scsi_debug: Add REPORTED LUNS DATA HAS CHANGED Unit Attention

Generate a REPORTED LUNS DATA HAS CHANGED Unit Attention if
sysfs "max_luns" is used to change the number of scsi_debug LUNs.
This is only done if scsi_debug_scsi_level is SPC-3 or above.
Additionally, implement SPC-4 behavior which only generates
this Unit Attention on the first LUN on the target to receive
a command after the change.  This condition is cleared when
a REPORT LUNS command is received.

Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Tested-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 7b8b51bc29b4353debc9bd9911fcbf939753c782..1435b15029751f6334079a8fbfc8dc6cb950c7f3 100644 (file)
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -80,6 +80,8 @@ static const char *scsi_debug_version_date = "20141022";
 #define INVALID_FIELD_IN_PARAM_LIST 0x26
 #define UA_RESET_ASC 0x29
 #define UA_CHANGED_ASC 0x2a
+#define TARGET_CHANGED_ASC 0x3f
+#define LUNS_CHANGED_ASCQ 0x0e
 #define INSUFF_RES_ASC 0x55
 #define INSUFF_RES_ASCQ 0x3
 #define POWER_ON_RESET_ASCQ 0x0
@@ -180,7 +182,8 @@ static const char *scsi_debug_version_date = "20141022";
 #define SDEBUG_UA_BUS_RESET 1
 #define SDEBUG_UA_MODE_CHANGED 2
 #define SDEBUG_UA_CAPACITY_CHANGED 3
-#define SDEBUG_NUM_UAS 4
+#define SDEBUG_UA_LUNS_CHANGED 4
+#define SDEBUG_NUM_UAS 5
 
 /* for check_readiness() */
 #define UAS_ONLY 1     /* check for UAs only */
@@ -782,6 +785,22 @@ static int scsi_debug_ioctl(struct scsi_device *dev, int cmd, void __user *arg)
        /* return -ENOTTY; // correct return but upsets fdisk */
 }
 
+static void clear_luns_changed_on_target(struct sdebug_dev_info *devip)
+{
+       struct sdebug_host_info *sdhp;
+       struct sdebug_dev_info *dp;
+
+       spin_lock(&sdebug_host_list_lock);
+       list_for_each_entry(sdhp, &sdebug_host_list, host_list) {
+               list_for_each_entry(dp, &sdhp->dev_info_list, dev_list) {
+                       if ((devip->sdbg_host == dp->sdbg_host) &&
+                           (devip->target == dp->target))
+                               clear_bit(SDEBUG_UA_LUNS_CHANGED, dp->uas_bm);
+               }
+       }
+       spin_unlock(&sdebug_host_list_lock);
+}
+
 static int check_readiness(struct scsi_cmnd *SCpnt, int uas_only,
                           struct sdebug_dev_info * devip)
 {
@@ -817,6 +836,23 @@ static int check_readiness(struct scsi_cmnd *SCpnt, int uas_only,
                        if (debug)
                                cp = "capacity data changed";
                        break;
+               case SDEBUG_UA_LUNS_CHANGED:
+                       /*
+                        * SPC-3 behavior is to report a UNIT ATTENTION with
+                        * ASC/ASCQ REPORTED LUNS DATA HAS CHANGED on every LUN
+                        * on the target, until a REPORT LUNS command is
+                        * received.  SPC-4 behavior is to report it only once.
+                        * NOTE:  scsi_debug_scsi_level does not use the same
+                        * values as struct scsi_device->scsi_level.
+                        */
+                       if (scsi_debug_scsi_level >= 6) /* SPC-4 and above */
+                               clear_luns_changed_on_target(devip);
+                       mk_sense_buffer(SCpnt, UNIT_ATTENTION,
+                                       TARGET_CHANGED_ASC,
+                                       LUNS_CHANGED_ASCQ);
+                       if (debug)
+                               cp = "reported luns data has changed";
+                       break;
                default:
                        pr_warn("%s: unexpected unit attention code=%d\n",
                                __func__, k);
@@ -3229,6 +3265,7 @@ static int resp_report_luns(struct scsi_cmnd * scp,
        unsigned char arr[SDEBUG_RLUN_ARR_SZ];
        unsigned char * max_addr;
 
+       clear_luns_changed_on_target(devip);
        alloc_len = cmd[9] + (cmd[8] << 8) + (cmd[7] << 16) + (cmd[6] << 24);
        shortish = (alloc_len < 4);
        if (shortish || (select_report > 2)) {
@@ -4369,10 +4406,27 @@ static ssize_t max_luns_store(struct device_driver *ddp, const char *buf,
                              size_t count)
 {
         int n;
+       bool changed;
 
        if ((count > 0) && (1 == sscanf(buf, "%d", &n)) && (n >= 0)) {
+               changed = (scsi_debug_max_luns != n);
                scsi_debug_max_luns = n;
                sdebug_max_tgts_luns();
+               if (changed && (scsi_debug_scsi_level >= 5)) {  /* >= SPC-3 */
+                       struct sdebug_host_info *sdhp;
+                       struct sdebug_dev_info *dp;
+
+                       spin_lock(&sdebug_host_list_lock);
+                       list_for_each_entry(sdhp, &sdebug_host_list,
+                                           host_list) {
+                               list_for_each_entry(dp, &sdhp->dev_info_list,
+                                                   dev_list) {
+                                       set_bit(SDEBUG_UA_LUNS_CHANGED,
+                                               dp->uas_bm);
+                               }
+                       }
+                       spin_unlock(&sdebug_host_list_lock);
+               }
                return count;
        }
        return -EINVAL;