[SCSI] iscsi: kill dtask mempools

Discovered by steven@hayter.me.uk and patch by michaelc@cs.wisc.edu

The dtask mempool is reserving 261120 items per session! Since we are now
sending headers with sendmsg there is no reason for the mempool and that
was causing us to us carzy amounts of mem. We can preallicate a header in
the r2t and task struct and reuse them
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/iscsi_tcp.c

@@ -67,9 +67,6 @@ MODULE_VERSION("0:4.445");
 static unsigned int iscsi_max_lun = 512;
 module_param_named(max_lun, iscsi_max_lun, uint, S_IRUGO);
 
-/* global data */
-static kmem_cache_t *taskcache;
-
 static inline void
 iscsi_buf_init_iov(struct iscsi_buf *ibuf, char *vbuf, int size)
 {
@@ -195,16 +192,6 @@ __iscsi_ctask_cleanup(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
 	if (unlikely(!sc))
 		return;
 
-	if (sc->sc_data_direction == DMA_TO_DEVICE) {
-		struct iscsi_data_task *dtask, *n;
-
-		/* WRITE: cleanup Data-Out's if any */
-		list_for_each_entry_safe(dtask, n, &tcp_ctask->dataqueue,
-					 item) {
-			list_del(&dtask->item);
-			mempool_free(dtask, tcp_ctask->datapool);
-		}
-	}
 	tcp_ctask->xmstate = XMSTATE_IDLE;
 	tcp_ctask->r2t = NULL;
 }
@@ -286,14 +273,10 @@ iscsi_solicit_data_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
 			struct iscsi_r2t_info *r2t)
 {
 	struct iscsi_data *hdr;
-	struct iscsi_data_task *dtask;
 	struct scsi_cmnd *sc = ctask->sc;
 	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
 
-	dtask = mempool_alloc(tcp_ctask->datapool, GFP_ATOMIC);
-	BUG_ON(!dtask);
-	INIT_LIST_HEAD(&dtask->item);
-	hdr = &dtask->hdr;
+	hdr = &r2t->dtask.hdr;
 	memset(hdr, 0, sizeof(struct iscsi_data));
 	hdr->ttt = r2t->ttt;
 	hdr->datasn = cpu_to_be32(r2t->solicit_datasn);
@@ -319,8 +302,6 @@ iscsi_solicit_data_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
 	iscsi_buf_init_iov(&r2t->headbuf, (char*)hdr,
 			   sizeof(struct iscsi_hdr));
 
-	r2t->dtask = dtask;
-
 	if (sc->use_sg) {
 		int i, sg_count = 0;
 		struct scatterlist *sg = sc->request_buffer;
@@ -352,8 +333,6 @@ iscsi_solicit_data_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
 		iscsi_buf_init_iov(&tcp_ctask->sendbuf,
 			    (char*)sc->request_buffer + r2t->data_offset,
 			    r2t->data_count);
-
-	list_add(&dtask->item, &tcp_ctask->dataqueue);
 }
 
 /**
@@ -1229,14 +1208,10 @@ iscsi_solicit_data_cont(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
 {
 	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
 	struct iscsi_data *hdr;
-	struct iscsi_data_task *dtask;
 	struct scsi_cmnd *sc = ctask->sc;
 	int new_offset;
 
-	dtask = mempool_alloc(tcp_ctask->datapool, GFP_ATOMIC);
-	BUG_ON(!dtask);
-	INIT_LIST_HEAD(&dtask->item);
-	hdr = &dtask->hdr;
+	hdr = &r2t->dtask.hdr;
 	memset(hdr, 0, sizeof(struct iscsi_data));
 	hdr->ttt = r2t->ttt;
 	hdr->datasn = cpu_to_be32(r2t->solicit_datasn);
@@ -1260,8 +1235,6 @@ iscsi_solicit_data_cont(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
 	iscsi_buf_init_iov(&r2t->headbuf, (char*)hdr,
 			   sizeof(struct iscsi_hdr));
 
