drivers/mmc/core/queue.c - arm/linux - Git at Google

 /*
  *  Copyright (C) 2003 Russell King, All Rights Reserved.
  *  Copyright 2006-2007 Pierre Ossman
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  */
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/blkdev.h>
 #include <linux/freezer.h>
 #include <linux/kthread.h>
 #include <linux/scatterlist.h>
 #include <linux/dma-mapping.h>

 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>

 #include "queue.h"
 #include "block.h"
 #include "core.h"
 #include "card.h"

 #define MMC_QUEUE_BOUNCESZ	65536

 /*
  * Prepare a MMC request. This just filters out odd stuff.
  */
 static int mmc_prep_request(struct request_queue *q, struct request *req)
 {
 	struct mmc_queue *mq = q->queuedata;

 	if (mq && (mmc_card_removed(mq->card) || mmc_access_rpmb(mq)))
 		return BLKPREP_KILL;

 	req->rq_flags |= RQF_DONTPREP;

 	return BLKPREP_OK;
 }

 static int mmc_queue_thread(void *d)
 {
 	struct mmc_queue *mq = d;
 	struct request_queue *q = mq->queue;
 	struct mmc_context_info *cntx = &mq->card->host->context_info;

 	current->flags |= PF_MEMALLOC;

 	down(&mq->thread_sem);
 	do {
 		struct request *req;

 		spin_lock_irq(q->queue_lock);
 		set_current_state(TASK_INTERRUPTIBLE);
 		req = blk_fetch_request(q);
 		mq->asleep = false;
 		cntx->is_waiting_last_req = false;
 		cntx->is_new_req = false;
 		if (!req) {
 			/*
 			 * Dispatch queue is empty so set flags for
 			 * mmc_request_fn() to wake us up.
 			 */
 			if (mq->qcnt)
 				cntx->is_waiting_last_req = true;
 			else
 				mq->asleep = true;
 		}
 		spin_unlock_irq(q->queue_lock);

 		if (req || mq->qcnt) {
 			set_current_state(TASK_RUNNING);
 			mmc_blk_issue_rq(mq, req);
 			cond_resched();
 		} else {
 			if (kthread_should_stop()) {
 				set_current_state(TASK_RUNNING);
 				break;
 			}
 			up(&mq->thread_sem);
 			schedule();
 			down(&mq->thread_sem);
 		}
 	} while (1);
 	up(&mq->thread_sem);

 	return 0;
 }

 /*
  * Generic MMC request handler.  This is called for any queue on a
  * particular host.  When the host is not busy, we look for a request
  * on any queue on this host, and attempt to issue it.  This may
  * not be the queue we were asked to process.
  */
 static void mmc_request_fn(struct request_queue *q)
 {
 	struct mmc_queue *mq = q->queuedata;
 	struct request *req;
 	struct mmc_context_info *cntx;

 	if (!mq) {
 		while ((req = blk_fetch_request(q)) != NULL) {
 			req->rq_flags |= RQF_QUIET;
 			__blk_end_request_all(req, BLK_STS_IOERR);
 		}
 		return;
 	}

 	cntx = &mq->card->host->context_info;

 	if (cntx->is_waiting_last_req) {
 		cntx->is_new_req = true;
 		wake_up_interruptible(&cntx->wait);
 	}

 	if (mq->asleep)
 		wake_up_process(mq->thread);
 }

 static struct scatterlist *mmc_alloc_sg(int sg_len, gfp_t gfp)
 {
 	struct scatterlist *sg;

 	sg = kmalloc_array(sg_len, sizeof(*sg), gfp);
 	if (sg)
 		sg_init_table(sg, sg_len);

 	return sg;
 }

 static void mmc_queue_setup_discard(struct request_queue *q,
 				    struct mmc_card *card)
 {
 	unsigned max_discard;

 	max_discard = mmc_calc_max_discard(card);
 	if (!max_discard)
 		return;

