[PATCH v2 12/21] fat: check for a metadata write error with buffer_write_io_error()

fat_sync_bhs() waits for the writes it issued and then tests
!buffer_uptodate() to find the ones that failed.  That relies on the write
completion handler clearing BH_Uptodate on error, which this series
removes: a buffer whose write failed still holds the data the filesystem
asked to be written, so declaring it not up to date is wrong and makes
callers re-read it.

Test BH_Write_EIO, which is what the completion handler sets and what this
code actually wants to know.

No behaviour change today - a failed write sets BH_Write_EIO and clears
BH_Uptodate together.  It stops being a no-op at the end of the series,
where the new test is the one that still works.

Acked-by: Weidong Zhu <[email protected]>
Signed-off-by: Chao Shi <[email protected]>
---
 fs/fat/misc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index be18f6b5819b..4a4cd0111e47 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -356,7 +356,7 @@ int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 
 	for (i = 0; i < nr_bhs; i++) {
 		wait_on_buffer(bhs[i]);
-		if (!err && !buffer_uptodate(bhs[i]))
+		if (!err && buffer_write_io_error(bhs[i]))
 			err = -EIO;
 	}
 	return err;
-- 
2.43.0