po 30. 1. 2023 v 0:45 odesílatel Mike Christie
<michael.christie@xxxxxxxxxx> napsal:
>
> iSCSI needs to wait on outstanding commands like how srp and the FC/fcoe
> drivers do. It can't use target_stop_session because for MCS support we
> can't stop the entire session during recovery because if other connections
> are ok then we want to be able to continue to execute IO on them.
>
> This patch moves the per session cmd counters to a new struct, so iSCSI
> can allocate it per connection. The xcopy code can also just not allocate
> it in the future since it doesn't need to track commands.
>
> Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
> ---
> drivers/target/target_core_tpg.c | 2 +-
> drivers/target/target_core_transport.c | 135 ++++++++++++++++-------
> include/target/iscsi/iscsi_target_core.h | 1 +
> include/target/target_core_base.h | 13 ++-
> 4 files changed, 107 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
> index 736847c933e5..8ebccdbd94f0 100644
> --- a/drivers/target/target_core_tpg.c
> +++ b/drivers/target/target_core_tpg.c
> @@ -328,7 +328,7 @@ static void target_shutdown_sessions(struct se_node_acl *acl)
> restart:
> spin_lock_irqsave(&acl->nacl_sess_lock, flags);
> list_for_each_entry(sess, &acl->acl_sess_list, sess_acl_list) {
> - if (atomic_read(&sess->stopped))
> + if (sess->cmd_cnt && atomic_read(&sess->cmd_cnt->stopped))
> continue;
>
> list_del_init(&sess->sess_acl_list);
> diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> index 5926316252eb..3d6034f00dcd 100644
> --- a/drivers/target/target_core_transport.c
> +++ b/drivers/target/target_core_transport.c
> @@ -220,11 +220,49 @@ void transport_subsystem_check_init(void)
> sub_api_initialized = 1;
> }
>
> -static void target_release_sess_cmd_refcnt(struct percpu_ref *ref)
> +static void target_release_cmd_refcnt(struct percpu_ref *ref)
> {
> - struct se_session *sess = container_of(ref, typeof(*sess), cmd_count);
> + struct target_cmd_counter *cmd_cnt = container_of(ref,
> + typeof(*cmd_cnt),
> + refcnt);
> + wake_up(&cmd_cnt->refcnt_wq);
> +}
> +
> +static struct target_cmd_counter *target_alloc_cmd_counter(void)
> +{
> + struct target_cmd_counter *cmd_cnt;
> + int rc;
> +
> + cmd_cnt = kzalloc(sizeof(*cmd_cnt), GFP_KERNEL);
> + if (!cmd_cnt)
> + return NULL;
>
> - wake_up(&sess->cmd_count_wq);
> + init_completion(&cmd_cnt->stop_done);
> + init_waitqueue_head(&cmd_cnt->refcnt_wq);
> + atomic_set(&cmd_cnt->stopped, 0);
> +
> + rc = percpu_ref_init(&cmd_cnt->refcnt, target_release_cmd_refcnt, 0,
> + GFP_KERNEL);
> + if (rc)
> + goto free_cmd_cnt;
> +
> + return cmd_cnt;
> +
> +free_cmd_cnt:
> + kfree(cmd_cnt);
> + return NULL;
> +}
> +
> +static void target_free_cmd_counter(struct target_cmd_counter *cmd_cnt)
> +{
> + /*
> + * Drivers like loop do not call target_stop_session during session
> + * shutdown so we have to drop the ref taken at init time here.
> + */
> + if (!atomic_read(&cmd_cnt->stopped))
> + percpu_ref_put(&cmd_cnt->refcnt);
> +
> + percpu_ref_exit(&cmd_cnt->refcnt);
> }
>
> /**
> @@ -238,25 +276,17 @@ int transport_init_session(struct se_session *se_sess)
> INIT_LIST_HEAD(&se_sess->sess_list);
> INIT_LIST_HEAD(&se_sess->sess_acl_list);
> spin_lock_init(&se_sess->sess_cmd_lock);
> - init_waitqueue_head(&se_sess->cmd_count_wq);
> - init_completion(&se_sess->stop_done);
> - atomic_set(&se_sess->stopped, 0);
> - return percpu_ref_init(&se_sess->cmd_count,
> - target_release_sess_cmd_refcnt, 0, GFP_KERNEL);
> + se_sess->cmd_cnt = target_alloc_cmd_counter();
> + if (!se_sess->cmd_cnt)
> + return -ENOMEM;
> +
> + return 0;
> }
> EXPORT_SYMBOL(transport_init_session);
>
> void transport_uninit_session(struct se_session *se_sess)
> {
> - /*
> - * Drivers like iscsi and loop do not call target_stop_session
> - * during session shutdown so we have to drop the ref taken at init
> - * time here.
