mm/shmem: use pagevec_lookup in shmem_unlock_mapping

The comment shows that the reason for using find_get_entries() is now
stale; find_get_pages() will not return 0 if it hits a consecutive run of
swap entries, and I don't believe it has since 2011.  pagevec_lookup() is
a simpler function to use than find_get_pages(), so use it instead.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: William Kucharski <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Yang Shi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 1 insertions, 10 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index ff741d229701..5ea1fa53db3f 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -842,7 +842,6 @@ unsigned long shmem_swap_usage(struct vm_area_struct *vma)
 void shmem_unlock_mapping(struct address_space *mapping)
 {
 	struct pagevec pvec;
-	pgoff_t indices[PAGEVEC_SIZE];
 	pgoff_t index = 0;
 
 	pagevec_init(&pvec);
@@ -850,16 +849,8 @@ void shmem_unlock_mapping(struct address_space *mapping)
 	 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
 	 */
 	while (!mapping_unevictable(mapping)) {
-		/*
-		 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
-		 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
-		 */
-		pvec.nr = find_get_entries(mapping, index,
-					   PAGEVEC_SIZE, pvec.pages, indices);
-		if (!pvec.nr)
+		if (!pagevec_lookup(&pvec, mapping, &index))
 			break;
-		index = indices[pvec.nr - 1] + 1;
-		pagevec_remove_exceptionals(&pvec);
 		check_move_unevictable_pages(&pvec);
 		pagevec_release(&pvec);
 		cond_resched();