WebSVN – Kolibri OS – Diff – /drivers/ddk/linux/scatterlist.c


/*
 * Copyright (C) 2007 Jens Axboe 
 *
 * Scatterlist handling helpers.
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2. See the file COPYING for more details.
 */
#include 
#include 
#include 
 
/**
 * sg_next - return the next scatterlist entry in a list
 * @sg:		The current sg entry
 *
 * Description:
 *   Usually the next entry will be @sg@ + 1, but if this sg element is part
 *   of a chained scatterlist, it could jump to the start of a new
 *   scatterlist array.
 *
 **/
struct scatterlist *sg_next(struct scatterlist *sg)
{
#ifdef CONFIG_DEBUG_SG
	BUG_ON(sg->sg_magic != SG_MAGIC);
#endif
	if (sg_is_last(sg))
		return NULL;
 
	sg++;
	if (unlikely(sg_is_chain(sg)))
		sg = sg_chain_ptr(sg);
 
	return sg;
}
EXPORT_SYMBOL(sg_next);
 
/**
 * sg_nents - return total count of entries in scatterlist
 * @sg:		The scatterlist
 *
 * Description:
 * Allows to know how many entries are in sg, taking into acount
 * chaining as well
 *
 **/
int sg_nents(struct scatterlist *sg)
{
	int nents;
	for (nents = 0; sg; sg = sg_next(sg))
		nents++;
	return nents;
}
EXPORT_SYMBOL(sg_nents);
 
/**
 * sg_nents_for_len - return total count of entries in scatterlist
 *                    needed to satisfy the supplied length
 * @sg:		The scatterlist
 * @len:	The total required length
 *
 * Description:
 * Determines the number of entries in sg that are required to meet
 * the supplied length, taking into acount chaining as well
 *
 * Returns:
 *   the number of sg entries needed, negative error on failure
 *
 **/
int sg_nents_for_len(struct scatterlist *sg, u64 len)
{
	int nents;
	u64 total;
 
	if (!len)
		return 0;
 
	for (nents = 0, total = 0; sg; sg = sg_next(sg)) {
		nents++;
		total += sg->length;
		if (total >= len)
			return nents;
	}
 
	return -EINVAL;
}
EXPORT_SYMBOL(sg_nents_for_len);
 
/**
 * sg_last - return the last scatterlist entry in a list
 * @sgl:	First entry in the scatterlist
 * @nents:	Number of entries in the scatterlist
 *
 * Description:
 *   Should only be used casually, it (currently) scans the entire list
 *   to get the last entry.
 *
 *   Note that the @sgl@ pointer passed in need not be the first one,
 *   the important bit is that @nents@ denotes the number of entries that
 *   exist from @sgl@.
 *
 **/
struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
{
	struct scatterlist *sg, *ret = NULL;
	unsigned int i;
 
	for_each_sg(sgl, sg, nents, i)
		ret = sg;
 
#ifdef CONFIG_DEBUG_SG
	BUG_ON(sgl[0].sg_magic != SG_MAGIC);
	BUG_ON(!sg_is_last(ret));
#endif
	return ret;
}
EXPORT_SYMBOL(sg_last);
 
/**
 * sg_init_table - Initialize SG table
 * @sgl:	   The SG table
 * @nents:	   Number of entries in table
 *
 * Notes:
 *   If this is part of a chained sg table, sg_mark_end() should be
 *   used only on the last table part.
 *
 **/
void sg_init_table(struct scatterlist *sgl, unsigned int nents)
{
	memset(sgl, 0, sizeof(*sgl) * nents);
#ifdef CONFIG_DEBUG_SG
	{
		unsigned int i;
		for (i = 0; i < nents; i++)
			sgl[i].sg_magic = SG_MAGIC;
	}
#endif
	sg_mark_end(&sgl[nents - 1]);
}
EXPORT_SYMBOL(sg_init_table);
 
/**
 * sg_init_one - Initialize a single entry sg list
 * @sg:		 SG entry
 * @buf:	 Virtual address for IO
 * @buflen:	 IO length
 *
 **/
//void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
//{
//   sg_init_table(sg, 1);
//   sg_set_buf(sg, buf, buflen);
//}
EXPORT_SYMBOL(sg_init_one);
 
/*
 * The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
 * helpers.
 */
static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
{
	return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
}
 
static void sg_kfree(struct scatterlist *sg, unsigned int nents)
{
	kfree(sg);
}
 
/**
 * __sg_free_table - Free a previously mapped sg table
 * @table:	The sg table header to use
 * @max_ents:	The maximum number of entries per single scatterlist
 * @skip_first_chunk: don't free the (preallocated) first scatterlist chunk
 * @free_fn:	Free function
 *
 *  Description:
 *    Free an sg table previously allocated and setup with
 *    __sg_alloc_table().  The @max_ents value must be identical to
 *    that previously used with __sg_alloc_table().
 *
 **/
void __sg_free_table(struct sg_table *table, unsigned int max_ents,
		     bool skip_first_chunk, sg_free_fn *free_fn)
{
	struct scatterlist *sgl, *next;
 
	if (unlikely(!table->sgl))
		return;
 
	sgl = table->sgl;
	while (table->orig_nents) {
		unsigned int alloc_size = table->orig_nents;
		unsigned int sg_size;
 
		/*
		 * If we have more than max_ents segments left,
		 * then assign 'next' to the sg table after the current one.
		 * sg_size is then one less than alloc size, since the last
		 * element is the chain pointer.
		 */
		if (alloc_size > max_ents) {
			next = sg_chain_ptr(&sgl[max_ents - 1]);
			alloc_size = max_ents;
			sg_size = alloc_size - 1;
		} else {
			sg_size = alloc_size;
			next = NULL;
		}
 
		table->orig_nents -= sg_size;
		if (skip_first_chunk)
			skip_first_chunk = false;
		else
			free_fn(sgl, alloc_size);
		sgl = next;
	}
 
	table->sgl = NULL;
}
EXPORT_SYMBOL(__sg_free_table);
 
/**
 * sg_free_table - Free a previously allocated sg table
 * @table:	The mapped sg table header
 *
 **/
void sg_free_table(struct sg_table *table)
{
	__sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
}
EXPORT_SYMBOL(sg_free_table);
 
