target: Untangle front-end and back-end meanings of max_sectors attribute
se_dev_attrib.max_sectors currently has two independent meanings:
- It is reported in the block limits VPD page as the maximum transfer
length, ie the largest IO that the front-end (fabric) can handle.
Also the target core doesn't enforce this maximum transfer length.
- It is used to hold the size of the largest IO that the back-end can
handle, so we know when to split SCSI commands into multiple tasks.
Fix this by adding a new se_dev_attrib.fabric_max_sectors to hold the
maximum transfer length, and checking incoming IOs against that limit.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 0b25b50..27da4e4 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -889,10 +889,15 @@
limits->logical_block_size);
dev->se_sub_dev->se_dev_attrib.max_sectors = limits->max_sectors;
/*
- * Set optimal_sectors from max_sectors, which can be lowered via
- * configfs.
+ * Set fabric_max_sectors, which is reported in block limits
+ * VPD page (B0h).
*/
- dev->se_sub_dev->se_dev_attrib.optimal_sectors = limits->max_sectors;
+ dev->se_sub_dev->se_dev_attrib.fabric_max_sectors = DA_FABRIC_MAX_SECTORS;
+ /*
+ * Set optimal_sectors from fabric_max_sectors, which can be
+ * lowered via configfs.
+ */
+ dev->se_sub_dev->se_dev_attrib.optimal_sectors = DA_FABRIC_MAX_SECTORS;
/*
* queue_depth is based on subsystem plugin dependent requirements.
*/
@@ -1224,6 +1229,54 @@
return 0;
}
+int se_dev_set_fabric_max_sectors(struct se_device *dev, u32 fabric_max_sectors)
+{
+ if (atomic_read(&dev->dev_export_obj.obj_access_count)) {
+ pr_err("dev[%p]: Unable to change SE Device"
+ " fabric_max_sectors while dev_export_obj: %d count exists\n",
+ dev, atomic_read(&dev->dev_export_obj.obj_access_count));
+ return -EINVAL;
+ }
+ if (!fabric_max_sectors) {
+ pr_err("dev[%p]: Illegal ZERO value for"
+ " fabric_max_sectors\n", dev);
+ return -EINVAL;
+ }
+ if (fabric_max_sectors < DA_STATUS_MAX_SECTORS_MIN) {
+ pr_err("dev[%p]: Passed fabric_max_sectors: %u less than"
+ " DA_STATUS_MAX_SECTORS_MIN: %u\n", dev, fabric_max_sectors,
+ DA_STATUS_MAX_SECTORS_MIN);
+ return -EINVAL;
+ }
+ if (dev->transport->transport_type == TRANSPORT_PLUGIN_PHBA_PDEV) {
+ if (fabric_max_sectors > dev->se_sub_dev->se_dev_attrib.hw_max_sectors) {
+ pr_err("dev[%p]: Passed fabric_max_sectors: %u"
+ " greater than TCM/SE_Device max_sectors:"
+ " %u\n", dev, fabric_max_sectors,
+ dev->se_sub_dev->se_dev_attrib.hw_max_sectors);
+ return -EINVAL;
+ }
+ } else {
+ if (fabric_max_sectors > DA_STATUS_MAX_SECTORS_MAX) {
+ pr_err("dev[%p]: Passed fabric_max_sectors: %u"
+ " greater than DA_STATUS_MAX_SECTORS_MAX:"
+ " %u\n", dev, fabric_max_sectors,
+ DA_STATUS_MAX_SECTORS_MAX);
+ return -EINVAL;
+ }
+ }
+ /*
+ * Align max_sectors down to PAGE_SIZE to follow transport_allocate_data_tasks()
+ */
+ fabric_max_sectors = se_dev_align_max_sectors(fabric_max_sectors,
+ dev->se_sub_dev->se_dev_attrib.block_size);
+
+ dev->se_sub_dev->se_dev_attrib.fabric_max_sectors = fabric_max_sectors;
+ pr_debug("dev[%p]: SE Device max_sectors changed to %u\n",
+ dev, fabric_max_sectors);
+ return 0;
+}
+
int se_dev_set_optimal_sectors(struct se_device *dev, u32 optimal_sectors)
{
if (atomic_read(&dev->dev_export_obj.obj_access_count)) {
@@ -1237,10 +1290,10 @@
" changed for TCM/pSCSI\n", dev);
return -EINVAL;
}
- if (optimal_sectors > dev->se_sub_dev->se_dev_attrib.max_sectors) {
+ if (optimal_sectors > dev->se_sub_dev->se_dev_attrib.fabric_max_sectors) {
pr_err("dev[%p]: Passed optimal_sectors %u cannot be"
- " greater than max_sectors: %u\n", dev,
- optimal_sectors, dev->se_sub_dev->se_dev_attrib.max_sectors);
+ " greater than fabric_max_sectors: %u\n", dev,
+ optimal_sectors, dev->se_sub_dev->se_dev_attrib.fabric_max_sectors);
return -EINVAL;
}