Christoph Hellwig <hch@xxxxxx> writes:
> Currently blkdev_issue_zeroout cascades down from discards (if the driver
> gurantees that discards zero data), to WRITE SAME and then to a loop
> writing zeroes. Unfortunately we ignore tun-time EOPNOTSUPP errors in the
> block layer blkdev_issue_discard helper to work around DM volumes that
> may have mixed discard support underneath.
>
> This path 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@xxxxxx>
> ---
> block/blk-lib.c | 17 +++++++++++------
> include/linux/blkdev.h | 4 +++-
> 2 files changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/block/blk-lib.c b/block/blk-lib.c
> index 78626c2..45b35b1 100644
> --- a/block/blk-lib.c
> +++ b/block/blk-lib.c
> @@ -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;
Should this be -EINVAL?
-Jeff
> 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,
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 9d1e0a4..b65ca66 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1136,7 +1136,9 @@ 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,
--
To unsubscribe from this list: send the line "unsubscribe linux-block" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
