mirror of
https://github.com/koverstreet/bcachefs-tools.git
synced 2025-02-03 00:00:07 +03:00
110 lines
2.5 KiB
C
110 lines
2.5 KiB
C
#ifndef _LINUX_SCATTERLIST_H
|
|
#define _LINUX_SCATTERLIST_H
|
|
|
|
#include <linux/bug.h>
|
|
#include <linux/slab.h>
|
|
|
|
struct scatterlist {
|
|
unsigned long page_link;
|
|
unsigned int offset;
|
|
unsigned int length;
|
|
};
|
|
|
|
#define sg_is_chain(sg) ((sg)->page_link & 0x01)
|
|
#define sg_is_last(sg) ((sg)->page_link & 0x02)
|
|
#define sg_chain_ptr(sg) \
|
|
((struct scatterlist *) ((sg)->page_link & ~0x03))
|
|
|
|
static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
|
|
{
|
|
unsigned long page_link = sg->page_link & 0x3;
|
|
|
|
/*
|
|
* In order for the low bit stealing approach to work, pages
|
|
* must be aligned at a 32-bit boundary as a minimum.
|
|
*/
|
|
BUG_ON((unsigned long) page & 0x03);
|
|
sg->page_link = page_link | (unsigned long) page;
|
|
}
|
|
|
|
static inline void sg_set_page(struct scatterlist *sg, struct page *page,
|
|
unsigned int len, unsigned int offset)
|
|
{
|
|
sg_assign_page(sg, page);
|
|
sg->offset = offset;
|
|
sg->length = len;
|
|
}
|
|
|
|
static inline struct page *sg_page(struct scatterlist *sg)
|
|
{
|
|
return (struct page *)((sg)->page_link & ~0x3);
|
|
}
|
|
|
|
static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
|
|
unsigned int buflen)
|
|
{
|
|
sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
|
|
}
|
|
|
|
static inline struct scatterlist *sg_next(struct scatterlist *sg)
|
|
{
|
|
if (sg_is_last(sg))
|
|
return NULL;
|
|
|
|
sg++;
|
|
if (unlikely(sg_is_chain(sg)))
|
|
sg = sg_chain_ptr(sg);
|
|
|
|
return sg;
|
|
}
|
|
|
|
#define for_each_sg(sglist, sg, nr, __i) \
|
|
for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
|
|
|
|
static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
|
|
struct scatterlist *sgl)
|
|
{
|
|
/*
|
|
* offset and length are unused for chain entry. Clear them.
|
|
*/
|
|
prv[prv_nents - 1].offset = 0;
|
|
prv[prv_nents - 1].length = 0;
|
|
|
|
/*
|
|
* Set lowest bit to indicate a link pointer, and make sure to clear
|
|
* the termination bit if it happens to be set.
|
|
*/
|
|
prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02;
|
|
}
|
|
|
|
static inline void sg_mark_end(struct scatterlist *sg)
|
|
{
|
|
sg->page_link |= 0x02;
|
|
sg->page_link &= ~0x01;
|
|
}
|
|
|
|
static inline void sg_unmark_end(struct scatterlist *sg)
|
|
{
|
|
sg->page_link &= ~0x02;
|
|
}
|
|
|
|
static inline void *sg_virt(struct scatterlist *sg)
|
|
{
|
|
return page_address(sg_page(sg)) + sg->offset;
|
|
}
|
|
|
|
static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
|
|
{
|
|
memset(sgl, 0, sizeof(*sgl) * nents);
|
|
sg_mark_end(&sgl[nents - 1]);
|
|
}
|
|
|
|
static inline void sg_init_one(struct scatterlist *sg, const void *buf,
|
|
unsigned int buflen)
|
|
{
|
|
sg_init_table(sg, 1);
|
|
sg_set_buf(sg, buf, buflen);
|
|
}
|
|
|
|
#endif /* _LINUX_SCATTERLIST_H */
|