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Commit e464eafd authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: Support suspending of IO to regions of an md array 



This allows user-space to access data safely.  This is needed for raid5
reshape as user-space needs to take a backup of the first few stripes before
allowing reshape to commence.

It will also be useful in cluster-aware raid1 configurations so that all
cluster members can leave a section of the array untouched while a
resync/recovery happens.

A 'start' and 'end' of the suspended range are written to 2 sysfs attributes.
Note that only one range can be suspended at a time.

Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 16484bf5

drivers/md/md.c

+59 −0
Original line number Diff line number Diff line
@@ -2365,6 +2365,63 @@ sync_completed_show(mddev_t *mddev, char *page) 
static struct md_sysfs_entry

md_sync_completed = __ATTR_RO(sync_completed);



static ssize_t

suspend_lo_show(mddev_t *mddev, char *page)

{

	return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_lo);

}



static ssize_t

suspend_lo_store(mddev_t *mddev, const char *buf, size_t len)

{

	char *e;

	unsigned long long new = simple_strtoull(buf, &e, 10);



	if (mddev->pers->quiesce == NULL)

		return -EINVAL;

	if (buf == e || (*e && *e != '\n'))

		return -EINVAL;

	if (new >= mddev->suspend_hi ||

	    (new > mddev->suspend_lo && new < mddev->suspend_hi)) {

		mddev->suspend_lo = new;

		mddev->pers->quiesce(mddev, 2);

		return len;

	} else

		return -EINVAL;

}

static struct md_sysfs_entry md_suspend_lo =

__ATTR(suspend_lo, S_IRUGO|S_IWUSR, suspend_lo_show, suspend_lo_store);





static ssize_t

suspend_hi_show(mddev_t *mddev, char *page)

{

	return sprintf(page, "%llu\n", (unsigned long long)mddev->suspend_hi);

}



static ssize_t

suspend_hi_store(mddev_t *mddev, const char *buf, size_t len)

{

	char *e;

	unsigned long long new = simple_strtoull(buf, &e, 10);



	if (mddev->pers->quiesce == NULL)

		return -EINVAL;

	if (buf == e || (*e && *e != '\n'))

		return -EINVAL;

	if ((new <= mddev->suspend_lo && mddev->suspend_lo >= mddev->suspend_hi) ||

	    (new > mddev->suspend_lo && new > mddev->suspend_hi)) {

		mddev->suspend_hi = new;

		mddev->pers->quiesce(mddev, 1);

		mddev->pers->quiesce(mddev, 0);

		return len;

	} else

		return -EINVAL;

}

static struct md_sysfs_entry md_suspend_hi =

__ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);





static struct attribute *md_default_attrs[] = {

	&md_level.attr,

	&md_raid_disks.attr,
@@ -2382,6 +2439,8 @@ static struct attribute *md_redundancy_attrs[] = { 
	&md_sync_max.attr,

	&md_sync_speed.attr,

	&md_sync_completed.attr,

	&md_suspend_lo.attr,

	&md_suspend_hi.attr,

	NULL,

};

static struct attribute_group md_redundancy_group = {

drivers/md/raid5.c

+14 −0
Original line number Diff line number Diff line
@@ -1805,6 +1805,15 @@ static int make_request(request_queue_t *q, struct bio * bi) 
					goto retry;

				}

			}

			/* FIXME what if we get a false positive because these

			 * are being updated.

			 */

			if (logical_sector >= mddev->suspend_lo &&

			    logical_sector < mddev->suspend_hi) {

				release_stripe(sh);

				schedule();

				goto retry;

			}



			if (test_bit(STRIPE_EXPANDING, &sh->state) ||

			    !add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK))) {
@@ -2725,6 +2734,10 @@ static void raid5_quiesce(mddev_t *mddev, int state) 
	raid5_conf_t *conf = mddev_to_conf(mddev);



	switch(state) {

	case 2: /* resume for a suspend */

		wake_up(&conf->wait_for_overlap);

		break;



	case 1: /* stop all writes */

		spin_lock_irq(&conf->device_lock);

		conf->quiesce = 1;
@@ -2738,6 +2751,7 @@ static void raid5_quiesce(mddev_t *mddev, int state) 
		spin_lock_irq(&conf->device_lock);

		conf->quiesce = 0;

		wake_up(&conf->wait_for_stripe);

		wake_up(&conf->wait_for_overlap);

		spin_unlock_irq(&conf->device_lock);

		break;

	}

include/linux/raid/md_k.h

+4 −0
Original line number Diff line number Diff line
@@ -151,6 +151,10 @@ struct mddev_s 
	sector_t			resync_mismatches; /* count of sectors where

							    * parity/replica mismatch found

							    */



	/* allow user-space to request suspension of IO to regions of the array */

	sector_t			suspend_lo;

	sector_t			suspend_hi;

	/* if zero, use the system-wide default */

	int				sync_speed_min;

	int				sync_speed_max;