/**
 * __sg_alloc_table - Allocate and initialize an sg table with given allocator
 * @table:	The sg table header to use
 * @nents:	Number of entries in sg list
 * @max_ents:	The maximum number of entries the allocator returns per call
 * @gfp_mask:	GFP allocation mask
 * @alloc_fn:	Allocator to use
 *
 * Description:
 *   This function returns a @table @nents long. The allocator is
 *   defined to return scatterlist chunks of maximum size @max_ents.
 *   Thus if @nents is bigger than @max_ents, the scatterlists will be
 *   chained in units of @max_ents.
 *
 * Notes:
 *   If this function returns non-0 (eg failure), the caller must call
 *   __sg_free_table() to cleanup any leftover allocations.
 *
 **/
int __sg_alloc_table(struct sg_table *table, unsigned int nents,
		     unsigned int max_ents, struct scatterlist *first_chunk,
		     gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
{
	struct scatterlist *sg, *prv;
	unsigned int left;
 
	memset(table, 0, sizeof(*table));
 
	if (nents == 0)
		return -EINVAL;
#ifndef CONFIG_ARCH_HAS_SG_CHAIN
	if (WARN_ON_ONCE(nents > max_ents))
		return -EINVAL;
#endif
 
	left = nents;
	prv = NULL;
	do {
		unsigned int sg_size, alloc_size = left;
 
		if (alloc_size > max_ents) {
			alloc_size = max_ents;
			sg_size = alloc_size - 1;
		} else
			sg_size = alloc_size;
 
		left -= sg_size;
 
		if (first_chunk) {
			sg = first_chunk;
			first_chunk = NULL;
		} else {
			sg = alloc_fn(alloc_size, gfp_mask);
		}
		if (unlikely(!sg)) {
			/*
			 * Adjust entry count to reflect that the last
			 * entry of the previous table won't be used for
			 * linkage.  Without this, sg_kfree() may get
			 * confused.
			 */
			if (prv)
				table->nents = ++table->orig_nents;
 
 			return -ENOMEM;
		}
 
		sg_init_table(sg, alloc_size);
		table->nents = table->orig_nents += sg_size;
 
		/*
		 * If this is the first mapping, assign the sg table header.
		 * If this is not the first mapping, chain previous part.
		 */
		if (prv)
			sg_chain(prv, max_ents, sg);
		else
			table->sgl = sg;
 
		/*
		 * If no more entries after this one, mark the end
		 */
		if (!left)
			sg_mark_end(&sg[sg_size - 1]);
 
		prv = sg;
	} while (left);
 
	return 0;
}
EXPORT_SYMBOL(__sg_alloc_table);
 
/**
 * sg_alloc_table - Allocate and initialize an sg table
 * @table:	The sg table header to use
 * @nents:	Number of entries in sg list
 * @gfp_mask:	GFP allocation mask
 *
 *  Description:
 *    Allocate and initialize an sg table. If @nents@ is larger than
 *    SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
 *
 **/
int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
{
	int ret;
 
	ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
			       NULL, gfp_mask, sg_kmalloc);
	if (unlikely(ret))
		__sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
 
	return ret;
}
EXPORT_SYMBOL(sg_alloc_table);
 
/**
 * sg_alloc_table_from_pages - Allocate and initialize an sg table from
 *			       an array of pages
 * @sgt:	The sg table header to use
 * @pages:	Pointer to an array of page pointers
 * @n_pages:	Number of pages in the pages array
 * @offset:     Offset from start of the first page to the start of a buffer
 * @size:       Number of valid bytes in the buffer (after offset)
 * @gfp_mask:	GFP allocation mask
 *
 *  Description:
 *    Allocate and initialize an sg table from a list of pages. Contiguous
 *    ranges of the pages are squashed into a single scatterlist node. A user
 *    may provide an offset at a start and a size of valid data in a buffer
 *    specified by the page array. The returned sg table is released by
 *    sg_free_table.
 *
 * Returns:
 *   0 on success, negative error on failure
 */
int sg_alloc_table_from_pages(struct sg_table *sgt,
	struct page **pages, unsigned int n_pages,
	unsigned long offset, unsigned long size,
	gfp_t gfp_mask)
{
	unsigned int chunks;
	unsigned int i;
	unsigned int cur_page;
	int ret;
	struct scatterlist *s;
 
	/* compute number of contiguous chunks */
	chunks = 1;
	for (i = 1; i < n_pages; ++i)
		if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1)
			++chunks;
 
	ret = sg_alloc_table(sgt, chunks, gfp_mask);
	if (unlikely(ret))
		return ret;
 
	/* merging chunks and putting them into the scatterlist */
	cur_page = 0;
	for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
		unsigned long chunk_size;
		unsigned int j;
 
		/* look for the end of the current chunk */
		for (j = cur_page + 1; j < n_pages; ++j)
			if (page_to_pfn(pages[j]) !=
			    page_to_pfn(pages[j - 1]) + 1)
				break;
 
		chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
		sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);
		size -= chunk_size;
		offset = 0;
		cur_page = j;
	}
 
	return 0;
}
EXPORT_SYMBOL(sg_alloc_table_from_pages);
 
void __sg_page_iter_start(struct sg_page_iter *piter,
			  struct scatterlist *sglist, unsigned int nents,
			  unsigned long pgoffset)
{
	piter->__pg_advance = 0;
	piter->__nents = nents;
 
	piter->sg = sglist;
	piter->sg_pgoffset = pgoffset;
}
EXPORT_SYMBOL(__sg_page_iter_start);
 
static int sg_page_count(struct scatterlist *sg)
{
	return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
}
 
bool __sg_page_iter_next(struct sg_page_iter *piter)
{
	if (!piter->__nents || !piter->sg)
		return false;
 
	piter->sg_pgoffset += piter->__pg_advance;
	piter->__pg_advance = 1;
 
	while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
		piter->sg_pgoffset -= sg_page_count(piter->sg);
		piter->sg = sg_next(piter->sg);
		if (!--piter->__nents || !piter->sg)
			return false;
	}
 
	return true;
}
EXPORT_SYMBOL(__sg_page_iter_next);
 
/**
 * sg_miter_start - start mapping iteration over a sg list
 * @miter: sg mapping iter to be started
 * @sgl: sg list to iterate over
 * @nents: number of sg entries
 *
 * Description:
 *   Starts mapping iterator @miter.
 *
 * Context:
 *   Don't care.
 */
void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
		    unsigned int nents, unsigned int flags)
{
	memset(miter, 0, sizeof(struct sg_mapping_iter));
 
