Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755217AbaGILZR (ORCPT ); Wed, 9 Jul 2014 07:25:17 -0400 Received: from cantor2.suse.de ([195.135.220.15]:41758 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753786AbaGILZO (ORCPT ); Wed, 9 Jul 2014 07:25:14 -0400 Message-ID: <53BD2698.1010706@suse.de> Date: Wed, 09 Jul 2014 13:25:12 +0200 From: Hannes Reinecke User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Christoph Hellwig , James Bottomley CC: Jens Axboe , Bart Van Assche , Robert Elliott , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 13/14] scsi: add support for a blk-mq based I/O path. References: <1403715121-1201-1-git-send-email-hch@lst.de> <1403715121-1201-14-git-send-email-hch@lst.de> In-Reply-To: <1403715121-1201-14-git-send-email-hch@lst.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/25/2014 06:52 PM, Christoph Hellwig wrote: > This patch adds support for an alternate I/O path in the scsi midlayer > which uses the blk-mq infrastructure instead of the legacy request code. > > Use of blk-mq is fully transparent to drivers, although for now a host > template field is provided to opt out of blk-mq usage in case any unforseen > incompatibilities arise. > > In general replacing the legacy request code with blk-mq is a simple and > mostly mechanical transformation. The biggest exception is the new code > that deals with the fact the I/O submissions in blk-mq must happen from > process context, which slightly complicates the I/O completion handler. > The second biggest differences is that blk-mq is build around the concept > of preallocated requests that also include driver specific data, which > in SCSI context means the scsi_cmnd structure. This completely avoids > dynamic memory allocations for the fast path through I/O submission. > > Due the preallocated requests the MQ code path exclusively uses the > host-wide shared tag allocator instead of a per-LUN one. This only > affects drivers actually using the block layer provided tag allocator > instead of their own. Unlike the old path blk-mq always provides a tag, > although drivers don't have to use it. > > For now the blk-mq path is disable by defauly and must be enabled using > the "use_blk_mq" module parameter. Once the remaining work in the block > layer to make blk-mq more suitable for slow devices is complete I hope > to make it the default and eventually even remove the old code path. > > Based on the earlier scsi-mq prototype by Nicholas Bellinger. > > Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and > various sugestions and code contributions. > > Signed-off-by: Christoph Hellwig > --- > drivers/scsi/hosts.c | 30 ++- > drivers/scsi/scsi.c | 5 +- > drivers/scsi/scsi_lib.c | 475 +++++++++++++++++++++++++++++++++++++++------ > drivers/scsi/scsi_priv.h | 3 + > drivers/scsi/scsi_scan.c | 5 +- > drivers/scsi/scsi_sysfs.c | 2 + > include/scsi/scsi_host.h | 18 +- > include/scsi/scsi_tcq.h | 28 ++- > 8 files changed, 494 insertions(+), 72 deletions(-) > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > index 0632eee..6322e6c 100644 > --- a/drivers/scsi/hosts.c > +++ b/drivers/scsi/hosts.c > @@ -213,9 +213,24 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, > goto fail; > } > > + if (shost_use_blk_mq(shost)) { > + error = scsi_mq_setup_tags(shost); > + if (error) > + goto fail; > + } > + > + /* > + * Note that we allocate the freelist even for the MQ case for now, > + * as we need a command set aside for scsi_reset_provider. Having > + * the full host freelist and one command available for that is a > + * little heavy-handed, but avoids introducing a special allocator > + * just for this. Eventually the structure of scsi_reset_provider > + * will need a major overhaul. > + */ > error = scsi_setup_command_freelist(shost); > if (error) > - goto fail; > + goto out_destroy_tags; > + > > if (!shost->shost_gendev.parent) > shost->shost_gendev.parent = dev ? dev : &platform_bus; > @@ -226,7 +241,7 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, > > error = device_add(&shost->shost_gendev); > if (error) > - goto out; > + goto