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, 2 insertions, 2 deletions

diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 43b03b19731b..5f20eafba8ec 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -507,7 +507,7 @@ int nfs_readpage(struct file *file, struct page *page)
                 goto out_error;
 
         if (file == NULL) {
-                ctx = nfs_find_open_context(inode, FMODE_READ);
+                ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
                 if (ctx == NULL)
                         return -EBADF;
         } else
@@ -576,7 +576,7 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
                         nr_pages);
 
         if (filp == NULL) {
-                desc.ctx = nfs_find_open_context(inode, FMODE_READ);
+                desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
                 if (desc.ctx == NULL)
                         return -EBADF;
         } else