block/blk-map.c - maze/linux - Git at Google

 /*
  * Functions related to mapping data to requests
  */
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/bio.h>
 #include <linux/blkdev.h>
 #include <scsi/sg.h>		/* for struct sg_iovec */

 #include "blk.h"

 int blk_rq_append_bio(struct request_queue *q, struct request *rq,
 		      struct bio *bio)
 {
 	if (!rq->bio)
 		blk_rq_bio_prep(q, rq, bio);
 	else if (!ll_back_merge_fn(q, rq, bio))
 		return -EINVAL;
 	else {
 		rq->biotail->bi_next = bio;
 		rq->biotail = bio;

 		rq->__data_len += bio->bi_iter.bi_size;
 	}
 	return 0;
 }

 static int __blk_rq_unmap_user(struct bio *bio)
 {
 	int ret = 0;

 	if (bio) {
 		if (bio_flagged(bio, BIO_USER_MAPPED))
 			bio_unmap_user(bio);
 		else
 			ret = bio_uncopy_user(bio);
 	}

 	return ret;
 }

 static int __blk_rq_map_user(struct request_queue *q, struct request *rq,
 			     struct rq_map_data *map_data, void __user *ubuf,
 			     unsigned int len, gfp_t gfp_mask)
 {
 	unsigned long uaddr;
 	struct bio *bio, *orig_bio;
 	int reading, ret;

 	reading = rq_data_dir(rq) == READ;

 	/*
 	 * if alignment requirement is satisfied, map in user pages for
 	 * direct dma. else, set up kernel bounce buffers
 	 */
 	uaddr = (unsigned long) ubuf;
 	if (blk_rq_aligned(q, uaddr, len) && !map_data)
 		bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask);
 	else
 		bio = bio_copy_user(q, map_data, uaddr, len, reading, gfp_mask);

 	if (IS_ERR(bio))
 		return PTR_ERR(bio);

 	if (map_data && map_data->null_mapped)
 		bio->bi_flags |= (1 << BIO_NULL_MAPPED);

 	orig_bio = bio;
 	blk_queue_bounce(q, &bio);

 	/*
 	 * We link the bounce buffer in and could have to traverse it
 	 * later so we have to get a ref to prevent it from being freed
 	 */
 	bio_get(bio);

 	ret = blk_rq_append_bio(q, rq, bio);
 	if (!ret)
 		return bio->bi_iter.bi_size;

 	/* if it was boucned we must call the end io function */
 	bio_endio(bio, 0);
 	__blk_rq_unmap_user(orig_bio);
 	bio_put(bio);
 	return ret;
 }

 /**
  * blk_rq_map_user - map user data to a request, for REQ_TYPE_BLOCK_PC usage
  * @q:		request queue where request should be inserted
  * @rq:		request structure to fill
  * @map_data:   pointer to the rq_map_data holding pages (if necessary)
  * @ubuf:	the user buffer
  * @len:	length of user data
  * @gfp_mask:	memory allocation flags
  *
  * Description:
  *    Data will be mapped directly for zero copy I/O, if possible. Otherwise
  *    a kernel bounce buffer is used.
  *
  *    A matching blk_rq_unmap_user() must be issued at the end of I/O, while
  *    still in process context.
  *
  *    Note: The mapped bio may need to be bounced through blk_queue_bounce()
  *    before being submitted to the device, as pages mapped may be out of
  *    reach. It's the callers responsibility to make sure this happens. The
  *    original bio must be passed back in to blk_rq_unmap_user() for proper
  *    unmapping.
  */
 int blk_rq_map_user(struct request_queue *q, struct request *rq,
 		    struct rq_map_data *map_data, void __user *ubuf,
 		    unsigned long len, gfp_t gfp_mask)
 {
 	unsigned long bytes_read = 0;
 	struct bio *bio = NULL;
 	int ret;

 	if (len > (queue_max_hw_sectors(q) << 9))
 		return -EINVAL;
 	if (!len)
 		return -EINVAL;

 	if (!ubuf && (!map_data || !map_data->null_mapped))
 		return -EINVAL;

 	while (bytes_read != len) {
 		unsigned long map_len, end, start;

 		map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
 		end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
 								>> PAGE_SHIFT;
 		start = (unsigned long)ubuf >> PAGE_SHIFT;

