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authorNeilBrown <neilb@suse.de>2006-01-06 00:20:19 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-06 08:34:03 -0800
commitddaf22abaa831763e75775e6d4c7693504237997 (patch)
tree4f6ba4cb056f8c7cea82c7d548769b879d0fb405
parentd69762e98456b71167865db9e33e732a28dd36ab (diff)
[PATCH] md: attempt to auto-correct read errors in raid1
On a read-error we suspend the array, then synchronously read the block from other arrays until we find one where we can read it. Then we try writing the good data back everywhere and make sure it works. If any write or subsequent read fails, only then do we fail the device out of the array. To be able to suspend the array, we need to also keep track of how many requests are queued for handling by raid1d. Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/md/md.c1
-rw-r--r--drivers/md/raid1.c115
-rw-r--r--include/linux/raid/raid1.h3
3 files changed, 109 insertions, 10 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 64e7da3701a..1364a1c97e6 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -461,6 +461,7 @@ int sync_page_io(struct block_device *bdev, sector_t sector, int size,
bio_put(bio);
return ret;
}
+EXPORT_SYMBOL(sync_page_io);
static int read_disk_sb(mdk_rdev_t * rdev, int size)
{
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index c618015f07f..b3856db8d6c 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -191,6 +191,7 @@ static void reschedule_retry(r1bio_t *r1_bio)
spin_lock_irqsave(&conf->device_lock, flags);
list_add(&r1_bio->retry_list, &conf->retry_list);
+ conf->nr_queued ++;
spin_unlock_irqrestore(&conf->device_lock, flags);
wake_up(&conf->wait_barrier);
@@ -245,9 +246,9 @@ static int raid1_end_read_request(struct bio *bio, unsigned int bytes_done, int
/*
* this branch is our 'one mirror IO has finished' event handler:
*/
- if (!uptodate)
- md_error(r1_bio->mddev, conf->mirrors[mirror].rdev);
- else
+ update_head_pos(mirror, r1_bio);
+
+ if (uptodate || conf->working_disks <= 1) {
/*
* Set R1BIO_Uptodate in our master bio, so that
* we will return a good error code for to the higher
@@ -259,14 +260,8 @@ static int raid1_end_read_request(struct bio *bio, unsigned int bytes_done, int
*/
set_bit(R1BIO_Uptodate, &r1_bio->state);
- update_head_pos(mirror, r1_bio);
-
- /*
- * we have only one bio on the read side
- */
- if (uptodate)
raid_end_bio_io(r1_bio);
- else {
+ } else {
/*
* oops, read error:
*/
@@ -653,6 +648,32 @@ static void allow_barrier(conf_t *conf)
wake_up(&conf->wait_barrier);
}
+static void freeze_array(conf_t *conf)
+{
+ /* stop syncio and normal IO and wait for everything to
+ * go quite.
+ * We increment barrier and nr_waiting, and then
+ * wait until barrier+nr_pending match nr_queued+2
+ */
+ spin_lock_irq(&conf->resync_lock);
+ conf->barrier++;
+ conf->nr_waiting++;
+ wait_event_lock_irq(conf->wait_barrier,
+ conf->barrier+conf->nr_pending == conf->nr_queued+2,
+ conf->resync_lock,
+ raid1_unplug(conf->mddev->queue));
+ spin_unlock_irq(&conf->resync_lock);
+}
+static void unfreeze_array(conf_t *conf)
+{
+ /* reverse the effect of the freeze */
+ spin_lock_irq(&conf->resync_lock);
+ conf->barrier--;
+ conf->nr_waiting--;
+ wake_up(&conf->wait_barrier);
+ spin_unlock_irq(&conf->resync_lock);
+}
+
/* duplicate the data pages for behind I/O */
static struct page **alloc_behind_pages(struct bio *bio)
@@ -1196,6 +1217,7 @@ static void raid1d(mddev_t *mddev)
break;
r1_bio = list_entry(head->prev, r1bio_t, retry_list);
list_del(head->prev);
+ conf->nr_queued--;
spin_unlock_irqrestore(&conf->device_lock, flags);
mddev = r1_bio->mddev;
@@ -1235,6 +1257,74 @@ static void raid1d(mddev_t *mddev)
}
} else {
int disk;
+
+ /* we got a read error. Maybe the drive is bad. Maybe just
+ * the block and we can fix it.