out_destroy_freelist; > > pm_runtime_set_active(&shost->shost_gendev); > pm_runtime_enable(&shost->shost_gendev); > @@ -279,8 +294,11 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, > device_del(&shost->shost_dev); > out_del_gendev: > device_del(&shost->shost_gendev); > - out: > + out_destroy_freelist: > scsi_destroy_command_freelist(shost); > + out_destroy_tags: > + if (shost_use_blk_mq(shost)) > + scsi_mq_destroy_tags(shost); > fail: > return error; > } > @@ -309,7 +327,9 @@ static void scsi_host_dev_release(struct device *dev) > } > > scsi_destroy_command_freelist(shost); > - if (shost->bqt) > + if (shost_use_blk_mq(shost) && shost->tag_set.tags) > + scsi_mq_destroy_tags(shost); > + else if (shost->bqt) > blk_free_tags(shost->bqt); > > kfree(shost->shost_data); > @@ -436,6 +456,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) > else > shost->dma_boundary = 0xffffffff; > > + shost->use_blk_mq = scsi_use_blk_mq && !shost->hostt->disable_blk_mq; > + > device_initialize(&shost->shost_gendev); > dev_set_name(&shost->shost_gendev, "host%d", shost->host_no); > shost->shost_gendev.bus = &scsi_bus_type; > diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c > index b362058..c089812 100644 > --- a/drivers/scsi/scsi.c > +++ b/drivers/scsi/scsi.c > @@ -809,7 +809,7 @@ void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags) > * is more IO than the LLD's can_queue (so there are not enuogh > * tags) request_fn's host queue ready check will handle it. > */ > - if (!sdev->host->bqt) { > + if (!shost_use_blk_mq(sdev->host) && !sdev->host->bqt) { > if (blk_queue_tagged(sdev->request_queue) && > blk_queue_resize_tags(sdev->request_queue, tags) != 0) > goto out; > @@ -1363,6 +1363,9 @@ MODULE_LICENSE("GPL"); > module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR); > MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels"); > > +bool scsi_use_blk_mq = false; > +module_param_named(use_blk_mq, scsi_use_blk_mq, bool, S_IWUSR | S_IRUGO); > + > static int __init init_scsi(void) > { > int error; > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 900b1c0..5d39cfc 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1,5 +1,6 @@ > /* > - * scsi_lib.c Copyright (C) 1999 Eric Youngdale > + * Copyright (C) 1999 Eric Youngdale > + * Copyright (C) 2014 Christoph Hellwig > * > * SCSI queueing library. > * Initial versions: Eric Youngdale (eric@andante.org). > @@ -20,6 +21,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -113,6 +115,16 @@ scsi_set_blocked(struct scsi_cmnd *cmd, int reason) > } > } > > +static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd) > +{ > + struct scsi_device *sdev = cmd->device; > + struct request_queue *q = cmd->request->q; > + > + blk_mq_requeue_request(cmd->request); > + blk_mq_kick_requeue_list(q); > + put_device(&sdev->sdev_gendev); > +} > + > /** > * __scsi_queue_insert - private queue insertion > * @cmd: The SCSI command being requeued > @@ -150,6 +162,10 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy) > * before blk_cleanup_queue() finishes. > */ > cmd->result = 0; > + if (q->mq_ops) { > + scsi_mq_requeue_cmd(cmd); > + return; > + } > spin_lock_irqsave(q->queue_lock, flags); > blk_requeue_request(q, cmd->request); > kblockd_schedule_work(&device->requeue_work); > @@ -308,6 +324,14 @@ void scsi_device_unbusy(struct scsi_device *sdev) > atomic_dec(&sdev->device_busy); > } > > +static void scsi_kick_queue(struct request_queue *q) > +{ > + if (q->mq_ops) > + blk_mq_start_hw_queues(q); > + else > + blk_run_queue(q); > +} > + > /* > * Called for single_lun devices on IO completion. Clear starget_sdev_user, > * and call blk_run_queue for all the scsi_devices on the target - > @@ -332,7 +356,7 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev) > * but in most cases, we will be first. Ideally, each LU on the > * target would get some limited time or requests on the target. > */ > - blk_run_queue(current_sdev->request_queue); > + scsi_kick_queue(current_sdev->request_queue); > > spin_lock_irqsave(shost->host_lock, flags); > if (starget->starget_sdev_user) > @@ -345,7 +369,7 @@ static void scsi_single_lun_run(struct scsi_device *current_sdev) > continue; > > spin_unlock_irqrestore(shost->host_lock, flags); > - blk_run_queue(sdev->request_queue); > + scsi_kick_queue(sdev->request_queue); > spin_lock_irqsave(shost->host_lock, flags); > > scsi_device_put(sdev); > @@ -438,7 +462,7 @@ static void scsi_starved_list_run(struct Scsi_Host *shost) > continue; > spin_unlock_irqrestore(shost->host_lock, flags); > > - blk_run_queue(slq); > + scsi_kick_queue(slq); > blk_put_queue(slq); > > spin_lock_irqsave(shost->host_lock, flags); > @@ -469,7 +493,10 @@ static void scsi_run_queue(struct request_queue *q) > if (!list_empty(&sdev->host->starved_list)) > scsi_starved_list_run(sdev->host); > > - blk_run_queue(q); > + if (q->mq_ops) > + blk_mq_start_stopped_hw_queues(q, false); > + else > + blk_run_queue(q); > } > > void scsi_requeue_run_queue(struct work_struct *work) > @@ -567,25 +594,72 @@ static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask) > return mempool_alloc(sgp->pool, gfp_mask); > } > > -static void scsi_free_sgtable(struct scsi_data_buffer *sdb) > +static void scsi_free_sgtable(struct scsi_data_buffer *sdb, bool mq) > { > - __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, false, scsi_sg_free); > + if (mq && sdb->table.nents <= SCSI_MAX_SG_SEGMENTS) > + return; > + __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, mq, scsi_sg_free); > } > > static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents, > - gfp_t gfp_mask) > + gfp_t gfp_mask, bool mq) > { > + struct scatterlist *first_chunk = NULL; > int ret; > > BUG_ON(!nents); > > + if (mq) { > + if (nents <= SCSI_MAX_SG_SEGMENTS) { > + sdb->table.nents = nents; > + sg_init_table(sdb->table.sgl, sdb->table.nents); > + return 0; > + } > + first_chunk = sdb->table.sgl; > + } > + > ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS, > - NULL, gfp_mask, scsi_sg_alloc); > + first_chunk, gfp_mask, scsi_sg_alloc); > if (unlikely(ret)) > - scsi_free_sgtable(sdb); > + scsi_free_sgtable(sdb, mq); > return ret; > } > > +static void scsi_uninit_cmd(struct scsi_cmnd *cmd) > +{ > + if (cmd->request->cmd_type == REQ_TYPE_FS) { > + struct scsi_driver *drv = scsi_cmd_to_driver(cmd); > + > + if (drv->uninit_command) > + drv->uninit_command(cmd); > + } > +} > + > +static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd) > +{ > + if (cmd->sdb.table.nents) > + scsi_free_sgtable(&cmd->sdb, true); > + if (cmd->request->next_rq && cmd->request->next_rq->special) > + scsi_free_sgtable(cmd->request->next_rq->special, true); > + if (scsi_prot_sg_count(cmd)) > + scsi_free_sgtable(cmd->prot_sdb, true); > +} > + > +static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd) > +{ > + struct scsi_device *sdev = cmd->device; > + unsigned long flags; > + > + BUG_ON(list_empty(&cmd->list)); > + > + scsi_mq_free_sgtables(cmd); > + scsi_uninit_cmd(cmd); > + > + spin_lock_irqsave(&sdev->list_lock, flags); > + list_del_init(&cmd->list); > + spin_unlock_irqrestore(&sdev->list_lock, flags); > +} > + > /* > * Function: scsi_release_buffers() > * > @@ -605,12 +679,12 @@ static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents, > void scsi_release_buffers(struct scsi_cmnd *cmd) > { > if (cmd->sdb.table.nents) > - scsi_free_sgtable(&cmd->sdb); > + scsi_free_sgtable(&cmd->sdb, false); > > memset(&cmd->sdb, 0, sizeof(cmd->sdb)); > > if (scsi_prot_sg_count(cmd)) > - scsi_free_sgtable(cmd->prot_sdb); > + scsi_free_sgtable(cmd->prot_sdb, false); > } > EXPORT_SYMBOL(scsi_release_buffers); > > @@ -618,7 +692,7 @@ static void scsi_release_bidi_buffers(struct scsi_cmnd *cmd) > { > struct scsi_data_buffer *bidi_sdb = cmd->request->next_rq->special; > > - scsi_free_sgtable(bidi_sdb); > + scsi_free_sgtable(bidi_sdb, false); > kmem_cache_free(scsi_sdb_cache, bidi_sdb); > cmd->request->next_rq->special = NULL; > } > @@ -629,8 +703,6 @@ static bool scsi_end_request(struct request *req, int error, > struct scsi_cmnd *cmd = req->special; > struct scsi_device *sdev = cmd->device; > struct request_queue *q = sdev->request_queue; > - unsigned long flags; > - > > if (blk_update_request(req, error, bytes)) > return true; > @@ -643,14 +715,38 @@ static bool scsi_end_request(struct request *req, int error, > if (blk_queue_add_random(q)) > add_disk_randomness(req->rq_disk); > > - spin_lock_irqsave(q->queue_lock, flags); > - blk_finish_request(req, error); > - spin_unlock_irqrestore(q->queue_lock, flags); > + if (req->mq_ctx) { > + /* > + * In the MQ case the command gets freed by __blk_mq_end_io, > + * so we have to do all cleanup that depends on it earlier. > + * > + * We also can't kick the queues from irq context, so we > + * will have to defer it to a workqueue. > + */ > + scsi_mq_uninit_cmd(cmd); > + > + __blk_mq_end_io(req, error); > + > + if (scsi_target(sdev)->single_lun || > + !list_empty(&sdev->host->starved_list)) > + kblockd_schedule_work(&sdev->requeue_work); > + else > + blk_mq_start_stopped_hw_queues(q, true); > + > + put_device(&sdev->sdev_gendev); > + } else { > + unsigned long flags; > + > + spin_lock_irqsave(q->queue_lock, flags); > + blk_finish_request(req, error); > + spin_unlock_irqrestore(q->queue_lock, flags); > + > + if (bidi_bytes) > + scsi_release_bidi_buffers(cmd); > + scsi_release_buffers(cmd); > + scsi_next_command(cmd); > + } > > - if (bidi_bytes) > - scsi_release_bidi_buffers(cmd); > - scsi_release_buffers(cmd); > - scsi_next_command(cmd); > return false; > } > > @@ -981,8 +1077,14 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) > /* Unprep the request and put it back at the head of the queue. > * A new command will be prepared and issued. > */ > - scsi_release_buffers(cmd); > - scsi_requeue_command(q, cmd); > + if (q->mq_ops) { > + cmd->request->cmd_flags &= ~REQ_DONTPREP; > + scsi_mq_uninit_cmd(cmd); > + scsi_mq_requeue_cmd(cmd); > + } else { > + scsi_release_buffers(cmd); > + scsi_requeue_command(q, cmd); > + } > break; > case ACTION_RETRY: > /* Retry the same command immediately */ > @@ -1004,9 +1106,8 @@ static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb, > * If sg table allocation fails, requeue request later. > */ > if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments, > - gfp_mask))) { > + gfp_mask, req->mq_ctx != NULL))) > return BLKPREP_DEFER; > - } > > /* > * Next, walk the list, and fill in the addresses and sizes of > @@ -1034,21 +1135,27 @@ int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask) > { > struct scsi_device *sdev = cmd->device; > struct request *rq = cmd->request; > + bool is_mq = (rq->mq_ctx != NULL); > + int error; > > - int error = scsi_init_sgtable(rq, &cmd->sdb, gfp_mask); > + error = scsi_init_sgtable(rq, &cmd->sdb, gfp_mask); > if (error) > goto err_exit; > > if (blk_bidi_rq(rq)) { > - struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc( > - scsi_sdb_cache, GFP_ATOMIC); > - if (!bidi_sdb) { > - error = BLKPREP_DEFER; > - goto err_exit; > + if (!rq->q->mq_ops) { > + struct scsi_data_buffer *bidi_sdb = > + kmem_cache_zalloc(scsi_sdb_cache, GFP_ATOMIC); > + if (!bidi_sdb) { > + error = BLKPREP_DEFER; > + goto err_exit; > + } > + > + rq->next_rq->special = bidi_sdb; > } > > - rq->next_rq->special = bidi_sdb; > - error = scsi_init_sgtable(rq->next_rq, bidi_sdb, GFP_ATOMIC); > + error = scsi_init_sgtable(rq->next_rq, rq->next_rq->special, > + GFP_ATOMIC); > if (error) > goto err_exit; > } > @@ -1060,7 +1167,7 @@ int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask) > BUG_ON(prot_sdb == NULL); > ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio); > > - if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) { > + if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask, is_mq)) { > error = BLKPREP_DEFER; > goto err_exit; > } > @@ -1074,13 +1181,16 @@ int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask) > cmd->prot_sdb->table.nents = count; > } > > - return BLKPREP_OK ; > - > + return BLKPREP_OK; > err_exit: > - scsi_release_buffers(cmd); > - cmd->request->special = NULL; > - scsi_put_command(cmd); > - put_device(&sdev->sdev_gendev); > + if (is_mq) { > + scsi_mq_free_sgtables(cmd); > + } else { > + scsi_release_buffers(cmd); > + cmd->request->special = NULL; > + scsi_put_command(cmd); > + put_device(&sdev->sdev_gendev); > + } > return error; > } > EXPORT_SYMBOL(scsi_init_io); > @@ -1295,13 +1405,7 @@ out: > > static void scsi_unprep_fn(struct request_queue *q, struct request *req) > { > - if (req->cmd_type == REQ_TYPE_FS) { > - struct scsi_cmnd *cmd = req->special; > - struct scsi_driver *drv = scsi_cmd_to_driver(cmd); > - > - if (drv->uninit_command) > - drv->uninit_command(cmd); > - } > + scsi_uninit_cmd(req->special); > } > > /* > @@ -1318,7 +1422,11 @@ static inline int scsi_dev_queue_ready(struct request_queue *q, > busy = atomic_inc_return(&sdev->device_busy) - 1; > if (busy == 0 && atomic_read(&sdev->device_blocked) > 0) { > if (atomic_dec_return(&sdev->device_blocked) > 0) { > - blk_delay_queue(q, SCSI_QUEUE_DELAY); > + /* > + * For the MQ case we take care of this in the caller. > + */ > + if (!q->mq_ops) > + blk_delay_queue(q, SCSI_QUEUE_DELAY); > goto out_dec; > } > SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, > @@ -1688,6 +1796,188 @@ out_delay: > blk_delay_queue(q, SCSI_QUEUE_DELAY); > } > > +static inline int prep_to_mq(int ret) > +{ > + switch (ret) { > + case BLKPREP_OK: > + return 0; > + case BLKPREP_DEFER: > + return BLK_MQ_RQ_QUEUE_BUSY; > + default: > + return BLK_MQ_RQ_QUEUE_ERROR; > + } > +} > + > +static int scsi_mq_prep_fn(struct request *req) > +{ > + struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req); > + struct scsi_device *sdev = req->q->queuedata; > + struct Scsi_Host *shost = sdev->host; > + unsigned char *sense_buf = cmd->sense_buffer; > + struct scatterlist *sg; > + > + memset(cmd, 0, sizeof(struct scsi_cmnd)); > + > + req->special = cmd; > + > + cmd->request = req; > + cmd->device = sdev; > + cmd->sense_buffer = sense_buf; > + > + cmd->tag = req->tag; > + > + req->cmd = req->__cmd; > + cmd->cmnd = req->cmd; > + cmd->prot_op = SCSI_PROT_NORMAL; > + > + INIT_LIST_HEAD(&cmd->list); > + INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler); > + cmd->jiffies_at_alloc = jiffies; > + > + /* > + * XXX: cmd_list lookups are only used by two drivers, try to get > + * rid of this list in common code. > + */ > + spin_lock_irq(&sdev->list_lock); > + list_add_tail(&cmd->list, &sdev->cmd_list); > + spin_unlock_irq(&sdev->list_lock); > + > + sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size; > + cmd->sdb.table.sgl = sg; > + > + if (scsi_host_get_prot(shost)) { > + cmd->prot_sdb = (void *)sg + > + shost->sg_tablesize * sizeof(struct scatterlist); > + memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer)); > + > + cmd->prot_sdb->table.sgl = > + (struct scatterlist *)(cmd->prot_sdb + 1); > + } > + > + if (blk_bidi_rq(req)) { > + struct request *next_rq = req->next_rq; > + struct scsi_data_buffer *bidi_sdb = blk_mq_rq_to_pdu(next_rq); > + > + memset(bidi_sdb, 0, sizeof(struct scsi_data_buffer)); > + bidi_sdb->table.sgl = > + (struct scatterlist *)(bidi_sdb + 1); > + > + next_rq->special = bidi_sdb; > + } > + > + switch (req->cmd_type) { > + case REQ_TYPE_FS: > + return scsi_cmd_to_driver(cmd)->init_command(cmd); > + case REQ_TYPE_BLOCK_PC: > + return scsi_setup_blk_pc_cmnd(cmd->device, req); > + default: > + return BLKPREP_KILL; > + } > +} > + > +static void scsi_mq_done(struct scsi_cmnd *cmd) > +{ > + trace_scsi_dispatch_cmd_done(cmd); > + blk_mq_complete_request(cmd->request); > +} > + > +static int scsi_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req) > +{ > + struct request_queue *q = req->q; > + struct scsi_device *sdev = q->queuedata; > + struct Scsi_Host *shost = sdev->host; > + struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req); > + int ret; > + int reason; > + > + ret = prep_to_mq(scsi_prep_state_check(sdev, req)); > + if (ret) > + goto out; > + > + ret = BLK_MQ_RQ_QUEUE_BUSY; > + if (!get_device(&sdev->sdev_gendev)) > + goto out; > + > + if (!scsi_dev_queue_ready(q, sdev)) > + goto out_put_device; > + if (!scsi_target_queue_ready(shost, sdev)) > + goto out_dec_device_busy; > + if (!scsi_host_queue_ready(q, shost, sdev)) > + goto out_dec_target_busy; > + > + if (!