 		/*
 		 * A bad offset could cause us to require BIO_MAX_PAGES + 1
 		 * pages. If this happens we just lower the requested
 		 * mapping len by a page so that we can fit
 		 */
 		if (end - start > BIO_MAX_PAGES)
 			map_len -= PAGE_SIZE;

 		ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len,
 					gfp_mask);
 		if (ret < 0)
 			goto unmap_rq;
 		if (!bio)
 			bio = rq->bio;
 		bytes_read += ret;
 		ubuf += ret;

 		if (map_data)
 			map_data->offset += ret;
 	}

 	if (!bio_flagged(bio, BIO_USER_MAPPED))
 		rq->cmd_flags |= REQ_COPY_USER;

 	rq->buffer = NULL;
 	return 0;
 unmap_rq:
 	blk_rq_unmap_user(bio);
 	rq->bio = NULL;
 	return ret;
 }
 EXPORT_SYMBOL(blk_rq_map_user);

 /**
  * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
  * @q:		request queue where request should be inserted
  * @rq:		request to map data to
  * @map_data:   pointer to the rq_map_data holding pages (if necessary)
  * @iov:	pointer to the iovec
  * @iov_count:	number of elements in the iovec
  * @len:	I/O byte count
  * @gfp_mask:	memory allocation flags
  *
  * Description:
  *    Data will be mapped directly for zero copy I/O, if possible. Otherwise
  *    a kernel bounce buffer is used.
  *
  *    A matching blk_rq_unmap_user() must be issued at the end of I/O, while
  *    still in process context.
  *
  *    Note: The mapped bio may need to be bounced through blk_queue_bounce()
  *    before being submitted to the device, as pages mapped may be out of
  *    reach. It's the callers responsibility to make sure this happens. The
  *    original bio must be passed back in to blk_rq_unmap_user() for proper
  *    unmapping.
  */
 int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
 			struct rq_map_data *map_data, const struct sg_iovec *iov,
 			int iov_count, unsigned int len, gfp_t gfp_mask)
 {
 	struct bio *bio;
 	int i, read = rq_data_dir(rq) == READ;
 	int unaligned = 0;

 	if (!iov || iov_count <= 0)
 		return -EINVAL;

 	for (i = 0; i < iov_count; i++) {
 		unsigned long uaddr = (unsigned long)iov[i].iov_base;

 		if (!iov[i].iov_len)
 			return -EINVAL;

 		/*
 		 * Keep going so we check length of all segments
 		 */
 		if (uaddr & queue_dma_alignment(q))
 			unaligned = 1;
 	}

 	if (unaligned || (q->dma_pad_mask & len) || map_data)
 		bio = bio_copy_user_iov(q, map_data, iov, iov_count, read,
 					gfp_mask);
 	else
 		bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask);

 	if (IS_ERR(bio))
 		return PTR_ERR(bio);

 	if (bio->bi_iter.bi_size != len) {
 		/*
 		 * Grab an extra reference to this bio, as bio_unmap_user()
 		 * expects to be able to drop it twice as it happens on the
 		 * normal IO completion path
 		 */
 		bio_get(bio);
 		bio_endio(bio, 0);
 		__blk_rq_unmap_user(bio);
 		return -EINVAL;
 	}

 	if (!bio_flagged(bio, BIO_USER_MAPPED))
 		rq->cmd_flags |= REQ_COPY_USER;

 	blk_queue_bounce(q, &bio);
 	bio_get(bio);
 	blk_rq_bio_prep(q, rq, bio);
 	rq->buffer = NULL;
 	return 0;
 }
 EXPORT_SYMBOL(blk_rq_map_user_iov);

