[RFC PATCH 0/2] Kernel space btrfs missing device detection.

[RFC PATCH 0/2] Kernel space btrfs missing device detection.

[Qu Wenruo]

Original btrfs will not detection any missing device since there is no
notification mechanism for fs layer to detect missing device in block layer.

However we don't really need to notify fs layer upon dev remove, probing in
dev_info/rm_dev ioctl is good enough since they are the only two ioctls caring
about missing device.

This patchset will do ioctl time missing dev detection and return device missing
status in dev_info ioctl using a new member in btrfs_ioctl_dev_info_args with a
backward compatible method.

Cc: Anand Jain <Anand.Jain@oracle.com>
Qu Wenruo (2):
  btrfs: Add missing device check in dev_info/rm_dev ioctl
  btrfs: Add new member of btrfs_ioctl_dev_info_args.

 fs/btrfs/ioctl.c           |  4 ++++
 fs/btrfs/volumes.c         | 25 ++++++++++++++++++++++++-
 fs/btrfs/volumes.h         |  2 ++
 include/uapi/linux/btrfs.h |  5 ++++-
 4 files changed, 34 insertions(+), 2 deletions(-)

-- 
1.9.2

[RFC PATCH 1/2] btrfs: Add missing device check in dev_info/rm_dev ioctl

[Qu Wenruo]

Old btrfs can't find a missing btrfs device since there is no
mechanism for block layer to inform fs layer.

But we can use a workaround that only check status(by using
request_queue->queue_flags) of every device in a btrfs
filesystem when calling dev_info/rm_dev ioctl, since other ioctls
do not really cares about missing device.

Cc: Anand Jain <Anand.Jain@oracle.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 fs/btrfs/ioctl.c   |  1 +
 fs/btrfs/volumes.c | 25 ++++++++++++++++++++++++-
 fs/btrfs/volumes.h |  2 ++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0401397..7680a40 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2606,6 +2606,7 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
 		goto out;
 	}
 
+	btrfs_check_dev_missing(root, dev, 1);
 	di_args->devid = dev->devid;
 	di_args->bytes_used = dev->bytes_used;
 	di_args->total_bytes = dev->total_bytes;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index d241130a..c7d7908 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1548,9 +1548,10 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 		 * is held.
 		 */
 		list_for_each_entry(tmp, devices, dev_list) {
+			btrfs_check_dev_missing(root, tmp, 0);
 			if (tmp->in_fs_metadata &&
 			    !tmp->is_tgtdev_for_dev_replace &&
-			    !tmp->bdev) {
+			    (!tmp->bdev || tmp->missing)) {
 				device = tmp;
 				break;
 			}
@@ -6300,3 +6301,25 @@ int btrfs_scratch_superblock(struct btrfs_device *device)
 
 	return 0;
 }
+
+/* If need_lock is set, uuid_mutex will be used */
+int btrfs_check_dev_missing(struct btrfs_root *root, struct btrfs_device *dev,
+			    int need_lock)
+{
+	struct request_queue *q;
+
+	if (unlikely(!dev || !dev->bdev || !dev->bdev->bd_queue))
+		return -ENOENT;
+	q = dev->bdev->bd_queue;
+
+	if (need_lock)
+		mutex_lock(&uuid_mutex);
+	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
+	    test_bit(QUEUE_FLAG_DYING, &q->queue_flags)) {
+		dev->missing = 1;
+		root->fs_info->fs_devices->missing_devices++;
+	}
+	if (need_lock)
+		mutex_unlock(&uuid_mutex);
+	return 0;
+}
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 80754f9..47a44af 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -356,6 +356,8 @@ unsigned long btrfs_full_stripe_len(struct btrfs_root *root,
 int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
 				struct btrfs_root *extent_root,
 				u64 chunk_offset, u64 chunk_size);
+int btrfs_check_dev_missing(struct btrfs_root *root, struct btrfs_device *dev,
+			    int need_lock);
 static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
 				      int index)
 {
-- 
1.9.2

Re: [RFC PATCH 1/2] btrfs: Add missing device check in dev_info/rm_dev ioctl

[Anand Jain]

Thanks for working on this.
I am running some tests will let you know.