-	r2t->dtask = dtask;
-
 	if (sc->use_sg && !iscsi_buf_left(&r2t->sendbuf)) {
 		BUG_ON(tcp_ctask->bad_sg == r2t->sg);
 		iscsi_buf_init_sg(&r2t->sendbuf, r2t->sg);
@@ -1270,8 +1243,6 @@ iscsi_solicit_data_cont(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
 		iscsi_buf_init_iov(&tcp_ctask->sendbuf,
 			    (char*)sc->request_buffer + new_offset,
 			    r2t->data_count);
-
-	list_add(&dtask->item, &tcp_ctask->dataqueue);
 }
 
 static void
@@ -1280,17 +1251,11 @@ iscsi_unsolicit_data_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
 	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
 	struct iscsi_data_task *dtask;
 
-	dtask = mempool_alloc(tcp_ctask->datapool, GFP_ATOMIC);
-	BUG_ON(!dtask);
-	INIT_LIST_HEAD(&dtask->item);
-
+	dtask = tcp_ctask->dtask = &tcp_ctask->unsol_dtask;
 	iscsi_prep_unsolicit_data_pdu(ctask, &dtask->hdr,
 				      tcp_ctask->r2t_data_count);
 	iscsi_buf_init_iov(&tcp_ctask->headbuf, (char*)&dtask->hdr,
 			   sizeof(struct iscsi_hdr));
-
-	list_add(&dtask->item, &tcp_ctask->dataqueue);
-	tcp_ctask->dtask = dtask;
 }
 
 /**
@@ -1534,7 +1499,6 @@ handle_xmstate_uns_hdr(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
 	tcp_ctask->xmstate |= XMSTATE_UNS_DATA;
 	if (tcp_ctask->xmstate & XMSTATE_UNS_INIT) {
 		iscsi_unsolicit_data_init(conn, ctask);
-		BUG_ON(!tcp_ctask->dtask);
 		dtask = tcp_ctask->dtask;
 		if (conn->hdrdgst_en)
 			iscsi_hdr_digest(conn, &tcp_ctask->headbuf,
@@ -1643,7 +1607,7 @@ handle_xmstate_sol_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
 	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
 	struct iscsi_r2t_info *r2t = tcp_ctask->r2t;
-	struct iscsi_data_task *dtask = r2t->dtask;
+	struct iscsi_data_task *dtask = &r2t->dtask;
 	int left;
 
 	tcp_ctask->xmstate &= ~XMSTATE_SOL_DATA;
@@ -1857,7 +1821,7 @@ iscsi_tcp_ctask_xmit(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
 		r2t = tcp_ctask->r2t;
 		if (conn->hdrdgst_en)
 			iscsi_hdr_digest(conn, &r2t->headbuf,
-					(u8*)r2t->dtask->hdrext);
+					(u8*)r2t->dtask.hdrext);
 		if (iscsi_sendhdr(conn, &r2t->headbuf, r2t->data_count)) {
 			tcp_ctask->xmstate &= ~XMSTATE_SOL_DATA;
 			tcp_ctask->xmstate |= XMSTATE_SOL_HDR;
@@ -2113,21 +2077,6 @@ iscsi_r2tpool_alloc(struct iscsi_session *session)
 					(void**)tcp_ctask->r2ts);
 			goto r2t_alloc_fail;
 		}
-
-		/*
-		 * number of
-		 * Data-Out PDU's within R2T-sequence can be quite big;
-		 * using mempool
-		 */
-		tcp_ctask->datapool = mempool_create_slab_pool(ISCSI_DTASK_DEFAULT_MAX,
-							       taskcache);
-		if (tcp_ctask->datapool == NULL) {
-			kfifo_free(tcp_ctask->r2tqueue);
-			iscsi_pool_free(&tcp_ctask->r2tpool,
-					(void**)tcp_ctask->r2ts);
-			goto r2t_alloc_fail;
-		}
-		INIT_LIST_HEAD(&tcp_ctask->dataqueue);
 	}
 
 	return 0;
@@ -2137,7 +2086,6 @@ iscsi_r2tpool_alloc(struct iscsi_session *session)
 		struct iscsi_cmd_task *ctask = session->cmds[i];
 		struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
 
