Message-Id: <1414933255-3795-1-git-send-email-richard@nod.at>
Date:	Sun,  2 Nov 2014 14:00:55 +0100
From:	Richard Weinberger <richard@....at>
To:	hch@...radead.org, axboe@...com, dedekind1@...il.com,
	ezequiel.garcia@...e-electrons.com
Cc:	dwmw2@...radead.org, computersforpeace@...il.com,
	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Richard Weinberger <richard@....at>
Subject: [PATCH] UBI: Block: Add blk-mq support

Convert the driver to blk-mq.

Signed-off-by: Richard Weinberger <richard@....at>
---
 drivers/mtd/ubi/block.c | 241 ++++++++++++++++++++++++++++--------------------
 1 file changed, 143 insertions(+), 98 deletions(-)

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index 8876c7d..aac956a 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -42,11 +42,12 @@
 #include <linux/list.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
-#include <linux/vmalloc.h>
 #include <linux/mtd/ubi.h>
 #include <linux/workqueue.h>
 #include <linux/blkdev.h>
+#include <linux/blk-mq.h>
 #include <linux/hdreg.h>
+#include <linux/scatterlist.h>
 #include <asm/div64.h>
 
 #include "ubi-media.h"
@@ -61,12 +62,25 @@
 /* Maximum number of comma-separated items in the 'block=' parameter */
 #define UBIBLOCK_PARAM_COUNT 2
 
+#define UBIBLOCK_SG_COUNT 64
+
 struct ubiblock_param {
 	int ubi_num;
 	int vol_id;
 	char name[UBIBLOCK_PARAM_LEN+1];
 };
 
+struct ubiblock_pdu {
+	struct request *req;
+	sector_t req_sec;
+	int req_len;
+	struct ubiblock *dev;
+	struct work_struct work;
+	int sglist_pos;
+	int sgpage_pos;
+	struct scatterlist sglist[UBIBLOCK_SG_COUNT];
+};
+
 /* Numbers of elements set in the @ubiblock_param array */
 static int ubiblock_devs __initdata;
 
@@ -84,11 +98,10 @@ struct ubiblock {
 	struct request_queue *rq;
 
 	struct workqueue_struct *wq;
-	struct work_struct work;
 
 	struct mutex dev_mutex;
-	spinlock_t queue_lock;
 	struct list_head list;
+	struct blk_mq_tag_set tag_set;
 };
 
 /* Linked list of all ubiblock instances */
@@ -181,28 +194,53 @@ static struct ubiblock *find_dev_nolock(int ubi_num, int vol_id)
 	return NULL;
 }
 
-static int ubiblock_read_to_buf(struct ubiblock *dev, char *buffer,
-				int leb, int offset, int len)
+static int ubiblock_read_to_sg(struct ubiblock_pdu *pdu, int leb,
+				int leb_offset, int len)
 {
+	int to_read;
 	int ret;
+	struct scatterlist *sg;
+	struct ubiblock *dev = pdu->dev;
+
+	for (;;) {
+		sg = &pdu->sglist[pdu->sglist_pos];
+		if (len < sg->length - pdu->sgpage_pos)
+			to_read = len;
+		else
+			to_read = sg->length - pdu->sgpage_pos;
+
+		ret = ubi_read(dev->desc, leb, sg_virt(sg) + pdu->sgpage_pos,
+			       leb_offset, to_read);
+		if (ret < 0)
+			goto out;
 
-	ret = ubi_read(dev->desc, leb, buffer, offset, len);
-	if (ret) {
-		ubi_err("%s: error %d while reading from LEB %d (offset %d, "
-		        "length %d)", dev->gd->disk_name, ret, leb, offset,
-			len);
-		return ret;
+		leb_offset += to_read;
+		len -= to_read;
+		if (!len) {
+			pdu->sgpage_pos += to_read;
+			if (pdu->sgpage_pos == sg->length) {
+				pdu->sglist_pos++;
+				pdu->sgpage_pos = 0;
+			}
+
+			break;
+		}
+
+		pdu->sglist_pos++;
+		pdu->sgpage_pos = 0;
 	}
-	return 0;
+
+out:
+	return ret;
 }
 
-static int ubiblock_read(struct ubiblock *dev, char *buffer,
-			 sector_t sec, int len)
+static int ubiblock_read(struct ubiblock_pdu *pdu)
 {
 	int ret, leb, offset;
-	int bytes_left = len;
-	int to_read = len;
-	u64 pos = sec << 9;
+	int bytes_left = pdu->req_len;
+	int to_read = pdu->req_len;
+	struct ubiblock *dev = pdu->dev;
+	u64 pos = pdu->req_sec << 9;
 
