[PATCH 4.4 57/86] cachefiles: Handle readpage error correctly

[Greg Kroah-Hartman]

From: Matthew Wilcox (Oracle) <wi...@infradead.org>

commit 9480b4e75b7108ee68ecf5bc6b4bd68e8031c521 upstream.

If ->readpage returns an error, it has already unlocked the page.

Fixes: 5e929b33c393 ("CacheFiles: Handle truncate unlocking the page we're 
reading")
Cc: sta...@vger.kernel.org
Signed-off-by: Matthew Wilcox (Oracle) <wi...@infradead.org>
Signed-off-by: David Howells <dhowe...@redhat.com>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

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

--- a/fs/cachefiles/rdwr.c
+++ b/fs/cachefiles/rdwr.c
@@ -125,7 +125,7 @@ static int cachefiles_read_reissue(struc
                _debug("reissue read");
                ret = bmapping->a_ops->readpage(NULL, backpage);
                if (ret < 0)
-                       goto unlock_discard;
+                       goto discard;
        }
 
        /* but the page may have been read before the monitor was installed, so
@@ -142,6 +142,7 @@ static int cachefiles_read_reissue(struc
 
 unlock_discard:
        unlock_page(backpage);
+discard:
        spin_lock_irq(&object->work_lock);
        list_del(&monitor->op_link);
        spin_unlock_irq(&object->work_lock);