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md: raid0: make hash_spacing and preshift sector-based.

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This patch renames the hash_spacing and preshift members of struct
raid0_private_data to spacing and sector_shift respectively and
changes the semantics as follows:

We always have spacing = 2 * hash_spacing. In case
sizeof(sector_t) > sizeof(u32) we also have sector_shift = preshift + 1
while sector_shift = preshift = 0 otherwise.

Note that the values of nb_zone and zone are unaffected by these changes
because in the sector_div() preceeding the assignement of these two
variables both arguments double.

Signed-off-by: Andre Noll <maan@systemlinux.org>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
Andre Noll 2009-01-09 08:31:08 +11:00 committed by NeilBrown
parent 83838ed878
commit ccacc7d2cf
2 changed files with 31 additions and 31 deletions
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58
drivers/md/raid0.c
View file

@ -213,16 +213,16 @@ static int create_strip_zones (mddev_t *mddev)
* strip though as it's size has no bearing on the efficacy of the hash
* table.
*/
conf->hash_spacing = curr_zone_start / 2;
min_spacing = curr_zone_start / 2;
conf->spacing = curr_zone_start;
min_spacing = curr_zone_start;
sector_div(min_spacing, PAGE_SIZE/sizeof(struct strip_zone*));
for (i=0; i < conf->nr_strip_zones-1; i++) {
sector_t sz = 0;
for (j=i; j<conf->nr_strip_zones-1 &&
sz < min_spacing ; j++)
sz += conf->strip_zone[j].sectors / 2;
if (sz >= min_spacing && sz < conf->hash_spacing)
conf->hash_spacing = sz;
sector_t s = 0;
for (j = i; j < conf->nr_strip_zones - 1 &&
s < min_spacing; j++)
s += conf->strip_zone[j].sectors;
if (s >= min_spacing && s < conf->spacing)
conf->spacing = s;
}
mddev->queue->unplug_fn = raid0_unplug;
@ -265,7 +265,7 @@ static int raid0_mergeable_bvec(struct request_queue *q,
static int raid0_run (mddev_t *mddev)
{
unsigned cur=0, i=0, nb_zone;
s64 size;
s64 sectors;
raid0_conf_t *conf;
mdk_rdev_t *rdev;
struct list_head *tmp;
@ -297,51 +297,51 @@ static int raid0_run (mddev_t *mddev)
rdev_for_each(rdev, tmp, mddev)
mddev->array_sectors += rdev->size * 2;
printk("raid0 : md_size is %llu blocks.\n",
(unsigned long long)mddev->array_sectors / 2);
printk("raid0 : conf->hash_spacing is %llu blocks.\n",
(unsigned long long)conf->hash_spacing);
printk(KERN_INFO "raid0 : md_size is %llu sectors.\n",
(unsigned long long)mddev->array_sectors);
printk(KERN_INFO "raid0 : conf->spacing is %llu sectors.\n",
(unsigned long long)conf->spacing);
{
sector_t s = mddev->array_sectors / 2;
sector_t space = conf->hash_spacing;
sector_t s = mddev->array_sectors;
sector_t space = conf->spacing;
int round;
conf->preshift = 0;
conf->sector_shift = 0;
if (sizeof(sector_t) > sizeof(u32)) {
/*shift down space and s so that sector_div will work */
while (space > (sector_t) (~(u32)0)) {
s >>= 1;
space >>= 1;
s += 1; /* force round-up */
conf->preshift++;
conf->sector_shift++;
}
}
round = sector_div(s, (u32)space) ? 1 : 0;
nb_zone = s + round;
}
printk("raid0 : nb_zone is %d.\n", nb_zone);
printk(KERN_INFO "raid0 : nb_zone is %d.\n", nb_zone);
printk("raid0 : Allocating %Zd bytes for hash.\n",
printk(KERN_INFO "raid0 : Allocating %zu bytes for hash.\n",
nb_zone*sizeof(struct strip_zone*));
conf->hash_table = kmalloc (sizeof (struct strip_zone *)*nb_zone, GFP_KERNEL);
if (!conf->hash_table)
goto out_free_conf;
size = conf->strip_zone[cur].sectors / 2;
sectors = conf->strip_zone[cur].sectors;
conf->hash_table[0] = conf->strip_zone + cur;
for (i=1; i< nb_zone; i++) {
while (size <= conf->hash_spacing) {
while (sectors <= conf->spacing) {
cur++;
size += conf->strip_zone[cur].sectors / 2;
sectors += conf->strip_zone[cur].sectors;
}
size -= conf->hash_spacing;
sectors -= conf->spacing;
conf->hash_table[i] = conf->strip_zone + cur;
}
if (conf->preshift) {
conf->hash_spacing >>= conf->preshift;
/* round hash_spacing up so when we divide by it, we
if (conf->sector_shift) {
conf->spacing >>= conf->sector_shift;
/* round spacing up so when we divide by it, we
* err on the side of too-low, which is safest
*/
conf->hash_spacing++;
conf->spacing++;
}
/* calculate the max read-ahead size.
@ -435,8 +435,8 @@ static int raid0_make_request (struct request_queue *q, struct bio *bio)
{
sector_t x = sector >> (conf->preshift + 1);
sector_div(x, (u32)conf->hash_spacing);
sector_t x = sector >> conf->sector_shift;
sector_div(x, (u32)conf->spacing);
zone = conf->hash_table[x];
}

4
include/linux/raid/raid0.h
View file

@ -19,8 +19,8 @@ struct raid0_private_data
mdk_rdev_t **devlist; /* lists of rdevs, pointed to by strip_zone->dev */
int nr_strip_zones;
sector_t hash_spacing;
int preshift; /* shift this before divide by hash_spacing */
sector_t spacing;
int sector_shift; /* shift this before divide by spacing */
};
typedef struct raid0_private_data raid0_conf_t;