swap: convert swapon() to use a folio

Retrieve a folio from the page cache rather than a page.  Saves a couple
of conversions between page & folio.

Link: https://lkml.kernel.org/r/20240826202138.3804238-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 8e317c495bfb90048a7baa3f194bc607470f9b12..0cded32414a1f13f70ebd87f5b37bbaa4821b427 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3357,7 +3357,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
        unsigned char *swap_map = NULL;
        unsigned long *zeromap = NULL;
        struct swap_cluster_info *cluster_info = NULL;
-       struct page *page = NULL;
+       struct folio *folio = NULL;
        struct inode *inode = NULL;
        bool inced_nr_rotate_swap = false;
 
@@ -3415,12 +3415,12 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
                error = -EINVAL;
                goto bad_swap_unlock_inode;
        }
-       page = read_mapping_page(mapping, 0, swap_file);
-       if (IS_ERR(page)) {
-               error = PTR_ERR(page);
+       folio = read_mapping_folio(mapping, 0, swap_file);
+       if (IS_ERR(folio)) {
+               error = PTR_ERR(folio);
                goto bad_swap_unlock_inode;
        }
-       swap_header = kmap(page);
+       swap_header = kmap_local_folio(folio, 0);
 
        maxpages = read_swap_header(si, swap_header, inode);
        if (unlikely(!maxpages)) {
@@ -3574,10 +3574,8 @@ bad_swap:
        if (swap_file)
                filp_close(swap_file, NULL);
 out:
-       if (page && !IS_ERR(page)) {
-               kunmap(page);
-               put_page(page);
-       }
+       if (!IS_ERR_OR_NULL(folio))
+               folio_release_kmap(folio, swap_header);
        if (name)
                putname(name);
        if (inode)