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Commit 9ff08979 authored by Richard Weinberger's avatar Richard Weinberger
Browse files

UBI: Add initial support for scatter gather 



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: default avatarRichard Weinberger <richard@nod.at>
Tested-by: default avatarEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
Reviewed-by: default avatarEzequiel Garcia <ezequiel@vanguardiasur.com.ar>
parent 892abde5

drivers/mtd/ubi/eba.c

+55 −0
Original line number Diff line number Diff line
@@ -479,6 +479,61 @@ int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum, 
	return err;

}



/**

 * ubi_eba_read_leb_sg - read data into a scatter gather list.

 * @ubi: UBI device description object

 * @vol: volume description object

 * @lnum: logical eraseblock number

 * @sgl: UBI scatter gather list to store the read data

 * @offset: offset from where to read

 * @len: how many bytes to read

 * @check: data CRC check flag

 *

 * This function works exactly like ubi_eba_read_leb(). But instead of

 * storing the read data into a buffer it writes to an UBI scatter gather

 * list.

 */

int ubi_eba_read_leb_sg(struct ubi_device *ubi, struct ubi_volume *vol,

			struct ubi_sgl *sgl, int lnum, int offset, int len,

			int check)

{

	int to_read;

	int ret;

	struct scatterlist *sg;



	for (;;) {

		ubi_assert(sgl->list_pos < UBI_MAX_SG_COUNT);

		sg = &sgl->sg[sgl->list_pos];

		if (len < sg->length - sgl->page_pos)

			to_read = len;

		else

			to_read = sg->length - sgl->page_pos;



		ret = ubi_eba_read_leb(ubi, vol, lnum,

				       sg_virt(sg) + sgl->page_pos, offset,

				       to_read, check);

		if (ret < 0)

			return ret;



		offset += to_read;

		len -= to_read;

		if (!len) {

			sgl->page_pos += to_read;

			if (sgl->page_pos == sg->length) {

				sgl->list_pos++;

				sgl->page_pos = 0;

			}



			break;

		}



		sgl->list_pos++;

		sgl->page_pos = 0;

	}



	return ret;

}



/**

 * recover_peb - recover from write failure.

 * @ubi: UBI device description object

drivers/mtd/ubi/kapi.c

+80 −15
Original line number Diff line number Diff line
@@ -365,6 +365,43 @@ void ubi_close_volume(struct ubi_volume_desc *desc) 
}

EXPORT_SYMBOL_GPL(ubi_close_volume);



/**

 * leb_read_sanity_check - does sanity checks on read requests.

 * @desc: volume descriptor

 * @lnum: logical eraseblock number to read from

 * @offset: offset within the logical eraseblock to read from

 * @len: how many bytes to read

 *

 * This function is used by ubi_leb_read() and ubi_leb_read_sg()

 * to perform sanity checks.

 */

static int leb_read_sanity_check(struct ubi_volume_desc *desc, int lnum,

				 int offset, int len)

{

	struct ubi_volume *vol = desc->vol;

	struct ubi_device *ubi = vol->ubi;

	int vol_id = vol->vol_id;



	if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||

	    lnum >= vol->used_ebs || offset < 0 || len < 0 ||

	    offset + len > vol->usable_leb_size)

		return -EINVAL;



	if (vol->vol_type == UBI_STATIC_VOLUME) {

		if (vol->used_ebs == 0)

			/* Empty static UBI volume */

			return 0;

		if (lnum == vol->used_ebs - 1 &&

		    offset + len > vol->last_eb_bytes)

			return -EINVAL;

	}



	if (vol->upd_marker)

		return -EBADF;



	return 0;

}



/**

 * ubi_leb_read - read data.

 * @desc: volume descriptor
@@ -401,26 +438,54 @@ int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset, 


	dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);



	if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||

	    lnum >= vol->used_ebs || offset < 0 || len < 0 ||

	    offset + len > vol->usable_leb_size)

		return -EINVAL;

	err = leb_read_sanity_check(desc, lnum, offset, len);

	if (err < 0)

		return err;



	if (vol->vol_type == UBI_STATIC_VOLUME) {

		if (vol->used_ebs == 0)

			/* Empty static UBI volume */

	if (len == 0)

		return 0;

		if (lnum == vol->used_ebs - 1 &&

		    offset + len > vol->last_eb_bytes)

			return -EINVAL;



	err = ubi_eba_read_leb(ubi, vol, lnum, buf, offset, len, check);

	if (err && mtd_is_eccerr(err) && vol->vol_type == UBI_STATIC_VOLUME) {

		ubi_warn(ubi, "mark volume %d as corrupted", vol_id);

		vol->corrupted = 1;

	}



	if (vol->upd_marker)

		return -EBADF;

	return err;

}

EXPORT_SYMBOL_GPL(ubi_leb_read);





/**

 * ubi_leb_read_sg - read data into a scatter gather list.

 * @desc: volume descriptor

 * @lnum: logical eraseblock number to read from

 * @buf: buffer where to store the read data

 * @offset: offset within the logical eraseblock to read from

 * @len: how many bytes to read

 * @check: whether UBI has to check the read data's CRC or not.

 *

 * This function works exactly like ubi_leb_read_sg(). But instead of

 * storing the read data into a buffer it writes to an UBI scatter gather

 * list.

 */

int ubi_leb_read_sg(struct ubi_volume_desc *desc, int lnum, struct ubi_sgl *sgl,

		    int offset, int len, int check)

{

	struct ubi_volume *vol = desc->vol;

	struct ubi_device *ubi = vol->ubi;

	int err, vol_id = vol->vol_id;



	dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);



	err = leb_read_sanity_check(desc, lnum, offset, len);

	if (err < 0)

		return err;



	if (len == 0)

		return 0;



	err = ubi_eba_read_leb(ubi, vol, lnum, buf, offset, len, check);

	err = ubi_eba_read_leb_sg(ubi, vol, sgl, lnum, offset, len, check);

	if (err && mtd_is_eccerr(err) && vol->vol_type == UBI_STATIC_VOLUME) {

		ubi_warn(ubi, "mark volume %d as corrupted", vol_id);

		vol->corrupted = 1;
@@ -428,7 +493,7 @@ int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset, 


	return err;

}

EXPORT_SYMBOL_GPL(ubi_leb_read);

EXPORT_SYMBOL_GPL(ubi_leb_read_sg);



/**

 * ubi_leb_write - write data.

drivers/mtd/ubi/ubi.h

+3 −0
Original line number Diff line number Diff line
@@ -795,6 +795,9 @@ int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol, 
		      int lnum);

int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,

		     void *buf, int offset, int len, int check);

int ubi_eba_read_leb_sg(struct ubi_device *ubi, struct ubi_volume *vol,

			struct ubi_sgl *sgl, int lnum, int offset, int len,

			int check);

int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,

		      const void *buf, int offset, int len);

int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,

include/linux/mtd/ubi.h

+48 −0
Original line number Diff line number Diff line
@@ -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__ */