Anand


On 05/06/2014 02:33 PM, Qu Wenruo wrote:
> Old btrfs can't find a missing btrfs device since there is no
> mechanism for block layer to inform fs layer.
>
> But we can use a workaround that only check status(by using
> request_queue->queue_flags) of every device in a btrfs
> filesystem when calling dev_info/rm_dev ioctl, since other ioctls
> do not really cares about missing device.
>
> Cc: Anand Jain <Anand.Jain@oracle.com>
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> ---
>   fs/btrfs/ioctl.c   |  1 +
>   fs/btrfs/volumes.c | 25 ++++++++++++++++++++++++-
>   fs/btrfs/volumes.h |  2 ++
>   3 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 0401397..7680a40 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -2606,6 +2606,7 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
>   		goto out;
>   	}
>
> +	btrfs_check_dev_missing(root, dev, 1);
>   	di_args->devid = dev->devid;
>   	di_args->bytes_used = dev->bytes_used;
>   	di_args->total_bytes = dev->total_bytes;
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index d241130a..c7d7908 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1548,9 +1548,10 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
>   		 * is held.
>   		 */
>   		list_for_each_entry(tmp, devices, dev_list) {
> +			btrfs_check_dev_missing(root, tmp, 0);
>   			if (tmp->in_fs_metadata &&
>   			    !tmp->is_tgtdev_for_dev_replace &&
> -			    !tmp->bdev) {
> +			    (!tmp->bdev || tmp->missing)) {
>   				device = tmp;
>   				break;
>   			}
> @@ -6300,3 +6301,25 @@ int btrfs_scratch_superblock(struct btrfs_device *device)
>
>   	return 0;
>   }
> +
> +/* If need_lock is set, uuid_mutex will be used */
> +int btrfs_check_dev_missing(struct btrfs_root *root, struct btrfs_device *dev,
> +			    int need_lock)
> +{
> +	struct request_queue *q;
> +
> +	if (unlikely(!dev || !dev->bdev || !dev->bdev->bd_queue))
> +		return -ENOENT;
> +	q = dev->bdev->bd_queue;
> +
> +	if (need_lock)
> +		mutex_lock(&uuid_mutex);
> +	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
> +	    test_bit(QUEUE_FLAG_DYING, &q->queue_flags)) {
> +		dev->missing = 1;
> +		root->fs_info->fs_devices->missing_devices++;
> +	}
> +	if (need_lock)
> +		mutex_unlock(&uuid_mutex);
> +	return 0;
> +}
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 80754f9..47a44af 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -356,6 +356,8 @@ unsigned long btrfs_full_stripe_len(struct btrfs_root *root,
>   int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
>   				struct btrfs_root *extent_root,
>   				u64 chunk_offset, u64 chunk_size);
> +int btrfs_check_dev_missing(struct btrfs_root *root, struct btrfs_device *dev,
> +			    int need_lock);
>   static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
>   				      int index)
>   {
>

Re: [RFC PATCH 1/2] btrfs: Add missing device check in dev_info/rm_dev ioctl

[Qu Wenruo]

-------- Original Message --------
Subject: Re: [RFC PATCH 1/2] btrfs: Add missing device check in 
dev_info/rm_dev ioctl
From: Anand Jain <Anand.Jain@oracle.com>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Date: 2014年05月07日 16:00
>
>
> Thanks for working on this.
> I am running some tests will let you know.
>
> Anand
>
Thanks for your tests.
I have only check the scsi_device/X:X:X:X/device/delete interface to 
remove the device,
so if you have some other device remove tests, that would be much nicer.

