gfs2: replace obvious uses of b_page with b_folio

These places just use b_page to get to the buffer's address_space.

Link: https://lkml.kernel.org/r/20221215214402.3522366-9-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/gfs2/glops.c

@@ -39,7 +39,7 @@ static void gfs2_ail_error(struct gfs2_glock *gl, const struct buffer_head *bh)
 	       "AIL buffer %p: blocknr %llu state 0x%08lx mapping %p page "
 	       "state 0x%lx\n",
 	       bh, (unsigned long long)bh->b_blocknr, bh->b_state,
-	       bh->b_page->mapping, bh->b_page->flags);
+	       bh->b_folio->mapping, bh->b_folio->flags);
 	fs_err(sdp, "AIL glock %u:%llu mapping %p\n",
 	       gl->gl_name.ln_type, gl->gl_name.ln_number,
 	       gfs2_glock2aspace(gl));

fs/gfs2/log.c

@@ -127,7 +127,7 @@ __acquires(&sdp->sd_ail_lock)
 			continue;
 		gl = bd->bd_gl;
 		list_move(&bd->bd_ail_st_list, &tr->tr_ail1_list);
-		mapping = bh->b_page->mapping;
+		mapping = bh->b_folio->mapping;
 		if (!mapping)
 			continue;
 		spin_unlock(&sdp->sd_ail_lock);

fs/gfs2/meta_io.c

@@ -334,7 +334,7 @@ int gfs2_meta_wait(struct gfs2_sbd *sdp, struct buffer_head *bh)
 
 void gfs2_remove_from_journal(struct buffer_head *bh, int meta)
 {
-	struct address_space *mapping = bh->b_page->mapping;
+	struct address_space *mapping = bh->b_folio->mapping;
 	struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
 	struct gfs2_bufdata *bd = bh->b_private;
 	struct gfs2_trans *tr = current->journal_info;