diff options
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r-- | drivers/scsi/scsi_lib.c | 185 |
1 files changed, 98 insertions, 87 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 72b12102f777..60c7a7d74852 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -293,21 +293,6 @@ int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd, } EXPORT_SYMBOL(__scsi_execute); -/** - * scsi_init_cmd_errh - Initialize cmd fields related to error handling. - * @cmd: command that is ready to be queued. - * - * This function has the job of initializing a number of fields related to error - * handling. Typically this will be called once for each command, as required. - */ -static void scsi_init_cmd_errh(struct scsi_cmnd *cmd) -{ - scsi_set_resid(cmd, 0); - memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); - if (cmd->cmd_len == 0) - cmd->cmd_len = scsi_command_size(cmd->cmnd); -} - /* * Wake up the error handler if necessary. Avoid as follows that the error * handler is not woken up if host in-flight requests number == @@ -530,7 +515,7 @@ static void scsi_uninit_cmd(struct scsi_cmnd *cmd) } } -static void scsi_free_sgtables(struct scsi_cmnd *cmd) +void scsi_free_sgtables(struct scsi_cmnd *cmd) { if (cmd->sdb.table.nents) sg_free_table_chained(&cmd->sdb.table, @@ -539,6 +524,7 @@ static void scsi_free_sgtables(struct scsi_cmnd *cmd) sg_free_table_chained(&cmd->prot_sdb->table, SCSI_INLINE_PROT_SG_CNT); } +EXPORT_SYMBOL_GPL(scsi_free_sgtables); static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd) { @@ -549,10 +535,27 @@ static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd) static void scsi_run_queue_async(struct scsi_device *sdev) { if (scsi_target(sdev)->single_lun || - !list_empty(&sdev->host->starved_list)) + !list_empty(&sdev->host->starved_list)) { kblockd_schedule_work(&sdev->requeue_work); - else - blk_mq_run_hw_queues(sdev->request_queue, true); + } else { + /* + * smp_mb() present in sbitmap_queue_clear() or implied in + * .end_io is for ordering writing .device_busy in + * scsi_device_unbusy() and reading sdev->restarts. + */ + int old = atomic_read(&sdev->restarts); + + /* + * ->restarts has to be kept as non-zero if new budget + * contention occurs. + * + * No need to run queue when either another re-run + * queue wins in updating ->restarts or a new budget + * contention occurs. + */ + if (old && atomic_cmpxchg(&sdev->restarts, old, 0) == old) + blk_mq_run_hw_queues(sdev->request_queue, true); + } } /* Returns false when no more bytes to process, true if there are more */ @@ -652,6 +655,23 @@ static void scsi_io_completion_reprep(struct scsi_cmnd *cmd, scsi_mq_requeue_cmd(cmd); } +static bool scsi_cmd_runtime_exceeced(struct scsi_cmnd *cmd) +{ + struct request *req = cmd->request; + unsigned long wait_for; + + if (cmd->allowed == SCSI_CMD_RETRIES_NO_LIMIT) + return false; + + wait_for = (cmd->allowed + 1) * req->timeout; + if (time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) { + scmd_printk(KERN_ERR, cmd, "timing out command, waited %lus\n", + wait_for/HZ); + return true; + } + return false; +} + /* Helper for scsi_io_completion() when special action required. */ static void scsi_io_completion_action(struct scsi_cmnd *cmd, int result) { @@ -660,7 +680,6 @@ static void scsi_io_completion_action(struct scsi_cmnd *cmd, int result) int level = 0; enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY, ACTION_DELAYED_RETRY} action; - unsigned long wait_for = (cmd->allowed + 1) * req->timeout; struct scsi_sense_hdr sshdr; bool sense_valid; bool sense_current = true; /* false implies "deferred sense" */ @@ -774,8 +793,7 @@ static void scsi_io_completion_action(struct scsi_cmnd *cmd, int result) } else action = ACTION_FAIL; - if (action != ACTION_FAIL && - time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) + if (action != ACTION_FAIL && scsi_cmd_runtime_exceeced(cmd)) action = ACTION_FAIL; switch (action) { @@ -975,7 +993,7 @@ static inline bool scsi_cmd_needs_dma_drain(struct scsi_device *sdev, } /** - * scsi_init_io - SCSI I/O initialization function. + * scsi_alloc_sgtables - allocate S/G tables for a command * @cmd: command descriptor we wish to initialize * * Returns: @@ -983,7 +1001,7 @@ static inline bool scsi_cmd_needs_dma_drain(struct scsi_device *sdev, * * BLK_STS_RESOURCE - if the failure is retryable * * BLK_STS_IOERR - if the failure is fatal */ -blk_status_t scsi_init_io(struct scsi_cmnd *cmd) +blk_status_t scsi_alloc_sgtables(struct scsi_cmnd *cmd) { struct scsi_device *sdev = cmd->device; struct request *rq = cmd->request; @@ -1075,7 +1093,7 @@ out_free_sgtables: scsi_free_sgtables(cmd); return ret; } -EXPORT_SYMBOL(scsi_init_io); +EXPORT_SYMBOL(scsi_alloc_sgtables); /** * scsi_initialize_rq - initialize struct scsi_cmnd partially @@ -1163,7 +1181,7 @@ static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev, * submit a request without an attached bio. */ if (req->bio) { - blk_status_t ret = scsi_init_io(cmd); + blk_status_t ret = scsi_alloc_sgtables(cmd); if (unlikely(ret != BLK_STS_OK)) return ret; } else { @@ -1173,58 +1191,16 @@ static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev, } cmd->cmd_len = scsi_req(req)->cmd_len; + if (cmd->cmd_len == 0) + cmd->cmd_len = scsi_command_size(cmd->cmnd); cmd->cmnd = scsi_req(req)->cmd; cmd->transfersize = blk_rq_bytes(req); cmd->allowed = scsi_req(req)->retries; return BLK_STS_OK; } -/* - * Setup a normal block command. These are simple request from filesystems - * that still need to be translated to SCSI CDBs from the ULD. - */ -static blk_status_t scsi_setup_fs_cmnd(struct scsi_device *sdev, - struct request *req) -{ - struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req); - - if (unlikely(sdev->handler && sdev->handler->prep_fn)) { - blk_status_t ret = sdev->handler->prep_fn(sdev, req); - if (ret != BLK_STS_OK) - return ret; - } - - cmd->cmnd = scsi_req(req)->cmd = scsi_req(req)->__cmd; - memset(cmd->cmnd, 0, BLK_MAX_CDB); - return scsi_cmd_to_driver(cmd)->init_command(cmd); -} - -static blk_status_t scsi_setup_cmnd(struct scsi_device *sdev, - struct request *req) -{ - struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req); - blk_status_t ret; - - if (!blk_rq_bytes(req)) - cmd->sc_data_direction = DMA_NONE; - else if (rq_data_dir(req) == WRITE) - cmd->sc_data_direction = DMA_TO_DEVICE; - else - cmd->sc_data_direction = DMA_FROM_DEVICE; - - if (blk_rq_is_scsi(req)) - ret = scsi_setup_scsi_cmnd(sdev, req); - else - ret = scsi_setup_fs_cmnd(sdev, req); - - if (ret != BLK_STS_OK) - scsi_free_sgtables(cmd); - - return ret; -} - static blk_status_t -scsi_prep_state_check(struct scsi_device *sdev, struct request *req) +scsi_device_state_check(struct scsi_device *sdev, struct request *req) { switch (sdev->sdev_state) { case SDEV_OFFLINE: @@ -1448,7 +1424,6 @@ static bool scsi_mq_lld_busy(struct request_queue *q) static void scsi_softirq_done(struct request *rq) { struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); - unsigned long wait_for = (cmd->allowed + 1) * rq->timeout; int disposition; INIT_LIST_HEAD(&cmd->eh_entry); @@ -1458,13 +1433,8 @@ static void scsi_softirq_done(struct request *rq) atomic_inc(&cmd->device->ioerr_cnt); disposition = scsi_decide_disposition(cmd); - if (disposition != SUCCESS && - time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) { - scmd_printk(KERN_ERR, cmd, - "timing out command, waited %lus\n", - wait_for/HZ); + if (disposition != SUCCESS && scsi_cmd_runtime_exceeced(cmd)) disposition = SUCCESS; - } scsi_log_completion(cmd, disposition); @@ -1572,7 +1542,7 @@ static