	__sg_page_iter_start(&miter->piter, sgl, nents, 0);
	WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
	miter->__flags = flags;
}
EXPORT_SYMBOL(sg_miter_start);
 
static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
{
	if (!miter->__remaining) {
		struct scatterlist *sg;
		unsigned long pgoffset;
 
		if (!__sg_page_iter_next(&miter->piter))
			return false;
 
		sg = miter->piter.sg;
		pgoffset = miter->piter.sg_pgoffset;
 
		miter->__offset = pgoffset ? 0 : sg->offset;
		miter->__remaining = sg->offset + sg->length -
				(pgoffset << PAGE_SHIFT) - miter->__offset;
		miter->__remaining = min_t(unsigned long, miter->__remaining,
					   PAGE_SIZE - miter->__offset);
	}
 
	return true;
}
 
/**
 * sg_miter_skip - reposition mapping iterator
 * @miter: sg mapping iter to be skipped
 * @offset: number of bytes to plus the current location
 *
 * Description:
 *   Sets the offset of @miter to its current location plus @offset bytes.
 *   If mapping iterator @miter has been proceeded by sg_miter_next(), this
 *   stops @miter.
 *
 * Context:
 *   Don't care if @miter is stopped, or not proceeded yet.
 *   Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
 *
 * Returns:
 *   true if @miter contains the valid mapping.  false if end of sg
 *   list is reached.
 */
bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
{
	sg_miter_stop(miter);
 
	while (offset) {
		off_t consumed;
 
		if (!sg_miter_get_next_page(miter))
			return false;
 
		consumed = min_t(off_t, offset, miter->__remaining);
		miter->__offset += consumed;
		miter->__remaining -= consumed;
		offset -= consumed;
	}
 
	return true;
}
EXPORT_SYMBOL(sg_miter_skip);
 
/**
 * sg_miter_next - proceed mapping iterator to the next mapping
 * @miter: sg mapping iter to proceed
 *
 * Description:
 *   Proceeds @miter to the next mapping.  @miter should have been started
 *   using sg_miter_start().  On successful return, @miter->page,
 *   @miter->addr and @miter->length point to the current mapping.
 *
 * Context:
 *   Preemption disabled if SG_MITER_ATOMIC.  Preemption must stay disabled
 *   till @miter is stopped.  May sleep if !SG_MITER_ATOMIC.
 *
 * Returns:
 *   true if @miter contains the next mapping.  false if end of sg
 *   list is reached.
 */
bool sg_miter_next(struct sg_mapping_iter *miter)
{
	sg_miter_stop(miter);
 
	/*
	 * Get to the next page if necessary.
	 * __remaining, __offset is adjusted by sg_miter_stop
	 */
	if (!sg_miter_get_next_page(miter))
		return false;
 
	miter->page = sg_page_iter_page(&miter->piter);
	miter->consumed = miter->length = miter->__remaining;
 
	if (miter->__flags & SG_MITER_ATOMIC)
		miter->addr = kmap_atomic(miter->page) + miter->__offset;
	else
		miter->addr = kmap(miter->page) + miter->__offset;
 
	return true;
}
EXPORT_SYMBOL(sg_miter_next);
 
/**
 * sg_miter_stop - stop mapping iteration
 * @miter: sg mapping iter to be stopped
 *
 * Description:
 *   Stops mapping iterator @miter.  @miter should have been started
 *   using sg_miter_start().  A stopped iteration can be resumed by
 *   calling sg_miter_next() on it.  This is useful when resources (kmap)
 *   need to be released during iteration.
 *
 * Context:
 *   Preemption disabled if the SG_MITER_ATOMIC is set.  Don't care
 *   otherwise.
 */
void sg_miter_stop(struct sg_mapping_iter *miter)
{
	WARN_ON(miter->consumed > miter->length);
 
	/* drop resources from the last iteration */
	if (miter->addr) {
		miter->__offset += miter->consumed;
		miter->__remaining -= miter->consumed;
 
		if (miter->__flags & SG_MITER_ATOMIC) {
			WARN_ON_ONCE(preemptible());
			kunmap_atomic(miter->addr);
		} else
			kunmap(miter->page);
 
		miter->page = NULL;
		miter->addr = NULL;
		miter->length = 0;
		miter->consumed = 0;
	}
}
EXPORT_SYMBOL(sg_miter_stop);
 
/**
 * sg_copy_buffer - Copy data between a linear buffer and an SG list
 * @sgl:		 The SG list
 * @nents:		 Number of SG entries
 * @buf:		 Where to copy from
 * @buflen:		 The number of bytes to copy
 * @skip:		 Number of bytes to skip before copying
 * @to_buffer:		 transfer direction (true == from an sg list to a
 *			 buffer, false == from a buffer to an sg list
 *
 * Returns the number of copied bytes.
 *
 **/
size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
		      size_t buflen, off_t skip, bool to_buffer)
{
	unsigned int offset = 0;
	struct sg_mapping_iter miter;
	unsigned long flags;
	unsigned int sg_flags = SG_MITER_ATOMIC;
 
	if (to_buffer)
		sg_flags |= SG_MITER_FROM_SG;
	else
		sg_flags |= SG_MITER_TO_SG;
 
	sg_miter_start(&miter, sgl, nents, sg_flags);
 
	if (!sg_miter_skip(&miter, skip))
		return false;
 
	local_irq_save(flags);
 
	while (sg_miter_next(&miter) && offset < buflen) {
		unsigned int len;
 
		len = min(miter.length, buflen - offset);
 
		if (to_buffer)
			memcpy(buf + offset, miter.addr, len);
		else
			memcpy(miter.addr, buf + offset, len);
 
		offset += len;
	}
 
	sg_miter_stop(&miter);
 
	local_irq_restore(flags);
	return offset;
}
EXPORT_SYMBOL(sg_copy_buffer);
 
/**
 * sg_copy_from_buffer - Copy from a linear buffer to an SG list
 * @sgl:		 The SG list
 * @nents:		 Number of SG entries
 * @buf:		 Where to copy from
 * @buflen:		 The number of bytes to copy
 *
 * Returns the number of copied bytes.
 *
 **/
size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
			   const void *buf, size_t buflen)
{
	return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false);
}
EXPORT_SYMBOL(sg_copy_from_buffer);
 
