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block: do not reassig ->bi_bdev when partition remapping

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There is no good reason to reassign ->bi_bdev when remapping the
partition-relative block number to the device wide one, as all the
information required by the drivers comes from the gendisk anyway.

Keeping the original ->bi_bdev alive will allow to greatly simplify
the partition-away I/O accounting.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-01-24 11:02:36 +01:00 committed by Jens Axboe
parent 2f9f6221b9
commit 30c5d3456c
3 changed files with 6 additions and 2 deletions
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5
block/blk-core.c
View File

@ -752,7 +752,7 @@ static int blk_partition_remap(struct bio *bio)
bio->bi_iter.bi_sector -
p->bd_start_sect);
}
bio->bi_bdev = bdev_whole(p);
bio_set_flag(bio, BIO_REMAPPED);
return 0;
}
@ -817,7 +817,8 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio)
goto end_io;
if (unlikely(bio_check_eod(bio)))
goto end_io;
if (bio->bi_bdev->bd_partno && unlikely(blk_partition_remap(bio)))
if (bio->bi_bdev->bd_partno && !bio_flagged(bio, BIO_REMAPPED) &&
unlikely(blk_partition_remap(bio)))
goto end_io;
/*

2
include/linux/bio.h
View File

@ -485,6 +485,7 @@ extern const char *bio_devname(struct bio *bio, char *buffer);
#define bio_set_dev(bio, bdev) \
do { \
bio_clear_flag(bio, BIO_REMAPPED); \
if ((bio)->bi_bdev != (bdev)) \
bio_clear_flag(bio, BIO_THROTTLED); \
(bio)->bi_bdev = (bdev); \
@ -493,6 +494,7 @@ do { \
#define bio_copy_dev(dst, src) \
do { \
bio_clear_flag(dst, BIO_REMAPPED); \
(dst)->bi_bdev = (src)->bi_bdev; \
bio_clone_blkg_association(dst, src); \
} while (0)

1
include/linux/blk_types.h
View File

@ -303,6 +303,7 @@ enum {
* of this bio. */
BIO_CGROUP_ACCT, /* has been accounted to a cgroup */
BIO_TRACKED, /* set if bio goes through the rq_qos path */
BIO_REMAPPED,
BIO_FLAG_LAST
};