unsigned int scsi_mq_inline_sgl_size(struct Scsi_Host *shost) sizeof(struct scatterlist); } -static blk_status_t scsi_mq_prep_fn(struct request *req) +static blk_status_t scsi_prepare_cmd(struct request *req) { struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req); struct scsi_device *sdev = req->q->queuedata; @@ -1584,6 +1554,10 @@ static blk_status_t scsi_mq_prep_fn(struct request *req) cmd->request = req; cmd->tag = req->tag; cmd->prot_op = SCSI_PROT_NORMAL; + if (blk_rq_bytes(req)) + cmd->sc_data_direction = rq_dma_dir(req); + else + cmd->sc_data_direction = DMA_NONE; sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size; cmd->sdb.table.sgl = sg; @@ -1595,9 +1569,23 @@ static blk_status_t scsi_mq_prep_fn(struct request *req) (struct scatterlist *)(cmd->prot_sdb + 1); } - blk_mq_start_request(req); + /* + * Special handling for passthrough commands, which don't go to the ULP + * at all: + */ + if (blk_rq_is_scsi(req)) + return scsi_setup_scsi_cmnd(sdev, req); + + if (sdev->handler && sdev->handler->prep_fn) { + blk_status_t ret = sdev->handler->prep_fn(sdev, req); + + if (ret != BLK_STS_OK) + return ret; + } - return scsi_setup_cmnd(sdev, req); + cmd->cmnd = scsi_req(req)->cmd = scsi_req(req)->__cmd; + memset(cmd->cmnd, 0, BLK_MAX_CDB); + return scsi_cmd_to_driver(cmd)->init_command(cmd); } static void scsi_mq_done(struct scsi_cmnd *cmd) @@ -1621,7 +1609,30 @@ static bool scsi_mq_get_budget(struct request_queue *q) { struct scsi_device *sdev = q->queuedata; - return scsi_dev_queue_ready(q, sdev); + if (scsi_dev_queue_ready(q, sdev)) + return true; + + atomic_inc(&sdev->restarts); + + /* + * Orders atomic_inc(&sdev->restarts) and atomic_read(&sdev->device_busy). + * .restarts must be incremented before .device_busy is read because the + * code in scsi_run_queue_async() depends on the order of these operations. + */ + smp_mb__after_atomic(); + + /* + * If all in-flight requests originated from this LUN are completed + * before reading .device_busy, sdev->device_busy will be observed as + * zero, then blk_mq_delay_run_hw_queues() will dispatch this request + * soon. Otherwise, completion of one of these requests will observe + * the .restarts flag, and the request queue will be run for handling + * this request, see scsi_end_request(). + */ + if (unlikely(atomic_read(&sdev->device_busy) == 0 && + !scsi_device_blocked(sdev))) + blk_mq_delay_run_hw_queues(sdev->request_queue, SCSI_QUEUE_DELAY); + return false; } static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, @@ -1640,7 +1651,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, * commands. */ if (unlikely(sdev->sdev_state != SDEV_RUNNING)) { - ret = scsi_prep_state_check(sdev, req); + ret = scsi_device_state_check(sdev, req); if (ret != BLK_STS_OK) goto out_put_budget; } @@ -1652,13 +1663,12 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, goto out_dec_target_busy; if (!(req->rq_flags & RQF_DONTPREP)) { - ret = scsi_mq_prep_fn(req); + ret = scsi_prepare_cmd(req); if (ret != BLK_STS_OK) goto out_dec_host_busy; req->rq_flags |= RQF_DONTPREP; } else { clear_bit(SCMD_STATE_COMPLETE, &cmd->state); - blk_mq_start_request(req); } cmd->flags &= SCMD_PRESERVED_FLAGS; @@ -1667,9 +1677,11 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, if (bd->last) cmd->flags |= SCMD_LAST; - scsi_init_cmd_errh(cmd); + scsi_set_resid(cmd, 0); + memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); cmd->scsi_done = scsi_mq_done; + blk_mq_start_request(req); reason = scsi_dispatch_cmd(cmd); if (reason) { scsi_set_blocked(cmd, reason); @@ -1930,7 +1942,6 @@ struct scsi_device *scsi_device_from_queue(struct request_queue *q) return sdev; } -EXPORT_SYMBOL_GPL(scsi_device_from_queue); /** * scsi_block_requests - Utility function used by low-level drivers to prevent |