Allocate buffer for READ BUFFER/WRITE BUFFER commands on demand.

These commands are rare, but consume additional 256KB RAM per LUN.

MFC after:	1 week

2 files changed, 17 insertions, 5 deletions

diff --git a/sys/cam/ctl/ctl.c b/sys/cam/ctl/ctl.c
index 2a7ed7f..0f34b75 100644
--- a/sys/cam/ctl/ctl.c
+++ b/sys/cam/ctl/ctl.c
@@ -4735,6 +4735,7 @@ ctl_free_lun(struct ctl_lun *lun)
 	ctl_tpc_lun_shutdown(lun);
 	mtx_destroy(&lun->lun_lock);
 	free(lun->lun_devid, M_CTL);
+	free(lun->write_buffer, M_CTL);
 	if (lun->flags & CTL_LUN_MALLOCED)
 		free(lun, M_CTL);
 
@@ -5726,7 +5727,7 @@ ctl_read_buffer(struct ctl_scsiio *ctsio)
 	len = scsi_3btoul(cdb->length);
 	buffer_offset = scsi_3btoul(cdb->offset);
 
-	if (buffer_offset + len > sizeof(lun->write_buffer)) {
+	if (buffer_offset + len > CTL_WRITE_BUFFER_SIZE) {
 		ctl_set_invalid_field(ctsio,
 				      /*sks_valid*/ 1,
 				      /*command*/ 1,
@@ -5739,14 +5740,19 @@ ctl_read_buffer(struct ctl_scsiio *ctsio)
 
 	if ((cdb->byte2 & RWB_MODE) == RWB_MODE_DESCR) {
 		descr[0] = 0;
-		scsi_ulto3b(sizeof(lun->write_buffer), &descr[1]);
+		scsi_ulto3b(CTL_WRITE_BUFFER_SIZE, &descr[1]);
 		ctsio->kern_data_ptr = descr;
 		len = min(len, sizeof(descr));
 	} else if ((cdb->byte2 & RWB_MODE) == RWB_MODE_ECHO_DESCR) {
 		ctsio->kern_data_ptr = echo_descr;
 		len = min(len, sizeof(echo_descr));
-	} else
+	} else {
+		if (lun->write_buffer == NULL) {
+			lun->write_buffer = malloc(CTL_WRITE_BUFFER_SIZE,
+			    M_CTL, M_WAITOK);
+		}
 		ctsio->kern_data_ptr = lun->write_buffer + buffer_offset;
+	}
 	ctsio->kern_data_len = len;
 	ctsio->kern_total_len = len;
 	ctsio->kern_data_resid = 0;
@@ -5784,7 +5790,7 @@ ctl_write_buffer(struct ctl_scsiio *ctsio)
 	len = scsi_3btoul(cdb->length);
 	buffer_offset = scsi_3btoul(cdb->offset);
 
-	if (buffer_offset + len > sizeof(lun->write_buffer)) {
+	if (buffer_offset + len > CTL_WRITE_BUFFER_SIZE) {
 		ctl_set_invalid_field(ctsio,
 				      /*sks_valid*/ 1,
 				      /*command*/ 1,
@@ -5800,6 +5806,10 @@ ctl_write_buffer(struct ctl_scsiio *ctsio)
 	 * malloc it and tell the caller the data buffer is here.
 	 */
 	if ((ctsio->io_hdr.flags & CTL_FLAG_ALLOCATED) == 0) {
+		if (lun->write_buffer == NULL) {
+			lun->write_buffer = malloc(CTL_WRITE_BUFFER_SIZE,
+			    M_CTL, M_WAITOK);
+		}
 		ctsio->kern_data_ptr = lun->write_buffer + buffer_offset;
 		ctsio->kern_data_len = len;
 		ctsio->kern_total_len = len;
diff --git a/sys/cam/ctl/ctl_private.h b/sys/cam/ctl/ctl_private.h
index c470345..bb9a32d 100644
--- a/sys/cam/ctl/ctl_private.h
+++ b/sys/cam/ctl/ctl_private.h
@@ -384,6 +384,8 @@ struct ctl_devid {
  */
 #define NUM_TARGET_PORT_GROUPS	2
 
+#define CTL_WRITE_BUFFER_SIZE	262144
+
 struct tpc_list;
 struct ctl_lun {
 	struct mtx			lun_lock;
@@ -417,7 +419,7 @@ struct ctl_lun {
 	int				pr_key_count;
 	uint32_t			pr_res_idx;
 	uint8_t				res_type;
-	uint8_t				write_buffer[262144];
+	uint8_t				*write_buffer;
 	struct ctl_devid		*lun_devid;
 	TAILQ_HEAD(tpc_lists, tpc_list) tpc_lists;
 };