[PATCH] pnfs: fix refcount leak in pnfs_report_layoutstat()

[WenTao Liang <vulab@iscas.ac.cn>]

When pnfs_report_layoutstat() calls pnfs_get_layout_hdr() and passes
the reference through the inode field of the layoutstats data to
nfs42_proc_layoutstats_generic(), if rpc_run_task() in that function
fails (IS_ERR), nfs42_proc_layoutstats_generic() returns immediately
without releasing the reference.  This leaks the layout header
reference, leaks the allocated data, and leaves the
NFS_INO_LAYOUTSTATS flag stuck on the inode, preventing further
layoutstat reporting.

Fix by calling nfs42_layoutstat_release(data) before returning on
rpc_run_task() error, matching the existing error handling for a
missing inode.

Cc: stable@vger.kernel.org
Fixes: be3a5d233922 ("NFSv.2/pnfs Add a LAYOUTSTATS rpc function")
Signed-off-by: WenTao Liang <vulab@iscas.ac.cn>
---
 fs/nfs/nfs42proc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/nfs42proc.c b/fs/nfs/nfs42proc.c
index 7602ede6f75f..7637ad894563 100644
--- a/fs/nfs/nfs42proc.c
+++ b/fs/nfs/nfs42proc.c
@@ -1076,8 +1076,10 @@ int nfs42_proc_layoutstats_generic(struct nfs_server *server,
 	nfs4_init_sequence(server->nfs_client, &data->args.seq_args,
 			   &data->res.seq_res, 0, 0);
 	task = rpc_run_task(&task_setup);
-	if (IS_ERR(task))
+	if (IS_ERR(task)) {
+		nfs42_layoutstat_release(data);
 		return PTR_ERR(task);
+	}
 	rpc_put_task(task);
 	return 0;
 }
-- 
2.50.1 (Apple Git-155)