From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756113AbaHVLT3 (ORCPT ); Fri, 22 Aug 2014 07:19:29 -0400 Received: from mail-wg0-f45.google.com ([74.125.82.45]:44188 "EHLO mail-wg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756052AbaHVLT0 (ORCPT ); Fri, 22 Aug 2014 07:19:26 -0400 From: Arianna Avanzini To: konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, david.vrabel@citrix.com, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: bob.liu@oracle.com, felipe.franciosi@citrix.com, axboe@fb.com, avanzini.arianna@gmail.com Subject: [PATCH RFC 1/4] xen, blkfront: add support for the multi-queue block layer API Date: Fri, 22 Aug 2014 13:20:01 +0200 Message-Id: <1408706404-6614-2-git-send-email-avanzini.arianna@gmail.com> X-Mailer: git-send-email 2.0.4 In-Reply-To: <1408706404-6614-1-git-send-email-avanzini.arianna@gmail.com> References: <1408706404-6614-1-git-send-email-avanzini.arianna@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This commit introduces support for the multi-queue block layer API. The changes are only structural, and force both the use of the multi-queue API and the use of a single I/O ring, by initializing statically the number of hardware queues to one. Signed-off-by: Arianna Avanzini --- drivers/block/xen-blkfront.c | 133 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 116 insertions(+), 17 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 5deb235..0407ad5 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -37,6 +37,7 @@ #include #include +#include #include #include #include @@ -98,6 +99,8 @@ static unsigned int xen_blkif_max_segments = 32; module_param_named(max, xen_blkif_max_segments, int, S_IRUGO); MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 32)"); +static unsigned int hardware_queues = 1; + #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE) /* @@ -134,6 +137,8 @@ struct blkfront_info unsigned int feature_persistent:1; unsigned int max_indirect_segments; int is_ready; + /* Block layer tags. */ + struct blk_mq_tag_set tag_set; }; static unsigned int nr_minors; @@ -385,6 +390,7 @@ static int blkif_ioctl(struct block_device *bdev, fmode_t mode, * and writes are handled as expected. * * @req: a request struct + * @ring_idx: index of the ring the request is to be inserted in */ static int blkif_queue_request(struct request *req) { @@ -632,6 +638,61 @@ wait: flush_requests(info); } +static int blkfront_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req) +{ + struct blkfront_info *info = req->rq_disk->private_data; + + pr_debug("Entered blkfront_queue_rq\n"); + + spin_lock_irq(&info->io_lock); + if (RING_FULL(&info->ring)) + goto wait; + + if ((req->cmd_type != REQ_TYPE_FS) || + ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) && + !info->flush_op)) { + req->errors = -EIO; + blk_mq_complete_request(req); + spin_unlock_irq(&info->io_lock); + return BLK_MQ_RQ_QUEUE_ERROR; + } + + pr_debug("blkfront_queue_req %p: cmd %p, sec %lx, ""(%u/%u) [%s]\n", + req, req->cmd, (unsigned long)blk_rq_pos(req), + blk_rq_cur_sectors(req), blk_rq_sectors(req), + rq_data_dir(req) ? "write" : "read"); + + if (blkif_queue_request(req)) { +wait: + /* Avoid pointless unplugs. */ + blk_mq_stop_hw_queue(hctx); + spin_unlock_irq(&info->io_lock); + return BLK_MQ_RQ_QUEUE_BUSY; + } + + flush_requests(info); + spin_unlock_irq(&info->io_lock); + return BLK_MQ_RQ_QUEUE_OK; +} + +static int blkfront_init_hctx(struct blk_mq_hw_ctx *hctx, void *data, + unsigned int index) +{ + return 0; +} + +static void blkfront_complete(struct request *req) +{ + blk_mq_end_io(req, req->errors); +} + +static struct blk_mq_ops blkfront_mq_ops = { + .queue_rq = blkfront_queue_rq, + .init_hctx = blkfront_init_hctx, + .complete = blkfront_complete, + .map_queue = blk_mq_map_queue, +}; + static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, unsigned int physical_sector_size, unsigned int segments) @@ -639,9 +700,29 @@ static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, struct request_queue *rq; struct blkfront_info *info = gd->private_data; - rq = blk_init_queue(do_blkif_request, &info->io_lock); - if (rq == NULL) - return -1; + if (hardware_queues) { + memset(&info->tag_set, 0, sizeof(info->tag_set)); + info->tag_set.ops = &blkfront_mq_ops; + info->tag_set.nr_hw_queues = hardware_queues; + info->tag_set.queue_depth = BLK_RING_SIZE; + info->tag_set.numa_node = NUMA_NO_NODE; + info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; + info->tag_set.cmd_size = 0; + info->tag_set.driver_data = info; + + if (blk_mq_alloc_tag_set(&info->tag_set)) + return -1; + rq = blk_mq_init_queue(&info->tag_set); + if (!rq) { + blk_mq_free_tag_set(&info->tag_set); + return -1; + } + } else { + rq = blk_init_queue(do_blkif_request, &info->io_lock); + if (rq == NULL) + return -1; + } + rq->queuedata = info; queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); @@ -871,7 +952,10 @@ static void xlvbd_release_gendisk(struct blkfront_info *info) spin_lock_irqsave(&info->io_lock, flags); /* No more blkif_request(). */ - blk_stop_queue(info->rq); + if (hardware_queues) + blk_mq_stop_hw_queues(info->rq); + else + blk_stop_queue(info->rq); /* No more gnttab callback work. */ gnttab_cancel_free_callback(&info->callback); @@ -887,6 +971,7 @@ static void xlvbd_release_gendisk(struct blkfront_info *info) xlbd_release_minors(minor, nr_minors); blk_cleanup_queue(info->rq); + blk_mq_free_tag_set(&info->tag_set); info->rq = NULL; put_disk(info->gd); @@ -896,10 +981,14 @@ static void xlvbd_release_gendisk(struct blkfront_info *info) static void kick_pending_request_queues(struct blkfront_info *info) { if (!RING_FULL(&info->ring)) { - /* Re-enable calldowns. */ - blk_start_queue(info->rq); - /* Kick things off immediately. */ - do_blkif_request(info->rq); + if (hardware_queues) { + blk_mq_start_stopped_hw_queues(info->rq, 0); + } else { + /* Re-enable calldowns. */ + blk_start_queue(info->rq); + /* Kick things off immediately. */ + do_blkif_request(info->rq); + } } } @@ -924,8 +1013,12 @@ static void blkif_free(struct blkfront_info *info, int suspend) info->connected = suspend ? BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; /* No more blkif_request(). */ - if (info->rq) - blk_stop_queue(info->rq); + if (info->rq) { + if (hardware_queues) + blk_mq_stop_hw_queues(info->rq); + else + blk_stop_queue(info->rq); + } /* Remove all persistent grants */ if (!list_empty(&info->grants)) { @@ -1150,37 +1243,40 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) continue; } - error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; + error = req->errors = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; switch (bret->operation) { case BLKIF_OP_DISCARD: if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { struct request_queue *rq = info->rq; printk(KERN_WARNING "blkfront: %s: %s op failed\n", info->gd->disk_name, op_name(bret->operation)); - error = -EOPNOTSUPP; + error = req->errors = -EOPNOTSUPP; info->feature_discard = 0; info->feature_secdiscard = 0; queue_flag_clear(QUEUE_FLAG_DISCARD, rq); queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq); } - __blk_end_request_all(req, error); + if (hardware_queues) + blk_mq_complete_request(req); + else + __blk_end_request_all(req, error); break; case BLKIF_OP_FLUSH_DISKCACHE: case BLKIF_OP_WRITE_BARRIER: if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { printk(KERN_WARNING "blkfront: %s: %s op failed\n", info->gd->disk_name, op_name(bret->operation)); - error = -EOPNOTSUPP; + error = req->errors = -EOPNOTSUPP; } if (unlikely(bret->status == BLKIF_RSP_ERROR && info->shadow[id].req.u.rw.nr_segments == 0)) { printk(KERN_WARNING "blkfront: %s: empty %s op failed\n", info->gd->disk_name, op_name(bret->operation)); - error = -EOPNOTSUPP; + error = req->errors = -EOPNOTSUPP; } if (unlikely(error)) { if (error == -EOPNOTSUPP) - error = 0; + error = req->errors = 0; info->feature_flush = 0; info->flush_op = 0; xlvbd_flush(info); @@ -1192,7 +1288,10 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " "request: %x\n", bret->status); - __blk_end_request_all(req, error); + if (hardware_queues) + blk_mq_complete_request(req); + else + __blk_end_request_all(req, error); break; default: BUG(); -- 2.0.4