target: Add MAXIMUM COMPARE AND WRITE LENGTH in Block Limits VPD

This patch adds the MAXIMUM COMPARE AND WRITE LENGTH bit, currently
hardcoded to a single logical block (NoLB=1) within the Block Limits
VPD in spc_emulate_evpd_b0().

Also add emulate_caw device attribute in configfs (enabled by default)
to allow the exposure of this bit to be disabled, if necessary.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Martin Petersen <martin.petersen@oracle.com>
Cc: Chris Mason <chris.mason@fusionio.com>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Nicholas Bellinger <nab@daterainc.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 7fdb3fae2961..61a4dc890701 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -97,6 +97,8 @@
  * block/blk-lib.c:blkdev_issue_discard()
  */
 #define DA_EMULATE_TPWS                         0
+/* Emulation for CompareAndWrite (AtomicTestandSet) by default */
+#define DA_EMULATE_CAW                          1
 /* No Emulation for PSCSI by default */
 #define DA_EMULATE_ALUA                         0
 /* Enforce SCSI Initiator Port TransportID with 'ISID' for PR */
@@ -602,6 +604,7 @@ struct se_dev_attrib {
         int             emulate_tas;
         int             emulate_tpu;
         int             emulate_tpws;
+        int             emulate_caw;
         int             enforce_pr_isids;
         int             is_nonrot;
         int             emulate_rest_reord;