squashfs: convert squashfs_readpage_block() to take a folio

Remove a few accesses to page->mapping.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
Cc: Phillip Lougher <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

fs/squashfs/file.c

···
 		if (res == 0)
 			res = squashfs_readpage_sparse(&folio->page, expected);
 		else
-			res = squashfs_readpage_block(&folio->page, block, res, expected);
+			res = squashfs_readpage_block(folio, block, res, expected);
 	} else
 		res = squashfs_readpage_fragment(folio, expected);
 

fs/squashfs/file_cache.c

···
 #include "squashfs.h"
 
 /* Read separately compressed datablock and memcopy into page cache */
-int squashfs_readpage_block(struct page *page, u64 block, int bsize, int expected)
+int squashfs_readpage_block(struct folio *folio, u64 block, int bsize, int expected)
 {
-	struct inode *i = page->mapping->host;
+	struct inode *i = folio->mapping->host;
 	struct squashfs_cache_entry *buffer = squashfs_get_datablock(i->i_sb,
 		block, bsize);
 	int res = buffer->error;
···
 		ERROR("Unable to read page, block %llx, size %x\n", block,
 			bsize);
 	else
-		squashfs_copy_cache(page, buffer, expected, 0);
+		squashfs_copy_cache(&folio->page, buffer, expected, 0);
 
 	squashfs_cache_put(buffer);
 	return res;

fs/squashfs/file_direct.c

···
 #include "page_actor.h"
 
 /* Read separately compressed datablock directly into page cache */
-int squashfs_readpage_block(struct page *target_page, u64 block, int bsize,
-	int expected)
-
+int squashfs_readpage_block(struct folio *folio, u64 block, int bsize,
+		int expected)
 {
-	struct folio *folio = page_folio(target_page);
-	struct inode *inode = target_page->mapping->host;
+	struct page *target_page = &folio->page;
+	struct inode *inode = folio->mapping->host;
 	struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
 	loff_t file_end = (i_size_read(inode) - 1) >> PAGE_SHIFT;
 	int mask = (1 << (msblk->block_log - PAGE_SHIFT)) - 1;
···
 	/* Try to grab all the pages covered by the Squashfs block */
 	for (i = 0, index = start_index; index <= end_index; index++) {
 		page[i] = (index == folio->index) ? target_page :
-			grab_cache_page_nowait(target_page->mapping, index);
+			grab_cache_page_nowait(folio->mapping, index);
 
 		if (page[i] == NULL)
 			continue;

fs/squashfs/squashfs.h

···
 				int);
 
 /* file_xxx.c */
-extern int squashfs_readpage_block(struct page *, u64, int, int);
+int squashfs_readpage_block(struct folio *, u64 block, int bsize, int expected);
 
 /* id.c */
 extern int squashfs_get_id(struct super_block *, unsigned int, unsigned int *);