fuse: writepages: protect secondary requests from fuse file release

All async fuse requests must be supplied with extra reference to a fuse
file.  This is necessary to ensure that the fuse file is not released until
all in-flight requests are completed.  Fuse secondary writeback requests
must obey this rule as well.

Signed-off-by: Maxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index e6fdd59a7906..7e70506297bc 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1505,6 +1505,7 @@ static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req)
                 struct fuse_req *next = req->misc.write.next;
                 req->misc.write.next = next->misc.write.next;
                 next->misc.write.next = NULL;
+                next->ff = fuse_file_get(req->ff);
                 list_add(&next->writepages_entry, &fi->writepages);
 
                 /*