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authorNeilBrown <neilb@suse.com>2016-06-02 16:19:52 +1000
committerShaohua Li <shli@fb.com>2016-06-13 11:54:13 -0700
commit414e6b9a7032a6c2f5ddf018fdb199190b075170 (patch)
treec9876ef9b5a3b111ee93d0215bb27190f5cb6505 /drivers/md/raid10.c
parent8430e7e0af9a15063b90343e3beebc164c8e90f3 (diff)
downloadop-kernel-dev-414e6b9a7032a6c2f5ddf018fdb199190b075170.zip
op-kernel-dev-414e6b9a7032a6c2f5ddf018fdb199190b075170.tar.gz
md/raid1, raid10: don't recheck "Faulty" flag in read-balance.
Re-checking the faulty flag here brings no value. The comment about "risk" refers to the risk that the device could be in the process of being removed by ->hot_remove_disk(). However providing that the ->nr_pending count is incremented inside an rcu_read_locked() region, there is no risk of that happening. This is because the rdev pointer (in the personalities array) is set to NULL before synchronize_rcu(), and ->nr_pending is tested afterwards. If the rcu_read_locked region happens before the synchronize_rcu(), the test will see that nr_pending has been incremented. If it happens afterwards, the rdev pointer will be NULL so there is nothing to increment. Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md/raid10.c')
-rw-r--r--drivers/md/raid10.c8
1 files changed, 0 insertions, 8 deletions
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 3578d3a..ae4dce1 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -707,7 +707,6 @@ static struct md_rdev *read_balance(struct r10conf *conf,
raid10_find_phys(conf, r10_bio);
rcu_read_lock();
-retry:
sectors = r10_bio->sectors;
best_slot = -1;
best_rdev = NULL;
@@ -804,13 +803,6 @@ retry:
if (slot >= 0) {
atomic_inc(&rdev->nr_pending);
- if (test_bit(Faulty, &rdev->flags)) {
- /* Cannot risk returning a device that failed
- * before we inc'ed nr_pending
- */
- rdev_dec_pending(rdev, conf->mddev);
- goto retry;
- }
r10_bio->read_slot = slot;
} else
rdev = NULL;
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