NFS: Don't hold the group lock when calling nfs_release_request()

That can deadlock if this is the last reference since
nfs_page_group_destroy() calls nfs_page_group_sync_on_bit().
Note that even if the page was removed from the subpage list,
the req->wb_head could still be pointing to the old head.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 121218d..36d34a4 100644 (file)
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -532,9 +532,9 @@ try_again:
                } else if (WARN_ON_ONCE(subreq->wb_offset < head->wb_offset ||
                            ((subreq->wb_offset + subreq->wb_bytes) >
                             (head->wb_offset + total_bytes)))) {
+                       nfs_page_group_unlock(head);
                        nfs_unroll_locks(inode, head, subreq);
                        nfs_unlock_and_release_request(subreq);
-                       nfs_page_group_unlock(head);
                        nfs_unlock_and_release_request(head);
                        return ERR_PTR(-EIO);
                }