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authorTrond Myklebust <Trond.Myklebust@netapp.com>2012-05-09 14:30:35 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2012-05-09 15:16:07 -0400
commit3aff4ebb95b20ad8db2c1447e8c52097d89af5a7 (patch)
treead56aceafbcbd0650e71e029ffa138eedffd33ba /include/linux/nfs_page.h
parentdc327ed4cd320be689596365372a3683208c3ba0 (diff)
downloadlinux-3aff4ebb95b20ad8db2c1447e8c52097d89af5a7.tar.gz
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 <Trond.Myklebust@netapp.com> Cc: Fred Isaman <iisaman@netapp.com>
Diffstat (limited to 'include/linux/nfs_page.h')
-rw-r--r--include/linux/nfs_page.h1
1 files changed, 1 insertions, 0 deletions
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