+ * We freeze all other IO, and try reading the block from
+ * other devices. When we find one, we re-write
+ * and check it that fixes the read error.
+ * This is all done synchronously while the array is
+ * frozen
+ */
+ sector_t sect = r1_bio->sector;
+ int sectors = r1_bio->sectors;
+ freeze_array(conf);
+ while(sectors) {
+ int s = sectors;
+ int d = r1_bio->read_disk;
+ int success = 0;
+
+ if (s > (PAGE_SIZE>>9))
+ s = PAGE_SIZE >> 9;
+
+ do {
+ rdev = conf->mirrors[d].rdev;
+ if (rdev &&
+ test_bit(In_sync, &rdev->flags) &&
+ sync_page_io(rdev->bdev,
+ sect + rdev->data_offset,
+ s<<9,
+ conf->tmppage, READ))
+ success = 1;
+ else {
+ d++;
+ if (d == conf->raid_disks)
+ d = 0;
+ }
+ } while (!success && d != r1_bio->read_disk);
+
+ if (success) {
+ /* write it back and re-read */
+ while (d != r1_bio->read_disk) {
+ if (d==0)
+ d = conf->raid_disks;
+ d--;
+ rdev = conf->mirrors[d].rdev;
+ if (rdev &&
+ test_bit(In_sync, &rdev->flags)) {
+ if (sync_page_io(rdev->bdev,
+ sect + rdev->data_offset,
+ s<<9, conf->tmppage, WRITE) == 0 ||
+ sync_page_io(rdev->bdev,
+ sect + rdev->data_offset,
+ s<<9, conf->tmppage, READ) == 0) {
+ /* Well, this device is dead */
+ md_error(mddev, rdev);
+ }
+ }
+ }
+ } else {
+ /* Cannot read from anywhere -- bye bye array */
+ md_error(mddev, conf->mirrors[r1_bio->read_disk].rdev);
+ break;
+ }
+ sectors -= s;
+ sect += s;
+ }
+
+
+ unfreeze_array(conf);
+
bio = r1_bio->bios[r1_bio->read_disk];
if ((disk=read_balance(conf, r1_bio)) == -1) {
printk(KERN_ALERT "raid1: %s: unrecoverable I/O"
@@ -1529,6 +1619,10 @@ static int run(mddev_t *mddev)
memset(conf->mirrors, 0, sizeof(struct mirror_info)*mddev->raid_disks);
+ conf->tmppage = alloc_page(GFP_KERNEL);
+ if (!conf->tmppage)
+ goto out_no_mem;
+
conf->poolinfo = kmalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
if (!conf->poolinfo)
goto out_no_mem;
@@ -1635,6 +1729,7 @@ out_free_conf:
if (conf->r1bio_pool)
mempool_destroy(conf->r1bio_pool);
kfree(conf->mirrors);
+ __free_page(conf->tmppage);
kfree(conf->poolinfo);
kfree(conf);
mddev->private = NULL;
diff --git a/include/linux/raid/raid1.h b/include/linux/raid/raid1.h
index c5567425253..cbe4238d3f9 100644
--- a/include/linux/raid/raid1.h
+++ b/include/linux/raid/raid1.h
@@ -46,6 +46,7 @@ struct r1_private_data_s {
spinlock_t resync_lock;
int nr_pending;
int nr_waiting;
+ int nr_queued;
int barrier;
sector_t next_resync;
int fullsync; /* set to 1 if a full sync is needed,
@@ -57,6 +58,8 @@ struct r1_private_data_s {
struct pool_info *poolinfo;
+ struct page *tmppage;
+
mempool_t *r1bio_pool;
mempool_t *r1buf_pool;
};