[PATCH 1/3] xfs: don't try to mark uncached buffers stale on error.

Dave Chinner
2013-09-17T01:44:40Z

fsstress failed during a shutdown with the following assert:

XFS: Assertion failed: xfs_buf_islocked(bp), file: fs/xfs/xfs_buf.c, line: 143
.....
xfs_buf_stale+0x3f/0xf0
xfs_bioerror_relse+0x2d/0x90
xfsbdstrat+0x51/0xa0
xfs_zero_remaining_bytes+0x1d1/0x2d0
xfs_free_file_space+0x5d0/0x600
xfs_change_file_space+0x251/0x3a0
xfs_ioc_space+0xcc/0x130
.....

xfs_zero_remaining_bytes() works with uncached buffers, and hence if
we are preventing IO due to a shutdown, we should not be marking it
stale as that is only for cached buffers. Instead, just mark it with
an error and make sure it gets to the caller.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_buf.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 2634700..956685f 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1093,25 +1093,20 @@ xfs_bioerror_relse(
struct xfs_buf *bp)
{
int64_t fl = bp->b_flags;
+
/*
- * No need to wait until the buffer is unpinned.
- * We aren't flushing it.
- *
- * chunkhold expects B_DONE to be set, whether
- * we actually finish the I/O or not. We don't want to
- * change that interface.
+ * No need to wait until the buffer is unpinned. We aren't flushing it.
*/
XFS_BUF_UNREAD(bp);
XFS_BUF_DONE(bp);
xfs_buf_stale(bp);
bp->b_iodone = NULL;
+
+ /*
+ * There's no reason to mark error for ASYNC buffers as there is no-one
+ * waiting to collect the error.
+ */
if (!(fl & XBF_ASYNC)) {
- /*
- * Mark b_error and B_ERROR _both_.
- * Lot's of chunkcache code assumes that.
- * There's no reason to mark error for
- * ASYNC buffers.
- */
xfs_buf_ioerror(bp, EIO);
complete(&bp->b_iowait);
} else {
@@ -1128,11 +1123,15 @@ xfs_bdstrat_cb(
if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
trace_xfs_bdstrat_shut(bp, _RET_IP_);
/*
- * Metadata write that didn't get logged but
- * written delayed anyway. These aren't associated
- * with a transaction, and can be ignored.
+ * If this is a cached write, then it is likely to be a delayed
+ * write metadata buffer that can be ignored because the
+ * contents are logged. If it's an uncached buffer or a read
+ * operation, then the caller will get the error through the
+ * normal IO completion path. We can tell if the buffer is
+ * cached or not by looking to see if the b_pag field is NULL or
+ * not.
*/
- if (!bp->b_iodone && !XFS_BUF_ISREAD(bp))
+ if (!bp->b_iodone && !XFS_BUF_ISREAD(bp) && bp->b_pag)
return xfs_bioerror_relse(bp);
else
return xfs_bioerror(bp);