/**
 * sg_copy_to_buffer - Copy from an SG list to a linear buffer
 * @sgl:		 The SG list
 * @nents:		 Number of SG entries
 * @buf:		 Where to copy to
 * @buflen:		 The number of bytes to copy
 *
 * Returns the number of copied bytes.
 *
 **/
size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
			 void *buf, size_t buflen)
{
	return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
}
EXPORT_SYMBOL(sg_copy_to_buffer);
 
/**
 * sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
 * @sgl:		 The SG list
 * @nents:		 Number of SG entries
 * @buf:		 Where to copy from
 * @buflen:		 The number of bytes to copy
 * @skip:		 Number of bytes to skip before copying
 *
 * Returns the number of copied bytes.
 *
 **/
size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
			    const void *buf, size_t buflen, off_t skip)
{
	return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false);
}
EXPORT_SYMBOL(sg_pcopy_from_buffer);
 
/**
 * sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
 * @sgl:		 The SG list
 * @nents:		 Number of SG entries
 * @buf:		 Where to copy to
 * @buflen:		 The number of bytes to copy
 * @skip:		 Number of bytes to skip before copying
 *
 * Returns the number of copied bytes.
 *
 **/
size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
			  void *buf, size_t buflen, off_t skip)
{
	return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
}
EXPORT_SYMBOL(sg_pcopy_to_buffer);