 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
 	blk_queue_max_discard_sectors(q, max_discard);
 	q->limits.discard_granularity = card->pref_erase << 9;
 	/* granularity must not be greater than max. discard */
 	if (card->pref_erase > max_discard)
 		q->limits.discard_granularity = 0;
 	if (mmc_can_secure_erase_trim(card))
 		queue_flag_set_unlocked(QUEUE_FLAG_SECERASE, q);
 }

 static unsigned int mmc_queue_calc_bouncesz(struct mmc_host *host)
 {
 	unsigned int bouncesz = MMC_QUEUE_BOUNCESZ;

 	if (host->max_segs != 1 || (host->caps & MMC_CAP_NO_BOUNCE_BUFF))
 		return 0;

 	if (bouncesz > host->max_req_size)
 		bouncesz = host->max_req_size;
 	if (bouncesz > host->max_seg_size)
 		bouncesz = host->max_seg_size;
 	if (bouncesz > host->max_blk_count * 512)
 		bouncesz = host->max_blk_count * 512;

 	if (bouncesz <= 512)
 		return 0;

 	return bouncesz;
 }

 /**
  * mmc_init_request() - initialize the MMC-specific per-request data
  * @q: the request queue
  * @req: the request
  * @gfp: memory allocation policy
  */
 static int mmc_init_request(struct request_queue *q, struct request *req,
 			    gfp_t gfp)
 {
 	struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);
 	struct mmc_queue *mq = q->queuedata;
 	struct mmc_card *card = mq->card;
 	struct mmc_host *host = card->host;

 	if (card->bouncesz) {
 		mq_rq->bounce_buf = kmalloc(card->bouncesz, gfp);
 		if (!mq_rq->bounce_buf)
 			return -ENOMEM;
 		if (card->bouncesz > 512) {
 			mq_rq->sg = mmc_alloc_sg(1, gfp);
 			if (!mq_rq->sg)
 				return -ENOMEM;
 			mq_rq->bounce_sg = mmc_alloc_sg(card->bouncesz / 512,
 							gfp);
 			if (!mq_rq->bounce_sg)
 				return -ENOMEM;
 		}
 	} else {
 		mq_rq->bounce_buf = NULL;
 		mq_rq->bounce_sg = NULL;
 		mq_rq->sg = mmc_alloc_sg(host->max_segs, gfp);
 		if (!mq_rq->sg)
 			return -ENOMEM;
 	}

 	return 0;
 }

 static void mmc_exit_request(struct request_queue *q, struct request *req)
 {
 	struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);

 	/* It is OK to kfree(NULL) so this will be smooth */
 	kfree(mq_rq->bounce_sg);
 	mq_rq->bounce_sg = NULL;

 	kfree(mq_rq->bounce_buf);
 	mq_rq->bounce_buf = NULL;

 	kfree(mq_rq->sg);
 	mq_rq->sg = NULL;
 }

 /**
  * mmc_init_queue - initialise a queue structure.
  * @mq: mmc queue
  * @card: mmc card to attach this queue
  * @lock: queue lock
  * @subname: partition subname
  *
  * Initialise a MMC card request queue.
  */
 int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
 		   spinlock_t *lock, const char *subname)
 {
 	struct mmc_host *host = card->host;
 	u64 limit = BLK_BOUNCE_HIGH;
 	int ret = -ENOMEM;

 	if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask)
 		limit = (u64)dma_max_pfn(mmc_dev(host)) << PAGE_SHIFT;

 	mq->card = card;
 	mq->queue = blk_alloc_queue(GFP_KERNEL);
 	if (!mq->queue)
 		return -ENOMEM;
 	mq->queue->queue_lock = lock;
 	mq->queue->request_fn = mmc_request_fn;
 	mq->queue->init_rq_fn = mmc_init_request;
 	mq->queue->exit_rq_fn = mmc_exit_request;
 	mq->queue->cmd_size = sizeof(struct mmc_queue_req);
 	mq->queue->queuedata = mq;
 	mq->qcnt = 0;
 	ret = blk_init_allocated_queue(mq->queue);
 	if (ret) {
 		blk_cleanup_queue(mq->queue);
 		return ret;
 	}

 	blk_queue_prep_rq(mq->queue, mmc_prep_request);
 	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
 	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, mq->queue);
 	if (mmc_can_erase(card))
 		mmc_queue_setup_discard(mq->queue, card);

 	card->bouncesz = mmc_queue_calc_bouncesz(host);
 	if (card->bouncesz) {
 		blk_queue_max_hw_sectors(mq->queue, card->bouncesz / 512);
 		blk_queue_max_segments(mq->queue, card->bouncesz / 512);
 		blk_queue_max_segment_size(mq->queue, card->bouncesz);
 	} else {
 		blk_queue_bounce_limit(mq->queue, limit);
 		blk_queue_max_hw_sectors(mq->queue,
 			min(host->max_blk_count, host->max_req_size / 512));
 		blk_queue_max_segments(mq->queue, host->max_segs);
 		blk_queue_max_segment_size(mq->queue, host->max_seg_size);
 	}

