xfs: end sync buffer I/O properly on shutdown error

Brian Foster · djwong · commit 465fa17f4a30 · 2019-02-03T14:03:06.000-08:00
As of commit e339dd8 ("xfs: use sync buffer I/O for sync delwri queue submission"), the delwri submission code uses sync buffer I/O for sync delwri I/O. Instead of waiting on async I/O to unlock the buffer, it uses the underlying sync I/O completion mechanism. If delwri buffer submission fails due to a shutdown scenario, an error is set on the buffer and buffer completion never occurs. This can cause xfs_buf_delwri_submit() to deadlock waiting on a completion event. We could check the error state before waiting on such buffers, but that doesn't serialize against the case of an error set via a racing I/O completion. Instead, invoke I/O completion in the shutdown case regardless of buffer I/O type. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
@@ -1536,8 +1536,7 @@ __xfs_buf_submit(
 		xfs_buf_ioerror(bp, -EIO);
 		bp->b_flags &= ~XBF_DONE;
 		xfs_buf_stale(bp);
-		if (bp->b_flags & XBF_ASYNC)
-			xfs_buf_ioend(bp);
+		xfs_buf_ioend(bp);
 		return -EIO;
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -1536,8 +1536,7 @@ __xfs_buf_submit(`
`1536`	`1536`	`xfs_buf_ioerror(bp, -EIO);`
`1537`	`1537`	`bp->b_flags &= ~XBF_DONE;`
`1538`	`1538`	`xfs_buf_stale(bp);`
`1539`		`- if (bp->b_flags & XBF_ASYNC)`
`1540`		`- xfs_buf_ioend(bp);`
	`1539`	`+ xfs_buf_ioend(bp);`
`1541`	`1540`	`return -EIO;`
`1542`	`1541`	`}`
`1543`	`1542`