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| author |   NeilBrown <neilb@suse.com> | 2016-06-02 16:19:53 +1000 |
|---|---|---|
| committer |   Shaohua Li <shli@fb.com> | 2016-06-13 11:54:21 -0700 |
| commit | f5b67ae86ee317db20c0e10d54f16a0bbbd3207d (patch) | |
| tree | 8db4539e9c9f05624f2b198ddd1ccce54b281ce6 /drivers/md/multipath.c | |
| parent | md/multipath: add rcu protection to rdev access in multipath_status. (diff) | |
| download | linux-dev-f5b67ae86ee317db20c0e10d54f16a0bbbd3207d.tar.xz linux-dev-f5b67ae86ee317db20c0e10d54f16a0bbbd3207d.zip | |
md: be extra careful not to take a reference to a Faulty device.
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>
Diffstat (limited to 'drivers/md/multipath.c')
| -rw-r--r-- | drivers/md/multipath.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c index 69244de2036b..7eb9972a37e6 100644 --- a/drivers/md/multipath.c +++ b/drivers/md/multipath.c @@ -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; |