On Thu, 2012-06-14 at 12:12 -0400, andros@xxxxxxxxxx wrote:
> ---
> fs/nfs/client.c | 88 ++++++++++++++++++++++++++++++++++++++++++-
> fs/nfs/internal.h | 1 +
> fs/nfs/nfs4filelayoutdev.c | 29 ++++++++++++--
> include/linux/nfs_fs_sb.h | 1 +
> 4 files changed, 112 insertions(+), 7 deletions(-)
Hi Andy,
Is there any reason why the following wouldn't work instead? It is
essentially the same idea.
Cheers
Trond
8<-------------------------------------------------------
>From dbee3513f10c3324aa0683d415193a5d2af6a31e Mon Sep 17 00:00:00 2001
From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Date: Thu, 14 Jun 2012 13:08:38 -0400
Subject: [PATCH] NFSv4.1: Fix umount when filelayout DS is also the MDS
Currently there is a 'chicken and egg' issue when the DS is also the mounted
MDS. The nfs_match_client() reference from nfs4_set_ds_client bumps the
cl_count, the nfs_client is not freed at umount, and nfs4_deviceid_purge_client
is not called to dereference the MDS usage of a deviceid which holds a
reference to the DS nfs_client. The result is the umount program returns,
but the nfs_client is not freed, and the cl_session hearbeat continues.
The MDS (and all other nfs mounts) lose their last nfs_client reference in
nfs_free_server when the last nfs_server (fsid) is umounted.
The file layout DS lose their last nfs_client reference in destroy_ds
when the last deviceid referencing the data server is put and destroy_ds is
called. This is triggered by a call to nfs4_deviceid_purge_client which
removes references to a pNFS deviceid used by an MDS mount.
The fix is to track how many filesystems are mounted from this server,
and then to purge the device id cache once that count is zero.
Reported-by: Jorge Mora <Jorge.Mora@xxxxxxxxxx>
Reported-by: Andy Adamson <andros@xxxxxxxxxx>
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
---
fs/nfs/client.c | 43 +++++++++++++++++++++++++++++++++++++------
include/linux/nfs_fs_sb.h | 1 +
2 files changed, 38 insertions(+), 6 deletions(-)
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 17ba6b9..faa58d5 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -207,16 +207,25 @@ error_0:
static void nfs4_shutdown_session(struct nfs_client *clp)
{
if (nfs4_has_session(clp)) {
- nfs4_deviceid_purge_client(clp);
nfs4_destroy_session(clp->cl_session);
nfs4_destroy_clientid(clp);
}
}
+
+static void nfs4_purge_dataservers(struct nfs_client *clp)
+{
+ if (nfs4_has_session(clp))
+ nfs4_deviceid_purge_client(clp);
+}
#else /* CONFIG_NFS_V4_1 */
static void nfs4_shutdown_session(struct nfs_client *clp)
{
}
+
+static void nfs4_purge_dataservers(struct nfs_client *clp)
+{
+}
#endif /* CONFIG_NFS_V4_1 */
/*
@@ -801,6 +810,29 @@ static int nfs_init_server_rpcclient(struct nfs_server *server,
return 0;
}
+static int
+nfs_server_set_client(struct nfs_server *server, struct nfs_client *clp)
+{
+ /* Track the number of filesystems being mounted from this server */
+ atomic_inc(&clp->cl_server_count);
+ server->nfs_client = clp;
+ return 0;
+}
+
+static void
+nfs_server_unset_client(struct nfs_server *server)
+{
+ struct nfs_client *clp = server->nfs_client;
+
+ /* Purge the list of pNFS data servers once the number of mounted
+ * filesystems falls to zero.
+ */
+ if (atomic_dec_and_test(&clp->cl_server_count))
+ nfs4_purge_dataservers(clp);
+
+ nfs_put_client(clp);
+}
+
/**
* nfs_init_client - Initialise an NFS2 or NFS3 client
*
@@ -887,7 +919,7 @@ static int nfs_init_server(struct nfs_server *server,
return PTR_ERR(clp);
}
- server->nfs_client = clp;
+ nfs_server_set_client(server, clp);
/* Initialise the client representation from the mount data */
server->flags = data->flags;
@@ -934,8 +966,7 @@ static int nfs_init_server(struct nfs_server *server,
return 0;
error:
- server->nfs_client = NULL;
- nfs_put_client(clp);
+ nfs_server_unset_client(server);
dprintk("<-- nfs_init_server() = xerror %d\n", error);
return error;
}
@@ -1149,7 +1180,7 @@ void nfs_free_server(struct nfs_server *server)
if (!IS_ERR(server->client))
rpc_shutdown_client(server->client);
- nfs_put_client(server->nfs_client);
+ nfs_server_unset_client(server);
ida_destroy(&server->lockowner_id);
ida_destroy(&server->openowner_id);
@@ -1469,7 +1500,7 @@ static int nfs4_set_client(struct nfs_server *server,
*/
set_bit(NFS_CS_CHECK_LEASE_TIME, &clp->cl_res_state);
- server->nfs_client = clp;
+ nfs_server_set_client(server, clp);
dprintk("<-- nfs4_set_client() = 0 [new %p]\n", clp);
return 0;
error:
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index fbb78fb..2d51077 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -25,6 +25,7 @@ struct nfs41_impl_id;
*/
struct nfs_client {
atomic_t cl_count;
+ atomic_t cl_server_count;
int cl_cons_state; /* current construction state (-ve: init error) */
#define NFS_CS_READY 0 /* ready to be used */
#define NFS_CS_INITING 1 /* busy initialising */
--
1.7.10.2
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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