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Date: Fri, 12 Sep 2014 01:57:20 +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: hch@...radead.org, bob.liu@...cle.com, felipe.franciosi@...rix.com,
axboe@...com, avanzini.arianna@...il.com
Subject: [PATCH RFC v2 1/5] xen, blkfront: port to the the multi-queue block layer API
This commit introduces support for the multi-queue block layer API,
and at the same time removes the existing request_queue API support.
The changes are only structural, and the number of supported hardware
contexts is forcedly set to one.
Signed-off-by: Arianna Avanzini <avanzini.arianna@...il.com>
---
drivers/block/xen-blkfront.c | 171 ++++++++++++++++++++-----------------------
1 file changed, 80 insertions(+), 91 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 5deb235..109add6 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>
@@ -134,6 +135,8 @@ 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;
@@ -582,66 +585,69 @@ static inline void flush_requests(struct blkfront_info *info)
notify_remote_via_irq(info->irq);
}
-/*
- * do_blkif_request
- * read a block; request is in a request queue
- */
-static void do_blkif_request(struct request_queue *rq)
+static int blkfront_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
{
- struct blkfront_info *info = NULL;
- struct request *req;
- int queued;
-
- pr_debug("Entered do_blkif_request\n");
-
- queued = 0;
-
- while ((req = blk_peek_request(rq)) != NULL) {
- info = req->rq_disk->private_data;
+ struct blkfront_info *info = req->rq_disk->private_data;
- if (RING_FULL(&info->ring))
- goto wait;
+ spin_lock_irq(&info->io_lock);
+ if (RING_FULL(&info->ring))
+ goto wait;
- blk_start_request(req);
+ 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;
+ }
- if ((req->cmd_type != REQ_TYPE_FS) ||
- ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) &&
- !info->flush_op)) {
- __blk_end_request_all(req, -EIO);
- continue;
- }
+ if (blkif_queue_request(req)) {
+ blk_mq_requeue_request(req);
+ goto wait;
+ }
- pr_debug("do_blk_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");
+ flush_requests(info);
+ spin_unlock_irq(&info->io_lock);
+ return BLK_MQ_RQ_QUEUE_OK;
- if (blkif_queue_request(req)) {
- blk_requeue_request(rq, req);
wait:
- /* Avoid pointless unplugs. */
- blk_stop_queue(rq);
- break;
- }
-
- queued++;
- }
-
- if (queued != 0)
- flush_requests(info);
+ /* Avoid pointless unplugs. */
+ blk_mq_stop_hw_queue(hctx);
+ spin_unlock_irq(&info->io_lock);
+ return BLK_MQ_RQ_QUEUE_BUSY;
}
+static struct blk_mq_ops blkfront_mq_ops = {
+ .queue_rq = blkfront_queue_rq,
+ .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)
{
struct request_queue *rq;
struct blkfront_info *info = gd->private_data;
+ int ret;
+
+ memset(&info->tag_set, 0, sizeof(info->tag_set));
+ info->tag_set.ops = &blkfront_mq_ops;
+ info->tag_set.nr_hw_queues = 1;
+ 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 | BLK_MQ_F_SG_MERGE;
+ info->tag_set.cmd_size = 0;
+ info->tag_set.driver_data = info;
- rq = blk_init_queue(do_blkif_request, &info->io_lock);
- if (rq == NULL)
- return -1;
+ if ((ret = blk_mq_alloc_tag_set(&info->tag_set)))
+ return ret;
+ rq = blk_mq_init_queue(&info->tag_set);
+ if (IS_ERR(rq)) {
+ blk_mq_free_tag_set(&info->tag_set);
+ return PTR_ERR(rq);
+ }
+ rq->queuedata = info;
queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
@@ -871,7 +877,7 @@ 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);
+ blk_mq_stop_hw_queues(info->rq);
/* No more gnttab callback work. */
gnttab_cancel_free_callback(&info->callback);
@@ -887,30 +893,32 @@ 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);
info->gd = NULL;
}
-static void kick_pending_request_queues(struct blkfront_info *info)
+static void kick_pending_request_queues(struct blkfront_info *info,
+ unsigned long *flags)
{
if (!RING_FULL(&info->ring)) {
- /* Re-enable calldowns. */
- blk_start_queue(info->rq);
- /* Kick things off immediately. */
- do_blkif_request(info->rq);
