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>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index 599374e6d245..54439bc42dab 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -706,6 +706,16 @@ int se_dev_set_unmap_granularity_alignment(
         return 0;
 }
 
+int se_dev_set_max_write_same_len(
+        struct se_device *dev,
+        u32 max_write_same_len)
+{
+        dev->dev_attrib.max_write_same_len = max_write_same_len;
+        pr_debug("dev[%p]: Set max_write_same_len: %u\n",
+                        dev, dev->dev_attrib.max_write_same_len);
+        return 0;
+}
+
 int se_dev_set_emulate_dpo(struct se_device *dev, int flag)
 {
         if (flag != 0 && flag != 1) {
@@ -1393,6 +1403,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
         dev->dev_attrib.unmap_granularity = DA_UNMAP_GRANULARITY_DEFAULT;
         dev->dev_attrib.unmap_granularity_alignment =
                                 DA_UNMAP_GRANULARITY_ALIGNMENT_DEFAULT;
+        dev->dev_attrib.max_write_same_len = DA_MAX_WRITE_SAME_LEN;
         dev->dev_attrib.fabric_max_sectors = DA_FABRIC_MAX_SECTORS;
         dev->dev_attrib.optimal_sectors = DA_FABRIC_MAX_SECTORS;