From 5277797dc4ed873d067477d84e910b39d113f649 Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Wed, 6 Nov 2013 21:03:43 -0800 Subject: target: Add percpu refcounting for se_lun access 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 Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_device.c | 10 ++++++---- drivers/target/target_core_internal.h | 2 +- drivers/target/target_core_tpg.c | 27 ++++++++++++++++++++++++--- drivers/target/target_core_transport.c | 18 ++++++++---------- drivers/target/target_core_xcopy.c | 1 + 5 files changed, 40 insertions(+), 18 deletions(-) (limited to 'drivers') diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index d90dbb0f1a69..569a3c7c9e5a 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -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); diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h index 889af4df8562..47b63b094cdc 100644 --- a/drivers/target/target_core_internal.h +++ b/drivers/target/target_core_internal.h @@ -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); diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c index ec992208dc55..f321af04ef03 100644 --- a/drivers/target/target_core_tpg.c +++ b/drivers/target/target_core_tpg.c @@ -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( diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 84747cc1aac0..ad143d7293ec 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -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 @@ check_cond: 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"); diff --git a/drivers/target/target_core_xcopy.c b/drivers/target/target_core_xcopy.c index 4d22e7d2adca..7a870f6add7b 100644 --- a/drivers/target/target_core_xcopy.c +++ b/drivers/target/target_core_xcopy.c @@ -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; -- cgit v1.2.3