 	/* Get LEB:offset address to read from */
 	offset = do_div(pos, dev->leb_size);
@@ -216,11 +254,10 @@ static int ubiblock_read(struct ubiblock *dev, char *buffer,
 		if (offset + to_read > dev->leb_size)
 			to_read = dev->leb_size - offset;
 
-		ret = ubiblock_read_to_buf(dev, buffer, leb, offset, to_read);
-		if (ret)
+		ret = ubiblock_read_to_sg(pdu, leb, offset, to_read);
+		if (ret < 0)
 			return ret;
 
-		buffer += to_read;
 		bytes_left -= to_read;
 		to_read = bytes_left;
 		leb += 1;
@@ -229,79 +266,6 @@ static int ubiblock_read(struct ubiblock *dev, char *buffer,
 	return 0;
 }
 
-static int do_ubiblock_request(struct ubiblock *dev, struct request *req)
-{
-	int len, ret;
-	sector_t sec;
-
-	if (req->cmd_type != REQ_TYPE_FS)
-		return -EIO;
-
-	if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
-	    get_capacity(req->rq_disk))
-		return -EIO;
-
-	if (rq_data_dir(req) != READ)
-		return -ENOSYS; /* Write not implemented */
-
-	sec = blk_rq_pos(req);
-	len = blk_rq_cur_bytes(req);
-
-	/*
-	 * Let's prevent the device from being removed while we're doing I/O
-	 * work. Notice that this means we serialize all the I/O operations,
-	 * but it's probably of no impact given the NAND core serializes
-	 * flash access anyway.
-	 */
-	mutex_lock(&dev->dev_mutex);
-	ret = ubiblock_read(dev, bio_data(req->bio), sec, len);
-	mutex_unlock(&dev->dev_mutex);
-
-	return ret;
-}
-
-static void ubiblock_do_work(struct work_struct *work)
-{
-	struct ubiblock *dev =
-		container_of(work, struct ubiblock, work);
-	struct request_queue *rq = dev->rq;
-	struct request *req;
-	int res;
-
-	spin_lock_irq(rq->queue_lock);
-
-	req = blk_fetch_request(rq);
-	while (req) {
-
-		spin_unlock_irq(rq->queue_lock);
-		res = do_ubiblock_request(dev, req);
-		spin_lock_irq(rq->queue_lock);
-
-		/*
-		 * If we're done with this request,
-		 * we need to fetch a new one
-		 */
-		if (!__blk_end_request_cur(req, res))
-			req = blk_fetch_request(rq);
-	}
-
-	spin_unlock_irq(rq->queue_lock);
-}
-
-static void ubiblock_request(struct request_queue *rq)
-{
-	struct ubiblock *dev;
-	struct request *req;
-
-	dev = rq->queuedata;
-
-	if (!dev)
-		while ((req = blk_fetch_request(rq)) != NULL)
-			__blk_end_request_all(req, -ENODEV);
-	else
-		queue_work(dev->wq, &dev->work);
-}
-
 static int ubiblock_open(struct block_device *bdev, fmode_t mode)
 {
 	struct ubiblock *dev = bdev->bd_disk->private_data;
@@ -375,6 +339,67 @@ static const struct block_device_operations ubiblock_ops = {
 	.getgeo	= ubiblock_getgeo,
 };
 
