target: Add MI_REPORT_TARGET_PGS ext. header + implict_trans_secs attribute

This patch adds support for ALUA MI_REPORT_TARGET_PGS extended header
format defined within SPC-4.  It changes target core ALUA emulation logic
within target_emulate_report_target_port_groups() to support both the
extended and original length only header formats.

It includes adding a new 'implict_trans_secs' attribute for each ALUA
target port group to control the value returned to the application client
for an recommended implict translation timeout in seconds.  By default
this value is currently set to zero, and limited up to 255 by virtue of
using a single byte in the extended header format.

This value is used by target_emulate_report_target_port_groups() within
the extended header logic to set IMPLICIT TRANSITION TIME as defined by
spc4r30.

Cc: Hannes Reinecke <hare@suse.de>
Cc: Rob Evers <revers@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 931521cc4e4f..801efa892046 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -2447,6 +2447,26 @@ static ssize_t target_core_alua_tg_pt_gp_store_attr_trans_delay_msecs(
 SE_DEV_ALUA_TG_PT_ATTR(trans_delay_msecs, S_IRUGO | S_IWUSR);
 
 /*
+ * implict_trans_secs
+ */
+static ssize_t target_core_alua_tg_pt_gp_show_attr_implict_trans_secs(
+        struct t10_alua_tg_pt_gp *tg_pt_gp,
+        char *page)
+{
+        return core_alua_show_implict_trans_secs(tg_pt_gp, page);
+}
+
+static ssize_t target_core_alua_tg_pt_gp_store_attr_implict_trans_secs(
+        struct t10_alua_tg_pt_gp *tg_pt_gp,
+        const char *page,
+        size_t count)
+{
+        return core_alua_store_implict_trans_secs(tg_pt_gp, page, count);
+}
+
+SE_DEV_ALUA_TG_PT_ATTR(implict_trans_secs, S_IRUGO | S_IWUSR);
+
+/*
  * preferred
  */
 
@@ -2570,6 +2590,7 @@ static struct configfs_attribute *target_core_alua_tg_pt_gp_attrs[] = {
         &target_core_alua_tg_pt_gp_alua_write_metadata.attr,
         &target_core_alua_tg_pt_gp_nonop_delay_msecs.attr,
         &target_core_alua_tg_pt_gp_trans_delay_msecs.attr,
+        &target_core_alua_tg_pt_gp_implict_trans_secs.attr,
         &target_core_alua_tg_pt_gp_preferred.attr,
         &target_core_alua_tg_pt_gp_tg_pt_gp_id.attr,
         &target_core_alua_tg_pt_gp_members.attr,