From: Mike Christie Date: Sun, 22 Feb 2026 23:27:01 +0000 (-0600) Subject: scsi: target: Add support for completing commands from backend context X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=06933066d88a3093953b062922c016a67d2cdbf8;p=thirdparty%2Fkernel%2Fstable.git scsi: target: Add support for completing commands from backend context To complete a command several drivers just drop their reference and add it to list to be processed by a driver specific thread. So there's no need to go from backend context to the LIO thread then to the driver's thread. When avoiding the LIO thread, IOPS can increase from 20-30% for workloads like: fio --filename=/dev/sdb --direct=1 --rw=randrw --bs=8K \ --ioengine=libaio --iodepth=128 --numjobs=$jobs where increasing jobs increases the performance improvement (this is using NVMe drives with LIO's submit_type=1 to directly submit). Add the infrastructure so drivers and userspace can control how to complete a command like is done for the submission path. In this commit there is no behavior change and we continue to defer to the LIO workqueue thread. In the subsequent commits we will allow drivers to report what they support and allow userspace to control the behavior. Signed-off-by: Mike Christie Link: https://patch.msgid.link/20260222232946.7637-2-michael.christie@oracle.com Signed-off-by: Martin K. Petersen --- diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c index 74c6383f9eede..883a866e96ab2 100644 --- a/drivers/target/target_core_device.c +++ b/drivers/target/target_core_device.c @@ -813,6 +813,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name) DA_UNMAP_ZEROES_DATA_DEFAULT; dev->dev_attrib.max_write_same_len = DA_MAX_WRITE_SAME_LEN; dev->dev_attrib.submit_type = TARGET_FABRIC_DEFAULT_SUBMIT; + dev->dev_attrib.submit_type = TARGET_QUEUE_COMPL; /* Skip allocating lun_stats since we can't export them. */ xcopy_lun = &dev->xcopy_lun; diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index a7330c4fedde3..34249fb80c678 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -902,13 +902,59 @@ static bool target_cmd_interrupted(struct se_cmd *cmd) return false; } +static void target_complete(struct se_cmd *cmd, int success) +{ + struct se_wwn *wwn = cmd->se_sess->se_tpg->se_tpg_wwn; + struct se_dev_attrib *da; + u8 compl_type; + int cpu; + + if (!wwn) { + cpu = cmd->cpuid; + goto queue_work; + } + + da = &cmd->se_dev->dev_attrib; + if (da->complete_type == TARGET_FABRIC_DEFAULT_COMPL) + compl_type = wwn->wwn_tf->tf_ops->default_compl_type; + else if (da->complete_type == TARGET_DIRECT_SUBMIT && + wwn->wwn_tf->tf_ops->direct_compl_supp) + compl_type = TARGET_DIRECT_COMPL; + else + compl_type = TARGET_QUEUE_COMPL; + + if (compl_type == TARGET_DIRECT_COMPL) { + /* + * Failure handling and processing secondary stages of + * complex commands can be too heavy to handle from the + * fabric driver so always defer. + */ + if (success && !cmd->transport_complete_callback) { + target_complete_ok_work(&cmd->work); + return; + } + + compl_type = TARGET_QUEUE_COMPL; + } + +queue_work: + INIT_WORK(&cmd->work, success ? target_complete_ok_work : + target_complete_failure_work); + + if (!wwn || wwn->cmd_compl_affinity == SE_COMPL_AFFINITY_CPUID) + cpu = cmd->cpuid; + else + cpu = wwn->cmd_compl_affinity; + + queue_work_on(cpu, target_completion_wq, &cmd->work); +} + /* May be called from interrupt context so must not sleep. */ void target_complete_cmd_with_sense(struct se_cmd *cmd, u8 scsi_status, sense_reason_t sense_reason) { - struct se_wwn *wwn = cmd->se_sess->se_tpg->se_tpg_wwn; - int success, cpu; unsigned long flags; + int success; if (target_cmd_interrupted(cmd)) return; @@ -933,15 +979,7 @@ void target_complete_cmd_with_sense(struct se_cmd *cmd, u8 scsi_status, cmd->transport_state |= (CMD_T_COMPLETE | CMD_T_ACTIVE); spin_unlock_irqrestore(&cmd->t_state_lock, flags); - INIT_WORK(&cmd->work, success ? target_complete_ok_work : - target_complete_failure_work); - - if (!wwn || wwn->cmd_compl_affinity == SE_COMPL_AFFINITY_CPUID) - cpu = cmd->cpuid; - else - cpu = wwn->cmd_compl_affinity; - - queue_work_on(cpu, target_completion_wq, &cmd->work); + target_complete(cmd, success); } EXPORT_SYMBOL(target_complete_cmd_with_sense); diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index b62d5fcce950d..9a0e9f9e1ec44 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -111,6 +111,15 @@ /* Peripheral Device Text Identification Information */ #define PD_TEXT_ID_INFO_LEN 256 +enum target_compl_type { + /* Use the fabric driver's default completion type */ + TARGET_FABRIC_DEFAULT_COMPL, + /* Complete from the backend calling context */ + TARGET_DIRECT_COMPL, + /* Defer completion to the LIO workqueue */ + TARGET_QUEUE_COMPL, +}; + enum target_submit_type { /* Use the fabric driver's default submission type */ TARGET_FABRIC_DEFAULT_SUBMIT, @@ -741,6 +750,7 @@ struct se_dev_attrib { u32 atomic_granularity; u32 atomic_max_with_boundary; u32 atomic_max_boundary; + u8 complete_type; u8 submit_type; struct se_device *da_dev; struct config_group da_group; diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h index 3378ff9ee271c..e9039e73d058a 100644 --- a/include/target/target_core_fabric.h +++ b/include/target/target_core_fabric.h @@ -118,15 +118,21 @@ struct target_core_fabric_ops { * its entirety before a command is aborted. */ unsigned int write_pending_must_be_called:1; + /* + * Set this if the driver does not require calling queue_data_in + * queue_status and check_stop_free from a worker thread when + * completing successful commands. + */ + unsigned int direct_compl_supp:1; /* * Set this if the driver supports submitting commands to the backend * from target_submit/target_submit_cmd. */ unsigned int direct_submit_supp:1; - /* - * Set this to a target_submit_type value. - */ + /* Set this to a target_submit_type value. */ u8 default_submit_type; + /* Set this to the target_compl_type value. */ + u8 default_compl_type; }; int target_register_template(const struct target_core_fabric_ops *fo);