From f69806af2a2f3c9c51ab246f483f651dc42a07c6 Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Wed, 6 May 2020 13:25:20 -0700 Subject: [PATCH] xfs: reset buffer write failure state on successful completion [ Upstream commit b6983e80b03bd4fd42de71993b3ac7403edac758 ] The buffer write failure flag is intended to control the internal write retry that XFS has historically implemented to help mitigate the severity of transient I/O errors. The flag is set when a buffer is resubmitted from the I/O completion path due to a previous failure. It is checked on subsequent I/O completions to skip the internal retry and fall through to the higher level configurable error handling mechanism. The flag is cleared in the synchronous and delwri submission paths and also checked in various places to log write failure messages. There are a couple minor problems with the current usage of this flag. One is that we issue an internal retry after every submission from xfsaild due to how delwri submission clears the flag. This results in double the expected or configured number of write attempts when under sustained failures. Another more subtle issue is that the flag is never cleared on successful I/O completion. This can cause xfs_wait_buftarg() to suggest that dirty buffers are being thrown away due to the existence of the flag, when the reality is that the flag might still be set because the write succeeded on the retry. Clear the write failure flag on successful I/O completion to address both of these problems. This means that the internal retry attempt occurs once since the last time a buffer write failed and that various other contexts only see the flag set when the immediately previous write attempt has failed. Signed-off-by: Brian Foster Reviewed-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Reviewed-by: Allison Collins Signed-off-by: Darrick J. Wong Signed-off-by: Sasha Levin --- fs/xfs/xfs_buf.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 0abba171aa89..1264ac63e4e5 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -1162,8 +1162,10 @@ xfs_buf_ioend( bp->b_ops->verify_read(bp); } - if (!bp->b_error) + if (!bp->b_error) { + bp->b_flags &= ~XBF_WRITE_FAIL; bp->b_flags |= XBF_DONE; + } if (bp->b_iodone) (*(bp->b_iodone))(bp); @@ -1223,7 +1225,7 @@ xfs_bwrite( bp->b_flags |= XBF_WRITE; bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q | - XBF_WRITE_FAIL | XBF_DONE); + XBF_DONE); error = xfs_buf_submit(bp); if (error) @@ -1929,7 +1931,7 @@ xfs_buf_delwri_submit_buffers( * synchronously. Otherwise, drop the buffer from the delwri * queue and submit async. */ - bp->b_flags &= ~(_XBF_DELWRI_Q | XBF_WRITE_FAIL); + bp->b_flags &= ~_XBF_DELWRI_Q; bp->b_flags |= XBF_WRITE; if (wait_list) { bp->b_flags &= ~XBF_ASYNC;