Thanks,
Qu
>
> On 05/06/2014 02:33 PM, Qu Wenruo wrote:
>> Old btrfs can't find a missing btrfs device since there is no
>> mechanism for block layer to inform fs layer.
>>
>> But we can use a workaround that only check status(by using
>> request_queue->queue_flags) of every device in a btrfs
>> filesystem when calling dev_info/rm_dev ioctl, since other ioctls
>> do not really cares about missing device.
>>
>> Cc: Anand Jain <Anand.Jain@oracle.com>
>> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
>> ---
>>   fs/btrfs/ioctl.c   |  1 +
>>   fs/btrfs/volumes.c | 25 ++++++++++++++++++++++++-
>>   fs/btrfs/volumes.h |  2 ++
>>   3 files changed, 27 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
>> index 0401397..7680a40 100644
>> --- a/fs/btrfs/ioctl.c
>> +++ b/fs/btrfs/ioctl.c
>> @@ -2606,6 +2606,7 @@ static long btrfs_ioctl_dev_info(struct 
>> btrfs_root *root, void __user *arg)
>>           goto out;
>>       }
>>
>> +    btrfs_check_dev_missing(root, dev, 1);
>>       di_args->devid = dev->devid;
>>       di_args->bytes_used = dev->bytes_used;
>>       di_args->total_bytes = dev->total_bytes;
>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>> index d241130a..c7d7908 100644
>> --- a/fs/btrfs/volumes.c
>> +++ b/fs/btrfs/volumes.c
>> @@ -1548,9 +1548,10 @@ int btrfs_rm_device(struct btrfs_root *root, 
>> char *device_path)
>>            * is held.
>>            */
>>           list_for_each_entry(tmp, devices, dev_list) {
>> +            btrfs_check_dev_missing(root, tmp, 0);
>>               if (tmp->in_fs_metadata &&
>>                   !tmp->is_tgtdev_for_dev_replace &&
>> -                !tmp->bdev) {
>> +                (!tmp->bdev || tmp->missing)) {
>>                   device = tmp;
>>                   break;
>>               }
>> @@ -6300,3 +6301,25 @@ int btrfs_scratch_superblock(struct 
>> btrfs_device *device)
>>
>>       return 0;
>>   }
>> +
>> +/* If need_lock is set, uuid_mutex will be used */
>> +int btrfs_check_dev_missing(struct btrfs_root *root, struct 
>> btrfs_device *dev,
>> +                int need_lock)
>> +{
>> +    struct request_queue *q;
>> +
>> +    if (unlikely(!dev || !dev->bdev || !dev->bdev->bd_queue))
>> +        return -ENOENT;
>> +    q = dev->bdev->bd_queue;
>> +
>> +    if (need_lock)
>> +        mutex_lock(&uuid_mutex);
>> +    if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
>> +        test_bit(QUEUE_FLAG_DYING, &q->queue_flags)) {
>> +        dev->missing = 1;
>> +        root->fs_info->fs_devices->missing_devices++;
>> +    }
>> +    if (need_lock)
>> +        mutex_unlock(&uuid_mutex);
>> +    return 0;
>> +}
>> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
>> index 80754f9..47a44af 100644
>> --- a/fs/btrfs/volumes.h
>> +++ b/fs/btrfs/volumes.h
>> @@ -356,6 +356,8 @@ unsigned long btrfs_full_stripe_len(struct 
>> btrfs_root *root,
>>   int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
>>                   struct btrfs_root *extent_root,
>>                   u64 chunk_offset, u64 chunk_size);
>> +int btrfs_check_dev_missing(struct btrfs_root *root, struct 
>> btrfs_device *dev,
>> +                int need_lock);
>>   static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
>>                         int index)
>>   {
>>

Re: [RFC PATCH 1/2] btrfs: Add missing device check in dev_info/rm_dev ioctl

[Qu Wenruo]

I'm sorry to bother your but it has been about 2 weeks after your last 
reply.

Is there any problem?

