[PATCH 16/18] xfs: refactor the tail of xfs_writepage_map

Christoph Hellwig
2018-05-30T10:01:26Z

Rejuggle how we deal with the different error vs non-error and have
ioends vs not have ioend cases to keep the fast path streamlined, and
the duplicate code at a minimum.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/xfs_aops.c | 65 +++++++++++++++++++++++------------------------
1 file changed, 32 insertions(+), 33 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 38021023131e..ac417ef326a9 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -873,7 +873,14 @@ xfs_writepage_map(
* submission of outstanding ioends on the writepage context so they are
* treated correctly on error.
*/
- if (count) {
+ if (unlikely(error)) {
+ if (!count) {
+ xfs_aops_discard_page(page);
+ ClearPageUptodate(page);
+ unlock_page(page);
+ goto done;
+ }
+
/*
* If the page was not fully cleaned, we need to ensure that the
* higher layers come back to it correctly. That means we need
@@ -882,43 +889,35 @@ xfs_writepage_map(
* so another attempt to write this page in this writeback sweep
* will be made.
*/
- if (error) {
- set_page_writeback_keepwrite(page);
- } else {
- clear_page_dirty_for_io(page);
- set_page_writeback(page);
- }
- unlock_page(page);
-
- /*
- * Preserve the original error if there was one, otherwise catch
- * submission errors here and propagate into subsequent ioend
- * submissions.
- */
- list_for_each_entry_safe(ioend, next, &submit_list, io_list) {
- int error2;
-
- list_del_init(&ioend->io_list);
- error2 = xfs_submit_ioend(wbc, ioend, error);
- if (error2 && !error)
- error = error2;
- }
- } else if (error) {
- xfs_aops_discard_page(page);
- ClearPageUptodate(page);
- unlock_page(page);
+ set_page_writeback_keepwrite(page);
} else {
- /*
- * We can end up here with no error and nothing to write if we
- * race with a partial page truncate on a sub-page block sized
- * filesystem. In that case we need to mark the page clean.
- */
clear_page_dirty_for_io(page);
set_page_writeback(page);
- unlock_page(page);
- end_page_writeback(page);
}

+ unlock_page(page);
+
+ /*
+ * Preserve the original error if there was one, otherwise catch
+ * submission errors here and propagate into subsequent ioend
+ * submissions.
+ */
+ list_for_each_entry_safe(ioend, next, &submit_list, io_list) {
+ int error2;
+
+ list_del_init(&ioend->io_list);
+ error2 = xfs_submit_ioend(wbc, ioend, error);
+ if (error2 && !error)
+ error = error2;
+ }
+
+ /*
+ * We can end up here with no error and nothing to write if we race with
+ * a partial page truncate on a sub-page block sized filesystem.
+ */
+ if (!count)
+ end_page_writeback(page);
+done:
mapping_set_error(page->mapping, error);
return error;
}
--
2.17.0