buffer: use a folio in __find_get_block_slow()

Saves a call to compound_head() and may be needed to support block size >
PAGE_SIZE.

Link: https://lkml.kernel.org/r/20230612210141.730128-14-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/buffer.c b/fs/buffer.c
index 4ca2eb2..c38fdca 100644 (file)
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -195,19 +195,19 @@ __find_get_block_slow(struct block_device *bdev, sector_t block)
        pgoff_t index;
        struct buffer_head *bh;
        struct buffer_head *head;
-       struct page *page;
+       struct folio *folio;
        int all_mapped = 1;
        static DEFINE_RATELIMIT_STATE(last_warned, HZ, 1);
 
        index = block >> (PAGE_SHIFT - bd_inode->i_blkbits);
-       page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED);
-       if (!page)
+       folio = __filemap_get_folio(bd_mapping, index, FGP_ACCESSED, 0);
+       if (IS_ERR(folio))
                goto out;
 
        spin_lock(&bd_mapping->private_lock);
-       if (!page_has_buffers(page))
+       head = folio_buffers(folio);
+       if (!head)
                goto out_unlock;
-       head = page_buffers(page);
        bh = head;
        do {
                if (!buffer_mapped(bh))
@@ -237,7 +237,7 @@ __find_get_block_slow(struct block_device *bdev, sector_t block)
        }
 out_unlock:
        spin_unlock(&bd_mapping->private_lock);
-       put_page(page);
+       folio_put(folio);
 out:
        return ret;
 }