 	sema_init(&mq->thread_sem, 1);

 	mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd/%d%s",
 		host->index, subname ? subname : "");

 	if (IS_ERR(mq->thread)) {
 		ret = PTR_ERR(mq->thread);
 		goto cleanup_queue;
 	}

 	return 0;

 cleanup_queue:
 	blk_cleanup_queue(mq->queue);
 	return ret;
 }

 void mmc_cleanup_queue(struct mmc_queue *mq)
 {
 	struct request_queue *q = mq->queue;
 	unsigned long flags;

 	/* Make sure the queue isn't suspended, as that will deadlock */
 	mmc_queue_resume(mq);

 	/* Then terminate our worker thread */
 	kthread_stop(mq->thread);

 	/* Empty the queue */
 	spin_lock_irqsave(q->queue_lock, flags);
 	q->queuedata = NULL;
 	blk_start_queue(q);
 	spin_unlock_irqrestore(q->queue_lock, flags);

 	mq->card = NULL;
 }
 EXPORT_SYMBOL(mmc_cleanup_queue);

 /**
  * mmc_queue_suspend - suspend a MMC request queue
  * @mq: MMC queue to suspend
  *
  * Stop the block request queue, and wait for our thread to
  * complete any outstanding requests.  This ensures that we
  * won't suspend while a request is being processed.
  */
 void mmc_queue_suspend(struct mmc_queue *mq)
 {
 	struct request_queue *q = mq->queue;
 	unsigned long flags;

 	if (!mq->suspended) {
 		mq->suspended |= true;

 		spin_lock_irqsave(q->queue_lock, flags);
 		blk_stop_queue(q);
 		spin_unlock_irqrestore(q->queue_lock, flags);

 		down(&mq->thread_sem);
 	}
 }

 /**
  * mmc_queue_resume - resume a previously suspended MMC request queue
  * @mq: MMC queue to resume
  */
 void mmc_queue_resume(struct mmc_queue *mq)
 {
 	struct request_queue *q = mq->queue;
 	unsigned long flags;

 	if (mq->suspended) {
 		mq->suspended = false;

 		up(&mq->thread_sem);

 		spin_lock_irqsave(q->queue_lock, flags);
 		blk_start_queue(q);
 		spin_unlock_irqrestore(q->queue_lock, flags);
 	}
 }

 /*
  * Prepare the sg list(s) to be handed of to the host driver
  */
 unsigned int mmc_queue_map_sg(struct mmc_queue *mq, struct mmc_queue_req *mqrq)
 {
 	unsigned int sg_len;
 	size_t buflen;
 	struct scatterlist *sg;
 	struct request *req = mmc_queue_req_to_req(mqrq);
 	int i;

 	if (!mqrq->bounce_buf)
 		return blk_rq_map_sg(mq->queue, req, mqrq->sg);

 	sg_len = blk_rq_map_sg(mq->queue, req, mqrq->bounce_sg);

 	mqrq->bounce_sg_len = sg_len;

 	buflen = 0;
 	for_each_sg(mqrq->bounce_sg, sg, sg_len, i)
 		buflen += sg->length;

 	sg_init_one(mqrq->sg, mqrq->bounce_buf, buflen);

 	return 1;
 }

 /*
  * If writing, bounce the data to the buffer before the request
  * is sent to the host driver
  */
 void mmc_queue_bounce_pre(struct mmc_queue_req *mqrq)
 {
 	if (!mqrq->bounce_buf)
 		return;

 	if (rq_data_dir(mmc_queue_req_to_req(mqrq)) != WRITE)
 		return;

 	sg_copy_to_buffer(mqrq->bounce_sg, mqrq->bounce_sg_len,
 		mqrq->bounce_buf, mqrq->sg[0].length);
 }

