NFSv4: Fix problem with OPEN_DOWNGRADE

 RFC 3530 states that for OPEN_DOWNGRADE "The share_access and share_deny
 bits specified must be exactly equal to the union of the share_access and
 share_deny bits specified for some subset of the OPENs in effect for
 current openowner on the current file.

 Setattr is currently violating the NFSv4 rules for OPEN_DOWNGRADE in that
 it may cause a downgrade from OPEN4_SHARE_ACCESS_BOTH to
 OPEN4_SHARE_ACCESS_WRITE despite the fact that there exists no open file
 with O_WRONLY access mode.

 Fix the problem by replacing nfs4_find_state() with a modified version of
 nfs_find_open_context().

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 819a65f5071f..1bdbd4f9fdd2 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -294,7 +294,7 @@ int nfs_writepage(struct page *page, struct writeback_control *wbc)
         if (page->index >= end_index+1 || !offset)
                 goto out;
 do_it:
-        ctx = nfs_find_open_context(inode, FMODE_WRITE);
+        ctx = nfs_find_open_context(inode, NULL, FMODE_WRITE);
         if (ctx == NULL) {
                 err = -EBADF;
                 goto out;