Rev 6293	Rev 6936
1	/*	1	/*
2	* Copyright (C) 2007 Jens Axboe	2	* Copyright (C) 2007 Jens Axboe
3	*	3	*
4	* Scatterlist handling helpers.	4	* Scatterlist handling helpers.
5	*	5	*
6	* This source code is licensed under the GNU General Public License,	6	* This source code is licensed under the GNU General Public License,
7	* Version 2. See the file COPYING for more details.	7	* Version 2. See the file COPYING for more details.
8	*/	8	*/
9	#include	9	#include
10	#include	10	#include
11	#include	11	#include
12		12
13	/**	13	/**
14	* sg_next - return the next scatterlist entry in a list	14	* sg_next - return the next scatterlist entry in a list
15	* @sg: The current sg entry	15	* @sg: The current sg entry
16	*	16	*
17	* Description:	17	* Description:
18	* Usually the next entry will be @sg@ + 1, but if this sg element is part	18	* Usually the next entry will be @sg@ + 1, but if this sg element is part
19	* of a chained scatterlist, it could jump to the start of a new	19	* of a chained scatterlist, it could jump to the start of a new
20	* scatterlist array.	20	* scatterlist array.
21	*	21	*
22	**/	22	**/
23	struct scatterlist sg_next(struct scatterlist sg)	23	struct scatterlist sg_next(struct scatterlist sg)
24	{	24	{
25	#ifdef CONFIG_DEBUG_SG	25	#ifdef CONFIG_DEBUG_SG
26	BUG_ON(sg->sg_magic != SG_MAGIC);	26	BUG_ON(sg->sg_magic != SG_MAGIC);
27	#endif	27	#endif
28	if (sg_is_last(sg))	28	if (sg_is_last(sg))
29	return NULL;	29	return NULL;
30		30
31	sg++;	31	sg++;
32	if (unlikely(sg_is_chain(sg)))	32	if (unlikely(sg_is_chain(sg)))
33	sg = sg_chain_ptr(sg);	33	sg = sg_chain_ptr(sg);
34		34
35	return sg;	35	return sg;
36	}	36	}
37	EXPORT_SYMBOL(sg_next);	37	EXPORT_SYMBOL(sg_next);
38		38
39	/**	39	/**
40	* sg_nents - return total count of entries in scatterlist	40	* sg_nents - return total count of entries in scatterlist
41	* @sg: The scatterlist	41	* @sg: The scatterlist
42	*	42	*
43	* Description:	43	* Description:
44	* Allows to know how many entries are in sg, taking into acount	44	* Allows to know how many entries are in sg, taking into acount
45	* chaining as well	45	* chaining as well
46	*	46	*
47	**/	47	**/
48	int sg_nents(struct scatterlist *sg)	48	int sg_nents(struct scatterlist *sg)
49	{	49	{
50	int nents;	50	int nents;
51	for (nents = 0; sg; sg = sg_next(sg))	51	for (nents = 0; sg; sg = sg_next(sg))
52	nents++;	52	nents++;
53	return nents;	53	return nents;
54	}	54	}
55	EXPORT_SYMBOL(sg_nents);	55	EXPORT_SYMBOL(sg_nents);
56		56
57	/**	57	/**
58	* sg_nents_for_len - return total count of entries in scatterlist	58	* sg_nents_for_len - return total count of entries in scatterlist
59	* needed to satisfy the supplied length	59	* needed to satisfy the supplied length
60	* @sg: The scatterlist	60	* @sg: The scatterlist
61	* @len: The total required length	61	* @len: The total required length
62	*	62	*
63	* Description:	63	* Description:
64	* Determines the number of entries in sg that are required to meet	64	* Determines the number of entries in sg that are required to meet
65	* the supplied length, taking into acount chaining as well	65	* the supplied length, taking into acount chaining as well
66	*	66	*
67	* Returns:	67	* Returns:
68	* the number of sg entries needed, negative error on failure	68	* the number of sg entries needed, negative error on failure
69	*	69	*
70	**/	70	**/
71	int sg_nents_for_len(struct scatterlist *sg, u64 len)	71	int sg_nents_for_len(struct scatterlist *sg, u64 len)
72	{	72	{
73	int nents;	73	int nents;
74	u64 total;	74	u64 total;
75		75
76	if (!len)	76	if (!len)
77	return 0;	77	return 0;
78		78
79	for (nents = 0, total = 0; sg; sg = sg_next(sg)) {	79	for (nents = 0, total = 0; sg; sg = sg_next(sg)) {
80	nents++;	80	nents++;
81	total += sg->length;	81	total += sg->length;
82	if (total >= len)	82	if (total >= len)
83	return nents;	83	return nents;
84	}	84	}
85		85
86	return -EINVAL;	86	return -EINVAL;
87	}	87	}
88	EXPORT_SYMBOL(sg_nents_for_len);	88	EXPORT_SYMBOL(sg_nents_for_len);
89		89
90	/**	90	/**
91	* sg_last - return the last scatterlist entry in a list	91	* sg_last - return the last scatterlist entry in a list
92	* @sgl: First entry in the scatterlist	92	* @sgl: First entry in the scatterlist
93	* @nents: Number of entries in the scatterlist	93	* @nents: Number of entries in the scatterlist
94	*	94	*
95	* Description:	95	* Description:
96	* Should only be used casually, it (currently) scans the entire list	96	* Should only be used casually, it (currently) scans the entire list
97	* to get the last entry.	97	* to get the last entry.
98	*	98	*
99	* Note that the @sgl@ pointer passed in need not be the first one,	99	* Note that the @sgl@ pointer passed in need not be the first one,
100	* the important bit is that @nents@ denotes the number of entries that	100	* the important bit is that @nents@ denotes the number of entries that
101	* exist from @sgl@.	101	* exist from @sgl@.
102	*	102	*
103	**/	103	**/
104	struct scatterlist sg_last(struct scatterlist sgl, unsigned int nents)	104	struct scatterlist sg_last(struct scatterlist sgl, unsigned int nents)
105	{	105	{
106	struct scatterlist sg, ret = NULL;	106	struct scatterlist sg, ret = NULL;
107	unsigned int i;	107	unsigned int i;
108		108
109	for_each_sg(sgl, sg, nents, i)	109	for_each_sg(sgl, sg, nents, i)
110	ret = sg;	110	ret = sg;
111		111
112	#ifdef CONFIG_DEBUG_SG	112	#ifdef CONFIG_DEBUG_SG
113	BUG_ON(sgl[0].sg_magic != SG_MAGIC);	113	BUG_ON(sgl[0].sg_magic != SG_MAGIC);
114	BUG_ON(!sg_is_last(ret));	114	BUG_ON(!sg_is_last(ret));
115	#endif	115	#endif
116	return ret;	116	return ret;
117	}	117	}
118	EXPORT_SYMBOL(sg_last);	118	EXPORT_SYMBOL(sg_last);
119		119
120	/**	120	/**
121	* sg_init_table - Initialize SG table	121	* sg_init_table - Initialize SG table
122	* @sgl: The SG table	122	* @sgl: The SG table
123	* @nents: Number of entries in table	123	* @nents: Number of entries in table
124	*	124	*
125	* Notes:	125	* Notes:
126	* If this is part of a chained sg table, sg_mark_end() should be	126	* If this is part of a chained sg table, sg_mark_end() should be
127	* used only on the last table part.	127	* used only on the last table part.
128	*	128	*
129	**/	129	**/
130	void sg_init_table(struct scatterlist *sgl, unsigned int nents)	130	void sg_init_table(struct scatterlist *sgl, unsigned int nents)
131	{	131	{
132	memset(sgl, 0, sizeof(sgl) nents);	132	memset(sgl, 0, sizeof(sgl) nents);
133	#ifdef CONFIG_DEBUG_SG	133	#ifdef CONFIG_DEBUG_SG
134	{	134	{
135	unsigned int i;	135	unsigned int i;
136	for (i = 0; i < nents; i++)	136	for (i = 0; i < nents; i++)
137	sgl[i].sg_magic = SG_MAGIC;	137	sgl[i].sg_magic = SG_MAGIC;
138	}	138	}
139	#endif	139	#endif
140	sg_mark_end(&sgl[nents - 1]);	140	sg_mark_end(&sgl[nents - 1]);