Thanks,
Qu
-------- Original Message --------
Subject: Re: [RFC PATCH 1/2] btrfs: Add missing device check in 
dev_info/rm_dev ioctl
From: Anand Jain <Anand.Jain@oracle.com>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Date: 2014年05月07日 16:00
>
>
> Thanks for working on this.
> I am running some tests will let you know.
>
> Anand
>
>
> On 05/06/2014 02:33 PM, Qu Wenruo wrote:
>> Old btrfs can't find a missing btrfs device since there is no
>> mechanism for block layer to inform fs layer.
>>
>> But we can use a workaround that only check status(by using
>> request_queue->queue_flags) of every device in a btrfs
>> filesystem when calling dev_info/rm_dev ioctl, since other ioctls
>> do not really cares about missing device.
>>
>> Cc: Anand Jain <Anand.Jain@oracle.com>
>> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
>> ---
>>   fs/btrfs/ioctl.c   |  1 +
>>   fs/btrfs/volumes.c | 25 ++++++++++++++++++++++++-
>>   fs/btrfs/volumes.h |  2 ++
>>   3 files changed, 27 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
>> index 0401397..7680a40 100644
>> --- a/fs/btrfs/ioctl.c
>> +++ b/fs/btrfs/ioctl.c
>> @@ -2606,6 +2606,7 @@ static long btrfs_ioctl_dev_info(struct 
>> btrfs_root *root, void __user *arg)
>>           goto out;
>>       }
>>
>> +    btrfs_check_dev_missing(root, dev, 1);
>>       di_args->devid = dev->devid;
>>       di_args->bytes_used = dev->bytes_used;
>>       di_args->total_bytes = dev->total_bytes;
>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>> index d241130a..c7d7908 100644
>> --- a/fs/btrfs/volumes.c
>> +++ b/fs/btrfs/volumes.c
>> @@ -1548,9 +1548,10 @@ int btrfs_rm_device(struct btrfs_root *root, 
>> char *device_path)
>>            * is held.
>>            */
>>           list_for_each_entry(tmp, devices, dev_list) {
>> +            btrfs_check_dev_missing(root, tmp, 0);
>>               if (tmp->in_fs_metadata &&
>>                   !tmp->is_tgtdev_for_dev_replace &&
>> -                !tmp->bdev) {
>> +                (!tmp->bdev || tmp->missing)) {
>>                   device = tmp;
>>                   break;
>>               }
>> @@ -6300,3 +6301,25 @@ int btrfs_scratch_superblock(struct 
>> btrfs_device *device)
>>
>>       return 0;
>>   }
>> +
>> +/* If need_lock is set, uuid_mutex will be used */
>> +int btrfs_check_dev_missing(struct btrfs_root *root, struct 
>> btrfs_device *dev,
>> +                int need_lock)
>> +{
>> +    struct request_queue *q;
>> +
>> +    if (unlikely(!dev || !dev->bdev || !dev->bdev->bd_queue))
>> +        return -ENOENT;
>> +    q = dev->bdev->bd_queue;
>> +
>> +    if (need_lock)
>> +        mutex_lock(&uuid_mutex);
>> +    if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
>> +        test_bit(QUEUE_FLAG_DYING, &q->queue_flags)) {
>> +        dev->missing = 1;
>> +        root->fs_info->fs_devices->missing_devices++;
>> +    }
>> +    if (need_lock)
>> +        mutex_unlock(&uuid_mutex);
>> +    return 0;
>> +}
>> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
>> index 80754f9..47a44af 100644
>> --- a/fs/btrfs/volumes.h
>> +++ b/fs/btrfs/volumes.h
>> @@ -356,6 +356,8 @@ unsigned long btrfs_full_stripe_len(struct 
>> btrfs_root *root,
>>   int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
>>                   struct btrfs_root *extent_root,
>>                   u64 chunk_offset, u64 chunk_size);
>> +int btrfs_check_dev_missing(struct btrfs_root *root, struct 
>> btrfs_device *dev,
>> +                int need_lock);
>>   static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
>>                         int index)
>>   {
>>

Re: [RFC PATCH 1/2] btrfs: Add missing device check in dev_info/rm_dev ioctl

[Anand Jain]

Hi Qu,

  Thanks for checking with me. sorry for the delay. The
  preliminary RFC patch which was sent and mentioned in
  the other emails took time more than expected.