 /*
  * If reading, bounce the data from the buffer after the request
  * has been handled by the host driver
  */
 void mmc_queue_bounce_post(struct mmc_queue_req *mqrq)
 {
 	if (!mqrq->bounce_buf)
 		return;

 	if (rq_data_dir(mmc_queue_req_to_req(mqrq)) != READ)
 		return;

 	sg_copy_from_buffer(mqrq->bounce_sg, mqrq->bounce_sg_len,
 		mqrq->bounce_buf, mqrq->sg[0].length);
 }
	/*
	* Copyright (C) 2003 Russell King, All Rights Reserved.
	* Copyright 2006-2007 Pierre Ossman
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	*/
	#include <linux/slab.h>
	#include <linux/module.h>
	#include <linux/blkdev.h>
	#include <linux/freezer.h>
	#include <linux/kthread.h>
	#include <linux/scatterlist.h>
	#include <linux/dma-mapping.h>

	#include <linux/mmc/card.h>
	#include <linux/mmc/host.h>

	#include "queue.h"
	#include "block.h"
	#include "core.h"
	#include "card.h"

	#define MMC_QUEUE_BOUNCESZ 65536

	/*
	* Prepare a MMC request. This just filters out odd stuff.
	*/
	static int mmc_prep_request(struct request_queue q, struct request req)
	{
	struct mmc_queue *mq = q->queuedata;

	if (mq && (mmc_card_removed(mq->card) \|\| mmc_access_rpmb(mq)))
	return BLKPREP_KILL;

	req->rq_flags \|= RQF_DONTPREP;

	return BLKPREP_OK;
	}

	static int mmc_queue_thread(void *d)
	{
	struct mmc_queue *mq = d;
	struct request_queue *q = mq->queue;
	struct mmc_context_info *cntx = &mq->card->host->context_info;

	current->flags \|= PF_MEMALLOC;

	down(&mq->thread_sem);
	do {
	struct request *req;

	spin_lock_irq(q->queue_lock);
	set_current_state(TASK_INTERRUPTIBLE);
	req = blk_fetch_request(q);
	mq->asleep = false;
	cntx->is_waiting_last_req = false;
	cntx->is_new_req = false;
	if (!req) {
	/*
	* Dispatch queue is empty so set flags for
	* mmc_request_fn() to wake us up.
	*/
	if (mq->qcnt)
	cntx->is_waiting_last_req = true;
	else
	mq->asleep = true;
	}
	spin_unlock_irq(q->queue_lock);

	if (req \|\| mq->qcnt) {
	set_current_state(TASK_RUNNING);
	mmc_blk_issue_rq(mq, req);
	cond_resched();
	} else {
	if (kthread_should_stop()) {
	set_current_state(TASK_RUNNING);
	break;
	}
	up(&mq->thread_sem);
	schedule();
	down(&mq->thread_sem);
	}
	} while (1);
	up(&mq->thread_sem);

	return 0;
	}

	/*
	* Generic MMC request handler. This is called for any queue on a
	* particular host. When the host is not busy, we look for a request
	* on any queue on this host, and attempt to issue it. This may
	* not be the queue we were asked to process.
	*/
	static void mmc_request_fn(struct request_queue *q)
	{
	struct mmc_queue *mq = q->queuedata;
	struct request *req;
	struct mmc_context_info *cntx;

	if (!mq) {
	while ((req = blk_fetch_request(q)) != NULL) {
	req->rq_flags \|= RQF_QUIET;
	__blk_end_request_all(req, BLK_STS_IOERR);
	}
	return;
	}

	cntx = &mq->card->host->context_info;

	if (cntx->is_waiting_last_req) {
	cntx->is_new_req = true;
	wake_up_interruptible(&cntx->wait);
	}

	if (mq->asleep)
	wake_up_process(mq->thread);
	}

	static struct scatterlist *mmc_alloc_sg(int sg_len, gfp_t gfp)
	{
	struct scatterlist *sg;

	sg = kmalloc_array(sg_len, sizeof(*sg), gfp);
	if (sg)
	sg_init_table(sg, sg_len);

	return sg;
	}

	static void mmc_queue_setup_discard(struct request_queue *q,
	struct mmc_card *card)
	{
	unsigned max_discard;

	max_discard = mmc_calc_max_discard(card);
	if (!max_discard)
	return;

