NFS: Fix the locking in nfs4_callback_getattr

The delegation is protected by RCU now, so we need to replace the
nfsi->rwsem protection with an rcu protected section.

Reported-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index 7445dd0ae3f3..930d10fecdaf 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -37,8 +37,8 @@ __be32 nfs4_callback_getattr(struct cb_getattrargs *args, struct cb_getattrres *
         if (inode == NULL)
                 goto out_putclient;
         nfsi = NFS_I(inode);
-        down_read(&nfsi->rwsem);
-        delegation = nfsi->delegation;
+        rcu_read_lock();
+        delegation = rcu_dereference(nfsi->delegation);
         if (delegation == NULL || (delegation->type & FMODE_WRITE) == 0)
                 goto out_iput;
         res->size = i_size_read(inode);
@@ -53,7 +53,7 @@ __be32 nfs4_callback_getattr(struct cb_getattrargs *args, struct cb_getattrres *
                 args->bitmap[1];
         res->status = 0;
 out_iput:
-        up_read(&nfsi->rwsem);
+        rcu_read_unlock();
         iput(inode);
 out_putclient:
         nfs_put_client(clp);