On 12/30/2015 02:34 PM, Christoph Hellwig wrote:
On Tue, Dec 08, 2015 at 08:37:39AM +0100, Hannes Reinecke wrote:
Track attached SCSI devices and update the 'access_state' field
whenever an ALUA state change has been detected.
Signed-off-by: Hannes Reinecke <[email protected]>
---
drivers/scsi/device_handler/scsi_dh_alua.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c
b/drivers/scsi/device_handler/scsi_dh_alua.c
index 6c6ff0b..d01c86407 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -24,6 +24,7 @@
#include <linux/module.h>
#include <asm/unaligned.h>
#include <scsi/scsi.h>
+#include <scsi/scsi_proto.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_dh.h>
@@ -76,6 +77,7 @@ static struct workqueue_struct *kaluad_wq;
struct alua_port_group {
struct kref kref;
struct list_head node;
+ struct list_head dh_list;
unsigned char device_id_str[256];
int device_id_len;
int group_id;
@@ -93,6 +95,7 @@ struct alua_port_group {
};
struct alua_dh_data {
+ struct list_head node;
struct alua_port_group *pg;
int rel_port;
spinlock_t pg_lock;
@@ -243,6 +246,7 @@ struct alua_port_group *alua_get_pg(struct scsi_device
*sdev,
INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
INIT_LIST_HEAD(&pg->rtpg_list);
INIT_LIST_HEAD(&pg->node);
+ INIT_LIST_HEAD(&pg->dh_list);
spin_lock_init(&pg->lock);
/* Re-check list again to catch concurrent updates */
@@ -370,13 +374,26 @@ static int alua_check_vpd(struct scsi_device *sdev,
struct alua_dh_data *h,
old_pg = pg;
/* port_group has changed. Update to new port group */
if (h->pg != pg) {
+ unsigned long flags;
+
old_pg = h->pg;
rcu_assign_pointer(h->pg, pg);
+ spin_lock_irqsave(&old_pg->lock, flags);
+ list_del_rcu(&h->node);
+ spin_unlock_irqrestore(&old_pg->lock, flags);
+ spin_lock_irqsave(&pg->lock, flags);
+ list_add_rcu(&h->node, &pg->dh_list);
+ spin_unlock_irqrestore(&pg->lock, flags);
I think it makes more sense to remove it from the old list
before assining the new h->pg pointer to stay consistant.
Hmm. Yes, good point.
Also the add code is not common with the other half of the outer
branch, it would be nice to find a way to share the code between
those two branches.
Indeed, it would. But so far I haven't found a nice way for that...
list_for_each_entry(tmp_pg, &port_group_list, node) {
+ struct alua_dh_data *h;
+
if (tmp_pg->group_id != group_id)
continue;
if (tmp_pg->device_id_len != pg->device_id_len)
@@ -639,6 +658,12 @@ static int alua_rtpg(struct scsi_device *sdev, struct
alua_port_group *pg)
continue;
tmp_pg->state = desc[0] & 0x0f;
tmp_pg->pref = desc[0] >> 7;
+ rcu_read_lock();
+ list_for_each_entry_rcu(h, &tmp_pg->dh_list, node) {
+ if (h->sdev)
+ h->sdev->access_state = desc[0];
+ }
+ rcu_read_unlock();
І'd expect h->ѕdev to always be non-NULL. With a little tweak (see below)
that should indeed be the case.
@@ -1086,6 +1112,9 @@ static void alua_bus_detach(struct scsi_device *sdev)
h->sdev = NULL;
spin_unlock(&h->pg_lock);
if (pg) {
+ spin_lock(&pg->lock);
+ list_del_rcu(&h->node);
+ spin_unlock(&pg->lock);
synchronize_rcu();
if (pg->rtpg_sdev)
flush_delayed_work(&pg->rtpg_work);
Here we'd just need to make sure to do the list_del before setting
h->sdev to NULL.
Okay, true. Will do.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
[email protected] +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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