[PATCH 5/9] xfs: xfs_bioerror can die.

Dave Chinner
2014-08-15T06:39:17Z

From: Dave Chinner <dchinner@redhat.com>

Internal buffer write error handling is a mess due to the unnatural
split between xfs_bioerror and xfs_bioerror_relse(). The buffer
reference counting is also wrong for the xfs_bioerror path for
xfs_bwrite - it uses sync IO and so xfs_buf_ioend will release a
hold count that was never taken.

Further, xfs_bwrite only does sync IO and determines the handler to
call based on b_iodone, so for this caller the only difference
between xfs_bioerror() and xfs_bioerror_release() is the XBF_DONE
flag. We don't care what the XBF_DONE flag state is because we stale
the buffer in both paths - the next buffer lookup will clear
XBF_DONE anyway because XBF_STALE is set. Hence we can use common
error handling for xfs_bwrite().

__xfs_buf_delwri_submit() is a similar - it's only ever called
on writes - all sync or async - and again there's no reason to
handle them any differently at all.

Clean up the nasty error handling and remove xfs_bioerror().

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_buf.c | 67 +++++++++++++++++---------------------------------------
1 file changed, 20 insertions(+), 47 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 98fcf5a..f444285 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1072,36 +1072,6 @@ xfs_buf_ioerror_alert(
}

/*
- * Called when we want to stop a buffer from getting written or read.
- * We attach the EIO error, muck with its flags, and call xfs_buf_ioend
- * so that the proper iodone callbacks get called.
- */
-STATIC int
-xfs_bioerror(
- xfs_buf_t *bp)
-{
-#ifdef XFSERRORDEBUG
- ASSERT(XFS_BUF_ISREAD(bp) || bp->b_iodone);
-#endif
-
- /*
- * No need to wait until the buffer is unpinned, we aren't flushing it.
- */
- xfs_buf_ioerror(bp, -EIO);
-
- /*
- * We're calling xfs_buf_ioend, so delete XBF_DONE flag.
- */
- XFS_BUF_UNREAD(bp);
- XFS_BUF_UNDONE(bp);
- xfs_buf_stale(bp);
-
- xfs_buf_ioend(bp);
-
- return -EIO;
-}
-
-/*
* Same as xfs_bioerror, except that we are releasing the buffer
* here ourselves, and avoiding the xfs_buf_ioend call.
* This is meant for userdata errors; metadata bufs come with
@@ -1149,19 +1119,19 @@ xfs_bwrite(
ASSERT(xfs_buf_islocked(bp));

bp->b_flags |= XBF_WRITE;
- bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q | XBF_WRITE_FAIL);
+ bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
+ XBF_WRITE_FAIL | XBF_DONE);

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 anyway.
- * These aren't associated with a transaction, and can be
- * ignored.
- */
- if (!bp->b_iodone)
- return xfs_bioerror_relse(bp);
- return xfs_bioerror(bp);
+ xfs_buf_ioerror(bp, -EIO);
+ xfs_buf_stale(bp);
+
+ /* sync IO, xfs_buf_ioend is going to remove a ref here */
+ xfs_buf_hold(bp);
+ xfs_buf_ioend(bp);
+ return -EIO;
}

xfs_buf_iorequest(bp);
@@ -1848,16 +1818,19 @@ __xfs_buf_delwri_submit(
if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
trace_xfs_bdstrat_shut(bp, _RET_IP_);

+ xfs_buf_ioerror(bp, -EIO);
+ xfs_buf_stale(bp);
+
/*
- * Metadata write that didn't get logged but written anyway.
- * These aren't associated with a transaction, and can be
- * ignored.
+ * if sync IO, xfs_buf_ioend is going to remove a
+ * ref here. We need to add that so we can collect
+ * all the buffer errors in the wait loop.
*/
- if (!bp->b_iodone)
- return xfs_bioerror_relse(bp);
- return xfs_bioerror(bp);
- }
- xfs_buf_iorequest(bp);
+ if (wait)
+ xfs_buf_hold(bp);
+ xfs_buf_ioend(bp);
+ } else
+ xfs_buf_iorequest(bp);
}
blk_finish_plug(&plug);

--
2.0.0