mm/shmem: use a folio in shmem_unused_huge_shrink

When calling split_huge_page() we usually have to find the precise page,
but that's not necessary here because we only need to unlock and put the
folio afterwards.  Saves 231 bytes of text (20% of this function).

Link: https://lkml.kernel.org/r/20220504182857.4013401-17-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index 7cfe763..6cba5fd 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -554,7 +554,7 @@ static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
        LIST_HEAD(to_remove);
        struct inode *inode;
        struct shmem_inode_info *info;
-       struct page *page;
+       struct folio *folio;
        unsigned long batch = sc ? sc->nr_to_scan : 128;
        int split = 0;
 
@@ -598,6 +598,7 @@ next:
 
        list_for_each_safe(pos, next, &list) {
                int ret;
+               pgoff_t index;
 
                info = list_entry(pos, struct shmem_inode_info, shrinklist);
                inode = &info->vfs_inode;
@@ -605,14 +606,14 @@ next:
                if (nr_to_split && split >= nr_to_split)
                        goto move_back;
 
-               page = find_get_page(inode->i_mapping,
-                               (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT);
-               if (!page)
+               index = (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT;
+               folio = filemap_get_folio(inode->i_mapping, index);
+               if (!folio)
                        goto drop;
 
                /* No huge page at the end of the file: nothing to split */
-               if (!PageTransHuge(page)) {
-                       put_page(page);
+               if (!folio_test_large(folio)) {
+                       folio_put(folio);
                        goto drop;
                }
 
@@ -623,14 +624,14 @@ next:
                 * Waiting for the lock may lead to deadlock in the
                 * reclaim path.
                 */
-               if (!trylock_page(page)) {
-                       put_page(page);
+               if (!folio_trylock(folio)) {
+                       folio_put(folio);
                        goto move_back;
                }
 
-               ret = split_huge_page(page);
-               unlock_page(page);
-               put_page(page);
+               ret = split_huge_page(&folio->page);
+               folio_unlock(folio);
+               folio_put(folio);
 
                /* If split failed move the inode on the list back to shrinklist */
                if (ret)