> - */
> - if (!atomic_read(&se_sess->stopped))
> - percpu_ref_put(&se_sess->cmd_count);
> -
> - percpu_ref_exit(&se_sess->cmd_count);
> + target_free_cmd_counter(se_sess->cmd_cnt);
> }
>
> /**
> @@ -2970,9 +3000,16 @@ int target_get_sess_cmd(struct se_cmd *se_cmd, bool ack_kref)
> se_cmd->se_cmd_flags |= SCF_ACK_KREF;
> }
>
> - if (!percpu_ref_tryget_live(&se_sess->cmd_count))
> - ret = -ESHUTDOWN;
> -
> + /*
> + * Users like xcopy do not use counters since they never do a stop
> + * and wait.
> + */
> + if (se_sess->cmd_cnt) {
> + if (!percpu_ref_tryget_live(&se_sess->cmd_cnt->refcnt))
> + ret = -ESHUTDOWN;
> + else
> + se_cmd->cmd_cnt = se_sess->cmd_cnt;
> + }
> if (ret && ack_kref)
> target_put_sess_cmd(se_cmd);
>
> @@ -2993,7 +3030,7 @@ static void target_free_cmd_mem(struct se_cmd *cmd)
> static void target_release_cmd_kref(struct kref *kref)
> {
> struct se_cmd *se_cmd = container_of(kref, struct se_cmd, cmd_kref);
> - struct se_session *se_sess = se_cmd->se_sess;
> + struct target_cmd_counter *cmd_cnt = se_cmd->cmd_cnt;
> struct completion *free_compl = se_cmd->free_compl;
> struct completion *abrt_compl = se_cmd->abrt_compl;
>
> @@ -3004,7 +3041,8 @@ static void target_release_cmd_kref(struct kref *kref)
> if (abrt_compl)
> complete(abrt_compl);
>
> - percpu_ref_put(&se_sess->cmd_count);
> + if (cmd_cnt)
> + percpu_ref_put(&cmd_cnt->refcnt);
> }
>
> /**
> @@ -3123,46 +3161,65 @@ void target_show_cmd(const char *pfx, struct se_cmd *cmd)
> }
> EXPORT_SYMBOL(target_show_cmd);
>
> -static void target_stop_session_confirm(struct percpu_ref *ref)
> +static void target_stop_cmd_counter_confirm(struct percpu_ref *ref)
> +{
> + struct target_cmd_counter *cmd_cnt = container_of(ref,
> + struct target_cmd_counter,
> + refcnt);
> + complete_all(&cmd_cnt->stop_done);
> +}
> +
> +/**
> + * target_stop_cmd_counter - Stop new IO from being added to the counter.
> + * @cmd_cnt: counter to stop
> + */
> +static void target_stop_cmd_counter(struct target_cmd_counter *cmd_cnt)
> {
> - struct se_session *se_sess = container_of(ref, struct se_session,
> - cmd_count);
> - complete_all(&se_sess->stop_done);
> + pr_debug("Stopping command counter.\n");
> + if (!atomic_cmpxchg(&cmd_cnt->stopped, 0, 1))
> + percpu_ref_kill_and_confirm(&cmd_cnt->refcnt,
> + target_stop_cmd_counter_confirm);
> }
>
> /**
> * target_stop_session - Stop new IO from being queued on the session.
