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Message-Id: <1432623445-25776-4-git-send-email-nab@daterainc.com>
Date: Tue, 26 May 2015 06:57:24 +0000
From: "Nicholas A. Bellinger" <nab@...erainc.com>
To: target-devel <target-devel@...r.kernel.org>
Cc: linux-scsi <linux-scsi@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Christoph Hellwig <hch@....de>, Hannes Reinecke <hare@...e.de>,
Sagi Grimberg <sagig@...lanox.com>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Nicholas Bellinger <nab@...ux-iscsi.org>
Subject: [PATCH-v2 3/4] target: Drop se_lun->lun_active for existing percpu lun_ref
From: Nicholas Bellinger <nab@...ux-iscsi.org>
With se_port_t and t10_alua_tg_pt_gp_member being absored into se_lun,
there is no need for an extra atomic_t based reference count for PR
ALL_TG_PT=1 and ALUA access state transition.
Go ahead and use the existing percpu se_lun->lun_ref instead, and
convert the two special cases to percpu_ref_tryget_live() to avoid
se_lun if transport_clear_lun_ref() has already been invoked to
shutdown the se_lun.
Cc: Christoph Hellwig <hch@....de>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
---
drivers/target/target_core_alua.c | 5 +++--
drivers/target/target_core_pr.c | 9 +++++----
drivers/target/target_core_tpg.c | 10 ++++++----
include/target/target_core_base.h | 1 -
4 files changed, 14 insertions(+), 11 deletions(-)
diff --git a/drivers/target/target_core_alua.c b/drivers/target/target_core_alua.c
index 314d230..5745dda 100644
--- a/drivers/target/target_core_alua.c
+++ b/drivers/target/target_core_alua.c
@@ -969,7 +969,8 @@ static void core_alua_do_transition_tg_pt_work(struct work_struct *work)
* every I_T nexus other than the I_T nexus on which the SET
* TARGET PORT GROUPS command
*/
- atomic_inc_mb(&lun->lun_active);
+ if (!percpu_ref_tryget_live(&lun->lun_ref))
+ continue;
spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
spin_lock_bh(&lun->lun_deve_lock);
@@ -997,7 +998,7 @@ static void core_alua_do_transition_tg_pt_work(struct work_struct *work)
spin_unlock_bh(&lun->lun_deve_lock);
spin_lock(&tg_pt_gp->tg_pt_gp_lock);
- atomic_dec_mb(&lun->lun_active);
+ percpu_ref_put(&lun->lun_ref);
}
spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
/*
diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index f036337..b3088b2 100644
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -704,7 +704,8 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
*/
spin_lock(&dev->se_port_lock);
list_for_each_entry_safe(lun_tmp, next, &dev->dev_sep_list, lun_dev_link) {
- atomic_inc_mb(&lun_tmp->lun_active);
+ if (!percpu_ref_tryget_live(&lun_tmp->lun_ref))
+ continue;
spin_unlock(&dev->se_port_lock);
spin_lock_bh(&lun_tmp->lun_deve_lock);
@@ -750,7 +751,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
if (ret < 0) {
pr_err("core_scsi3_lunacl_depend"
"_item() failed\n");
- atomic_dec_mb(&lun->lun_active);
+ percpu_ref_put(&lun_tmp->lun_ref);
kref_put(&deve_tmp->pr_kref, target_pr_kref_release);
goto out;
}
@@ -767,7 +768,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
deve_tmp, deve_tmp->mapped_lun,
NULL, sa_res_key, all_tg_pt, aptpl);
if (!pr_reg_atp) {
- atomic_dec_mb(&lun_tmp->lun_active);
+ percpu_ref_put(&lun_tmp->lun_ref);
core_scsi3_lunacl_undepend_item(deve_tmp);
goto out;
}
@@ -779,7 +780,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
spin_unlock_bh(&lun_tmp->lun_deve_lock);
spin_lock(&dev->se_port_lock);
- atomic_dec_mb(&lun_tmp->lun_active);
+ percpu_ref_put(&lun_tmp->lun_ref);
}
spin_unlock(&dev->se_port_lock);
diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index 5b9a229..2ec1ed1 100644
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -606,7 +606,6 @@ struct se_lun *core_tpg_alloc_lun(
mutex_init(&lun->lun_tg_pt_md_mutex);
INIT_LIST_HEAD(&lun->lun_tg_pt_gp_link);
spin_lock_init(&lun->lun_tg_pt_gp_lock);
- atomic_set(&lun->lun_active, 0);
lun->lun_tpg = tpg;
return lun;
@@ -662,13 +661,16 @@ void core_tpg_remove_lun(
struct se_device *dev = lockless_dereference(lun->lun_se_dev);
core_clear_lun_from_tpg(lun, tpg);
+ /*
+ * Wait for any active I/O references to percpu se_lun->lun_ref to
+ * be released. Also, se_lun->lun_ref is now used by PR and ALUA
+ * logic when referencing a remote target port during ALL_TGT_PT=1
+ * and generating UNIT_ATTENTIONs for ALUA access state transition.
+ */
transport_clear_lun_ref(lun);
mutex_lock(&tpg->tpg_lun_mutex);
if (lun->lun_se_dev) {
- while (atomic_read(&lun->lun_active))
- cpu_relax();
-
target_detach_tg_pt_gp(lun);
spin_lock(&dev->se_port_lock);
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index b82a989..eefc2b0 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -721,7 +721,6 @@ struct se_lun {
struct t10_alua_tg_pt_gp *lun_tg_pt_gp;
spinlock_t lun_tg_pt_gp_lock;
- atomic_t lun_active;
struct se_portal_group *lun_tpg;
struct scsi_port_stats lun_stats;
struct config_group lun_group;
--
1.9.1
--
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