ext4: remove references to bh->b_page

Buffer heads are attached to folios, not to pages.  Also
flush_dcache_page() is now deprecated in favour of flush_dcache_folio().

Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>

Author: Matthew Wilcox (Oracle)

fs/ext4/inode.c

@@ -752,7 +752,7 @@ static void ext4_update_bh_state(struct buffer_head *bh, unsigned long flags)
 	flags &= EXT4_MAP_FLAGS;
 
 	/* Dummy buffer_head? Set non-atomically. */
-	if (!bh->b_page) {
+	if (!bh->b_folio) {
 		bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | flags;
 		return;
 	}

fs/ext4/super.c

@@ -7306,7 +7306,7 @@ static ssize_t ext4_quota_write(struct super_block *sb, int type,
 	}
 	lock_buffer(bh);
 	memcpy(bh->b_data+offset, data, len);
-	flush_dcache_page(bh->b_page);
+	flush_dcache_folio(bh->b_folio);
 	unlock_buffer(bh);
 	err = ext4_handle_dirty_metadata(handle, NULL, bh);
 	brelse(bh);

fs/jbd2/journal.c

@@ -947,7 +947,7 @@ int jbd2_journal_bmap(journal_t *journal, unsigned long blocknr,
  * descriptor blocks we do need to generate bona fide buffers.
  *
  * After the caller of jbd2_journal_get_descriptor_buffer() has finished modifying
- * the buffer's contents they really should run flush_dcache_page(bh->b_page).
+ * the buffer's contents they really should run flush_dcache_folio(bh->b_folio).
  * But we don't bother doing that, so there will be coherency problems with
  * mmaps of blockdevs which hold live JBD-controlled filesystems.
  */