 /**
  * blk_rq_unmap_user - unmap a request with user data
  * @bio:	       start of bio list
  *
  * Description:
  *    Unmap a rq previously mapped by blk_rq_map_user(). The caller must
  *    supply the original rq->bio from the blk_rq_map_user() return, since
  *    the I/O completion may have changed rq->bio.
  */
 int blk_rq_unmap_user(struct bio *bio)
 {
 	struct bio *mapped_bio;
 	int ret = 0, ret2;

 	while (bio) {
 		mapped_bio = bio;
 		if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
 			mapped_bio = bio->bi_private;

 		ret2 = __blk_rq_unmap_user(mapped_bio);
 		if (ret2 && !ret)
 			ret = ret2;

 		mapped_bio = bio;
 		bio = bio->bi_next;
 		bio_put(mapped_bio);
 	}

 	return ret;
 }
 EXPORT_SYMBOL(blk_rq_unmap_user);

 /**
  * blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
  * @q:		request queue where request should be inserted
  * @rq:		request to fill
  * @kbuf:	the kernel buffer
  * @len:	length of user data
  * @gfp_mask:	memory allocation flags
  *
  * Description:
  *    Data will be mapped directly if possible. Otherwise a bounce
  *    buffer is used. Can be called multiple times to append multiple
  *    buffers.
  */
 int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 		    unsigned int len, gfp_t gfp_mask)
 {
 	int reading = rq_data_dir(rq) == READ;
 	unsigned long addr = (unsigned long) kbuf;
 	int do_copy = 0;
 	struct bio *bio;
 	int ret;

 	if (len > (queue_max_hw_sectors(q) << 9))
 		return -EINVAL;
 	if (!len || !kbuf)
 		return -EINVAL;

 	do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf);
 	if (do_copy)
 		bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
 	else
 		bio = bio_map_kern(q, kbuf, len, gfp_mask);

 	if (IS_ERR(bio))
 		return PTR_ERR(bio);

 	if (!reading)
 		bio->bi_rw |= REQ_WRITE;

 	if (do_copy)
 		rq->cmd_flags |= REQ_COPY_USER;

 	ret = blk_rq_append_bio(q, rq, bio);
 	if (unlikely(ret)) {
 		/* request is too big */
 		bio_put(bio);
 		return ret;
 	}

 	blk_queue_bounce(q, &rq->bio);
 	rq->buffer = NULL;
 	return 0;
 }
 EXPORT_SYMBOL(blk_rq_map_kern);
	/*
	* Functions related to mapping data to requests
	*/
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/bio.h>
	#include <linux/blkdev.h>
	#include <scsi/sg.h> /* for struct sg_iovec */

	#include "blk.h"

	int blk_rq_append_bio(struct request_queue q, struct request rq,
	struct bio *bio)
	{
	if (!rq->bio)
	blk_rq_bio_prep(q, rq, bio);
	else if (!ll_back_merge_fn(q, rq, bio))
	return -EINVAL;
	else {
	rq->biotail->bi_next = bio;
	rq->biotail = bio;

	rq->__data_len += bio->bi_iter.bi_size;
	}
	return 0;
	}

	static int __blk_rq_unmap_user(struct bio *bio)
	{
	int ret = 0;

	if (bio) {
	if (bio_flagged(bio, BIO_USER_MAPPED))
	bio_unmap_user(bio);
	else
	ret = bio_uncopy_user(bio);
	}

	return ret;
	}

	static int __blk_rq_map_user(struct request_queue q, struct request rq,
	struct rq_map_data map_data, void __user ubuf,
	unsigned int len, gfp_t gfp_mask)
	{
	unsigned long uaddr;
	struct bio bio, orig_bio;
	int reading, ret;

	reading = rq_data_dir(rq) == READ;

	/*
	* if alignment requirement is satisfied, map in user pages for
	* direct dma. else, set up kernel bounce buffers
	*/
	uaddr = (unsigned long) ubuf;
	if (blk_rq_aligned(q, uaddr, len) && !map_data)
	bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask);
	else
	bio = bio_copy_user(q, map_data, uaddr, len, reading, gfp_mask);

	if (IS_ERR(bio))
	return PTR_ERR(bio);

	if (map_data && map_data->null_mapped)
	bio->bi_flags \|= (1 << BIO_NULL_MAPPED);

	orig_bio = bio;
	blk_queue_bounce(q, &bio);