(req->cmd_flags & REQ_DONTPREP)) { > + ret = prep_to_mq(scsi_mq_prep_fn(req)); > + if (ret) > + goto out_dec_host_busy; > + req->cmd_flags |= REQ_DONTPREP; > + } > + > + scsi_init_cmd_errh(cmd); > + cmd->scsi_done = scsi_mq_done; > + > + reason = scsi_dispatch_cmd(cmd); > + if (reason) { > + scsi_set_blocked(cmd, reason); > + ret = BLK_MQ_RQ_QUEUE_BUSY; > + goto out_dec_host_busy; > + } > + > + return BLK_MQ_RQ_QUEUE_OK; > + > +out_dec_host_busy: > + cancel_delayed_work(&cmd->abort_work); > + atomic_dec(&shost->host_busy); > +out_dec_target_busy: > + if (scsi_target(sdev)->can_queue > 0) > + atomic_dec(&scsi_target(sdev)->target_busy); > +out_dec_device_busy: > + atomic_dec(&sdev->device_busy); > +out_put_device: > + put_device(&sdev->sdev_gendev); > +out: > + switch (ret) { > + case BLK_MQ_RQ_QUEUE_BUSY: > + blk_mq_stop_hw_queue(hctx); > + if (atomic_read(&sdev->device_busy) == 0 && > + !scsi_device_blocked(sdev)) > + blk_mq_delay_queue(hctx, SCSI_QUEUE_DELAY); > + break; > + case BLK_MQ_RQ_QUEUE_ERROR: > + /* > + * Make sure to release all allocated ressources when > + * we hit an error, as we will never see this command > + * again. > + */ > + if (req->cmd_flags & REQ_DONTPREP) > + scsi_mq_uninit_cmd(cmd); > + break; > + default: > + break; > + } > + return ret; > +} > + > +static int scsi_init_request(void *data, struct request *rq, > + unsigned int hctx_idx, unsigned int request_idx, > + unsigned int numa_node) > +{ > + struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); > + > + cmd->sense_buffer = kzalloc_node(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL, > + numa_node); > + if (!cmd->sense_buffer) > + return -ENOMEM; > + return 0; > +} > + > +static void scsi_exit_request(void *data, struct request *rq, > + unsigned int hctx_idx, unsigned int request_idx) > +{ > + struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); > + > + kfree(cmd->sense_buffer); > +} > + > u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost) > { > struct device *host_dev; > @@ -1710,16 +2000,10 @@ u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost) > } > EXPORT_SYMBOL(scsi_calculate_bounce_limit); > > -struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost, > - request_fn_proc *request_fn) > +static void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q) > { > - struct request_queue *q; > struct device *dev = shost->dma_dev; > > - q = blk_init_queue(request_fn, NULL); > - if (!q) > - return NULL; > - > /* > * this limit is imposed by hardware restrictions > */ > @@ -1750,7 +2034,17 @@ struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost, > * blk_queue_update_dma_alignment() later. > */ > blk_queue_dma_alignment(q, 0x03); > +} > > +struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost, > + request_fn_proc *request_fn) > +{ > + struct request_queue *q; > + > + q = blk_init_queue(request_fn, NULL); > + if (!q) > + return NULL; > + __scsi_init_queue(shost, q); > return q; > } > EXPORT_SYMBOL(__scsi_alloc_queue); > @@ -1771,6 +2065,55 @@ struct request_queue *scsi_alloc_queue(struct scsi_device *sdev) > return q; > } > > +static struct blk_mq_ops scsi_mq_ops = { > + .map_queue = blk_mq_map_queue, > + .queue_rq = scsi_queue_rq, > + .complete = scsi_softirq_done, > + .timeout = scsi_times_out, > + .init_request = scsi_init_request, > + .exit_request = scsi_exit_request, > +}; > + > +struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev) > +{ > + sdev->request_queue = blk_mq_init_queue(&sdev->host->tag_set); > + if (IS_ERR(sdev->request_queue)) > + return NULL; > + > + sdev->request_queue->queuedata = sdev; > + __scsi_init_queue(sdev->host, sdev->request_queue); > + return sdev->request_queue; > +} > + > +int scsi_mq_setup_tags(struct Scsi_Host *shost) > +{ > + unsigned int cmd_size, sgl_size, tbl_size; > + > + tbl_size = shost->sg_tablesize; > + if (tbl_size > SCSI_MAX_SG_SEGMENTS) > + tbl_size = SCSI_MAX_SG_SEGMENTS; > + sgl_size = tbl_size * sizeof(struct scatterlist); > + cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size; > + if (scsi_host_get_prot(shost)) > + cmd_size += sizeof(struct scsi_data_buffer) + sgl_size; > + > + memset(&shost->tag_set, 