Commit ccacc7d2 authored by Andre Noll's avatar Andre Noll Committed by NeilBrown
Browse files

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



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: default avatarAndre Noll <maan@systemlinux.org>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent 83838ed8

drivers/md/raid0.c

+29 −29
Original line number Diff line number Diff line
@@ -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;

		sector_t s = 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;

				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];

	}

include/linux/raid/raid0.h

+2 −2
Original line number Diff line number Diff line
@@ -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;

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