  Further on top of your check_missing patch I am writing
  code to to handle disk reappear. I should be sending them
  all soon.

Thanks, Anand


On 21/05/14 11:12, Qu Wenruo wrote:
>
> I'm sorry to bother your but it has been about 2 weeks after your last
> reply.
>
> Is there any problem?
>
> Thanks,
> Qu
> -------- Original Message --------
> Subject: Re: [RFC PATCH 1/2] btrfs: Add missing device check in
> dev_info/rm_dev ioctl
> From: Anand Jain <Anand.Jain@oracle.com>
> To: Qu Wenruo <quwenruo@cn.fujitsu.com>
> Date: 2014年05月07日 16:00
>>
>>
>> Thanks for working on this.
>> I am running some tests will let you know.
>>
>> Anand
>>
>>
>> On 05/06/2014 02:33 PM, Qu Wenruo wrote:
>>> Old btrfs can't find a missing btrfs device since there is no
>>> mechanism for block layer to inform fs layer.
>>>
>>> But we can use a workaround that only check status(by using
>>> request_queue->queue_flags) of every device in a btrfs
>>> filesystem when calling dev_info/rm_dev ioctl, since other ioctls
>>> do not really cares about missing device.
>>>
>>> Cc: Anand Jain <Anand.Jain@oracle.com>
>>> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
>>> ---
>>>   fs/btrfs/ioctl.c   |  1 +
>>>   fs/btrfs/volumes.c | 25 ++++++++++++++++++++++++-
>>>   fs/btrfs/volumes.h |  2 ++
>>>   3 files changed, 27 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
>>> index 0401397..7680a40 100644
>>> --- a/fs/btrfs/ioctl.c
>>> +++ b/fs/btrfs/ioctl.c
>>> @@ -2606,6 +2606,7 @@ static long btrfs_ioctl_dev_info(struct
>>> btrfs_root *root, void __user *arg)
>>>           goto out;
>>>       }
>>>
>>> +    btrfs_check_dev_missing(root, dev, 1);
>>>       di_args->devid = dev->devid;
>>>       di_args->bytes_used = dev->bytes_used;
>>>       di_args->total_bytes = dev->total_bytes;
>>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>>> index d241130a..c7d7908 100644
>>> --- a/fs/btrfs/volumes.c
>>> +++ b/fs/btrfs/volumes.c
>>> @@ -1548,9 +1548,10 @@ int btrfs_rm_device(struct btrfs_root *root,
>>> char *device_path)
>>>            * is held.
>>>            */
>>>           list_for_each_entry(tmp, devices, dev_list) {
>>> +            btrfs_check_dev_missing(root, tmp, 0);
>>>               if (tmp->in_fs_metadata &&
>>>                   !tmp->is_tgtdev_for_dev_replace &&
>>> -                !tmp->bdev) {
>>> +                (!tmp->bdev || tmp->missing)) {
>>>                   device = tmp;
>>>                   break;
>>>               }
>>> @@ -6300,3 +6301,25 @@ int btrfs_scratch_superblock(struct
>>> btrfs_device *device)
>>>
>>>       return 0;
>>>   }
>>> +
>>> +/* If need_lock is set, uuid_mutex will be used */
>>> +int btrfs_check_dev_missing(struct btrfs_root *root, struct
>>> btrfs_device *dev,
>>> +                int need_lock)
>>> +{
>>> +    struct request_queue *q;
>>> +
>>> +    if (unlikely(!dev || !dev->bdev || !dev->bdev->bd_queue))
>>> +        return -ENOENT;
>>> +    q = dev->bdev->bd_queue;
>>> +
>>> +    if (need_lock)
>>> +        mutex_lock(&uuid_mutex);
>>> +    if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
>>> +        test_bit(QUEUE_FLAG_DYING, &q->queue_flags)) {
>>> +        dev->missing = 1;
>>> +        root->fs_info->fs_devices->missing_devices++;
>>> +    }
>>> +    if (need_lock)
>>> +        mutex_unlock(&uuid_mutex);
>>> +    return 0;
>>> +}
>>> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
>>> index 80754f9..47a44af 100644
>>> --- a/fs/btrfs/volumes.h
>>> +++ b/fs/btrfs/volumes.h
>>> @@ -356,6 +356,8 @@ unsigned long btrfs_full_stripe_len(struct
>>> btrfs_root *root,
>>>   int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
>>>                   struct btrfs_root *extent_root,
>>>                   u64 chunk_offset, u64 chunk_size);
>>> +int btrfs_check_dev_missing(struct btrfs_root *root, struct
>>> btrfs_device *dev,
>>> +                int need_lock);
>>>   static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
>>>                         int index)
>>>   {
>>>
>
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Re: [RFC PATCH 1/2] btrfs: Add missing device check in dev_info/rm_dev ioctl

