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Date: Fri, 22 Aug 2014 13:20:01 +0200
From: Arianna Avanzini <avanzini.arianna@...il.com>
To: konrad.wilk@...cle.com, boris.ostrovsky@...cle.com,
david.vrabel@...rix.com, xen-devel@...ts.xenproject.org,
linux-kernel@...r.kernel.org
Cc: bob.liu@...cle.com, felipe.franciosi@...rix.com, axboe@...com,
avanzini.arianna@...il.com
Subject: [PATCH RFC 1/4] xen, blkfront: add support for the multi-queue block layer API
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 <avanzini.arianna@...il.com>
---
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 <linux/interrupt.h>
#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
#include <linux/hdreg.h>
#include <linux/cdrom.h>
#include <linux/module.h>
@@ -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
--
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