[PATCH v2 4/7] mm/khugepaged: minor cleanup for collapse_file

[Miaohe Lin <linmiaohe@huawei.com>]

nr_none is always 0 for non-shmem case because the page can be read from
the backend store. So when nr_none ! = 0, it must be in is_shmem case.
Also only adjust the nrpages and uncharge shmem when nr_none != 0 to save
cpu cycles.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
---
 mm/khugepaged.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index a36d9746c321..47514f2fabb9 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1852,8 +1852,8 @@ static void collapse_file(struct mm_struct *mm,
 
 	if (nr_none) {
 		__mod_lruvec_page_state(new_page, NR_FILE_PAGES, nr_none);
-		if (is_shmem)
-			__mod_lruvec_page_state(new_page, NR_SHMEM, nr_none);
+		/* nr_none is always 0 for non-shmem. */
+		__mod_lruvec_page_state(new_page, NR_SHMEM, nr_none);
 	}
 
 	/* Join all the small entries into a single multi-index entry */
@@ -1917,10 +1917,10 @@ static void collapse_file(struct mm_struct *mm,
 
 		/* Something went wrong: roll back page cache changes */
 		xas_lock_irq(&xas);
-		mapping->nrpages -= nr_none;
-
-		if (is_shmem)
+		if (nr_none) {
+			mapping->nrpages -= nr_none;
 			shmem_uncharge(mapping->host, nr_none);
+		}
 
 		xas_set(&xas, start);
 		xas_for_each(&xas, page, end - 1) {
-- 
2.23.0