We need to be careful when referencing mirrors[i].rdev. so it can
disappear under us at various times.
So:
fix a couple of problem places.
comment a couple of non-problem places
move an 'atomic_add' which deferences rdev down a little
way to some where where it is sure to not be NULL.
Signed-off-by: Neil Brown <[email protected]>
---
Index: mm-quilt/drivers/md/raid1.c
===================================================================
--- mm-quilt.orig/drivers/md/raid1.c 2006-08-28 08:57:30.000000000 +1000
+++ mm-quilt/drivers/md/raid1.c 2006-08-28 09:06:32.000000000 +1000
@@ -930,10 +930,13 @@ static void status(struct seq_file *seq,
seq_printf(seq, " [%d/%d] [", conf->raid_disks,
conf->working_disks);
- for (i = 0; i < conf->raid_disks; i++)
+ rcu_read_lock();
+ for (i = 0; i < conf->raid_disks; i++) {
+ mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
seq_printf(seq, "%s",
- conf->mirrors[i].rdev &&
- test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
+ rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
+ }
+ rcu_read_unlock();
seq_printf(seq, "]");
}
@@ -975,7 +978,6 @@ static void error(mddev_t *mddev, mdk_rd
static void print_conf(conf_t *conf)
{
int i;
- mirror_info_t *tmp;
printk("RAID1 conf printout:\n");
if (!conf) {
@@ -985,14 +987,17 @@ static void print_conf(conf_t *conf)
printk(" --- wd:%d rd:%d\n", conf->working_disks,
conf->raid_disks);
+ rcu_read_lock();
for (i = 0; i < conf->raid_disks; i++) {
char b[BDEVNAME_SIZE];
- tmp = conf->mirrors + i;
- if (tmp->rdev)
+ mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
+ if (rdev)
printk(" disk %d, wo:%d, o:%d, dev:%s\n",
- i, !test_bit(In_sync, &tmp->rdev->flags), !test_bit(Faulty, &tmp->rdev->flags),
- bdevname(tmp->rdev->bdev,b));
+ i, !test_bit(In_sync, &rdev->flags),
+ !test_bit(Faulty, &rdev->flags),
+ bdevname(rdev->bdev,b));
}
+ rcu_read_unlock();
}
static void close_sync(conf_t *conf)
@@ -1008,20 +1013,20 @@ static int raid1_spare_active(mddev_t *m
{
int i;
conf_t *conf = mddev->private;
- mirror_info_t *tmp;
/*
* Find all failed disks within the RAID1 configuration
- * and mark them readable
+ * and mark them readable.
+ * Called under mddev lock, so rcu protection not needed.
*/
for (i = 0; i < conf->raid_disks; i++) {
- tmp = conf->mirrors + i;
- if (tmp->rdev
- && !test_bit(Faulty, &tmp->rdev->flags)
- && !test_bit(In_sync, &tmp->rdev->flags)) {
+ mdk_rdev_t *rdev = conf->mirrors[i].rdev;
+ if (rdev
+ && !test_bit(Faulty, &rdev->flags)
+ && !test_bit(In_sync, &rdev->flags)) {
conf->working_disks++;
mddev->degraded--;
- set_bit(In_sync, &tmp->rdev->flags);
+ set_bit(In_sync, &rdev->flags);
}
}
@@ -1237,7 +1242,7 @@ static void sync_request_write(mddev_t *
/* ouch - failed to read all of that.
* Try some synchronous reads of other devices to get
* good data, much like with normal read errors. Only
- * read into the pages we already have so they we don't
+ * read into the pages we already have so we don't
* need to re-issue the read request.
* We don't need to freeze the array, because being in an
* active sync request, there is no normal IO, and
@@ -1257,6 +1262,10 @@ static void sync_request_write(mddev_t *
s = PAGE_SIZE >> 9;
do {
if (r1_bio->bios[d]->bi_end_io == end_sync_read) {
+ /* No rcu protection needed here devices
+ * can only be removed when no resync is
+ * active, and resync is currently active
+ */
rdev = conf->mirrors[d].rdev;
if (sync_page_io(rdev->bdev,
sect + rdev->data_offset,
@@ -1463,6 +1472,11 @@ static void raid1d(mddev_t *mddev)
s = PAGE_SIZE >> 9;
do {
+ /* Note: no rcu protection needed here
+ * as this is synchronous in the raid1d thread
+ * which is the thread that might remove
+ * a device. If raid1d ever becomes multi-threaded....
+ */
rdev = conf->mirrors[d].rdev;
if (rdev &&
test_bit(In_sync, &rdev->flags) &&
@@ -1486,7 +1500,6 @@ static void raid1d(mddev_t *mddev)
d = conf->raid_disks;
d--;
rdev = conf->mirrors[d].rdev;
- atomic_add(s, &rdev->corrected_errors);
if (rdev &&
test_bit(In_sync, &rdev->flags)) {
if (sync_page_io(rdev->bdev,
@@ -1509,9 +1522,11 @@ static void raid1d(mddev_t *mddev)
s<<9, conf->tmppage, READ) == 0)
/* Well, this device is dead */
md_error(mddev, rdev);
- else
+ else {
+ atomic_add(s, &rdev->corrected_errors);
printk(KERN_INFO "raid1:%s: read error corrected (%d sectors at %llu on %s)\n",
mdname(mddev), s, (unsigned long long)(sect + rdev->data_offset), bdevname(rdev->bdev, b));
+ }
}
}
} else {
@@ -1787,19 +1802,17 @@ static sector_t sync_request(mddev_t *md
for (i=0; i<conf->raid_disks; i++) {
bio = r1_bio->bios[i];
if (bio->bi_end_io == end_sync_read) {
- md_sync_acct(conf->mirrors[i].rdev->bdev, nr_sectors);
+ md_sync_acct(bio->bi_bdev, nr_sectors);
generic_make_request(bio);
}
}
} else {
atomic_set(&r1_bio->remaining, 1);
bio = r1_bio->bios[r1_bio->read_disk];
- md_sync_acct(conf->mirrors[r1_bio->read_disk].rdev->bdev,
- nr_sectors);
+ md_sync_acct(bio->bi_bdev, nr_sectors);
generic_make_request(bio);
}
-
return nr_sectors;
}
-
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