+static void ubiblock_do_work(struct work_struct *work)
+{
+	int ret;
+	struct ubiblock_pdu *pdu = container_of(work, struct ubiblock_pdu, work);
+
+	ret = ubiblock_read(pdu);
+	blk_mq_end_request(pdu->req, ret ?: 0);
+}
+
+static int ubiblock_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req,
+			     bool last)
+{
+	int ret;
+	struct ubiblock *dev = hctx->queue->queuedata;
+	struct ubiblock_pdu *pdu = blk_mq_rq_to_pdu(req);
+
+	if (req->cmd_type != REQ_TYPE_FS)
+		return BLK_MQ_RQ_QUEUE_ERROR;
+
+	if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
+	    get_capacity(req->rq_disk))
+		return BLK_MQ_RQ_QUEUE_ERROR;
+
+	if (rq_data_dir(req) != READ)
+		return BLK_MQ_RQ_QUEUE_ERROR; /* Write not implemented */
+
+	pdu->req = req;
+	pdu->req_sec = blk_rq_pos(req);
+	pdu->req_len = blk_rq_bytes(req);
+	pdu->dev = dev;
+	pdu->sglist_pos = 0;
+	pdu->sgpage_pos = 0;
+
+	blk_mq_start_request(req);
+	ret = blk_rq_map_sg(hctx->queue, req, pdu->sglist);
+	BUG_ON(ret > UBIBLOCK_SG_COUNT);
+
+	INIT_WORK(&pdu->work, ubiblock_do_work);
+	queue_work(dev->wq, &pdu->work);
+
+	return BLK_MQ_RQ_QUEUE_OK;
+}
+
+static int ubiblock_init_request(void *data, struct request *req,
+				 unsigned int hctx_idx,
+				 unsigned int request_idx,
+				 unsigned int numa_node)
+{
+	struct ubiblock_pdu *pdu = blk_mq_rq_to_pdu(req);
+
+	sg_init_table(pdu->sglist, UBIBLOCK_SG_COUNT);
+
+	return 0;
+}
+
+static struct blk_mq_ops ubiblock_mq_ops = {
+	.queue_rq       = ubiblock_queue_rq,
+	.init_request	= ubiblock_init_request,
+	.map_queue      = blk_mq_map_queue,
+};
+
 int ubiblock_create(struct ubi_volume_info *vi)
 {
 	struct ubiblock *dev;
@@ -418,12 +443,25 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	set_capacity(gd, disk_capacity);
 	dev->gd = gd;
 
-	spin_lock_init(&dev->queue_lock);
-	dev->rq = blk_init_queue(ubiblock_request, &dev->queue_lock);
+	dev->tag_set.ops = &ubiblock_mq_ops;
+	dev->tag_set.queue_depth = 64;
+	dev->tag_set.numa_node = NUMA_NO_NODE;
+	dev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
+	dev->tag_set.cmd_size = sizeof(struct ubiblock_pdu);
+	dev->tag_set.driver_data = dev;
+	dev->tag_set.nr_hw_queues = 1;
+
+	ret = blk_mq_alloc_tag_set(&dev->tag_set);
+	if (ret) {
+		ubi_err("block: blk_mq_alloc_tag_set failed");
+		goto out_put_disk;
+	}
+
+	dev->rq = blk_mq_init_queue(&dev->tag_set);
 	if (!dev->rq) {
-		ubi_err("block: blk_init_queue failed");
+		ubi_err("block: blk_mq_init_queue failed");
 		ret = -ENODEV;
-		goto out_put_disk;
+		goto out_free_tags;
 	}
 
 	dev->rq->queuedata = dev;
@@ -438,7 +476,6 @@ int ubiblock_create(struct ubi_volume_info *vi)
 		ret = -ENOMEM;
 		goto out_free_queue;
 	}
-	INIT_WORK(&dev->work, ubiblock_do_work);
 
 	mutex_lock(&devices_mutex);
 	list_add_tail(&dev->list, &ubiblock_devices);
@@ -452,6 +489,8 @@ int ubiblock_create(struct ubi_volume_info *vi)
 
 out_free_queue:
 	blk_cleanup_queue(dev->rq);
+out_free_tags:
+	blk_mq_free_tag_set(&dev->tag_set);
 out_put_disk:
 	put_disk(dev->gd);
 out_free_dev:
@@ -464,6 +503,7 @@ static void ubiblock_cleanup(struct ubiblock *dev)
 {
 	del_gendisk(dev->gd);
 	blk_cleanup_queue(dev->rq);
+	blk_mq_free_tag_set(&dev->tag_set);
 	ubi_msg("%s released", dev->gd->disk_name);
 	put_disk(dev->gd);
 }
@@ -491,6 +531,9 @@ int ubiblock_remove(struct ubi_volume_info *vi)
 	list_del(&dev->list);
 	mutex_unlock(&devices_mutex);
 
+	/* Make sure that no further work is queued */
+	blk_mq_stop_hw_queues(dev->rq);
+
 	/* Flush pending work and stop this workqueue */
 	destroy_workqueue(dev->wq);
 
@@ -621,6 +664,8 @@ static void ubiblock_remove_all(void)
 	struct ubiblock *dev;
 
 	list_for_each_entry_safe(dev, next, &ubiblock_devices, list) {
+		/* Make sure that no further work is queued */
+		blk_mq_stop_hw_queues(dev->rq);
 		/* Flush pending work and stop workqueue */
 		destroy_workqueue(dev->wq);
 		/* The module is being forcefully removed */
-- 
2.1.0

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