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NFSv4: fix delegated locking

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From: Linux Kernel Mailing List
Subject: NFSv4: fix delegated locking
Date: Tuesday, April 13, 2010 - 5:59 pm

Gitweb:     http://git.kernel.org/linus/0df5dd4aae211edeeeb84f7f84f6d093406d7c22
Commit:     0df5dd4aae211edeeeb84f7f84f6d093406d7c22
Parent:     2c61be0a9478258f77b66208a0c4b1f5f8161c3c
Author:     Trond Myklebust <Trond.Myklebust@netapp.com>
AuthorDate: Sun Apr 11 16:48:44 2010 -0400
Committer:  Trond Myklebust <Trond.Myklebust@netapp.com>
CommitDate: Mon Apr 12 07:55:15 2010 -0400

    NFSv4: fix delegated locking
    
    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>
    Cc: stable@kernel.org
---
 fs/nfs/client.c           |    3 ++-
 fs/nfs/nfs4proc.c         |    4 +++-
 include/linux/nfs_fs_sb.h |    1 +
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 2a3d352..a8766c4 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -1294,7 +1294,8 @@ 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 fe0cd9e..6380670 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1523,6 +1523,8 @@ 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)
@@ -1664,7 +1666,7 @@ 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);
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 717a5e5..e82957a 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -176,6 +176,7 @@ struct nfs_server {
 #define NFS_CAP_ATIME		(1U << 11)
 #define NFS_CAP_CTIME		(1U << 12)
 #define NFS_CAP_MTIME		(1U << 13)
+#define NFS_CAP_POSIX_LOCK	(1U << 14)
 
 
 /* maximum number of slots to use */
--
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NFSv4: fix delegated locking, Linux Kernel Mailing ..., (Tue Apr 13, 5:59 pm)