[PATCH 5.7 040/179] btrfs: fix page leaks after failure to lock page for delalloc

[Greg Kroah-Hartman]

From: Robbie Ko <robbi...@synology.com>

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: sta...@vger.kernel.org # 4.14+
Reviewed-by: Filipe Manana <fdman...@suse.com>
Reviewed-by: Nikolay Borisov <nbori...@suse.com>
Signed-off-by: Robbie Ko <robbi...@synology.com>
Reviewed-by: David Sterba <dste...@suse.com>
Signed-off-by: David Sterba <dste...@suse.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 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
@@ -1999,7 +1999,8 @@ 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;
                                }