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target: Add percpu refcounting for se_lun access

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This patch adds percpu refcounting for se_lun access that allows the
association of an se_lun + se_cmd in transport_lookup_cmd_lun() to
occur without an extra list_head for tracking outstanding I/O during
se_lun shutdown.

This effectively changes se_lun shutdown logic to wait for outstanding
I/O percpu references to complete in transport_lun_remove_cmd() using
se_lun->lun_ref_comp, instead of explicitly draining the per se_lun
command list and waiting for individual se_cmd descriptor processing
to complete.

Cc: Kent Overstreet <kmo@daterainc.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Nicholas Bellinger 2013-11-06 21:03:43 -08:00
parent c9e8d128fe
commit 5277797dc4
6 changed files with 45 additions and 18 deletions
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10
drivers/target/target_core_device.c
View file

@ -92,6 +92,9 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
se_cmd->pr_res_key = deve->pr_res_key;
se_cmd->orig_fe_lun = unpacked_lun;
se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
percpu_ref_get(&se_lun->lun_ref);
se_cmd->lun_ref_active = true;
}
spin_unlock_irqrestore(&se_sess->se_node_acl->device_list_lock, flags);
@ -119,6 +122,9 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
se_cmd->se_lun = &se_sess->se_tpg->tpg_virt_lun0;
se_cmd->orig_fe_lun = 0;
se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
percpu_ref_get(&se_lun->lun_ref);
se_cmd->lun_ref_active = true;
}
/* Directly associate cmd with se_dev */
@ -134,10 +140,6 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u32 unpacked_lun)
dev->read_bytes += se_cmd->data_length;
spin_unlock_irqrestore(&dev->stats_lock, flags);
spin_lock_irqsave(&se_lun->lun_cmd_lock, flags);
list_add_tail(&se_cmd->se_lun_node, &se_lun->lun_cmd_list);
spin_unlock_irqrestore(&se_lun->lun_cmd_lock, flags);
return 0;
}
EXPORT_SYMBOL(transport_lookup_cmd_lun);

2
drivers/target/target_core_internal.h
View file

@ -100,7 +100,7 @@ int transport_dump_vpd_assoc(struct t10_vpd *, unsigned char *, int);
int transport_dump_vpd_ident_type(struct t10_vpd *, unsigned char *, int);
int transport_dump_vpd_ident(struct t10_vpd *, unsigned char *, int);
bool target_stop_cmd(struct se_cmd *cmd, unsigned long *flags);
int transport_clear_lun_from_sessions(struct se_lun *);
int transport_clear_lun_ref(struct se_lun *);
void transport_send_task_abort(struct se_cmd *);
sense_reason_t target_cmd_size_check(struct se_cmd *cmd, unsigned int size);
void target_qf_do_work(struct work_struct *work);

