[PATCH 3/7] mm: tidy up swap_writeout

Christoph Hellwig
2025-05-08T05:50:01Z

Use a goto label to consolidate the unlock folio and return pattern
and don't bother with an else after a return / goto.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
mm/page_io.c | 36 ++++++++++++++++++------------------
1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/mm/page_io.c b/mm/page_io.c
index f7716b6569fa..c420b0aa0f22 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -239,12 +239,11 @@ static void swap_zeromap_folio_clear(struct folio *folio)
*/
int swap_writeout(struct folio *folio, struct writeback_control *wbc)
{
- int ret;
+ int ret = 0;
+
+ if (folio_free_swap(folio))
+ goto out_unlock;

- if (folio_free_swap(folio)) {
- folio_unlock(folio);
- return 0;
- }
/*
* Arch code may have to preserve more data than just the page
* contents, e.g. memory tags.
@@ -252,8 +251,7 @@ int swap_writeout(struct folio *folio, struct writeback_control *wbc)
ret = arch_prepare_to_swap(folio);
if (ret) {
folio_mark_dirty(folio);
- folio_unlock(folio);
- return ret;
+ goto out_unlock;
}

/*
@@ -264,20 +262,19 @@ int swap_writeout(struct folio *folio, struct writeback_control *wbc)
*/
if (is_folio_zero_filled(folio)) {
swap_zeromap_folio_set(folio);
- folio_unlock(folio);
- return 0;
- } else {
- /*
- * Clear bits this folio occupies in the zeromap to prevent
- * zero data being read in from any previous zero writes that
- * occupied the same swap entries.
- */
- swap_zeromap_folio_clear(folio);
+ goto out_unlock;
}
+
+ /*
+ * Clear bits this folio occupies in the zeromap to prevent zero data
+ * being read in from any previous zero writes that occupied the same
+ * swap entries.
+ */
+ swap_zeromap_folio_clear(folio);
+
if (zswap_store(folio)) {
count_mthp_stat(folio_order(folio), MTHP_STAT_ZSWPOUT);
- folio_unlock(folio);
- return 0;
+ goto out_unlock;
}
if (!mem_cgroup_zswap_writeback_enabled(folio_memcg(folio))) {
folio_mark_dirty(folio);
@@ -286,6 +283,9 @@ int swap_writeout(struct folio *folio, struct writeback_control *wbc)

__swap_writepage(folio, wbc);
return 0;
+out_unlock:
+ folio_unlock(folio);
+ return ret;
}

static inline void count_swpout_vm_event(struct folio *folio)
--
2.47.2