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/include/target/target_core_base.h b/include/target/target_core_base.h
index 99d7373..1641dea 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -86,6 +86,8 @@
#define DA_UNMAP_GRANULARITY_DEFAULT 0
/* Default unmap_granularity_alignment */
#define DA_UNMAP_GRANULARITY_ALIGNMENT_DEFAULT 0
+/* Default max transfer length */
+#define DA_FABRIC_MAX_SECTORS 8192
/* Emulation for Direct Page Out */
#define DA_EMULATE_DPO 0
/* Emulation for Forced Unit Access WRITEs */
@@ -726,6 +728,7 @@
u32 block_size;
u32 hw_max_sectors;
u32 max_sectors;
+ u32 fabric_max_sectors;
u32 optimal_sectors;
u32 hw_queue_depth;
u32 queue_depth;