141	}	141	}
142	EXPORT_SYMBOL(sg_init_table);	142	EXPORT_SYMBOL(sg_init_table);
143		143
144	/**	144	/**
145	* sg_init_one - Initialize a single entry sg list	145	* sg_init_one - Initialize a single entry sg list
146	* @sg: SG entry	146	* @sg: SG entry
147	* @buf: Virtual address for IO	147	* @buf: Virtual address for IO
148	* @buflen: IO length	148	* @buflen: IO length
149	*	149	*
150	**/	150	**/
151	//void sg_init_one(struct scatterlist sg, const void buf, unsigned int buflen)	151	//void sg_init_one(struct scatterlist sg, const void buf, unsigned int buflen)
152	//{	152	//{
153	// sg_init_table(sg, 1);	153	// sg_init_table(sg, 1);
154	// sg_set_buf(sg, buf, buflen);	154	// sg_set_buf(sg, buf, buflen);
155	//}	155	//}
156	EXPORT_SYMBOL(sg_init_one);	156	EXPORT_SYMBOL(sg_init_one);
157		157
158	/*	158	/*
159	* The default behaviour of sg_alloc_table() is to use these kmalloc/kfree	159	* The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
160	* helpers.	160	* helpers.
161	*/	161	*/
162	static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)	162	static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
163	{	163	{
164	return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);	164	return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
165	}	165	}
166		166
167	static void sg_kfree(struct scatterlist *sg, unsigned int nents)	167	static void sg_kfree(struct scatterlist *sg, unsigned int nents)
168	{	168	{
169	kfree(sg);	169	kfree(sg);
170	}	170	}
171		171
172	/**	172	/**
173	* __sg_free_table - Free a previously mapped sg table	173	* __sg_free_table - Free a previously mapped sg table
174	* @table: The sg table header to use	174	* @table: The sg table header to use
175	* @max_ents: The maximum number of entries per single scatterlist	175	* @max_ents: The maximum number of entries per single scatterlist
176	* @skip_first_chunk: don't free the (preallocated) first scatterlist chunk	176	* @skip_first_chunk: don't free the (preallocated) first scatterlist chunk
177	* @free_fn: Free function	177	* @free_fn: Free function
178	*	178	*
179	* Description:	179	* Description:
180	* Free an sg table previously allocated and setup with	180	* Free an sg table previously allocated and setup with
181	* __sg_alloc_table(). The @max_ents value must be identical to	181	* __sg_alloc_table(). The @max_ents value must be identical to
182	* that previously used with __sg_alloc_table().	182	* that previously used with __sg_alloc_table().
183	*	183	*
184	**/	184	**/
185	void __sg_free_table(struct sg_table *table, unsigned int max_ents,	185	void __sg_free_table(struct sg_table *table, unsigned int max_ents,
186	bool skip_first_chunk, sg_free_fn *free_fn)	186	bool skip_first_chunk, sg_free_fn *free_fn)
187	{	187	{
188	struct scatterlist sgl, next;	188	struct scatterlist sgl, next;
189		189
190	if (unlikely(!table->sgl))	190	if (unlikely(!table->sgl))
191	return;	191	return;
192		192
193	sgl = table->sgl;	193	sgl = table->sgl;
194	while (table->orig_nents) {	194	while (table->orig_nents) {
195	unsigned int alloc_size = table->orig_nents;	195	unsigned int alloc_size = table->orig_nents;
196	unsigned int sg_size;	196	unsigned int sg_size;
197		197
198	/*	198	/*
199	* If we have more than max_ents segments left,	199	* If we have more than max_ents segments left,
200	* then assign 'next' to the sg table after the current one.	200	* then assign 'next' to the sg table after the current one.
201	* sg_size is then one less than alloc size, since the last	201	* sg_size is then one less than alloc size, since the last
202	* element is the chain pointer.	202	* element is the chain pointer.
203	*/	203	*/
204	if (alloc_size > max_ents) {	204	if (alloc_size > max_ents) {
205	next = sg_chain_ptr(&sgl[max_ents - 1]);	205	next = sg_chain_ptr(&sgl[max_ents - 1]);
206	alloc_size = max_ents;	206	alloc_size = max_ents;
207	sg_size = alloc_size - 1;	207	sg_size = alloc_size - 1;
208	} else {	208	} else {
209	sg_size = alloc_size;	209	sg_size = alloc_size;
210	next = NULL;	210	next = NULL;
211	}	211	}
212		212
213	table->orig_nents -= sg_size;	213	table->orig_nents -= sg_size;
214	if (skip_first_chunk)	214	if (skip_first_chunk)
215	skip_first_chunk = false;	215	skip_first_chunk = false;
216	else	216	else
217	free_fn(sgl, alloc_size);	217	free_fn(sgl, alloc_size);
218	sgl = next;	218	sgl = next;
219	}	219	}
220		220
221	table->sgl = NULL;	221	table->sgl = NULL;
222	}	222	}
223	EXPORT_SYMBOL(__sg_free_table);	223	EXPORT_SYMBOL(__sg_free_table);
224		224
225	/**	225	/**
226	* sg_free_table - Free a previously allocated sg table	226	* sg_free_table - Free a previously allocated sg table
227	* @table: The mapped sg table header	227	* @table: The mapped sg table header
228	*	228	*
229	**/	229	**/
230	void sg_free_table(struct sg_table *table)	230	void sg_free_table(struct sg_table *table)
231	{	231	{
232	__sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);	232	__sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
233	}	233	}
234	EXPORT_SYMBOL(sg_free_table);	234	EXPORT_SYMBOL(sg_free_table);
235		235
236	/**	236	/**
237	* __sg_alloc_table - Allocate and initialize an sg table with given allocator	237	* __sg_alloc_table - Allocate and initialize an sg table with given allocator
238	* @table: The sg table header to use	238	* @table: The sg table header to use
239	* @nents: Number of entries in sg list	239	* @nents: Number of entries in sg list
240	* @max_ents: The maximum number of entries the allocator returns per call	240	* @max_ents: The maximum number of entries the allocator returns per call
241	* @gfp_mask: GFP allocation mask	241	* @gfp_mask: GFP allocation mask
242	* @alloc_fn: Allocator to use	242	* @alloc_fn: Allocator to use
243	*	243	*
244	* Description:	244	* Description:
245	* This function returns a @table @nents long. The allocator is	245	* This function returns a @table @nents long. The allocator is
246	* defined to return scatterlist chunks of maximum size @max_ents.	246	* defined to return scatterlist chunks of maximum size @max_ents.
247	* Thus if @nents is bigger than @max_ents, the scatterlists will be	247	* Thus if @nents is bigger than @max_ents, the scatterlists will be
248	* chained in units of @max_ents.	248	* chained in units of @max_ents.
249	*	249	*
250	* Notes:	250	* Notes:
251	* If this function returns non-0 (eg failure), the caller must call	251	* If this function returns non-0 (eg failure), the caller must call
252	* __sg_free_table() to cleanup any leftover allocations.	252	* __sg_free_table() to cleanup any leftover allocations.
253	*	253	*
254	**/	254	**/
255	int __sg_alloc_table(struct sg_table *table, unsigned int nents,	255	int __sg_alloc_table(struct sg_table *table, unsigned int nents,