[Qu Wenruo]

-------- Original Message --------
Subject: Re: [RFC PATCH 1/2] btrfs: Add missing device check in 
dev_info/rm_dev ioctl
From: Anand Jain <Anand.Jain@oracle.com>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Date: 2014年05月21日 11:54
>
> Hi Qu,
>
>  Thanks for checking with me. sorry for the delay. The
>  preliminary RFC patch which was sent and mentioned in
>  the other emails took time more than expected.
>
Thanks for the commenting, it seems that my RFC patches can only deal with
btrfs fi show but not sysfs things.
>  Further on top of your check_missing patch I am writing
>  code to to handle disk reappear. I should be sending them
>  all soon.
Disk reappear problem is also reproduce here.

I am intersting about how will your patch to deal with.
Is your patch going to check super genertion to determing previously 
missing device and
wipe reappeared superblock?(Wang mentioned it in the mail in Jan.)

IMO the reappear disk problem can also be resolved by not swap 
tgtdev->uuid and srcdev->uuid,
which means tgtdev will not use the same uuid of srcdev.

Thanks,
Qu
>
> Thanks, Anand
>

>
> On 21/05/14 11:12, Qu Wenruo wrote:
>>
>> I'm sorry to bother your but it has been about 2 weeks after your last
>> reply.
>>
>> Is there any problem?
>>
>> Thanks,
>> Qu
>> -------- Original Message --------
>> Subject: Re: [RFC PATCH 1/2] btrfs: Add missing device check in
>> dev_info/rm_dev ioctl
>> From: Anand Jain <Anand.Jain@oracle.com>
>> To: Qu Wenruo <quwenruo@cn.fujitsu.com>
>> Date: 2014年05月07日 16:00
>>>
>>>
>>> Thanks for working on this.
>>> I am running some tests will let you know.
>>>
>>> Anand
>>>
>>>
>>> On 05/06/2014 02:33 PM, Qu Wenruo wrote:
>>>> Old btrfs can't find a missing btrfs device since there is no
>>>> mechanism for block layer to inform fs layer.
>>>>
>>>> But we can use a workaround that only check status(by using
>>>> request_queue->queue_flags) of every device in a btrfs
>>>> filesystem when calling dev_info/rm_dev ioctl, since other ioctls
>>>> do not really cares about missing device.
>>>>
>>>> Cc: Anand Jain <Anand.Jain@oracle.com>
>>>> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
>>>> ---
>>>>   fs/btrfs/ioctl.c   |  1 +
>>>>   fs/btrfs/volumes.c | 25 ++++++++++++++++++++++++-
>>>>   fs/btrfs/volumes.h |  2 ++
>>>>   3 files changed, 27 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
>>>> index 0401397..7680a40 100644
>>>> --- a/fs/btrfs/ioctl.c
>>>> +++ b/fs/btrfs/ioctl.c
>>>> @@ -2606,6 +2606,7 @@ static long btrfs_ioctl_dev_info(struct
>>>> btrfs_root *root, void __user *arg)
>>>>           goto out;
>>>>       }
>>>>
>>>> +    btrfs_check_dev_missing(root, dev, 1);
>>>>       di_args->devid = dev->devid;
>>>>       di_args->bytes_used = dev->bytes_used;
>>>>       di_args->total_bytes = dev->total_bytes;
>>>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>>>> index d241130a..c7d7908 100644
>>>> --- a/fs/btrfs/volumes.c
>>>> +++ b/fs/btrfs/volumes.c
>>>> @@ -1548,9 +1548,10 @@ int btrfs_rm_device(struct btrfs_root *root,
