[PATCH] pnfs/blocklayout: serialize GETDEVICEINFO calls

Christoph Hellwig
2014-09-26T14:00:30Z

The rpc_pipefs code isn't thread safe, leading to occasional use after
frees when running xfstests generic/241 (dbench).

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/nfs/blocklayout/rpc_pipefs.c | 14 +++++++++-----
fs/nfs/netns.h | 1 +
2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/blocklayout/rpc_pipefs.c b/fs/nfs/blocklayout/rpc_pipefs.c
index 8d04bda..da58ff7 100644
--- a/fs/nfs/blocklayout/rpc_pipefs.c
+++ b/fs/nfs/blocklayout/rpc_pipefs.c
@@ -65,17 +65,18 @@ bl_resolve_deviceid(struct nfs_server *server, struct pnfs_block_volume *b,

dprintk("%s CREATING PIPEFS MESSAGE\n", __func__);

+ mutex_lock(&nn->bl_mutex);
bl_pipe_msg.bl_wq = &nn->bl_wq;

b->simple.len += 4; /* single volume */
if (b->simple.len > PAGE_SIZE)
- return -EIO;
+ goto out_unlock;

memset(msg, 0, sizeof(*msg));
msg->len = sizeof(*bl_msg) + b->simple.len;
msg->data = kzalloc(msg->len, gfp_mask);
if (!msg->data)
- goto out;
+ goto out_free_data;

bl_msg = msg->data;
bl_msg->type = BL_DEVICE_MOUNT,
@@ -87,7 +88,7 @@ bl_resolve_deviceid(struct nfs_server *server, struct pnfs_block_volume *b,
rc = rpc_queue_upcall(nn->bl_device_pipe, msg);
if (rc < 0) {
remove_wait_queue(&nn->bl_wq, &wq);
- goto out;
+ goto out_free_data;
}

set_current_state(TASK_UNINTERRUPTIBLE);
@@ -98,12 +99,14 @@ bl_resolve_deviceid(struct nfs_server *server, struct pnfs_block_volume *b,
if (reply->status != BL_DEVICE_REQUEST_PROC) {
printk(KERN_WARNING "%s failed to decode device: %d\n",
__func__, reply->status);
- goto out;
+ goto out_free_data;
}

dev = MKDEV(reply->major, reply->minor);
-out:
+out_free_data:
kfree(msg->data);
+out_unlock:
+ mutex_unlock(&nn->bl_mutex);
return dev;
}

@@ -233,6 +236,7 @@ static int nfs4blocklayout_net_init(struct net *net)
struct nfs_net *nn = net_generic(net, nfs_net_id);
struct dentry *dentry;

+ mutex_init(&nn->bl_mutex);
init_waitqueue_head(&nn->bl_wq);
nn->bl_device_pipe = rpc_mkpipe_data(&bl_upcall_ops, 0);
if (IS_ERR(nn->bl_device_pipe))
diff --git a/fs/nfs/netns.h b/fs/nfs/netns.h
index ef221fb..f0e06e4 100644
--- a/fs/nfs/netns.h
+++ b/fs/nfs/netns.h
@@ -19,6 +19,7 @@ struct nfs_net {
struct rpc_pipe *bl_device_pipe;
struct bl_dev_msg bl_mount_reply;
wait_queue_head_t bl_wq;
+ struct mutex bl_mutex;
struct list_head nfs_client_list;
struct list_head nfs_volume_list;
#if IS_ENABLED(CONFIG_NFS_V4)
--
1.9.1