block: reorganize rounding of max_discard_sectors
Mostly a preparation for the next patch.
In principle this fixes an infinite loop if max_discard_sectors < granularity, but that really shouldn't happen. Cc: Jens Axboe <axboe@kernel.dk> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- block/blk-lib.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/block/blk-lib.c b/block/blk-lib.c index 2b461b4..16b06f6 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -44,6 +44,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, struct request_queue *q = bdev_get_queue(bdev); int type = REQ_WRITE | REQ_DISCARD; unsigned int max_discard_sectors; + unsigned int granularity; struct bio_batch bb; struct bio *bio; int ret = 0; @@ -54,18 +55,18 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, if (!blk_queue_discard(q)) return -EOPNOTSUPP; + /* Zero-sector (unknown) and one-sector granularities are the same. */ + granularity = max(q->limits.discard_granularity >> 9, 1U); + /* * Ensure that max_discard_sectors is of the proper * granularity */ max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); + max_discard_sectors = round_down(max_discard_sectors, granularity); if (unlikely(!max_discard_sectors)) { /* Avoid infinite loop below. Being cautious never hurts. */ return -EOPNOTSUPP; - } else if (q->limits.discard_granularity) { - unsigned int disc_sects = q->limits.discard_granularity >> 9; - - max_discard_sectors &= ~(disc_sects - 1); } if (flags & BLKDEV_DISCARD_SECURE) { -- 1.7.1 -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel |
block: reorganize rounding of max_discard_sectors
Il 03/07/2012 04:49, Vivek Goyal ha scritto:
>> > + /* Zero-sector (unknown) and one-sector granularities are the same. */ >> > + granularity = max(q->limits.discard_granularity >> 9, 1U); >> > + >> > /* >> > * Ensure that max_discard_sectors is of the proper >> > * granularity >> > */ >> > max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); >> > + max_discard_sectors = round_down(max_discard_sectors, granularity); >> > if (unlikely(!max_discard_sectors)) { >> > /* Avoid infinite loop below. Being cautious never hurts. */ >> > return -EOPNOTSUPP; >> > - } else if (q->limits.discard_granularity) { >> > - unsigned int disc_sects = q->limits.discard_granularity >> 9; >> > - >> > - max_discard_sectors &= ~(disc_sects - 1); > This is kind of odd. If discard_granularity is zero, we assume that > discards are supported and granularity is 1. But if max_discard_sectors > is zero, we assume discards are disabled. Not sure if we should treat > max_discard_sectors and discard_granularity in same way or not. Yes, this keeps the same behavior as before. It is also the one that is consistent with drivers/scsi/sd.c. sd_config_discard always sets limits.discard_granularity and then uses limits.max_discard_sectors to disable discards. Paolo -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel |
block: reorganize rounding of max_discard_sectors
Mostly a preparation for the next patch.
In principle this fixes an infinite loop if max_discard_sectors < granularity, but that really shouldn't happen. Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- block/blk-lib.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/block/blk-lib.c b/block/blk-lib.c index 2b461b4..16b06f6 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -44,6 +44,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, struct request_queue *q = bdev_get_queue(bdev); int type = REQ_WRITE | REQ_DISCARD; unsigned int max_discard_sectors; + unsigned int granularity; struct bio_batch bb; struct bio *bio; int ret = 0; @@ -54,18 +55,18 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, if (!blk_queue_discard(q)) return -EOPNOTSUPP; + /* Zero-sector (unknown) and one-sector granularities are the same. */ + granularity = max(q->limits.discard_granularity >> 9, 1U); + /* * Ensure that max_discard_sectors is of the proper * granularity */ max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); + max_discard_sectors = round_down(max_discard_sectors, granularity); if (unlikely(!max_discard_sectors)) { /* Avoid infinite loop below. Being cautious never hurts. */ return -EOPNOTSUPP; - } else if (q->limits.discard_granularity) { - unsigned int disc_sects = q->limits.discard_granularity >> 9; - - max_discard_sectors &= ~(disc_sects - 1); } if (flags & BLKDEV_DISCARD_SECURE) { -- 1.7.1 -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel |
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