256	unsigned int max_ents, struct scatterlist *first_chunk,	256	unsigned int max_ents, struct scatterlist *first_chunk,
257	gfp_t gfp_mask, sg_alloc_fn *alloc_fn)	257	gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
258	{	258	{
259	struct scatterlist sg, prv;	259	struct scatterlist sg, prv;
260	unsigned int left;	260	unsigned int left;
261		261
262	memset(table, 0, sizeof(*table));	262	memset(table, 0, sizeof(*table));
263		263
264	if (nents == 0)	264	if (nents == 0)
265	return -EINVAL;	265	return -EINVAL;
266	#ifndef CONFIG_ARCH_HAS_SG_CHAIN	266	#ifndef CONFIG_ARCH_HAS_SG_CHAIN
267	if (WARN_ON_ONCE(nents > max_ents))	267	if (WARN_ON_ONCE(nents > max_ents))
268	return -EINVAL;	268	return -EINVAL;
269	#endif	269	#endif
270		270
271	left = nents;	271	left = nents;
272	prv = NULL;	272	prv = NULL;
273	do {	273	do {
274	unsigned int sg_size, alloc_size = left;	274	unsigned int sg_size, alloc_size = left;
275		275
276	if (alloc_size > max_ents) {	276	if (alloc_size > max_ents) {
277	alloc_size = max_ents;	277	alloc_size = max_ents;
278	sg_size = alloc_size - 1;	278	sg_size = alloc_size - 1;
279	} else	279	} else
280	sg_size = alloc_size;	280	sg_size = alloc_size;
281		281
282	left -= sg_size;	282	left -= sg_size;
283		283
284	if (first_chunk) {	284	if (first_chunk) {
285	sg = first_chunk;	285	sg = first_chunk;
286	first_chunk = NULL;	286	first_chunk = NULL;
287	} else {	287	} else {
288	sg = alloc_fn(alloc_size, gfp_mask);	288	sg = alloc_fn(alloc_size, gfp_mask);
289	}	289	}
290	if (unlikely(!sg)) {	290	if (unlikely(!sg)) {
291	/*	291	/*
292	* Adjust entry count to reflect that the last	292	* Adjust entry count to reflect that the last
293	* entry of the previous table won't be used for	293	* entry of the previous table won't be used for
294	* linkage. Without this, sg_kfree() may get	294	* linkage. Without this, sg_kfree() may get
295	* confused.	295	* confused.
296	*/	296	*/
297	if (prv)	297	if (prv)
298	table->nents = ++table->orig_nents;	298	table->nents = ++table->orig_nents;
299		299
300	return -ENOMEM;	300	return -ENOMEM;
301	}	301	}
302		302
303	sg_init_table(sg, alloc_size);	303	sg_init_table(sg, alloc_size);
304	table->nents = table->orig_nents += sg_size;	304	table->nents = table->orig_nents += sg_size;
305		305
306	/*	306	/*
307	* If this is the first mapping, assign the sg table header.	307	* If this is the first mapping, assign the sg table header.
308	* If this is not the first mapping, chain previous part.	308	* If this is not the first mapping, chain previous part.
309	*/	309	*/
310	if (prv)	310	if (prv)
311	sg_chain(prv, max_ents, sg);	311	sg_chain(prv, max_ents, sg);
312	else	312	else
313	table->sgl = sg;	313	table->sgl = sg;
314		314
315	/*	315	/*
316	* If no more entries after this one, mark the end	316	* If no more entries after this one, mark the end
317	*/	317	*/
318	if (!left)	318	if (!left)
319	sg_mark_end(&sg[sg_size - 1]);	319	sg_mark_end(&sg[sg_size - 1]);
320		320
321	prv = sg;	321	prv = sg;
322	} while (left);	322	} while (left);
323		323
324	return 0;	324	return 0;
325	}	325	}
326	EXPORT_SYMBOL(__sg_alloc_table);	326	EXPORT_SYMBOL(__sg_alloc_table);
327		327
328	/**	328	/**
329	* sg_alloc_table - Allocate and initialize an sg table	329	* sg_alloc_table - Allocate and initialize an sg table
330	* @table: The sg table header to use	330	* @table: The sg table header to use
331	* @nents: Number of entries in sg list	331	* @nents: Number of entries in sg list
332	* @gfp_mask: GFP allocation mask	332	* @gfp_mask: GFP allocation mask
333	*	333	*
334	* Description:	334	* Description:
335	* Allocate and initialize an sg table. If @nents@ is larger than	335	* Allocate and initialize an sg table. If @nents@ is larger than
336	* SG_MAX_SINGLE_ALLOC a chained sg table will be setup.	336	* SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
337	*	337	*
338	**/	338	**/
339	int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)	339	int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
340	{	340	{
341	int ret;	341	int ret;
342		342
343	ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,	343	ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
344	NULL, gfp_mask, sg_kmalloc);	344	NULL, gfp_mask, sg_kmalloc);
345	if (unlikely(ret))	345	if (unlikely(ret))
346	__sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);	346	__sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
347		347
348	return ret;	348	return ret;
349	}	349	}
350	EXPORT_SYMBOL(sg_alloc_table);	350	EXPORT_SYMBOL(sg_alloc_table);
351		351
352	/**	352	/**
353	* sg_alloc_table_from_pages - Allocate and initialize an sg table from	353	* sg_alloc_table_from_pages - Allocate and initialize an sg table from
354	* an array of pages	354	* an array of pages
355	* @sgt: The sg table header to use	355	* @sgt: The sg table header to use
356	* @pages: Pointer to an array of page pointers	356	* @pages: Pointer to an array of page pointers
357	* @n_pages: Number of pages in the pages array	357	* @n_pages: Number of pages in the pages array
358	* @offset: Offset from start of the first page to the start of a buffer	358	* @offset: Offset from start of the first page to the start of a buffer
359	* @size: Number of valid bytes in the buffer (after offset)	359	* @size: Number of valid bytes in the buffer (after offset)
360	* @gfp_mask: GFP allocation mask	360	* @gfp_mask: GFP allocation mask
361	*	361	*
362	* Description:	362	* Description:
363	* Allocate and initialize an sg table from a list of pages. Contiguous	363	* Allocate and initialize an sg table from a list of pages. Contiguous
364	* ranges of the pages are squashed into a single scatterlist node. A user	364	* ranges of the pages are squashed into a single scatterlist node. A user
365	* may provide an offset at a start and a size of valid data in a buffer	365	* may provide an offset at a start and a size of valid data in a buffer
366	* specified by the page array. The returned sg table is released by	366	* specified by the page array. The returned sg table is released by
367	* sg_free_table.	367	* sg_free_table.
368	*	368	*
369	* Returns:	369	* Returns:
370	* 0 on success, negative error on failure	370	* 0 on success, negative error on failure
371	*/	371	*/
372	int sg_alloc_table_from_pages(struct sg_table *sgt,	372	int sg_alloc_table_from_pages(struct sg_table *sgt,
373	struct page **pages, unsigned int n_pages,	373	struct page **pages, unsigned int n_pages,
374	unsigned long offset, unsigned long size,	374	unsigned long offset, unsigned long size,
375	gfp_t gfp_mask)	375	gfp_t gfp_mask)
376	{	376	{
377	unsigned int chunks;	377	unsigned int chunks;
378	unsigned int i;	378	unsigned int i;
379	unsigned int cur_page;	379	unsigned int cur_page;
