From 3aff4ebb95b20ad8db2c1447e8c52097d89af5a7 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 9 May 2012 14:30:35 -0400 Subject: NFS: Prevent a deadlock in the new writeback code We have to unlock the nfs_page before we call nfs_end_page_writeback to avoid races with functions that expect the page to be unlocked when PG_locked and PG_writeback are not set. The problem is that nfs_unlock_request also releases the nfs_page, causing a deadlock if the release of the nfs_open_context triggers an iput() while the PG_writeback flag is still set... The solution is to separate the unlocking and release of the nfs_page, so that we can do the former before nfs_end_page_writeback and the latter after. Signed-off-by: Trond Myklebust Cc: Fred Isaman --- include/linux/nfs_page.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h index f9ee9eba7f88..ef7504215446 100644 --- a/include/linux/nfs_page.h +++ b/include/linux/nfs_page.h @@ -96,6 +96,7 @@ extern bool nfs_generic_pg_test(struct nfs_pageio_descriptor *desc, struct nfs_page *req); extern int nfs_wait_on_request(struct nfs_page *); extern void nfs_unlock_request(struct nfs_page *req); +extern void nfs_unlock_request_dont_release(struct nfs_page *req); /* * Lock the page of an asynchronous request without getting a new reference -- cgit