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[SCSI] scsi_dh_alua: ALUA handler attach should succeed while TPG is transitioning

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During testing, it was discovered that when a device tries to attach to the
alua handler while in TPG state of transitioning, the alua_rtpg function will
wait for it to exit the state before allowing it to continue. As a result, if
the 60 second timeout expires, the alua handler will not attach to the device.

To fix this, I have introduced an input argument to alua_rtpg called
wait_for_transition.  The idea is that it will wait for the transition to
complete before an activation (because the current TPG state has some bearing
in that case), but during a discovery if it is transitioning, it will not
wait, and will store the state as standby for the time being.

I believe the precedent exists for this from commit
c0d289b3e5 Since if the device reports a state
of transitioning, it can transition to other more valid states, and it has
been established TPGS is supported on the device, if it is attaching.

Signed-off-by: Sean Stewart <Sean.Stewart@netapp.com>
Acked-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
This commit is contained in:
Stewart, Sean 2013-10-15 15:52:54 +00:00 committed by James Bottomley
parent c20ee7b56e
commit a8e5a2d593
1 changed files with 16 additions and 10 deletions
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26
drivers/scsi/device_handler/scsi_dh_alua.c
View file

@ -522,12 +522,13 @@ static int alua_check_sense(struct scsi_device *sdev,
/*
* alua_rtpg - Evaluate REPORT TARGET GROUP STATES
* @sdev: the device to be evaluated.
* @wait_for_transition: if nonzero, wait ALUA_FAILOVER_TIMEOUT seconds for device to exit transitioning state
*
* Evaluate the Target Port Group State.
* Returns SCSI_DH_DEV_OFFLINED if the path is
* found to be unusable.
*/
static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h, int wait_for_transition)
{
struct scsi_sense_hdr sense_hdr;
int len, k, off, valid_states = 0;
@ -599,7 +600,7 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
else
h->transition_tmo = ALUA_FAILOVER_TIMEOUT;
if (orig_transition_tmo != h->transition_tmo) {
if (wait_for_transition && (orig_transition_tmo != h->transition_tmo)) {
sdev_printk(KERN_INFO, sdev,
"%s: transition timeout set to %d seconds\n",
ALUA_DH_NAME, h->transition_tmo);
@ -637,14 +638,19 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_dh_data *h)
switch (h->state) {
case TPGS_STATE_TRANSITIONING:
if (time_before(jiffies, expiry)) {
/* State transition, retry */
interval += 2000;
msleep(interval);
goto retry;
if (wait_for_transition) {
if (time_before(jiffies, expiry)) {
/* State transition, retry */
interval += 2000;
msleep(interval);
goto retry;
}
err = SCSI_DH_RETRY;
} else {
err = SCSI_DH_OK;
}
/* Transitioning time exceeded, set port to standby */
err = SCSI_DH_RETRY;
h->state = TPGS_STATE_STANDBY;
break;
case TPGS_STATE_OFFLINE:
@ -678,7 +684,7 @@ static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
if (err != SCSI_DH_OK)
goto out;
err = alua_rtpg(sdev, h);
err = alua_rtpg(sdev, h, 0);
if (err != SCSI_DH_OK)
goto out;
@ -738,7 +744,7 @@ static int alua_activate(struct scsi_device *sdev,
int err = SCSI_DH_OK;
int stpg = 0;
err = alua_rtpg(sdev, h);
err = alua_rtpg(sdev, h, 1);
if (err != SCSI_DH_OK)
goto out;