ext4: Don't unlock page in ext4_bio_write_page()

Do not unlock the written page in ext4_bio_write_page(). Instead leave
the page locked and unlock it in the callers. We'll need to keep the
page locked for data=journal writeback for a bit longer.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230228051319.4085470-5-tytso@mit.edu

fs/ext4/inode.c

@@ -2076,6 +2076,7 @@ static int ext4_writepage(struct page *page,
 		return -ENOMEM;
 	}
 	ret = ext4_bio_write_page(&io_submit, page, len);
+	unlock_page(page);
 	ext4_io_submit(&io_submit);
 	/* Drop io_end reference we got from init */
 	ext4_put_io_end_defer(io_submit.io_end);
@@ -2110,6 +2111,7 @@ static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
 	else
 		len = PAGE_SIZE;
 	err = ext4_bio_write_page(&mpd->io_submit, page, len);
+	unlock_page(page);
 	if (!err)
 		mpd->wbc->nr_to_write--;
 	mpd->first_page++;

fs/ext4/page-io.c

@@ -502,7 +502,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 
 	/* Nothing to submit? Just unlock the page... */
 	if (!nr_to_submit)
-		goto unlock;
+		return 0;
 
 	bh = head = page_buffers(page);
 
@@ -550,7 +550,8 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 				}
 				bh = bh->b_this_page;
 			} while (bh != head);
-			goto unlock;
+
+			return ret;
 		}
 	}
 
@@ -565,7 +566,6 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
 			continue;
 		io_submit_add_bh(io, inode, page, bounce_page, bh);
 	} while ((bh = bh->b_this_page) != head);
-unlock:
-	unlock_page(page);
-	return ret;
+
+	return 0;
 }