target: Add/check max_write_same_len device attribute + update block limits VPD
This patch adds a new max_write_same_len device attribute for use with
WRITE_SAME w/ UNMAP=0 backend emulation. This can be useful for
lowering the default backend value (IBLOCK uses 0xFFFF).
Also, update block limits VPD emulation code in spc_emulate_evpd_b0() to
report MAXIMUM WRITE SAME LENGTH, and enforce max_write_same_len during
sbc_parse() -> sbc_setup_write_same() CDB sanity checking for all emulated
WRITE_SAME w/ UNMAP=0 cases.
(Robert: Move max_write_same_len check in sbc_setup_write_same() to
check both WRITE_SAME w/ UNMAP=1 and w/ UNMAP=0 cases)
Cc: Christoph Hellwig <hch@lst.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Robert Elliott <Elliott@hp.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index 4b3c183..cf1b8bb 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -465,7 +465,7 @@
* Exit now if we don't support TP.
*/
if (!have_tp)
- return 0;
+ goto max_write_same;
/*
* Set MAXIMUM UNMAP LBA COUNT
@@ -491,6 +491,12 @@
if (dev->dev_attrib.unmap_granularity_alignment != 0)
buf[32] |= 0x80; /* Set the UGAVALID bit */
+ /*
+ * MAXIMUM WRITE SAME LENGTH
+ */
+max_write_same:
+ put_unaligned_be64(dev->dev_attrib.max_write_same_len, &buf[36]);
+
return 0;
}