On 02/28/2017 02:31 AM, Shaohua Li wrote:
> On Tue, Feb 21, 2017 at 08:44:01PM +0100, Artur Paszkiewicz wrote:
>> Allow writing to 'consistency_policy' attribute when the array is
>> active. Add a new function 'change_consistency_policy' to the
>> md_personality operations structure to handle the change in the
>> personality code. Values "ppl" and "resync" are accepted and
>> turn PPL on and off respectively.
>>
>> When enabling PPL its location and size should first be set using
>> 'ppl_sector' and 'ppl_size' attributes and a valid PPL header should be
>> written at this location on each member device.
>>
>> Enabling or disabling PPL is performed under a suspended array. The
>> raid5_reset_stripe_cache function frees the stripe cache and allocates
>> it again in order to allocate or free the ppl_pages for the stripes in
>> the stripe cache.
>>
>> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@xxxxxxxxx>
>> ---
>> drivers/md/md.c | 12 ++++++++---
>> drivers/md/md.h | 2 ++
>> drivers/md/raid5-ppl.c | 4 ++++
>> drivers/md/raid5.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++
>> 4 files changed, 73 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/md/md.c b/drivers/md/md.c
>> index 3ff979d538d4..b70e19513588 100644
>> --- a/drivers/md/md.c
>> +++ b/drivers/md/md.c
>> @@ -5003,14 +5003,20 @@ consistency_policy_show(struct mddev *mddev, char *page)
>> static ssize_t
>> consistency_policy_store(struct mddev *mddev, const char *buf, size_t len)
>> {
>> + int err = 0;
>> +
>> if (mddev->pers) {
>> - return -EBUSY;
>> + if (mddev->pers->change_consistency_policy)
>> + err = mddev->pers->change_consistency_policy(mddev, buf);
>> + else
>> + err = -EBUSY;
>> } else if (mddev->external && strncmp(buf, "ppl", 3) == 0) {
>> set_bit(MD_HAS_PPL, &mddev->flags);
>> - return len;
>> } else {
>> - return -EINVAL;
>> + err = -EINVAL;
>> }
>> +
>> + return err ? err : len;
>> }
>>
>> static struct md_sysfs_entry md_consistency_policy =
>> diff --git a/drivers/md/md.h b/drivers/md/md.h
>> index 66a5a16e79f7..88a5155c152e 100644
>> --- a/drivers/md/md.h
>> +++ b/drivers/md/md.h
>> @@ -548,6 +548,8 @@ struct md_personality
>> /* congested implements bdi.congested_fn().
>> * Will not be called while array is 'suspended' */
>> int (*congested)(struct mddev *mddev, int bits);
>> + /* Changes the consistency policy of an active array. */
>> + int (*change_consistency_policy)(struct mddev *mddev, const char *buf);
>> };
>>
>> struct md_sysfs_entry {
>> diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
>> index c2070d124849..a5c4d3333bce 100644
>> --- a/drivers/md/raid5-ppl.c
>> +++ b/drivers/md/raid5-ppl.c
>> @@ -1095,6 +1095,10 @@ int ppl_init_log(struct r5conf *conf)
>> */
>> mddev->recovery_cp = MaxSector;
>> set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
>> + } else if (mddev->pers && ppl_conf->mismatch_count > 0) {
>> + /* no mismatch allowed when enabling PPL for a running array */
>> + ret = -EINVAL;
>> + goto err;
>> }
>>
>> conf->ppl = ppl_conf;
>> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
>> index b17e90f06f19..754fb8e1c76f 100644
>> --- a/drivers/md/raid5.c
>> +++ b/drivers/md/raid5.c
>> @@ -8319,6 +8319,63 @@ static void *raid6_takeover(struct mddev *mddev)
>> return setup_conf(mddev);
>> }
>>
>> +static void raid5_reset_stripe_cache(struct mddev *mddev)
>> +{
>> + struct r5conf *conf = mddev->private;
>> +
>> + mutex_lock(&conf->cache_size_mutex);
>> + while (conf->max_nr_stripes &&
>> + drop_one_stripe(conf))
>> + ;
>> + while (conf->min_nr_stripes > conf->max_nr_stripes &&
>> + grow_one_stripe(conf, GFP_KERNEL))
>> + ;
>> + mutex_unlock(&conf->cache_size_mutex);
>> +}
>> +
>> +static int raid5_change_consistency_policy(struct mddev *mddev, const char *buf)
>> +{
>> + struct r5conf *conf;
>> + int err;
>> +
>> + err = mddev_lock(mddev);
>> + if (err)
>> + return err;
>> + conf = mddev->private;
>> + if (!conf) {
>> + mddev_unlock(mddev);
>> + return -ENODEV;
>> + }
>> +
>> + if (strncmp(buf, "ppl", 3) == 0 &&
>> + !test_bit(MD_HAS_PPL, &mddev->flags)) {
>> + mddev_suspend(mddev);
>> + err = ppl_init_log(conf);
>
> I didn't see you check if all rdev have valid ppl setting in ppl_load. Am I
> missing anything? Is it possible some rdevs have ppl set, but some not. In the
> case, we should just bail out.
All rdevs should have valid ppl settings, this is checked in
ppl_validate_rdev(), just before ppl_load() is called.
> Also check if this is raid5
pers->change_consistency_policy is only set for raid5_personality, so it
is (currently) not necessary.
Thanks,
Artur
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