[PATCH 5.4 035/138] btrfs: fix page leaks after failure to lock page for delalloc

[Greg Kroah-Hartman]

From: Robbie Ko <robbieko@xxxxxxxxxxxx>

commit 5909ca110b29aa16b23b52b8de8d3bb1035fd738 upstream.

When locking pages for delalloc, we check if it's dirty and mapping still
matches. If it does not match, we need to return -EAGAIN and release all
pages. Only the current page was put though, iterate over all the
remaining pages too.

CC: stable@xxxxxxxxxxxxxxx # 4.14+
Reviewed-by: Filipe Manana <fdmanana@xxxxxxxx>
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
Signed-off-by: Robbie Ko <robbieko@xxxxxxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/btrfs/extent_io.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1923,7 +1923,8 @@ static int __process_pages_contig(struct
 				if (!PageDirty(pages[i]) ||
 				    pages[i]->mapping != mapping) {
 					unlock_page(pages[i]);
-					put_page(pages[i]);
+					for (; i < ret; i++)
+						put_page(pages[i]);
 					err = -EAGAIN;
 					goto out;
 				}