NFS/pNFS: Allow O_DIRECT to release the DS commitinfo

Add a pNFS callback to allow the O_DIRECT code to release the DS
commitinfo when freeing the dreq.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/direct.c

@@ -317,6 +317,7 @@ static void nfs_direct_req_free(struct kref *kref)
 {
 	struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
 
+	pnfs_release_ds_info(&dreq->ds_cinfo, dreq->inode);
 	nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo);
 	if (dreq->l_ctx != NULL)
 		nfs_put_lock_context(dreq->l_ctx);

fs/nfs/pnfs.h

@@ -149,6 +149,8 @@ struct pnfs_layoutdriver_type {
 	const struct nfs_pageio_ops *pg_write_ops;
 
 	struct pnfs_ds_commit_info *(*get_ds_info) (struct inode *inode);
+	void (*release_ds_info)(struct pnfs_ds_commit_info *,
+				struct inode *inode);
 	void (*mark_request_commit) (struct nfs_page *req,
 				     struct pnfs_layout_segment *lseg,
 				     struct nfs_commit_info *cinfo,
@@ -468,6 +470,15 @@ pnfs_init_ds_commit_info(struct pnfs_ds_commit_info *fl_cinfo)
 	INIT_LIST_HEAD(&fl_cinfo->commits);
 }
 
+static inline void
+pnfs_release_ds_info(struct pnfs_ds_commit_info *fl_cinfo, struct inode *inode)
+{
+	struct pnfs_layoutdriver_type *ld = NFS_SERVER(inode)->pnfs_curr_ld;
+
+	if (ld != NULL && ld->release_ds_info != NULL)
+		ld->release_ds_info(fl_cinfo, inode);
+}
+
 static inline void
 pnfs_generic_mark_devid_invalid(struct nfs4_deviceid_node *node)
 {
@@ -770,6 +781,11 @@ pnfs_init_ds_commit_info(struct pnfs_ds_commit_info *fl_cinfo)
 {
 }
 
+static inline void
+pnfs_release_ds_info(struct pnfs_ds_commit_info *fl_cinfo, struct inode *inode)
+{
+}
+
 static inline bool
 pnfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 			 struct nfs_commit_info *cinfo, u32 ds_commit_idx)