[PATCH] md: raid10 read-error handling - resync and read-only
Add in correct read-error handling for resync and read-only situations.
When read-only, we don't over-write, so we need to mark the failed drive in
the r10_bio so we don't re-try it. During resync, we always read all blocks,
so if there is a read error, we simply over-write it with the good block that
we found (assuming we found one).
Note that the recovery case still isn't handled in an interesting way. There
is nothing useful to do for the 2-copies case. If there are 3 or more copies,
then we could try reading from one of the non-missing copies, but this is a
bit complicated and very rarely would be used, so I'm leaving it for now.
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/raid10.c b/drivers/md/raid10.c
index 64bb4ddc..3f8df2e 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -172,7 +172,7 @@
for (i = 0; i < conf->copies; i++) {
struct bio **bio = & r10_bio->devs[i].bio;
- if (*bio)
+ if (*bio && *bio != IO_BLOCKED)
bio_put(*bio);
*bio = NULL;
}
@@ -500,6 +500,7 @@
disk = r10_bio->devs[slot].devnum;
while ((rdev = rcu_dereference(conf->mirrors[disk].rdev)) == NULL ||
+ r10_bio->devs[slot].bio == IO_BLOCKED ||
!test_bit(In_sync, &rdev->flags)) {
slot++;
if (slot == conf->copies) {
@@ -517,6 +518,7 @@
slot = 0;
disk = r10_bio->devs[slot].devnum;
while ((rdev=rcu_dereference(conf->mirrors[disk].rdev)) == NULL ||
+ r10_bio->devs[slot].bio == IO_BLOCKED ||
!test_bit(In_sync, &rdev->flags)) {
slot ++;
if (slot == conf->copies) {
@@ -537,6 +539,7 @@
if ((rdev=rcu_dereference(conf->mirrors[ndisk].rdev)) == NULL ||
+ r10_bio->devs[nslot].bio == IO_BLOCKED ||
!test_bit(In_sync, &rdev->flags))
continue;
@@ -1104,7 +1107,6 @@
static int end_sync_read(struct bio *bio, unsigned int bytes_done, int error)
{
- int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
r10bio_t * r10_bio = (r10bio_t *)(bio->bi_private);
conf_t *conf = mddev_to_conf(r10_bio->mddev);
int i,d;
@@ -1119,7 +1121,10 @@
BUG();
update_head_pos(i, r10_bio);
d = r10_bio->devs[i].devnum;
- if (!uptodate)
+
+ if (test_bit(BIO_UPTODATE, &bio->bi_flags))
+ set_bit(R10BIO_Uptodate, &r10_bio->state);
+ else if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
md_error(r10_bio->mddev,
conf->mirrors[d].rdev);
@@ -1209,25 +1214,30 @@
fbio = r10_bio->devs[i].bio;
/* now find blocks with errors */
- for (i=first+1 ; i < conf->copies ; i++) {
- int vcnt, j, d;
+ for (i=0 ; i < conf->copies ; i++) {
+ int j, d;
+ int vcnt = r10_bio->sectors >> (PAGE_SHIFT-9);
- if (!test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
- continue;
- /* We know that the bi_io_vec layout is the same for
- * both 'first' and 'i', so we just compare them.
- * All vec entries are PAGE_SIZE;
- */
tbio = r10_bio->devs[i].bio;
- vcnt = r10_bio->sectors >> (PAGE_SHIFT-9);
- for (j = 0; j < vcnt; j++)
- if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
- page_address(tbio->bi_io_vec[j].bv_page),
- PAGE_SIZE))
- break;
- if (j == vcnt)
+
+ if (tbio->bi_end_io != end_sync_read)
continue;
- mddev->resync_mismatches += r10_bio->sectors;
+ if (i == first)
+ continue;
+ if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
+ /* We know that the bi_io_vec layout is the same for
+ * both 'first' and 'i', so we just compare them.
+ * All vec entries are PAGE_SIZE;
+ */
+ for (j = 0; j < vcnt; j++)
+ if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
+ page_address(tbio->bi_io_vec[j].bv_page),
+ PAGE_SIZE))
+ break;
+ if (j == vcnt)
+ continue;
+ mddev->resync_mismatches += r10_bio->sectors;
+ }
if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
/* Don't fix anything. */
continue;
@@ -1308,7 +1318,10 @@
atomic_inc(&conf->mirrors[d].rdev->nr_pending);
md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
- generic_make_request(wbio);
+ if (test_bit(R10BIO_Uptodate, &r10_bio->state))
+ generic_make_request(wbio);
+ else
+ bio_endio(wbio, wbio->bi_size, -EIO);
}
@@ -1445,7 +1458,8 @@
unfreeze_array(conf);
bio = r10_bio->devs[r10_bio->read_slot].bio;
- r10_bio->devs[r10_bio->read_slot].bio = NULL;
+ r10_bio->devs[r10_bio->read_slot].bio =
+ mddev->ro ? IO_BLOCKED : NULL;
bio_put(bio);
mirror = read_balance(conf, r10_bio);
if (mirror == -1) {
diff --git a/include/linux/raid/raid10.h b/include/linux/raid/raid10.h
index dfa5283..b110329 100644
--- a/include/linux/raid/raid10.h
+++ b/include/linux/raid/raid10.h
@@ -104,6 +104,13 @@
} devs[0];
};
+/* when we get a read error on a read-only array, we redirect to another
+ * device without failing the first device, or trying to over-write to
+ * correct the read error. To keep track of bad blocks on a per-bio
+ * level, we store IO_BLOCKED in the appropriate 'bios' pointer
+ */
+#define IO_BLOCKED ((struct bio*)1)
+
/* bits for r10bio.state */
#define R10BIO_Uptodate 0
#define R10BIO_IsSync 1
