From: NeilBrown 'this_sector' is a virtual (array) address while 'head_position' is a physical (device) address, so substraction doesn't make any sense. devs[slot].addr should be used instead of this_sector. However, this patch doesn't make much practical different to the read balancing due to the effects of later code. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton --- drivers/md/raid10.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletion(-) diff -puN drivers/md/raid10.c~md-fix-minor-error-in-raid10-read-balancing-calculation drivers/md/raid10.c --- devel/drivers/md/raid10.c~md-fix-minor-error-in-raid10-read-balancing-calculation 2005-08-03 22:08:25.000000000 -0700 +++ devel-akpm/drivers/md/raid10.c 2005-08-03 22:08:25.000000000 -0700 @@ -538,7 +538,8 @@ static int read_balance(conf_t *conf, r1 } - current_distance = abs(this_sector - conf->mirrors[disk].head_position); + current_distance = abs(r10_bio->devs[slot].addr - + conf->mirrors[disk].head_position); /* Find the disk whose head is closest */ _