380	int ret;	380	int ret;
381	struct scatterlist *s;	381	struct scatterlist *s;
382		382
383	/* compute number of contiguous chunks */	383	/* compute number of contiguous chunks */
384	chunks = 1;	384	chunks = 1;
385	for (i = 1; i < n_pages; ++i)	385	for (i = 1; i < n_pages; ++i)
386	if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1)	386	if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1)
387	++chunks;	387	++chunks;
388		388
389	ret = sg_alloc_table(sgt, chunks, gfp_mask);	389	ret = sg_alloc_table(sgt, chunks, gfp_mask);
390	if (unlikely(ret))	390	if (unlikely(ret))
391	return ret;	391	return ret;
392		392
393	/* merging chunks and putting them into the scatterlist */	393	/* merging chunks and putting them into the scatterlist */
394	cur_page = 0;	394	cur_page = 0;
395	for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {	395	for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
396	unsigned long chunk_size;	396	unsigned long chunk_size;
397	unsigned int j;	397	unsigned int j;
398		398
399	/* look for the end of the current chunk */	399	/* look for the end of the current chunk */
400	for (j = cur_page + 1; j < n_pages; ++j)	400	for (j = cur_page + 1; j < n_pages; ++j)
401	if (page_to_pfn(pages[j]) !=	401	if (page_to_pfn(pages[j]) !=
402	page_to_pfn(pages[j - 1]) + 1)	402	page_to_pfn(pages[j - 1]) + 1)
403	break;	403	break;
404		404
405	chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;	405	chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
406	sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);	406	sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);
407	size -= chunk_size;	407	size -= chunk_size;
408	offset = 0;	408	offset = 0;
409	cur_page = j;	409	cur_page = j;
410	}	410	}
411		411
412	return 0;	412	return 0;
413	}	413	}
414	EXPORT_SYMBOL(sg_alloc_table_from_pages);	414	EXPORT_SYMBOL(sg_alloc_table_from_pages);
415		415
416	void __sg_page_iter_start(struct sg_page_iter *piter,	416	void __sg_page_iter_start(struct sg_page_iter *piter,
417	struct scatterlist *sglist, unsigned int nents,	417	struct scatterlist *sglist, unsigned int nents,
418	unsigned long pgoffset)	418	unsigned long pgoffset)
419	{	419	{
420	piter->__pg_advance = 0;	420	piter->__pg_advance = 0;
421	piter->__nents = nents;	421	piter->__nents = nents;
422		422
423	piter->sg = sglist;	423	piter->sg = sglist;
424	piter->sg_pgoffset = pgoffset;	424	piter->sg_pgoffset = pgoffset;
425	}	425	}
426	EXPORT_SYMBOL(__sg_page_iter_start);	426	EXPORT_SYMBOL(__sg_page_iter_start);
427		427
428	static int sg_page_count(struct scatterlist *sg)	428	static int sg_page_count(struct scatterlist *sg)
429	{	429	{
430	return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;	430	return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
431	}	431	}
432		432
433	bool __sg_page_iter_next(struct sg_page_iter *piter)	433	bool __sg_page_iter_next(struct sg_page_iter *piter)
434	{	434	{
435	if (!piter->__nents \|\| !piter->sg)	435	if (!piter->__nents \|\| !piter->sg)
436	return false;	436	return false;
437		437
438	piter->sg_pgoffset += piter->__pg_advance;	438	piter->sg_pgoffset += piter->__pg_advance;
439	piter->__pg_advance = 1;	439	piter->__pg_advance = 1;
440		440
441	while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {	441	while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
442	piter->sg_pgoffset -= sg_page_count(piter->sg);	442	piter->sg_pgoffset -= sg_page_count(piter->sg);
443	piter->sg = sg_next(piter->sg);	443	piter->sg = sg_next(piter->sg);
444	if (!--piter->__nents \|\| !piter->sg)	444	if (!--piter->__nents \|\| !piter->sg)
445	return false;	445	return false;
446	}	446	}
447		447
448	return true;	448	return true;
449	}	449	}
450	EXPORT_SYMBOL(__sg_page_iter_next);	450	EXPORT_SYMBOL(__sg_page_iter_next);
451		451
452	/**	452	/**
453	* sg_miter_start - start mapping iteration over a sg list	453	* sg_miter_start - start mapping iteration over a sg list
454	* @miter: sg mapping iter to be started	454	* @miter: sg mapping iter to be started
455	* @sgl: sg list to iterate over	455	* @sgl: sg list to iterate over
456	* @nents: number of sg entries	456	* @nents: number of sg entries
457	*	457	*
458	* Description:	458	* Description:
459	* Starts mapping iterator @miter.	459	* Starts mapping iterator @miter.
460	*	460	*
461	* Context:	461	* Context:
462	* Don't care.	462	* Don't care.
463	*/	463	*/
464	void sg_miter_start(struct sg_mapping_iter miter, struct scatterlist sgl,	464	void sg_miter_start(struct sg_mapping_iter miter, struct scatterlist sgl,
465	unsigned int nents, unsigned int flags)	465	unsigned int nents, unsigned int flags)
466	{	466	{
467	memset(miter, 0, sizeof(struct sg_mapping_iter));	467	memset(miter, 0, sizeof(struct sg_mapping_iter));
468		468
469	__sg_page_iter_start(&miter->piter, sgl, nents, 0);	469	__sg_page_iter_start(&miter->piter, sgl, nents, 0);
470	WARN_ON(!(flags & (SG_MITER_TO_SG \| SG_MITER_FROM_SG)));	470	WARN_ON(!(flags & (SG_MITER_TO_SG \| SG_MITER_FROM_SG)));
471	miter->__flags = flags;	471	miter->__flags = flags;
472	}	472	}
473	EXPORT_SYMBOL(sg_miter_start);	473	EXPORT_SYMBOL(sg_miter_start);
474		474
475	static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)	475	static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
476	{	476	{
477	if (!miter->__remaining) {	477	if (!miter->__remaining) {
478	struct scatterlist *sg;	478	struct scatterlist *sg;
479	unsigned long pgoffset;	479	unsigned long pgoffset;
480		480
481	if (!__sg_page_iter_next(&miter->piter))	481	if (!__sg_page_iter_next(&miter->piter))
482	return false;	482	return false;
483		483
484	sg = miter->piter.sg;	484	sg = miter->piter.sg;
485	pgoffset = miter->piter.sg_pgoffset;	485	pgoffset = miter->piter.sg_pgoffset;
486		486
487	miter->__offset = pgoffset ? 0 : sg->offset;	487	miter->__offset = pgoffset ? 0 : sg->offset;
488	miter->__remaining = sg->offset + sg->length -	488	miter->__remaining = sg->offset + sg->length -
489	(pgoffset << PAGE_SHIFT) - miter->__offset;	489	(pgoffset << PAGE_SHIFT) - miter->__offset;
490	miter->__remaining = min_t(unsigned long, miter->__remaining,	490	miter->__remaining = min_t(unsigned long, miter->__remaining,
491	PAGE_SIZE - miter->__offset);	491	PAGE_SIZE - miter->__offset);
492	}	492	}
493		493
494	return true;	494	return true;
495	}	495	}
496		496
497	/**	497	/**
498	* sg_miter_skip - reposition mapping iterator	498	* sg_miter_skip - reposition mapping iterator
499	* @miter: sg mapping iter to be skipped	499	* @miter: sg mapping iter to be skipped
500	* @offset: number of bytes to plus the current location	500	* @offset: number of bytes to plus the current location

Subversion Repositories Kolibri OS

(root)/drivers/ddk/linux/scatterlist.c – Rev 6293 → 6936