Commit a920f6b3 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
Browse files

dm: preserve bi_io_vec when resubmitting bios 



Device mapper saves and restores various fields in the bio, but it doesn't save
bi_io_vec.  If the device driver modifies this after a partially successful
request, dm-raid1 and dm-multipath may attempt to resubmit a bio that has
bi_size inconsistent with the size of vector.

To make requests resubmittable in dm-raid1 and dm-multipath, we must save
and restore the bio vector as well.

To reduce the memory overhead involved in this, we do not save the pages in a
vector and use a 16-bit field size if the page size is less than 65536.

Cc: stable@kernel.org
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 833bb304

drivers/md/dm-bio-record.h

+26 −0
Original line number Diff line number Diff line
@@ -16,30 +16,56 @@ 
 * functions in this file help the target record and restore the

 * original bio state.

 */



struct dm_bio_vec_details {

#if PAGE_SIZE < 65536

	__u16 bv_len;

	__u16 bv_offset;

#else

	unsigned bv_len;

	unsigned bv_offset;

#endif

};



struct dm_bio_details {

	sector_t bi_sector;

	struct block_device *bi_bdev;

	unsigned int bi_size;

	unsigned short bi_idx;

	unsigned long bi_flags;

	struct dm_bio_vec_details bi_io_vec[BIO_MAX_PAGES];

};



static inline void dm_bio_record(struct dm_bio_details *bd, struct bio *bio)

{

	unsigned i;



	bd->bi_sector = bio->bi_sector;

	bd->bi_bdev = bio->bi_bdev;

	bd->bi_size = bio->bi_size;

	bd->bi_idx = bio->bi_idx;

	bd->bi_flags = bio->bi_flags;



	for (i = 0; i < bio->bi_vcnt; i++) {

		bd->bi_io_vec[i].bv_len = bio->bi_io_vec[i].bv_len;

		bd->bi_io_vec[i].bv_offset = bio->bi_io_vec[i].bv_offset;

	}

}



static inline void dm_bio_restore(struct dm_bio_details *bd, struct bio *bio)

{

	unsigned i;



	bio->bi_sector = bd->bi_sector;

	bio->bi_bdev = bd->bi_bdev;

	bio->bi_size = bd->bi_size;

	bio->bi_idx = bd->bi_idx;

	bio->bi_flags = bd->bi_flags;



	for (i = 0; i < bio->bi_vcnt; i++) {

		bio->bi_io_vec[i].bv_len = bd->bi_io_vec[i].bv_len;

		bio->bi_io_vec[i].bv_offset = bd->bi_io_vec[i].bv_offset;

	}

}



#endif

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