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SUNRPC: fix races on PipeFS MOUNT notifications

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Below are races, when RPC client can be created without PiepFS dentries

CPU#0					CPU#1
-----------------------------		-----------------------------
rpc_new_client				rpc_fill_super
rpc_setup_pipedir
mutex_lock(&sn->pipefs_sb_lock)
rpc_get_sb_net == NULL
(no per-net PipeFS superblock)
					sn->pipefs_sb = sb;
					notifier_call_chain(MOUNT)
					(client is not in the list)
rpc_register_client
(client without pipes dentries)

To fix this patch:
1) makes PipeFS mount notification call with pipefs_sb_lock being held.
2) releases pipefs_sb_lock on new SUNRPC client creation only after
registration.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Stanislav Kinsbursky
2013-06-24 11:52:38 +04:00
committed by Trond Myklebust
parent 52fcac988a
commit 384816051c
2 changed files with 18 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
net/sunrpc/rpc_pipe.c
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@@ -1127,6 +1127,7 @@ rpc_fill_super(struct super_block *sb, void *data, int silent)
return -ENOMEM;
dprintk("RPC: sending pipefs MOUNT notification for net %p%s\n",
net, NET_NAME(net));
mutex_lock(&sn->pipefs_sb_lock);
sn->pipefs_sb = sb;
err = blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
RPC_PIPEFS_MOUNT,
@@ -1134,6 +1135,7 @@ rpc_fill_super(struct super_block *sb, void *data, int silent)
if (err)
goto err_depopulate;
sb->s_fs_info = get_net(net);
mutex_unlock(&sn->pipefs_sb_lock);
return 0;
err_depopulate:
@@ -1142,6 +1144,7 @@ err_depopulate:
sb);
sn->pipefs_sb = NULL;
__rpc_depopulate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF);
mutex_unlock(&sn->pipefs_sb_lock);
return err;
}