If the trylock fails and the buffer is pinned and stale, the
resulting xfs_log_force() can lead to lock recursion on the ailp
xa_lock. Call __xfs_buf_trylock() to attempt the buf lock with
xa_lock held, but to avoid the log force. If the trylock had raced
with the buffer being pinned, return XFS_ITEM_PINNED such that
xfsaild will pend up a log force on the next scan.
Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
---
fs/xfs/xfs_buf_item.c | 14 +++++++++++++-
1 files changed, 13 insertions(+), 1 deletions(-)
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 9c4c050..23a328e 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -469,8 +469,20 @@ xfs_buf_item_push(
if (xfs_buf_ispinned(bp))
return XFS_ITEM_PINNED;
- if (!xfs_buf_trylock(bp))
+
+ if (!__xfs_buf_trylock(bp, false)) {
+ /*
+ * We disable the log force via trylock because the buffer can
+ * become pinned and stale after the trylock fails and the log
+ * force is unsafe with xa_lock held.
+ *
+ * Check the buffer state once more and return pinned such that
+ * xfsaild pends up the log force when it drops xa_lock.
+ */
+ if (xfs_buf_ispinned(bp))
+ return XFS_ITEM_PINNED;
return XFS_ITEM_LOCKED;
+ }
ASSERT(!(bip->bli_flags & XFS_BLI_STALE));
--
1.7.7.6
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