libceph: preallocate message data items

Currently message data items are allocated with ceph_msg_data_create()
in setup_request_data() inside send_request().  send_request() has never
been allowed to fail, so each allocation is followed by a BUG_ON:

  data = ceph_msg_data_create(...);
  BUG_ON(!data);

It's been this way since support for multiple message data items was
added in commit 6644ed7b7e04 ("libceph: make message data be a pointer")
in 3.10.

There is no reason to delay the allocation of message data items until
the last possible moment and we certainly don't need a linked list of
them as they are only ever appended to the end and never erased.  Make
ceph_msg_new2() take max_data_items and adapt the rest of the code.

Reported-by: Jerry Lee <leisurelysw24@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 5 insertions, 19 deletions

diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
index fc2b4491ee0a..800a2128d411 100644
--- a/include/linux/ceph/messenger.h
+++ b/include/linux/ceph/messenger.h
@@ -82,22 +82,6 @@ enum ceph_msg_data_type {
 	CEPH_MSG_DATA_BVECS,	/* data source/destination is a bio_vec array */
 };
 
-static __inline__ bool ceph_msg_data_type_valid(enum ceph_msg_data_type type)
-{
-	switch (type) {
-	case CEPH_MSG_DATA_NONE:
-	case CEPH_MSG_DATA_PAGES:
-	case CEPH_MSG_DATA_PAGELIST:
-#ifdef CONFIG_BLOCK
-	case CEPH_MSG_DATA_BIO:
-#endif /* CONFIG_BLOCK */
-	case CEPH_MSG_DATA_BVECS:
-		return true;
-	default:
-		return false;
-	}
-}
-
 #ifdef CONFIG_BLOCK
 
 struct ceph_bio_iter {
@@ -181,7 +165,6 @@ struct ceph_bvec_iter {
 } while (0)
 
 struct ceph_msg_data {
-	struct list_head		links;	/* ceph_msg->data */
 	enum ceph_msg_data_type		type;
 	union {
 #ifdef CONFIG_BLOCK
@@ -202,7 +185,6 @@ struct ceph_msg_data {
 
 struct ceph_msg_data_cursor {
 	size_t			total_resid;	/* across all data items */
-	struct list_head	*data_head;	/* = &ceph_msg->data */
 
 	struct ceph_msg_data	*data;		/* current data item */
 	size_t			resid;		/* bytes not yet consumed */
@@ -240,7 +222,9 @@ struct ceph_msg {
 	struct ceph_buffer *middle;
 
 	size_t				data_length;
-	struct list_head		data;
+	struct ceph_msg_data		*data;
+	int				num_data_items;
+	int				max_data_items;
 	struct ceph_msg_data_cursor	cursor;
 
 	struct ceph_connection *con;
@@ -381,6 +365,8 @@ void ceph_msg_data_add_bio(struct ceph_msg *msg, struct ceph_bio_iter *bio_pos,
 void ceph_msg_data_add_bvecs(struct ceph_msg *msg,
 			     struct ceph_bvec_iter *bvec_pos);
 
+struct ceph_msg *ceph_msg_new2(int type, int front_len, int max_data_items,
+			       gfp_t flags, bool can_fail);
 extern struct ceph_msg *ceph_msg_new(int type, int front_len, gfp_t flags,
 				     bool can_fail);