0, sizeof(shost->tag_set)); > + shost->tag_set.ops = &scsi_mq_ops; > + shost->tag_set.nr_hw_queues = 1; > + shost->tag_set.queue_depth = shost->can_queue; > + shost->tag_set.cmd_size = cmd_size; > + shost->tag_set.numa_node = NUMA_NO_NODE; > + shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; > + shost->tag_set.driver_data = shost; > + > + return blk_mq_alloc_tag_set(&shost->tag_set); > +} > + > +void scsi_mq_destroy_tags(struct Scsi_Host *shost) > +{ > + blk_mq_free_tag_set(&shost->tag_set); > +} > + > /* > * Function: scsi_block_requests() > * > @@ -2516,9 +2859,13 @@ scsi_internal_device_block(struct scsi_device *sdev) > * block layer from calling the midlayer with this device's > * request queue. > */ > - spin_lock_irqsave(q->queue_lock, flags); > - blk_stop_queue(q); > - spin_unlock_irqrestore(q->queue_lock, flags); > + if (q->mq_ops) { > + blk_mq_stop_hw_queues(q); > + } else { > + spin_lock_irqsave(q->queue_lock, flags); > + blk_stop_queue(q); > + spin_unlock_irqrestore(q->queue_lock, flags); > + } > > return 0; > } > @@ -2564,9 +2911,13 @@ scsi_internal_device_unblock(struct scsi_device *sdev, > sdev->sdev_state != SDEV_OFFLINE) > return -EINVAL; > > - spin_lock_irqsave(q->queue_lock, flags); > - blk_start_queue(q); > - spin_unlock_irqrestore(q->queue_lock, flags); > + if (q->mq_ops) { > + blk_mq_start_stopped_hw_queues(q, false); > + } else { > + spin_lock_irqsave(q->queue_lock, flags); > + blk_start_queue(q); > + spin_unlock_irqrestore(q->queue_lock, flags); > + } > > return 0; > } > diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h > index a45d1c2..12b8e1b 100644 > --- a/drivers/scsi/scsi_priv.h > +++ b/drivers/scsi/scsi_priv.h > @@ -88,6 +88,9 @@ extern void scsi_next_command(struct scsi_cmnd *cmd); > extern void scsi_io_completion(struct scsi_cmnd *, unsigned int); > extern void scsi_run_host_queues(struct Scsi_Host *shost); > extern struct request_queue *scsi_alloc_queue(struct scsi_device *sdev); > +extern struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev); > +extern int scsi_mq_setup_tags(struct Scsi_Host *shost); > +extern void scsi_mq_destroy_tags(struct Scsi_Host *shost); > extern int scsi_init_queue(void); > extern void scsi_exit_queue(void); > struct request_queue; > diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c > index 4a6e4ba..b91cfaf 100644 > --- a/drivers/scsi/scsi_scan.c > +++ b/drivers/scsi/scsi_scan.c > @@ -273,7 +273,10 @@ static struct scsi_device *scsi_alloc_sdev(struct scsi_target *starget, > */ > sdev->borken = 1; > > - sdev->request_queue = scsi_alloc_queue(sdev); > + if (shost_use_blk_mq(shost)) > + sdev->request_queue = scsi_mq_alloc_queue(sdev); > + else > + sdev->request_queue = scsi_alloc_queue(sdev); > if (!sdev->request_queue) { > /* release fn is set up in scsi_sysfs_device_initialise, so > * have to free and put manually here */ > diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c > index deef063..6c9227f 100644 > --- a/drivers/scsi/scsi_sysfs.c > +++ b/drivers/scsi/scsi_sysfs.c > @@ -333,6 +333,7 @@ store_shost_eh_deadline(struct device *dev, struct device_attribute *attr, > > static DEVICE_ATTR(eh_deadline, S_IRUGO | S_IWUSR, show_shost_eh_deadline, store_shost_eh_deadline); > > +shost_rd_attr(use_blk_mq, "%d\n"); > shost_rd_attr(unique_id, "%u\n"); > shost_rd_attr(cmd_per_lun, "%hd\n"); > shost_rd_attr(can_queue, "%hd\n"); > @@ -352,6 +353,7 @@ show_host_busy(struct device *dev, struct device_attribute *attr, char *buf) > static DEVICE_ATTR(host_busy, S_IRUGO, show_host_busy, NULL); > > static struct attribute *scsi_sysfs_shost_attrs[] = { > + &dev_attr_use_blk_mq.attr, > &dev_attr_unique_id.attr, > &dev_attr_host_busy.attr, > &dev_attr_cmd_per_lun.attr, > diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h > index 7f9bbda..b54511e 100644 > --- a/include/scsi/scsi_host.h > +++ b/include/scsi/scsi_host.h > @@ -7,6 +7,7 @@ > #include > #include > #include > +#include > #include > > struct request_queue; > @@ -531,6 +532,9 @@ struct scsi_host_template { > */ > unsigned int cmd_size; > struct scsi_host_cmd_pool *cmd_pool; > + > + /* temporary