+ spin_unlock_irqrestore(&info->io_lock, *flags);
+ blk_mq_start_stopped_hw_queues(info->rq, 0);
+ spin_lock_irqsave(&info->io_lock, *flags);
}
}
static void blkif_restart_queue(struct work_struct *work)
{
struct blkfront_info *info = container_of(work, struct blkfront_info, work);
+ unsigned long flags;
- spin_lock_irq(&info->io_lock);
+ spin_lock_irqsave(&info->io_lock, flags);
if (info->connected == BLKIF_STATE_CONNECTED)
- kick_pending_request_queues(info);
- spin_unlock_irq(&info->io_lock);
+ kick_pending_request_queues(info, &flags);
+ spin_unlock_irqrestore(&info->io_lock, flags);
}
static void blkif_free(struct blkfront_info *info, int suspend)
@@ -925,7 +933,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
/* No more blkif_request(). */
if (info->rq)
- blk_stop_queue(info->rq);
+ blk_mq_stop_hw_queues(info->rq);
/* Remove all persistent grants */
if (!list_empty(&info->grants)) {
@@ -1150,37 +1158,37 @@ 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);
+ blk_mq_complete_request(req);
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 +1200,7 @@ 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);
+ blk_mq_complete_request(req);
break;
default:
BUG();
@@ -1209,7 +1217,7 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
} else
info->ring.sring->rsp_event = i + 1;
- kick_pending_request_queues(info);
+ blkif_restart_queue_callback(info);
spin_unlock_irqrestore(&info->io_lock, flags);
@@ -1439,6 +1447,7 @@ static int blkif_recover(struct blkfront_info *info)
struct bio *bio, *cloned_bio;
struct bio_list bio_list, merge_bio;
unsigned int segs, offset;
+ unsigned long flags;
int pending, size;
struct split_bio *split_bio;
struct list_head requests;
@@ -1492,45 +1501,24 @@ static int blkif_recover(struct blkfront_info *info)
kfree(copy);
- /*
- * Empty the queue, this is important because we might have
- * requests in the queue with more segments than what we
- * can handle now.
- */
- spin_lock_irq(&info->io_lock);
- while ((req = blk_fetch_request(info->rq)) != NULL) {
- if (req->cmd_flags &
- (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
- list_add(&req->queuelist, &requests);
- continue;
- }
- merge_bio.head = req->bio;
- merge_bio.tail = req->biotail;
- bio_list_merge(&bio_list, &merge_bio);
- req->bio = NULL;
- if (req->cmd_flags & (REQ_FLUSH | REQ_FUA))
- pr_alert("diskcache flush request found!\n");
- __blk_put_request(info->rq, req);
- }
- spin_unlock_irq(&info->io_lock);
-
xenbus_switch_state(info->xbdev, XenbusStateConnected);
- spin_lock_irq(&info->io_lock);
+ spin_lock_irqsave(&info->io_lock, flags);
/* Now safe for us to use the shared ring */
info->connected = BLKIF_STATE_CONNECTED;
/* Kick any other new requests queued since we resumed */
- kick_pending_request_queues(info);
+ kick_pending_request_queues(info, &flags);
list_for_each_entry_safe(req, n, &requests, queuelist) {
/* Requeue pending requests (flush or discard) */
list_del_init(&req->queuelist);
BUG_ON(req->nr_phys_segments > segs);
- blk_requeue_request(info->rq, req);
+ blk_mq_requeue_request(req);
}
- spin_unlock_irq(&info->io_lock);
+
+ spin_unlock_irqrestore(&info->io_lock, flags);
while ((bio = bio_list_pop(&bio_list)) != NULL) {
/* Traverse the list of pending bios and re-queue them */
@@ -1741,6 +1729,7 @@ static void blkfront_connect(struct blkfront_info *info)
{
unsigned long long sectors;
unsigned long sector_size;
+ unsigned long flags;
unsigned int physical_sector_size;
unsigned int binfo;
int err;
@@ -1865,10 +1854,10 @@ static void blkfront_connect(struct blkfront_info *info)
xenbus_switch_state(info->xbdev, XenbusStateConnected);
/* Kick pending requests. */
- spin_lock_irq(&info->io_lock);
+ spin_lock_irqsave(&info->io_lock, flags);
info->connected = BLKIF_STATE_CONNECTED;
- kick_pending_request_queues(info);
- spin_unlock_irq(&info->io_lock);
+ kick_pending_request_queues(info, &flags);
+ spin_unlock_irqrestore(&info->io_lock, flags);
add_disk(info->gd);
--
2.1.0
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