[PATCH 5.10 CANDIDATE 6/8] xfs: restore shutdown check in mapped write fault path

Amir Goldstein
2022-06-01T10:46:31Z

From: Brian Foster <bfoster@redhat.com>

commit e4826691cc7e5458bcb659935d0092bcf3f08c20 upstream.

XFS triggers an iomap warning in the write fault path due to a
!PageUptodate() page if a write fault happens to occur on a page
that recently failed writeback. The iomap writeback error handling
code can clear the Uptodate flag if no portion of the page is
submitted for I/O. This is reproduced by fstest generic/019, which
combines various forms of I/O with simulated disk failures that
inevitably lead to filesystem shutdown (which then unconditionally
fails page writeback).

This is a regression introduced by commit f150b4234397 ("xfs: split
the iomap ops for buffered vs direct writes") due to the removal of
a shutdown check and explicit error return in the ->iomap_begin()
path used by the write fault path. The explicit error return
historically translated to a SIGBUS, but now carries on with iomap
processing where it complains about the unexpected state. Restore
the shutdown check to xfs_buffered_write_iomap_begin() to restore
historical behavior.

Fixes: f150b4234397 ("xfs: split the iomap ops for buffered vs direct writes")
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/xfs/xfs_iomap.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 7b9ff824e82d..74bc2beadc23 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -870,6 +870,9 @@ xfs_buffered_write_iomap_begin(
int allocfork = XFS_DATA_FORK;
int error = 0;

+ if (XFS_FORCED_SHUTDOWN(mp))
+ return -EIO;
+
/* we can't use delayed allocations when using extent size hints */
if (xfs_get_extsz_hint(ip))
return xfs_direct_write_iomap_begin(inode, offset, count,
--
2.25.1