[PATCH] btrfs: fix memory leak for page count

[robbieko <robbieko@synology.com>]

From: Robbie Ko <robbieko@synology.com>

When lock_delalloc_page, we first lock the page and then
check that the page dirty, if the page is not dirty, we
will return -EAGAIN but all pages must be freed, otherwise
page leak.

Signed-off-by: Robbie Ko <robbieko@synology.com>
---
 fs/btrfs/extent_io.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 68c96057ad2d..34d55b1e2a88 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1951,7 +1951,7 @@ static int __process_pages_contig(struct address_space *mapping,
 	struct page *pages[16];
 	unsigned ret;
 	int err = 0;
-	int i;
+	int i, j;
 
 	if (page_ops & PAGE_LOCK) {
 		ASSERT(page_ops == PAGE_LOCK);
@@ -1999,7 +1999,8 @@ static int __process_pages_contig(struct address_space *mapping,
 				if (!PageDirty(pages[i]) ||
 				    pages[i]->mapping != mapping) {
 					unlock_page(pages[i]);
-					put_page(pages[i]);
+					for (j = i; j < ret; j++)
+						put_page(pages[j]);
 					err = -EAGAIN;
 					goto out;
 				}
-- 
2.17.1