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md/raid10: check In_sync flag in 'enough()'. 

It isn't really enough to check that the rdev is present, we need to
also be sure that the device is still In_sync.

Doing this requires using rcu_dereference to access the rdev, and
holding the rcu_read_lock() to ensure the rdev doesn't disappear while
we look at it.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2013-06-11 15:08:03 +10:00
parent 635f6416a2
commit 725d6e579f
1 changed files with 11 additions and 4 deletions
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15
drivers/md/raid10.c
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@ -1633,6 +1633,7 @@ static void status(struct seq_file *seq, struct mddev *mddev)
static int _enough(struct r10conf *conf, int previous, int ignore)
{
int first = 0;
int has_enough = 0;
int disks, ncopies;
if (previous) {
disks = conf->prev.raid_disks;
@ -1642,21 +1643,27 @@ static int _enough(struct r10conf *conf, int previous, int ignore)
ncopies = conf->geo.near_copies;
}
rcu_read_lock();
do {
int n = conf->copies;
int cnt = 0;
int this = first;
while (n--) {
if (conf->mirrors[this].rdev &&
this != ignore)
struct md_rdev *rdev;
if (this != ignore &&
(rdev = rcu_dereference(conf->mirrors[this].rdev)) &&
test_bit(In_sync, &rdev->flags))
cnt++;
this = (this+1) % disks;
}
if (cnt == 0)
return 0;
goto out;
first = (first + ncopies) % disks;
} while (first != 0);
return 1;
has_enough = 1;
out:
rcu_read_unlock();
return has_enough;
}
static int enough(struct r10conf *conf, int ignore)