flag to disable blk-mq I/O path */ > + bool disable_blk_mq; > }; > > /* > @@ -601,7 +605,10 @@ struct Scsi_Host { > * Area to keep a shared tag map (if needed, will be > * NULL if not). > */ > - struct blk_queue_tag *bqt; > + union { > + struct blk_queue_tag *bqt; > + struct blk_mq_tag_set tag_set; > + }; > > atomic_t host_busy; /* commands actually active on low-level */ > atomic_t host_blocked; > @@ -693,6 +700,8 @@ struct Scsi_Host { > /* The controller does not support WRITE SAME */ > unsigned no_write_same:1; > > + unsigned use_blk_mq:1; > + > /* > * Optional work queue to be utilized by the transport > */ > @@ -793,6 +802,13 @@ static inline int scsi_host_in_recovery(struct Scsi_Host *shost) > shost->tmf_in_progress; > } > > +extern bool scsi_use_blk_mq; > + > +static inline bool shost_use_blk_mq(struct Scsi_Host *shost) > +{ > + return shost->use_blk_mq; > +} > + > extern int scsi_queue_work(struct Scsi_Host *, struct work_struct *); > extern void scsi_flush_work(struct Scsi_Host *); > > diff --git a/include/scsi/scsi_tcq.h b/include/scsi/scsi_tcq.h > index 81dd12e..cdcc90b 100644 > --- a/include/scsi/scsi_tcq.h > +++ b/include/scsi/scsi_tcq.h > @@ -67,7 +67,8 @@ static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth) > if (!sdev->tagged_supported) > return; > > - if (!blk_queue_tagged(sdev->request_queue)) > + if (!shost_use_blk_mq(sdev->host) && > + blk_queue_tagged(sdev->request_queue)) > blk_queue_init_tags(sdev->request_queue, depth, > sdev->host->bqt); > > @@ -80,7 +81,8 @@ static inline void scsi_activate_tcq(struct scsi_device *sdev, int depth) > **/ > static inline void scsi_deactivate_tcq(struct scsi_device *sdev, int depth) > { > - if (blk_queue_tagged(sdev->request_queue)) > + if (!shost_use_blk_mq(sdev->host) && > + blk_queue_tagged(sdev->request_queue)) > blk_queue_free_tags(sdev->request_queue); > scsi_adjust_queue_depth(sdev, 0, depth); > } > @@ -108,6 +110,15 @@ static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg) > return 0; > } > > +static inline struct scsi_cmnd *scsi_mq_find_tag(struct Scsi_Host *shost, > + unsigned int hw_ctx, int tag) > +{ > + struct request *req; > + > + req = blk_mq_tag_to_rq(shost->tag_set.tags[hw_ctx], tag); > + return req ? (struct scsi_cmnd *)req->special : NULL; > +} > + > /** > * scsi_find_tag - find a tagged command by device > * @SDpnt: pointer to the ScSI device > @@ -118,10 +129,12 @@ static inline int scsi_populate_tag_msg(struct scsi_cmnd *cmd, char *msg) > **/ > static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag) > { > - > struct request *req; > > if (tag != SCSI_NO_TAG) { > + if (shost_use_blk_mq(sdev->host)) > + return scsi_mq_find_tag(sdev->host, 0, tag); > + > req = blk_queue_find_tag(sdev->request_queue, tag); > return req ? (struct scsi_cmnd *)req->special : NULL; > } > @@ -130,6 +143,7 @@ static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag) > return sdev->current_cmnd; > } > > + > /** > * scsi_init_shared_tag_map - create a shared tag map > * @shost: the host to share the tag map among all devices > @@ -138,6 +152,12 @@ static inline struct scsi_cmnd *scsi_find_tag(struct scsi_device *sdev, int tag) > static inline int scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth) > { > /* > + * We always have a shared tag map around when using blk-mq. > + */ > + if (shost_use_blk_mq(shost)) > + return 0; > + > + /* > * If the shared tag map isn't already initialized, do it now. > * This saves callers from having to check ->bqt when setting up > * devices on the shared host (for libata) > @@ -165,6 +185,8 @@ static inline struct scsi_cmnd *scsi_host_find_tag(struct Scsi_Host *shost, > struct request *req; > > if (tag != SCSI_NO_TAG) { > + if (shost_use_blk_mq(shost)) > + return scsi_mq_find_tag(shost, 0, tag); > req = blk_map_queue_find_tag(shost->bqt, tag); > return req ? (struct scsi_cmnd *)req->special : NULL; > } > Reviewed-by: Hannes Reinecke Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N?rnberg GF: J. Hawn, J. Guild, F. Imend?rffer, HRB 16746 (AG N?rnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/