>>>> char *device_path)
>>>>            * is held.
>>>>            */
>>>>           list_for_each_entry(tmp, devices, dev_list) {
>>>> +            btrfs_check_dev_missing(root, tmp, 0);
>>>>               if (tmp->in_fs_metadata &&
>>>>                   !tmp->is_tgtdev_for_dev_replace &&
>>>> -                !tmp->bdev) {
>>>> +                (!tmp->bdev || tmp->missing)) {
>>>>                   device = tmp;
>>>>                   break;
>>>>               }
>>>> @@ -6300,3 +6301,25 @@ int btrfs_scratch_superblock(struct
>>>> btrfs_device *device)
>>>>
>>>>       return 0;
>>>>   }
>>>> +
>>>> +/* If need_lock is set, uuid_mutex will be used */
>>>> +int btrfs_check_dev_missing(struct btrfs_root *root, struct
>>>> btrfs_device *dev,
>>>> +                int need_lock)
>>>> +{
>>>> +    struct request_queue *q;
>>>> +
>>>> +    if (unlikely(!dev || !dev->bdev || !dev->bdev->bd_queue))
>>>> +        return -ENOENT;
>>>> +    q = dev->bdev->bd_queue;
>>>> +
>>>> +    if (need_lock)
>>>> +        mutex_lock(&uuid_mutex);
>>>> +    if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
>>>> +        test_bit(QUEUE_FLAG_DYING, &q->queue_flags)) {
>>>> +        dev->missing = 1;
>>>> + root->fs_info->fs_devices->missing_devices++;
>>>> +    }
>>>> +    if (need_lock)
>>>> +        mutex_unlock(&uuid_mutex);
>>>> +    return 0;
>>>> +}
>>>> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
>>>> index 80754f9..47a44af 100644
>>>> --- a/fs/btrfs/volumes.h
>>>> +++ b/fs/btrfs/volumes.h
>>>> @@ -356,6 +356,8 @@ unsigned long btrfs_full_stripe_len(struct
>>>> btrfs_root *root,
>>>>   int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
>>>>                   struct btrfs_root *extent_root,
>>>>                   u64 chunk_offset, u64 chunk_size);
>>>> +int btrfs_check_dev_missing(struct btrfs_root *root, struct
>>>> btrfs_device *dev,
>>>> +                int need_lock);
>>>>   static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
>>>>                         int index)
>>>>   {
>>>>
>>
>> -- 
>> To unsubscribe from this list: send the line "unsubscribe 
>> linux-btrfs" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html

Re: [RFC PATCH 1/2] btrfs: Add missing device check in dev_info/rm_dev ioctl

[Brendan Hide]

On 2014/05/21 06:15 AM, Qu Wenruo wrote:
> [snip]
>>  Further on top of your check_missing patch I am writing
>>  code to to handle disk reappear. I should be sending them
>>  all soon.
> Disk reappear problem is also reproduce here.
>
> I am intersting about how will your patch to deal with.
> Is your patch going to check super genertion to determing previously 
> missing device and
> wipe reappeared superblock?(Wang mentioned it in the mail in Jan.)


With md we have the bitmap feature that helps prevent resynchronising 
the entire disk when doing a "re-add". Wiping the superblock is *better* 
than what we currently have (corruption) - but hopefully the end goal is 
to be able to have it re-add *without* introducing corruption.

