NFSv4: fix delegated locking

commit 0df5dd4aae211edeeeb84f7f84f6d093406d7c22 upstream.

Arnaud Giersch reports that NFSv4 locking is broken when we hold a
delegation since commit 8e469ebd6dc32cbaf620e134d79f740bf0ebab79 (NFSv4:
Don't allow posix locking against servers that don't support it).

According to Arnaud, the lock succeeds the first time he opens the file
(since we cannot do a delegated open) but then fails after we start using
delegated opens.

The following patch fixes it by ensuring that locking behaviour is
governed by a per-filesystem capability flag that is initially set, but
gets cleared if the server ever returns an OPEN without the
NFS4_OPEN_RESULT_LOCKTYPE_POSIX flag being set.

Reported-by: Arnaud Giersch <arnaud.giersch@iut-bm.univ-fcomte.fr>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 5 insertions, 2 deletions

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index ee77713ce68b..bd39abc51508 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -1293,7 +1293,8 @@ static int nfs4_init_server(struct nfs_server *server,
 
         /* Initialise the client representation from the mount data */
         server->flags = data->flags;
-        server->caps |= NFS_CAP_ATOMIC_OPEN|NFS_CAP_CHANGE_ATTR;
+        server->caps |= NFS_CAP_ATOMIC_OPEN|NFS_CAP_CHANGE_ATTR|
+                NFS_CAP_POSIX_LOCK;
         server->options = data->options;
 
         /* Get a client record */
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 375f0fae2c6a..ecf660204755 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1520,6 +1520,8 @@ static int _nfs4_proc_open(struct nfs4_opendata *data)
                 nfs_post_op_update_inode(dir, o_res->dir_attr);
         } else
                 nfs_refresh_inode(dir, o_res->dir_attr);
+        if ((o_res->rflags & NFS4_OPEN_RESULT_LOCKTYPE_POSIX) == 0)
+                server->caps &= ~NFS_CAP_POSIX_LOCK;
         if(o_res->rflags & NFS4_OPEN_RESULT_CONFIRM) {
                 status = _nfs4_proc_open_confirm(data);
                 if (status != 0)
@@ -1660,7 +1662,7 @@ static int _nfs4_do_open(struct inode *dir, struct path *path, fmode_t fmode, in
         status = PTR_ERR(state);
         if (IS_ERR(state))
                 goto err_opendata_put;
-        if ((opendata->o_res.rflags & NFS4_OPEN_RESULT_LOCKTYPE_POSIX) != 0)
+        if (server->caps & NFS_CAP_POSIX_LOCK)
                 set_bit(NFS_STATE_POSIX_LOCKS, &state->flags);
         nfs4_opendata_put(opendata);
         nfs4_put_state_owner(sp);