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[PATCH] md: Fix issues with referencing rdev in md/raid1

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We need to be careful when referencing mirrors[i].rdev.  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 <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
NeilBrown 2006-08-31 21:27:36 -07:00 committed by Linus Torvalds
parent df9ecaba3f
commit ddac7c7e3a
1 changed files with 35 additions and 22 deletions
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57
drivers/md/raid1.c
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@ -930,10 +930,13 @@ static void status(struct seq_file *seq, mddev_t *mddev)
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_rdev_t *rdev)
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 *mddev)
{
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 *mddev, r1bio_t *r1_bio)
/* 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 *mddev, r1bio_t *r1_bio)
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 *mddev, sector_t sector_nr, int *skipped, i
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;
}