-		mempool_destroy(tcp_ctask->datapool);
 		kfifo_free(tcp_ctask->r2tqueue);
 		iscsi_pool_free(&tcp_ctask->r2tpool,
 				(void**)tcp_ctask->r2ts);
@@ -2154,7 +2102,6 @@ iscsi_r2tpool_free(struct iscsi_session *session)
 		struct iscsi_cmd_task *ctask = session->cmds[i];
 		struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
 
-		mempool_destroy(tcp_ctask->datapool);
 		kfifo_free(tcp_ctask->r2tqueue);
 		iscsi_pool_free(&tcp_ctask->r2tpool,
 				(void**)tcp_ctask->r2ts);
@@ -2496,21 +2443,6 @@ iscsi_tcp_session_create(struct iscsi_transport *iscsit,
 
 static void iscsi_tcp_session_destroy(struct iscsi_cls_session *cls_session)
 {
-	struct iscsi_session *session = class_to_transport_session(cls_session);
-	struct iscsi_data_task *dtask, *n;
-	int cmd_i;
-
-	for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
-		struct iscsi_cmd_task *ctask = session->cmds[cmd_i];
-		struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
-
-		list_for_each_entry_safe(dtask, n, &tcp_ctask->dataqueue,
-					 item) {
-			list_del(&dtask->item);
-			mempool_free(dtask, tcp_ctask->datapool);
-		}
-	}
-
 	iscsi_r2tpool_free(class_to_transport_session(cls_session));
 	iscsi_session_teardown(cls_session);
 }
@@ -2592,14 +2524,8 @@ iscsi_tcp_init(void)
 	}
 	iscsi_tcp_transport.max_lun = iscsi_max_lun;
 
-	taskcache = kmem_cache_create("iscsi_taskcache",
-			sizeof(struct iscsi_data_task), 0,
-			SLAB_HWCACHE_ALIGN, NULL, NULL);
-	if (!taskcache)
-		return -ENOMEM;
-
 	if (!iscsi_register_transport(&iscsi_tcp_transport))
-		kmem_cache_destroy(taskcache);
+		return -ENODEV;
 
 	return 0;
 }
@@ -2608,7 +2534,6 @@ static void __exit
 iscsi_tcp_exit(void)
 {
 	iscsi_unregister_transport(&iscsi_tcp_transport);
-	kmem_cache_destroy(taskcache);
 }
 
 module_init(iscsi_tcp_init);

drivers/scsi/iscsi_tcp.h

@@ -118,11 +118,9 @@ struct iscsi_buf {
 struct iscsi_data_task {
 	struct iscsi_data	hdr;			/* PDU */
 	char			hdrext[sizeof(__u32)];	/* Header-Digest */
-	struct list_head	item;			/* data queue item */
 	struct iscsi_buf	digestbuf;		/* digest buffer */
 	uint32_t		digest;			/* data digest */
 };
-#define ISCSI_DTASK_DEFAULT_MAX	ISCSI_SG_TABLESIZE * PAGE_SIZE / 512
 
 struct iscsi_tcp_mgmt_task {
 	struct iscsi_hdr	hdr;
@@ -144,7 +142,7 @@ struct iscsi_r2t_info {
 	int			data_count;	/* DATA-Out payload progress */
 	struct scatterlist	*sg;		/* per-R2T SG list */
 	int			solicit_datasn;
-	struct iscsi_data_task   *dtask;        /* which data task */
+	struct iscsi_data_task   dtask;        /* which data task */
 };
 
 struct iscsi_tcp_cmd_task {
@@ -167,13 +165,12 @@ struct iscsi_tcp_cmd_task {
 	struct iscsi_queue	r2tpool;
 	struct kfifo		*r2tqueue;
 	struct iscsi_r2t_info	**r2ts;
-	struct list_head	dataqueue;		/* Data-Out dataqueue */
-	mempool_t		*datapool;
 	uint32_t		datadigest;		/* for recover digest */
 	int			digest_count;
 	uint32_t		immdigest;		/* for imm data */
 	struct iscsi_buf	immbuf;			/* for imm data digest */
 	struct iscsi_data_task	*dtask;		/* data task in progress*/
+	struct iscsi_data_task	unsol_dtask;	/* unsol data task */
 	int			digest_offset;	/* for partial buff digest */
 };