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>
This commit is contained in:
Roland Dreier
2012-02-13 16:18:17 -08:00
committed by Nicholas Bellinger
parent effc6cc882
commit 015487b89f
6 changed files with 76 additions and 7 deletions
+1
View File
@@ -53,6 +53,7 @@ int se_dev_set_is_nonrot(struct se_device *, int);
int se_dev_set_emulate_rest_reord(struct se_device *dev, int);
int se_dev_set_queue_depth(struct se_device *, u32);
int se_dev_set_max_sectors(struct se_device *, u32);
int se_dev_set_fabric_max_sectors(struct se_device *, u32);
int se_dev_set_optimal_sectors(struct se_device *, u32);
int se_dev_set_block_size(struct se_device *, u32);
struct se_lun *core_dev_add_lun(struct se_portal_group *, struct se_hba *,