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block: introduce BLKDEV_DISCARD_ZERO to fix zeroout

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Currently blkdev_issue_zeroout cascades down from discards (if the driver
guarantees that discards zero data), to WRITE SAME and then to a loop
writing zeroes.  Unfortunately we ignore run-time EOPNOTSUPP errors in the
block layer blkdev_issue_discard helper to work around DM volumes that
may have mixed discard support underneath.

This patch intoroduces a new BLKDEV_DISCARD_ZERO flag to
blkdev_issue_discard that indicates we are called for zeroing operation.
This allows both to ignore the EOPNOTSUPP hack and actually consolidating
the discard_zeroes_data check into the function.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Christoph Hellwig 2016-07-19 11:23:33 +02:00 committed by Jens Axboe
parent b09dcf585d
commit e950fdf71c
2 changed files with 14 additions and 7 deletions
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17
block/blk-lib.c
View file

@ -36,12 +36,17 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
return -ENXIO;
if (flags & BLKDEV_DISCARD_SECURE) {
if (flags & BLKDEV_DISCARD_ZERO)
return -EOPNOTSUPP;
if (!blk_queue_secure_erase(q))
return -EOPNOTSUPP;
op = REQ_OP_SECURE_ERASE;
} else {
if (!blk_queue_discard(q))
return -EOPNOTSUPP;
if ((flags & BLKDEV_DISCARD_ZERO) &&
!q->limits.discard_zeroes_data)
return -EOPNOTSUPP;
op = REQ_OP_DISCARD;
}
@ -116,7 +121,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
&bio);
if (!ret && bio) {
ret = submit_bio_wait(bio);
if (ret == -EOPNOTSUPP)
if (ret == -EOPNOTSUPP && !(flags & BLKDEV_DISCARD_ZERO))
ret = 0;
}
blk_finish_plug(&plug);
@ -241,11 +246,11 @@ static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
sector_t nr_sects, gfp_t gfp_mask, bool discard)
{
struct request_queue *q = bdev_get_queue(bdev);
if (discard && blk_queue_discard(q) && q->limits.discard_zeroes_data &&
blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, 0) == 0)
return 0;
if (discard) {
if (!blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask,
BLKDEV_DISCARD_ZERO))
return 0;
}
if (bdev_write_same(bdev) &&
blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,

4
include/linux/blkdev.h
View file

@ -1137,7 +1137,9 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
return bqt->tag_index[tag];
}
#define BLKDEV_DISCARD_SECURE 0x01 /* secure discard */
#define BLKDEV_DISCARD_SECURE (1 << 0) /* issue a secure erase */
#define BLKDEV_DISCARD_ZERO (1 << 1) /* must reliably zero data */
extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,