> - * @se_sess: session to stop
> + * @se_sess: session to stop
> */
> void target_stop_session(struct se_session *se_sess)
> {
> - pr_debug("Stopping session queue.\n");
> - if (atomic_cmpxchg(&se_sess->stopped, 0, 1) == 0)
> - percpu_ref_kill_and_confirm(&se_sess->cmd_count,
> - target_stop_session_confirm);
> + target_stop_cmd_counter(se_sess->cmd_cnt);
> }
> EXPORT_SYMBOL(target_stop_session);
>
> /**
> - * target_wait_for_sess_cmds - Wait for outstanding commands
> - * @se_sess: session to wait for active I/O
> + * target_wait_for_cmds - Wait for outstanding cmds.
> + * @cmd_cnt: counter to wait for active I/O for.
> */
> -void target_wait_for_sess_cmds(struct se_session *se_sess)
> +static void target_wait_for_cmds(struct target_cmd_counter *cmd_cnt)
> {
> int ret;
>
> - WARN_ON_ONCE(!atomic_read(&se_sess->stopped));
> + WARN_ON_ONCE(!atomic_read(&cmd_cnt->stopped));
>
> do {
> pr_debug("Waiting for running cmds to complete.\n");
> - ret = wait_event_timeout(se_sess->cmd_count_wq,
> - percpu_ref_is_zero(&se_sess->cmd_count),
> - 180 * HZ);
> + ret = wait_event_timeout(cmd_cnt->refcnt_wq,
> + percpu_ref_is_zero(&cmd_cnt->refcnt),
> + 180 * HZ);
> } while (ret <= 0);
>
> - wait_for_completion(&se_sess->stop_done);
> + wait_for_completion(&cmd_cnt->stop_done);
> pr_debug("Waiting for cmds done.\n");
> }
> +
> +/**
> + * target_wait_for_sess_cmds - Wait for outstanding commands
> + * @se_sess: session to wait for active I/O
> + */
> +void target_wait_for_sess_cmds(struct se_session *se_sess)
> +{
> + target_wait_for_cmds(se_sess->cmd_cnt);
> +}
> EXPORT_SYMBOL(target_wait_for_sess_cmds);
>
> /*
> diff --git a/include/target/iscsi/iscsi_target_core.h b/include/target/iscsi/iscsi_target_core.h
> index 94d06ddfd80a..229118156a1f 100644
> --- a/include/target/iscsi/iscsi_target_core.h
> +++ b/include/target/iscsi/iscsi_target_core.h
> @@ -600,6 +600,7 @@ struct iscsit_conn {
> struct iscsi_tpg_np *tpg_np;
> /* Pointer to parent session */
> struct iscsit_session *sess;
> + struct target_cmd_counter *cmd_cnt;
> int bitmap_id;
> int rx_thread_active;
> struct task_struct *rx_thread;
> diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
> index 12c9ba16217e..bd299790e99c 100644
> --- a/include/target/target_core_base.h
> +++ b/include/target/target_core_base.h
> @@ -494,6 +494,7 @@ struct se_cmd {
> struct se_lun *se_lun;
> /* Only used for internal passthrough and legacy TCM fabric modules */
> struct se_session *se_sess;
> + struct target_cmd_counter *cmd_cnt;
> struct se_tmr_req *se_tmr_req;
> struct llist_node se_cmd_list;
> struct completion *free_compl;
> @@ -619,22 +620,26 @@ static inline struct se_node_acl *fabric_stat_to_nacl(struct config_item *item)
> acl_fabric_stat_group);
> }
>
> -struct se_session {
> +struct target_cmd_counter {
> + struct percpu_ref refcnt;
> + wait_queue_head_t refcnt_wq;
> + struct completion stop_done;
> atomic_t stopped;
> +};
> +
> +struct se_session {
> u64 sess_bin_isid;
> enum target_prot_op sup_prot_ops;
> enum target_prot_type sess_prot_type;
> struct se_node_acl *se_node_acl;
> struct se_portal_group *se_tpg;
> void *fabric_sess_ptr;
> - struct percpu_ref cmd_count;
> struct list_head sess_list;
> struct list_head sess_acl_list;
> spinlock_t sess_cmd_lock;
> - wait_queue_head_t cmd_count_wq;
> - struct completion stop_done;
> void *sess_cmd_map;
> struct sbitmap_queue sess_tag_pool;
> + struct target_cmd_counter *cmd_cnt;
> };
>
> struct se_device;
> --
> 2.25.1
>
Reviewed-by: Maurizio Lombardi <mlombard@xxxxxxxxxx>