	/*
	* We link the bounce buffer in and could have to traverse it
	* later so we have to get a ref to prevent it from being freed
	*/
	bio_get(bio);

	ret = blk_rq_append_bio(q, rq, bio);
	if (!ret)
	return bio->bi_iter.bi_size;

	/* if it was boucned we must call the end io function */
	bio_endio(bio, 0);
	__blk_rq_unmap_user(orig_bio);
	bio_put(bio);
	return ret;
	}

	/**
	* blk_rq_map_user - map user data to a request, for REQ_TYPE_BLOCK_PC usage
	* @q: request queue where request should be inserted
	* @rq: request structure to fill
	* @map_data: pointer to the rq_map_data holding pages (if necessary)
	* @ubuf: the user buffer
	* @len: length of user data
	* @gfp_mask: memory allocation flags
	*
	* Description:
	* Data will be mapped directly for zero copy I/O, if possible. Otherwise
	* a kernel bounce buffer is used.
	*
	* A matching blk_rq_unmap_user() must be issued at the end of I/O, while
	* still in process context.
	*
	* Note: The mapped bio may need to be bounced through blk_queue_bounce()
	* before being submitted to the device, as pages mapped may be out of
	* reach. It's the callers responsibility to make sure this happens. The
	* original bio must be passed back in to blk_rq_unmap_user() for proper
	* unmapping.
	*/
	int blk_rq_map_user(struct request_queue q, struct request rq,
	struct rq_map_data map_data, void __user ubuf,
	unsigned long len, gfp_t gfp_mask)
	{
	unsigned long bytes_read = 0;
	struct bio *bio = NULL;
	int ret;

	if (len > (queue_max_hw_sectors(q) << 9))
	return -EINVAL;
	if (!len)
	return -EINVAL;

	if (!ubuf && (!map_data \|\| !map_data->null_mapped))
	return -EINVAL;

	while (bytes_read != len) {
	unsigned long map_len, end, start;

	map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
	end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
	>> PAGE_SHIFT;
	start = (unsigned long)ubuf >> PAGE_SHIFT;

	/*
	* A bad offset could cause us to require BIO_MAX_PAGES + 1
	* pages. If this happens we just lower the requested
	* mapping len by a page so that we can fit
	*/
	if (end - start > BIO_MAX_PAGES)
	map_len -= PAGE_SIZE;

	ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len,
	gfp_mask);
	if (ret < 0)
	goto unmap_rq;
	if (!bio)
	bio = rq->bio;
	bytes_read += ret;
	ubuf += ret;

	if (map_data)
	map_data->offset += ret;
	}

	if (!bio_flagged(bio, BIO_USER_MAPPED))
	rq->cmd_flags \|= REQ_COPY_USER;

	rq->buffer = NULL;
	return 0;
	unmap_rq:
	blk_rq_unmap_user(bio);
	rq->bio = NULL;
	return ret;
	}
	EXPORT_SYMBOL(blk_rq_map_user);

	/**
	* blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
	* @q: request queue where request should be inserted
	* @rq: request to map data to
	* @map_data: pointer to the rq_map_data holding pages (if necessary)
	* @iov: pointer to the iovec
	* @iov_count: number of elements in the iovec
	* @len: I/O byte count
	* @gfp_mask: memory allocation flags
	*
	* Description:
	* Data will be mapped directly for zero copy I/O, if possible. Otherwise
	* a kernel bounce buffer is used.
	*
	* A matching blk_rq_unmap_user() must be issued at the end of I/O, while
	* still in process context.
	*
	* Note: The mapped bio may need to be bounced through blk_queue_bounce()
	* before being submitted to the device, as pages mapped may be out of
	* reach. It's the callers responsibility to make sure this happens. The
	* original bio must be passed back in to blk_rq_unmap_user() for proper
	* unmapping.
	*/
	int blk_rq_map_user_iov(struct request_queue q, struct request rq,
	struct rq_map_data map_data, const struct sg_iovec iov,
	int iov_count, unsigned int len, gfp_t gfp_mask)
	{
	struct bio *bio;
	int i, read = rq_data_dir(rq) == READ;
	int unaligned = 0;

	if (!iov \|\| iov_count <= 0)
	return -EINVAL;

	for (i = 0; i < iov_count; i++) {
	unsigned long uaddr = (unsigned long)iov[i].iov_base;

	if (!iov[i].iov_len)
	return -EINVAL;

