wait_buftarg);
DEFINE_BUF_EVENT(xfs_trans_read_buf_io);
DEFINE_BUF_EVENT(xfs_trans_read_buf_shut);