block: break discard submissions into the user defined size

Don't build discards bigger than what the user asked for, if the
user decided to limit the size by writing to 'discard_max_bytes'.

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2018-05-08 15:09:41 -06:00
parent d3349b6b3c
commit af097f5d19

View File

@ -62,10 +62,16 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
unsigned int req_sects;
sector_t end_sect, tmp;
/* Make sure bi_size doesn't overflow */
req_sects = min_t(sector_t, nr_sects, UINT_MAX >> 9);
/*
* Issue in chunks of the user defined max discard setting,
* ensuring that bi_size doesn't overflow
*/
req_sects = min_t(sector_t, nr_sects,
q->limits.max_discard_sectors);
if (req_sects > UINT_MAX >> 9)
req_sects = UINT_MAX >> 9;
/**
/*
* If splitting a request, and the next starting sector would be
* misaligned, stop the discard at the previous aligned sector.
*/