	/*
	* Keep going so we check length of all segments
	*/
	if (uaddr & queue_dma_alignment(q))
	unaligned = 1;
	}

	if (unaligned \|\| (q->dma_pad_mask & len) \|\| map_data)
	bio = bio_copy_user_iov(q, map_data, iov, iov_count, read,
	gfp_mask);
	else
	bio = bio_map_user_iov(q, NULL, iov, iov_count, read, gfp_mask);

	if (IS_ERR(bio))
	return PTR_ERR(bio);

	if (bio->bi_iter.bi_size != len) {
	/*
	* Grab an extra reference to this bio, as bio_unmap_user()
	* expects to be able to drop it twice as it happens on the
	* normal IO completion path
	*/
	bio_get(bio);
	bio_endio(bio, 0);
	__blk_rq_unmap_user(bio);
	return -EINVAL;
	}

	if (!bio_flagged(bio, BIO_USER_MAPPED))
	rq->cmd_flags \|= REQ_COPY_USER;

	blk_queue_bounce(q, &bio);
	bio_get(bio);
	blk_rq_bio_prep(q, rq, bio);
	rq->buffer = NULL;
	return 0;
	}
	EXPORT_SYMBOL(blk_rq_map_user_iov);

	/**
	* blk_rq_unmap_user - unmap a request with user data
	* @bio: start of bio list
	*
	* Description:
	* Unmap a rq previously mapped by blk_rq_map_user(). The caller must
	* supply the original rq->bio from the blk_rq_map_user() return, since
	* the I/O completion may have changed rq->bio.
	*/
	int blk_rq_unmap_user(struct bio *bio)
	{
	struct bio *mapped_bio;
	int ret = 0, ret2;

	while (bio) {
	mapped_bio = bio;
	if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
	mapped_bio = bio->bi_private;

	ret2 = __blk_rq_unmap_user(mapped_bio);
	if (ret2 && !ret)
	ret = ret2;

	mapped_bio = bio;
	bio = bio->bi_next;
	bio_put(mapped_bio);
	}

	return ret;
	}
	EXPORT_SYMBOL(blk_rq_unmap_user);

	/**
	* blk_rq_map_kern - map kernel data to a request, for REQ_TYPE_BLOCK_PC usage
	* @q: request queue where request should be inserted
	* @rq: request to fill
	* @kbuf: the kernel buffer
	* @len: length of user data
	* @gfp_mask: memory allocation flags
	*
	* Description:
	* Data will be mapped directly if possible. Otherwise a bounce
	* buffer is used. Can be called multiple times to append multiple
	* buffers.
	*/
	int blk_rq_map_kern(struct request_queue q, struct request rq, void *kbuf,
	unsigned int len, gfp_t gfp_mask)
	{
	int reading = rq_data_dir(rq) == READ;
	unsigned long addr = (unsigned long) kbuf;
	int do_copy = 0;
	struct bio *bio;
	int ret;

	if (len > (queue_max_hw_sectors(q) << 9))
	return -EINVAL;
	if (!len \|\| !kbuf)
	return -EINVAL;

	do_copy = !blk_rq_aligned(q, addr, len) \|\| object_is_on_stack(kbuf);
	if (do_copy)
	bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
	else
	bio = bio_map_kern(q, kbuf, len, gfp_mask);

	if (IS_ERR(bio))
	return PTR_ERR(bio);

	if (!reading)
	bio->bi_rw \|= REQ_WRITE;

	if (do_copy)
	rq->cmd_flags \|= REQ_COPY_USER;

	ret = blk_rq_append_bio(q, rq, bio);
	if (unlikely(ret)) {
	/* request is too big */
	bio_put(bio);
	return ret;
	}

	blk_queue_bounce(q, &rq->bio);
	rq->buffer = NULL;
	return 0;
	}
	EXPORT_SYMBOL(blk_rq_map_kern);