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md: be extra careful not to take a reference to a Faulty device.

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It is important that we never increment rdev->nr_pending on a Faulty
device as ->hot_remove_disk() assumes that once the Faulty flag is visible
no code will take a new reference.

Some places take a new reference after only check In_sync.  This should
be safe as the two are changed together.  However to make the code more
obviously safe, add checks for 'Faulty' as well.

Note: the actual rule is:
  Never increment nr_pending if  Faulty is set and Blocked is clear,
  never clear Faulty, and never set Blocked without holding a reference
  through nr_pending.

fix build error (Shaohua)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
NeilBrown 2016-06-02 16:19:53 +10:00 committed by Shaohua Li
parent 40cf2123c5
commit f5b67ae86e
3 changed files with 10 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
drivers/md/multipath.c
View file

@ -43,7 +43,8 @@ static int multipath_map (struct mpconf *conf)
rcu_read_lock();
for (i = 0; i < disks; i++) {
struct md_rdev *rdev = rcu_dereference(conf->multipaths[i].rdev);
if (rdev && test_bit(In_sync, &rdev->flags)) {
if (rdev && test_bit(In_sync, &rdev->flags) &&
!test_bit(Faulty, &rdev->flags)) {
atomic_inc(&rdev->nr_pending);
rcu_read_unlock();
return i;

6
drivers/md/raid10.c
View file

@ -2287,6 +2287,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (rdev &&
test_bit(In_sync, &rdev->flags) &&
!test_bit(Faulty, &rdev->flags) &&
is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
&first_bad, &bad_sectors) == 0) {
atomic_inc(&rdev->nr_pending);
@ -2339,6 +2340,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
d = r10_bio->devs[sl].devnum;
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (!rdev ||
test_bit(Faulty, &rdev->flags) ||
!test_bit(In_sync, &rdev->flags))
continue;
@ -2378,6 +2380,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
d = r10_bio->devs[sl].devnum;
rdev = rcu_dereference(conf->mirrors[d].rdev);
if (!rdev ||
test_bit(Faulty, &rdev->flags) ||
!test_bit(In_sync, &rdev->flags))
continue;
@ -2953,6 +2956,7 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
mreplace = rcu_dereference(mirror->replacement);
if ((mrdev == NULL ||
test_bit(Faulty, &mrdev->flags) ||
test_bit(In_sync, &mrdev->flags)) &&
(mreplace == NULL ||
test_bit(Faulty, &mreplace->flags))) {
@ -2971,6 +2975,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
rcu_read_unlock();
continue;
}
if (mreplace && test_bit(Faulty, &mreplace->flags))
mreplace = NULL;
/* Unless we are doing a full sync, or a replacement
* we only need to recover the block if it is set in
* the bitmap

3
drivers/md/raid5.c
View file

@ -3080,7 +3080,8 @@ handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
struct md_rdev *rdev;
rcu_read_lock();
rdev = rcu_dereference(conf->disks[i].rdev);
if (rdev && test_bit(In_sync, &rdev->flags))
if (rdev && test_bit(In_sync, &rdev->flags) &&
!test_bit(Faulty, &rdev->flags))
atomic_inc(&rdev->nr_pending);
else
rdev = NULL;