[PATCH v5 02/11] btrfs: defrag: also check PagePrivate for subpage cases in cluster_pages_for_defrag()

[Qu Wenruo <wqu@suse.com>]

In function cluster_pages_for_defrag() we have a window where we unlock
page, either start the ordered range or read the content from disk.

When we re-lock the page, we need to make sure it still has the correct
page->private for subpage.

Thus add the extra PagePrivate check here to handle subpage cases
properly.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/ioctl.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index e63961192581..7c1ea4eed490 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1272,7 +1272,8 @@ static int cluster_pages_for_defrag(struct inode *inode,
 			 * we unlocked the page above, so we need check if
 			 * it was released or not.
 			 */
-			if (page->mapping != inode->i_mapping) {
+			if (page->mapping != inode->i_mapping ||
+			    !PagePrivate(page)) {
 				unlock_page(page);
 				put_page(page);
 				goto again;
@@ -1290,7 +1291,7 @@ static int cluster_pages_for_defrag(struct inode *inode,
 			}
 		}
 
-		if (page->mapping != inode->i_mapping) {
+		if (page->mapping != inode->i_mapping || !PagePrivate(page)) {
 			unlock_page(page);
 			put_page(page);
 			goto again;
-- 
2.32.0