[1/2] NFS: Don't hold the group lock when calling nfs_release_request()
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Message ID 20170910215242.4212-1-trond.myklebust@primarydata.com
State New
Headers show

Commit Message

Trond Myklebust Sept. 10, 2017, 9:52 p.m. UTC
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>
---
 fs/nfs/write.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch
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diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 121218d4e5ed..36d34a4c86bd 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -532,9 +532,9 @@  nfs_lock_and_join_requests(struct page *page)
 		} 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);
 		}