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UBI: Add initial support for scatter gather

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Adds a new set of functions to deal with scatter gather.
ubi_eba_read_leb_sg() will read from a LEB into a scatter gather list.
The new data structure struct ubi_sgl will be used within UBI to
hold the scatter gather list itself and metadata to have a cursor
within the list.

Signed-off-by: Richard Weinberger <richard@nod.at>
Tested-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
This commit is contained in:
Richard Weinberger
2015-01-10 22:52:13 +01:00
parent 892abde56c
commit 9ff08979e1
4 changed files with 186 additions and 15 deletions
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48
include/linux/mtd/ubi.h
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@@ -23,11 +23,18 @@
#include <linux/ioctl.h>
#include <linux/types.h>
#include <linux/scatterlist.h>
#include <mtd/ubi-user.h>
/* All voumes/LEBs */
#define UBI_ALL -1
/*
* Maximum number of scatter gather list entries,
* we use only 64 to have a lower memory foot print.
*/
#define UBI_MAX_SG_COUNT 64
/*
* enum ubi_open_mode - UBI volume open mode constants.
*
@@ -118,6 +125,35 @@ struct ubi_volume_info {
dev_t cdev;
};
/**
* struct ubi_sgl - UBI scatter gather list data structure.
* @list_pos: current position in @sg[]
* @page_pos: current position in @sg[@list_pos]
* @sg: the scatter gather list itself
*
* ubi_sgl is a wrapper around a scatter list which keeps track of the
* current position in the list and the current list item such that
* it can be used across multiple ubi_leb_read_sg() calls.
*/
struct ubi_sgl {
int list_pos;
int page_pos;
struct scatterlist sg[UBI_MAX_SG_COUNT];
};
/**
* ubi_sgl_init - initialize an UBI scatter gather list data structure.
* @usgl: the UBI scatter gather struct itself
*
* Please note that you still have to use sg_init_table() or any adequate
* function to initialize the unterlaying struct scatterlist.
*/
static inline void ubi_sgl_init(struct ubi_sgl *usgl)
{
usgl->list_pos = 0;
usgl->page_pos = 0;
}
/**
* struct ubi_device_info - UBI device description data structure.
* @ubi_num: ubi device number
@@ -213,6 +249,8 @@ int ubi_unregister_volume_notifier(struct notifier_block *nb);
void ubi_close_volume(struct ubi_volume_desc *desc);
int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
int len, int check);
int ubi_leb_read_sg(struct ubi_volume_desc *desc, int lnum, struct ubi_sgl *sgl,
int offset, int len, int check);
int ubi_leb_write(struct ubi_volume_desc *desc, int lnum, const void *buf,
int offset, int len);
int ubi_leb_change(struct ubi_volume_desc *desc, int lnum, const void *buf,
@@ -233,4 +271,14 @@ static inline int ubi_read(struct ubi_volume_desc *desc, int lnum, char *buf,
{
return ubi_leb_read(desc, lnum, buf, offset, len, 0);
}
/*
* This function is the same as the 'ubi_leb_read_sg()' function, but it does
* not provide the checking capability.
*/
static inline int ubi_read_sg(struct ubi_volume_desc *desc, int lnum,
struct ubi_sgl *sgl, int offset, int len)
{
return ubi_leb_read_sg(desc, lnum, sgl, offset, len, 0);
}
#endif /* !__LINUX_UBI_H__ */