[PATCH v2] nfs: fix pnfs direct write memory leak

[Peng Tao <tao.peng@primarydata.com>]

For pNFS direct writes, layout driver may dynamically allocate ds_cinfo.buckets.
So we need to take care to free them when freeing dreq.

Ideally this needs to be done inside layout driver where ds_cinfo.buckets
are allocated. But buckets are attached to dreq and reused across LD IO iterations.
So I feel it's OK to free them in the generic layer.

Cc: stable@vger.kernel.org [v3.4+]
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
---
 fs/nfs/direct.c         | 1 +
 include/linux/nfs_xdr.h | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 20cffc8..10bf072 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -266,6 +266,7 @@ static void nfs_direct_req_free(struct kref *kref)
 {
 	struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
 
+	nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo);
 	if (dreq->l_ctx != NULL)
 		nfs_put_lock_context(dreq->l_ctx);
 	if (dreq->ctx != NULL)
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 983876f..10dee95 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1224,11 +1224,20 @@ struct nfs41_free_stateid_res {
 	unsigned int			status;
 };
 
+static inline void
+nfs_free_pnfs_ds_cinfo(struct pnfs_ds_commit_info *cinfo)
+{
+	kfree(cinfo->buckets);
+}
+
 #else
 
 struct pnfs_ds_commit_info {
 };
 
+static inline void
+nfs_free_pnfs_ds_cinfo(struct pnfs_ds_commit_info *cinfo) {}
+
 #endif /* CONFIG_NFS_V4_1 */
 
 #ifdef CONFIG_NFS_V4_2
-- 
1.9.1