	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
	blk_queue_max_discard_sectors(q, max_discard);
	q->limits.discard_granularity = card->pref_erase << 9;
	/* granularity must not be greater than max. discard */
	if (card->pref_erase > max_discard)
	q->limits.discard_granularity = 0;
	if (mmc_can_secure_erase_trim(card))
	queue_flag_set_unlocked(QUEUE_FLAG_SECERASE, q);
	}

	static unsigned int mmc_queue_calc_bouncesz(struct mmc_host *host)
	{
	unsigned int bouncesz = MMC_QUEUE_BOUNCESZ;

	if (host->max_segs != 1 \|\| (host->caps & MMC_CAP_NO_BOUNCE_BUFF))
	return 0;

	if (bouncesz > host->max_req_size)
	bouncesz = host->max_req_size;
	if (bouncesz > host->max_seg_size)
	bouncesz = host->max_seg_size;
	if (bouncesz > host->max_blk_count * 512)
	bouncesz = host->max_blk_count * 512;

	if (bouncesz <= 512)
	return 0;

	return bouncesz;
	}

	/**
	* mmc_init_request() - initialize the MMC-specific per-request data
	* @q: the request queue
	* @req: the request
	* @gfp: memory allocation policy
	*/
	static int mmc_init_request(struct request_queue q, struct request req,
	gfp_t gfp)
	{
	struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);
	struct mmc_queue *mq = q->queuedata;
	struct mmc_card *card = mq->card;
	struct mmc_host *host = card->host;

	if (card->bouncesz) {
	mq_rq->bounce_buf = kmalloc(card->bouncesz, gfp);
	if (!mq_rq->bounce_buf)
	return -ENOMEM;
	if (card->bouncesz > 512) {
	mq_rq->sg = mmc_alloc_sg(1, gfp);
	if (!mq_rq->sg)
	return -ENOMEM;
	mq_rq->bounce_sg = mmc_alloc_sg(card->bouncesz / 512,
	gfp);
	if (!mq_rq->bounce_sg)
	return -ENOMEM;
	}
	} else {
	mq_rq->bounce_buf = NULL;
	mq_rq->bounce_sg = NULL;
	mq_rq->sg = mmc_alloc_sg(host->max_segs, gfp);
	if (!mq_rq->sg)
	return -ENOMEM;
	}

	return 0;
	}

	static void mmc_exit_request(struct request_queue q, struct request req)
	{
	struct mmc_queue_req *mq_rq = req_to_mmc_queue_req(req);

	/* It is OK to kfree(NULL) so this will be smooth */
	kfree(mq_rq->bounce_sg);
	mq_rq->bounce_sg = NULL;

	kfree(mq_rq->bounce_buf);
	mq_rq->bounce_buf = NULL;

	kfree(mq_rq->sg);
	mq_rq->sg = NULL;
	}

	/**
	* mmc_init_queue - initialise a queue structure.
	* @mq: mmc queue
	* @card: mmc card to attach this queue
	* @lock: queue lock
	* @subname: partition subname
	*
	* Initialise a MMC card request queue.
	*/
	int mmc_init_queue(struct mmc_queue mq, struct mmc_card card,
	spinlock_t lock, const char subname)
	{
	struct mmc_host *host = card->host;
	u64 limit = BLK_BOUNCE_HIGH;
	int ret = -ENOMEM;

	if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask)
	limit = (u64)dma_max_pfn(mmc_dev(host)) << PAGE_SHIFT;

	mq->card = card;
	mq->queue = blk_alloc_queue(GFP_KERNEL);
	if (!mq->queue)
	return -ENOMEM;
	mq->queue->queue_lock = lock;
	mq->queue->request_fn = mmc_request_fn;
	mq->queue->init_rq_fn = mmc_init_request;
	mq->queue->exit_rq_fn = mmc_exit_request;
	mq->queue->cmd_size = sizeof(struct mmc_queue_req);
	mq->queue->queuedata = mq;
	mq->qcnt = 0;
	ret = blk_init_allocated_queue(mq->queue);
	if (ret) {
	blk_cleanup_queue(mq->queue);
	return ret;
	}

	blk_queue_prep_rq(mq->queue, mmc_prep_request);
	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
	queue_flag_clear_unlocked(QUEUE_FLAG_ADD_RANDOM, mq->queue);
	if (mmc_can_erase(card))
	mmc_queue_setup_discard(mq->queue, card);

	card->bouncesz = mmc_queue_calc_bouncesz(host);
	if (card->bouncesz) {
	blk_queue_max_hw_sectors(mq->queue, card->bouncesz / 512);
	blk_queue_max_segments(mq->queue, card->bouncesz / 512);
	blk_queue_max_segment_size(mq->queue, card->bouncesz);
	} else {
	blk_queue_bounce_limit(mq->queue, limit);
	blk_queue_max_hw_sectors(mq->queue,
	min(host->max_blk_count, host->max_req_size / 512));
	blk_queue_max_segments(mq->queue, host->max_segs);
	blk_queue_max_segment_size(mq->queue, host->max_seg_size);
	}

