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md/raid1: add rcu protection to rdev in fix_read_error 

Since remove_and_add_spares() was added to hot_remove_disk() it has
been possible for an rdev to be hot-removed while fix_read_error()
was running, so we need to be more careful, and take a reference to
the rdev while performing IO.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
hifive-unleashed-5.1
NeilBrown 2016-06-02 16:19:52 +10:00 committed by Shaohua Li
parent 854abd7584
commit 707a6a420c
1 changed files with 32 additions and 20 deletions
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52
drivers/md/raid1.c
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@ -2056,29 +2056,30 @@ static void fix_read_error(struct r1conf *conf, int read_disk,
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....
*/
sector_t first_bad;
int bad_sectors;
rdev = conf->mirrors[d].rdev;
rcu_read_lock();
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev &&
(test_bit(In_sync, &rdev->flags) ||
(!test_bit(Faulty, &rdev->flags) &&
rdev->recovery_offset >= sect + s)) &&
is_badblock(rdev, sect, s,
&first_bad, &bad_sectors) == 0 &&
sync_page_io(rdev, sect, s<<9,
conf->tmppage, READ, false))
success = 1;
else {
d++;
if (d == conf->raid_disks * 2)
d = 0;
}
&first_bad, &bad_sectors) == 0) {
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
if (sync_page_io(rdev, sect, s<<9,
conf->tmppage, READ, false))
success = 1;
rdev_dec_pending(rdev, mddev);
if (success)
break;
} else
rcu_read_unlock();
d++;
if (d == conf->raid_disks * 2)
d = 0;
} while (!success && d != read_disk);
if (!success) {
@ -2094,11 +2095,17 @@ static void fix_read_error(struct r1conf *conf, int read_disk,
if (d==0)
d = conf->raid_disks * 2;
d--;
rdev = conf->mirrors[d].rdev;
rcu_read_lock();
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev &&
!test_bit(Faulty, &rdev->flags))
!test_bit(Faulty, &rdev->flags)) {
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
r1_sync_page_io(rdev, sect, s,
conf->tmppage, WRITE);
rdev_dec_pending(rdev, mddev);
} else
rcu_read_unlock();
}
d = start;
while (d != read_disk) {
@ -2106,9 +2113,12 @@ static void fix_read_error(struct r1conf *conf, int read_disk,
if (d==0)
d = conf->raid_disks * 2;
d--;
rdev = conf->mirrors[d].rdev;
rcu_read_lock();
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev &&
!test_bit(Faulty, &rdev->flags)) {
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
if (r1_sync_page_io(rdev, sect, s,
conf->tmppage, READ)) {
atomic_add(s, &rdev->corrected_errors);
@ -2117,10 +2127,12 @@ static void fix_read_error(struct r1conf *conf, int read_disk,
"(%d sectors at %llu on %s)\n",
mdname(mddev), s,
(unsigned long long)(sect +
rdev->data_offset),
rdev->data_offset),
bdevname(rdev->bdev, b));
}
}
rdev_dec_pending(rdev, mddev);
} else
rcu_read_unlock();
}
sectors -= s;
sect += s;