Re: [PATCH 4/5] btrfs: Allow barrier_all_devices to do per-chunk device check

[Anand Jain <anand.jain@oracle.com>]

On 10/30/2015 07:41 PM, Qu Wenruo wrote:
>
>
> 在 2015年10月30日 16:32, Anand Jain 写道:
>>
>>
>> Qu,
>>
>>   We shouldn't mark FS readonly when chunks are degradable.
>>   As below.
>>
>> Thanks, Anand
>>
>>
>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
>> index 39a2d57..dbb2483 100644
>> --- a/fs/btrfs/disk-io.c
>> +++ b/fs/btrfs/disk-io.c
>> @@ -3530,7 +3530,7 @@ static int write_all_supers(struct btrfs_root
>> *root, int max_mirrors)
>>
>>          if (do_barriers) {
>>                  ret = barrier_all_devices(root->fs_info);
>> -               if (ret) {
>> +               if (ret < 0) {
>>                          mutex_unlock(
>>
>> &root->fs_info->fs_devices->device_list_mutex);
>>                          btrfs_std_error(root->fs_info, ret,
>>
>>
>
> Sorry, I didn't got the point here.
>
> There should be no difference between ret and ret < 0,
> as barrier_all_devices() will only return -EIO or 0.

  oh sorry. you are right. I missed that point.

Thanks, Anand


> Thanks,
> Qu
>
>>
>>
>> On 09/21/2015 10:10 AM, Qu Wenruo wrote:
>>> The last user of num_tolerated_disk_barrier_failures is
>>> barrier_all_devices().
>>> But it's can be easily changed to new per-chunk degradable check
>>> framework.
>>>
>>> Now btrfs_device will have two extra members, representing send/wait
>>> error, set at write_dev_flush() time.
>>> And then check it in a similar but more accurate behavior than old code.
>>>
>>> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
>>> ---
>>>   fs/btrfs/disk-io.c | 13 +++++--------
>>>   fs/btrfs/volumes.c |  6 +++++-
>>>   fs/btrfs/volumes.h |  4 ++++
>>>   3 files changed, 14 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
>>> index d64299f..7cd94e7 100644
>>> --- a/fs/btrfs/disk-io.c
>>> +++ b/fs/btrfs/disk-io.c
>>> @@ -3400,8 +3400,6 @@ static int barrier_all_devices(struct
>>> btrfs_fs_info *info)
>>>   {
>>>       struct list_head *head;
>>>       struct btrfs_device *dev;
>>> -    int errors_send = 0;
>>> -    int errors_wait = 0;
>>>       int ret;
>>>
>>>       /* send down all the barriers */
>>> @@ -3410,7 +3408,7 @@ static int barrier_all_devices(struct
>>> btrfs_fs_info *info)
>>>           if (dev->missing)
>>>               continue;
>>>           if (!dev->bdev) {
>>> -            errors_send++;
>>> +            dev->err_send = 1;
>>>               continue;
>>>           }
>>>           if (!dev->in_fs_metadata || !dev->writeable)
>>> @@ -3418,7 +3416,7 @@ static int barrier_all_devices(struct
>>> btrfs_fs_info *info)
>>>
>>>           ret = write_dev_flush(dev, 0);
>>>           if (ret)
>>> -            errors_send++;
>>> +            dev->err_send = 1;
>>>       }
>>>
>>>       /* wait for all the barriers */
>>> @@ -3426,7 +3424,7 @@ static int barrier_all_devices(struct
>>> btrfs_fs_info *info)
>>>           if (dev->missing)
>>>               continue;
>>>           if (!dev->bdev) {
>>> -            errors_wait++;
>>> +            dev->err_wait = 1;
>>>               continue;
>>>           }
>>>           if (!dev->in_fs_metadata || !dev->writeable)
>>> @@ -3434,10 +3432,9 @@ static int barrier_all_devices(struct
>>> btrfs_fs_info *info)
>>>
>>>           ret = write_dev_flush(dev, 1);
>>>           if (ret)
>>> -            errors_wait++;
>>> +            dev->err_wait = 1;
>>>       }
>>> -    if (errors_send > info->num_tolerated_disk_barrier_failures ||
>>> -        errors_wait > info->num_tolerated_disk_barrier_failures)
>>> +    if (btrfs_check_degradable(info, info->sb->s_flags) < 0)
>>>           return -EIO;
>>>       return 0;
>>>   }
>>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>>> index f1ef215..88266fa 100644
>>> --- a/fs/btrfs/volumes.c
>>> +++ b/fs/btrfs/volumes.c
>>> @@ -6945,8 +6945,12 @@ int btrfs_check_degradable(struct btrfs_fs_info
>>> *fs_info, unsigned flags)
>>>               btrfs_get_num_tolerated_disk_barrier_failures(
>>>                       map->type);
>>>           for (i = 0; i < map->num_stripes; i++) {
>>> -            if (map->stripes[i].dev->missing)
>>> +            if (map->stripes[i].dev->missing ||
>>> +                map->stripes[i].dev->err_wait ||
>>> +                map->stripes[i].dev->err_send)
>>>                   missing++;
>>> +            map->stripes[i].dev->err_wait = 0;
>>> +            map->stripes[i].dev->err_send = 0;
>>>           }
>>>           if (missing > max_tolerated) {
>>>               ret = -EIO;
>>> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
>>> index fe758df..cd02556 100644
>>> --- a/fs/btrfs/volumes.h
>>> +++ b/fs/btrfs/volumes.h
>>> @@ -76,6 +76,10 @@ struct btrfs_device {
>>>       int can_discard;
>>>       int is_tgtdev_for_dev_replace;
>>>
>>> +    /* for barrier_all_devices() check */
>>> +    int err_send;
>>> +    int err_wait;
>>> +
>>>   #ifdef __BTRFS_NEED_DEVICE_DATA_ORDERED
>>>       seqcount_t data_seqcount;
>>>   #endif
>>>
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