	sema_init(&mq->thread_sem, 1);

	mq->thread = kthread_run(mmc_queue_thread, mq, "mmcqd/%d%s",
	host->index, subname ? subname : "");

	if (IS_ERR(mq->thread)) {
	ret = PTR_ERR(mq->thread);
	goto cleanup_queue;
	}

	return 0;

	cleanup_queue:
	blk_cleanup_queue(mq->queue);
	return ret;
	}

	void mmc_cleanup_queue(struct mmc_queue *mq)
	{
	struct request_queue *q = mq->queue;
	unsigned long flags;

	/* Make sure the queue isn't suspended, as that will deadlock */
	mmc_queue_resume(mq);

	/* Then terminate our worker thread */
	kthread_stop(mq->thread);

	/* Empty the queue */
	spin_lock_irqsave(q->queue_lock, flags);
	q->queuedata = NULL;
	blk_start_queue(q);
	spin_unlock_irqrestore(q->queue_lock, flags);

	mq->card = NULL;
	}
	EXPORT_SYMBOL(mmc_cleanup_queue);

	/**
	* mmc_queue_suspend - suspend a MMC request queue
	* @mq: MMC queue to suspend
	*
	* Stop the block request queue, and wait for our thread to
	* complete any outstanding requests. This ensures that we
	* won't suspend while a request is being processed.
	*/
	void mmc_queue_suspend(struct mmc_queue *mq)
	{
	struct request_queue *q = mq->queue;
	unsigned long flags;

	if (!mq->suspended) {
	mq->suspended \|= true;

	spin_lock_irqsave(q->queue_lock, flags);
	blk_stop_queue(q);
	spin_unlock_irqrestore(q->queue_lock, flags);

	down(&mq->thread_sem);
	}
	}

	/**
	* mmc_queue_resume - resume a previously suspended MMC request queue
	* @mq: MMC queue to resume
	*/
	void mmc_queue_resume(struct mmc_queue *mq)
	{
	struct request_queue *q = mq->queue;
	unsigned long flags;

	if (mq->suspended) {
	mq->suspended = false;

	up(&mq->thread_sem);

	spin_lock_irqsave(q->queue_lock, flags);
	blk_start_queue(q);
	spin_unlock_irqrestore(q->queue_lock, flags);
	}
	}

	/*
	* Prepare the sg list(s) to be handed of to the host driver
	*/
	unsigned int mmc_queue_map_sg(struct mmc_queue mq, struct mmc_queue_req mqrq)
	{
	unsigned int sg_len;
	size_t buflen;
	struct scatterlist *sg;
	struct request *req = mmc_queue_req_to_req(mqrq);
	int i;

	if (!mqrq->bounce_buf)
	return blk_rq_map_sg(mq->queue, req, mqrq->sg);

	sg_len = blk_rq_map_sg(mq->queue, req, mqrq->bounce_sg);

	mqrq->bounce_sg_len = sg_len;

	buflen = 0;
	for_each_sg(mqrq->bounce_sg, sg, sg_len, i)
	buflen += sg->length;

	sg_init_one(mqrq->sg, mqrq->bounce_buf, buflen);

	return 1;
	}

	/*
	* If writing, bounce the data to the buffer before the request
	* is sent to the host driver
	*/
	void mmc_queue_bounce_pre(struct mmc_queue_req *mqrq)
	{
	if (!mqrq->bounce_buf)
	return;

	if (rq_data_dir(mmc_queue_req_to_req(mqrq)) != WRITE)
	return;

	sg_copy_to_buffer(mqrq->bounce_sg, mqrq->bounce_sg_len,
	mqrq->bounce_buf, mqrq->sg[0].length);
	}

	/*
	* If reading, bounce the data from the buffer after the request
	* has been handled by the host driver
	*/
	void mmc_queue_bounce_post(struct mmc_queue_req *mqrq)
	{
	if (!mqrq->bounce_buf)
	return;

	if (rq_data_dir(mmc_queue_req_to_req(mqrq)) != READ)
	return;

	sg_copy_from_buffer(mqrq->bounce_sg, mqrq->bounce_sg_len,
	mqrq->bounce_buf, mqrq->sg[0].length);
	}