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Commit 70dd5bf3 authored by Martin K. Petersen's avatar Martin K. Petersen Committed by Jens Axboe
Browse files

block: Stack optimal I/O size 



When stacking block devices ensure that optimal I/O size is scaled
accordingly.

Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 7c958e32

block/blk-settings.c

+11 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include <linux/bio.h>

#include <linux/blkdev.h>

#include <linux/bootmem.h>	/* for max_pfn/max_low_pfn */

#include <linux/gcd.h>



#include "blk.h"
@@ -520,6 +521,16 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, 
		return -1;

	}



	/* Find lcm() of optimal I/O size */

	if (t->io_opt && b->io_opt)

		t->io_opt = (t->io_opt * b->io_opt) / gcd(t->io_opt, b->io_opt);

	else if (b->io_opt)

		t->io_opt = b->io_opt;



	/* Verify that optimal I/O size is a multiple of io_min */

	if (t->io_min && t->io_opt % t->io_min)

		return -1;



	return 0;

}

EXPORT_SYMBOL(blk_stack_limits);