27
drivers/target/target_core_tpg.c
View file

@ -634,6 +634,13 @@ int core_tpg_set_initiator_node_tag(
}
EXPORT_SYMBOL(core_tpg_set_initiator_node_tag);
static void core_tpg_lun_ref_release(struct percpu_ref *ref)
{
struct se_lun *lun = container_of(ref, struct se_lun, lun_ref);
complete(&lun->lun_ref_comp);
}
static int core_tpg_setup_virtual_lun0(struct se_portal_group *se_tpg)
{
/* Set in core_dev_setup_virtual_lun0() */
@ -651,11 +658,18 @@ static int core_tpg_setup_virtual_lun0(struct se_portal_group *se_tpg)
spin_lock_init(&lun->lun_acl_lock);
spin_lock_init(&lun->lun_cmd_lock);
spin_lock_init(&lun->lun_sep_lock);
init_completion(&lun->lun_ref_comp);
ret = core_tpg_post_addlun(se_tpg, lun, lun_access, dev);
ret = percpu_ref_init(&lun->lun_ref, core_tpg_lun_ref_release);
if (ret < 0)
return ret;
ret = core_tpg_post_addlun(se_tpg, lun, lun_access, dev);
if (ret < 0) {
percpu_ref_cancel_init(&lun->lun_ref);
return ret;
}
return 0;
}
@ -696,6 +710,7 @@ int core_tpg_register(
spin_lock_init(&lun->lun_acl_lock);
spin_lock_init(&lun->lun_cmd_lock);
spin_lock_init(&lun->lun_sep_lock);
init_completion(&lun->lun_ref_comp);
}
se_tpg->se_tpg_type = se_tpg_type;
@ -816,10 +831,16 @@ int core_tpg_post_addlun(
{
int ret;
ret = core_dev_export(lun_ptr, tpg, lun);
ret = percpu_ref_init(&lun->lun_ref, core_tpg_lun_ref_release);
if (ret < 0)
return ret;
ret = core_dev_export(lun_ptr, tpg, lun);
if (ret < 0) {
percpu_ref_cancel_init(&lun->lun_ref);
return ret;
}
spin_lock(&tpg->tpg_lun_lock);
lun->lun_access = lun_access;
lun->lun_status = TRANSPORT_LUN_STATUS_ACTIVE;
@ -833,7 +854,7 @@ static void core_tpg_shutdown_lun(
struct se_lun *lun)
{
core_clear_lun_from_tpg(lun, tpg);
transport_clear_lun_from_sessions(lun);
transport_clear_lun_ref(lun);
}
struct se_lun *core_tpg_pre_dellun(

18
drivers/target/target_core_transport.c
View file

@ -575,15 +575,11 @@ static int transport_cmd_check_stop_to_fabric(struct se_cmd *cmd)
static void transport_lun_remove_cmd(struct se_cmd *cmd)
{
struct se_lun *lun = cmd->se_lun;
unsigned long flags;
if (!lun)
if (!lun || !cmd->lun_ref_active)
return;
spin_lock_irqsave(&lun->lun_cmd_lock, flags);
if (!list_empty(&cmd->se_lun_node))
list_del_init(&cmd->se_lun_node);
spin_unlock_irqrestore(&lun->lun_cmd_lock, flags);
percpu_ref_put(&lun->lun_ref);
}
void transport_cmd_finish_abort(struct se_cmd *cmd, int remove)
@ -2537,21 +2533,23 @@ static void __transport_clear_lun_from_sessions(struct se_lun *lun)
spin_unlock_irqrestore(&lun->lun_cmd_lock, lun_flags);
}
static int transport_clear_lun_thread(void *p)
static int transport_clear_lun_ref_thread(void *p)
{
struct se_lun *lun = p;
__transport_clear_lun_from_sessions(lun);
percpu_ref_kill(&lun->lun_ref);
wait_for_completion(&lun->lun_ref_comp);
complete(&lun->lun_shutdown_comp);
return 0;
}
int transport_clear_lun_from_sessions(struct se_lun *lun)
int transport_clear_lun_ref(struct se_lun *lun)
{
struct task_struct *kt;
kt = kthread_run(transport_clear_lun_thread, lun,
kt = kthread_run(transport_clear_lun_ref_thread, lun,
"tcm_cl_%u", lun->unpacked_lun);
if (IS_ERR(kt)) {
pr_err("Unable to start clear_lun thread\n");

1
drivers/target/target_core_xcopy.c
View file

@ -579,6 +579,7 @@ static int target_xcopy_init_pt_lun(
spin_lock_init(&pt_cmd->se_lun->lun_acl_lock);
spin_lock_init(&pt_cmd->se_lun->lun_cmd_lock);
spin_lock_init(&pt_cmd->se_lun->lun_sep_lock);
init_completion(&pt_cmd->se_lun->lun_ref_comp);
pt_cmd->se_dev = se_dev;

5
include/target/target_core_base.h
View file

@ -499,6 +499,9 @@ struct se_cmd {
/* backend private data */
void *priv;
/* Used for lun->lun_ref counting */
bool lun_ref_active;
};
struct se_ua {
@ -757,6 +760,8 @@ struct se_lun {
struct se_port *lun_sep;
struct config_group lun_group;
struct se_port_stat_grps port_stat_grps;
struct completion lun_ref_comp;
struct percpu_ref lun_ref;
};
struct scsi_port_stats {