From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Sat, 9 Sep 2017 19:31:28 +0000 (-0400)
Subject: NFS: Don't hold the group lock when calling nfs_release_request()
X-Git-Tag: v4.14-rc1~16^2~4
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8b77484f2b3d8f1096a2231d513fc589e4857a73;p=platform%2Fkernel%2Flinux-exynos.git

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
--- 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);
 		}