[PATCH] md: tidyup some issues with raid1 resync and prepare for catching read errors
We are dereferencing ->rdev without an rcu lock!
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index b3856db..ea1f1eb 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -177,6 +177,13 @@
static inline void put_buf(r1bio_t *r1_bio)
{
conf_t *conf = mddev_to_conf(r1_bio->mddev);
+ int i;
+
+ for (i=0; i<conf->raid_disks; i++) {
+ struct bio *bio = r1_bio->bios[i];
+ if (bio->bi_end_io)
+ rdev_dec_pending(conf->mirrors[i].rdev, r1_bio->mddev);
+ }
mempool_free(r1_bio, conf->r1buf_pool);
@@ -1085,7 +1092,6 @@
conf->mirrors[r1_bio->read_disk].rdev);
} else
set_bit(R1BIO_Uptodate, &r1_bio->state);
- rdev_dec_pending(conf->mirrors[r1_bio->read_disk].rdev, conf->mddev);
reschedule_retry(r1_bio);
return 0;
}
@@ -1116,7 +1122,6 @@
md_done_sync(mddev, r1_bio->sectors, uptodate);
put_buf(r1_bio);
}
- rdev_dec_pending(conf->mirrors[mirror].rdev, mddev);
return 0;
}
@@ -1153,10 +1158,14 @@
atomic_set(&r1_bio->remaining, 1);
for (i = 0; i < disks ; i++) {
wbio = r1_bio->bios[i];
- if (wbio->bi_end_io != end_sync_write)
+ if (wbio->bi_end_io == NULL ||
+ (wbio->bi_end_io == end_sync_read &&
+ (i == r1_bio->read_disk ||
+ !test_bit(MD_RECOVERY_SYNC, &mddev->recovery))))
continue;
- atomic_inc(&conf->mirrors[i].rdev->nr_pending);
+ wbio->bi_rw = WRITE;
+ wbio->bi_end_io = end_sync_write;
atomic_inc(&r1_bio->remaining);
md_sync_acct(conf->mirrors[i].rdev->bdev, wbio->bi_size >> 9);
@@ -1388,14 +1397,13 @@
static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
{
conf_t *conf = mddev_to_conf(mddev);
- mirror_info_t *mirror;
r1bio_t *r1_bio;
struct bio *bio;
sector_t max_sector, nr_sectors;
- int disk;
+ int disk = -1;
int i;
- int wonly;
- int write_targets = 0;
+ int wonly = -1;
+ int write_targets = 0, read_targets = 0;
int sync_blocks;
int still_degraded = 0;
@@ -1447,44 +1455,24 @@
conf->next_resync = sector_nr;
- /*
- * If reconstructing, and >1 working disc,
- * could dedicate one to rebuild and others to
- * service read requests ..
- */
- disk = conf->last_used;
- /* make sure disk is operational */
- wonly = disk;
- while (conf->mirrors[disk].rdev == NULL ||
- !test_bit(In_sync, &conf->mirrors[disk].rdev->flags) ||
- test_bit(WriteMostly, &conf->mirrors[disk].rdev->flags)
- ) {
- if (conf->mirrors[disk].rdev &&
- test_bit(In_sync, &conf->mirrors[disk].rdev->flags))
- wonly = disk;
- if (disk <= 0)
- disk = conf->raid_disks;
- disk--;
- if (disk == conf->last_used) {
- disk = wonly;
- break;
- }
- }
- conf->last_used = disk;
- atomic_inc(&conf->mirrors[disk].rdev->nr_pending);
-
-
- mirror = conf->mirrors + disk;
-
r1_bio = mempool_alloc(conf->r1buf_pool, GFP_NOIO);
+ rcu_read_lock();
+ /*
+ * If we get a correctably read error during resync or recovery,
+ * we might want to read from a different device. So we
+ * flag all drives that could conceivably be read from for READ,
+ * and any others (which will be non-In_sync devices) for WRITE.
+ * If a read fails, we try reading from something else for which READ
+ * is OK.
+ */
r1_bio->mddev = mddev;
r1_bio->sector = sector_nr;
r1_bio->state = 0;
set_bit(R1BIO_IsSync, &r1_bio->state);
- r1_bio->read_disk = disk;
for (i=0; i < conf->raid_disks; i++) {
+ mdk_rdev_t *rdev;
bio = r1_bio->bios[i];
/* take from bio_init */
@@ -1499,35 +1487,49 @@
bio->bi_end_io = NULL;
bio->bi_private = NULL;
- if (i == disk) {
- bio->bi_rw = READ;
- bio->bi_end_io = end_sync_read;
- } else if (conf->mirrors[i].rdev == NULL ||
- test_bit(Faulty, &conf->mirrors[i].rdev->flags)) {
+ rdev = rcu_dereference(conf->mirrors[i].rdev);
+ if (rdev == NULL ||
+ test_bit(Faulty, &rdev->flags)) {
still_degraded = 1;
continue;
- } else if (!test_bit(In_sync, &conf->mirrors[i].rdev->flags) ||
- sector_nr + RESYNC_SECTORS > mddev->recovery_cp ||
- test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
+ } else if (!test_bit(In_sync, &rdev->flags)) {
bio->bi_rw = WRITE;
bio->bi_end_io = end_sync_write;
write_targets ++;
- } else
- /* no need to read or write here */
- continue;
- bio->bi_sector = sector_nr + conf->mirrors[i].rdev->data_offset;
- bio->bi_bdev = conf->mirrors[i].rdev->bdev;
+ } else {
+ /* may need to read from here */
+ bio->bi_rw = READ;
+ bio->bi_end_io = end_sync_read;
+ if (test_bit(WriteMostly, &rdev->flags)) {
+ if (wonly < 0)
+ wonly = i;
+ } else {
+ if (disk < 0)
+ disk = i;
+ }
+ read_targets++;
+ }
+ atomic_inc(&rdev->nr_pending);
+ bio->bi_sector = sector_nr + rdev->data_offset;
+ bio->bi_bdev = rdev->bdev;
bio->bi_private = r1_bio;
}
+ rcu_read_unlock();
+ if (disk < 0)
+ disk = wonly;
+ r1_bio->read_disk = disk;
- if (write_targets == 0) {
+ if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) && read_targets > 0)
+ /* extra read targets are also write targets */
+ write_targets += read_targets-1;
+
+ if (write_targets == 0 || read_targets == 0) {
/* There is nowhere to write, so all non-sync
* drives must be failed - so we are finished
*/
sector_t rv = max_sector - sector_nr;
*skipped = 1;
put_buf(r1_bio);
- rdev_dec_pending(conf->mirrors[disk].rdev, mddev);
return rv;
}
@@ -1578,10 +1580,10 @@
sync_blocks -= (len>>9);
} while (r1_bio->bios[disk]->bi_vcnt < RESYNC_PAGES);
bio_full:
- bio = r1_bio->bios[disk];
+ bio = r1_bio->bios[r1_bio->read_disk];
r1_bio->sectors = nr_sectors;
- md_sync_acct(mirror->rdev->bdev, nr_sectors);
+ md_sync_acct(conf->mirrors[r1_bio->read_disk].rdev->bdev, nr_sectors);
generic_make_request(bio);