>
> IMO the reappear disk problem can also be resolved by not swap 
> tgtdev->uuid and srcdev->uuid,
> which means tgtdev will not use the same uuid of srcdev.
>
> Thanks,
> Qu
>>
>> Thanks, Anand
>>


-- 
__________
Brendan Hide
http://swiftspirit.co.za/
http://www.webafrica.co.za/?AFF1E97

Re: [RFC PATCH 1/2] btrfs: Add missing device check in dev_info/rm_dev ioctl

[Anand Jain]

Hi Qu,


  Either we need to determine missing disk when disk disappear
  or when we hit by -ENODEV during IO.

  Discovering the same at the time when "user" run
  'btrfs fi show' or 'btrfs dev del', is just "not correct".

  You might use interface as proposed here.

  [PATCH RFC] btrfs: revamp /sys/fs/btrfs/<fsid>/devices

  further to this I will be sending another patch which will
  call the above sysfs interlace when we get the kobject
  notification when disk disappear.




On 05/06/2014 02:33 PM, Qu Wenruo wrote:
> Old btrfs can't find a missing btrfs device since there is no
> mechanism for block layer to inform fs layer.
>
> But we can use a workaround that only check status(by using
> request_queue->queue_flags) of every device in a btrfs
> filesystem when calling dev_info/rm_dev ioctl, since other ioctls
> do not really cares about missing device.


> Cc: Anand Jain <Anand.Jain@oracle.com>
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> ---
>   fs/btrfs/ioctl.c   |  1 +
>   fs/btrfs/volumes.c | 25 ++++++++++++++++++++++++-
>   fs/btrfs/volumes.h |  2 ++
>   3 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 0401397..7680a40 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -2606,6 +2606,7 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
>   		goto out;
>   	}
>
> +	btrfs_check_dev_missing(root, dev, 1);
>   	di_args->devid = dev->devid;
>   	di_args->bytes_used = dev->bytes_used;
>   	di_args->total_bytes = dev->total_bytes;
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index d241130a..c7d7908 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1548,9 +1548,10 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
>   		 * is held.
>   		 */
>   		list_for_each_entry(tmp, devices, dev_list) {
> +			btrfs_check_dev_missing(root, tmp, 0);
>   			if (tmp->in_fs_metadata &&
>   			    !tmp->is_tgtdev_for_dev_replace &&
> -			    !tmp->bdev) {
> +			    (!tmp->bdev || tmp->missing)) {
>   				device = tmp;
>   				break;
>   			}
> @@ -6300,3 +6301,25 @@ int btrfs_scratch_superblock(struct btrfs_device *device)
>
>   	return 0;
>   }
> +
> +/* If need_lock is set, uuid_mutex will be used */
> +int btrfs_check_dev_missing(struct btrfs_root *root, struct btrfs_device *dev,
> +			    int need_lock)
> +{
> +	struct request_queue *q;
> +
> +	if (unlikely(!dev || !dev->bdev || !dev->bdev->bd_queue))
> +		return -ENOENT;
> +	q = dev->bdev->bd_queue;
> +
> +	if (need_lock)
> +		mutex_lock(&uuid_mutex);
> +	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
> +	    test_bit(QUEUE_FLAG_DYING, &q->queue_flags)) {
> +		dev->missing = 1;
> +		root->fs_info->fs_devices->missing_devices++;
> +	}
> +	if (need_lock)
> +		mutex_unlock(&uuid_mutex);
> +	return 0;
> +}





> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 80754f9..47a44af 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -356,6 +356,8 @@ unsigned long btrfs_full_stripe_len(struct btrfs_root *root,
>   int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
>   				struct btrfs_root *extent_root,
>   				u64 chunk_offset, u64 chunk_size);
> +int btrfs_check_dev_missing(struct btrfs_root *root, struct btrfs_device *dev,
> +			    int need_lock);
>   static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
>   				      int index)
>   {
>

[RFC PATCH 2/2] btrfs: Add new member of btrfs_ioctl_dev_info_args.

[Qu Wenruo]

Add flags member for btrfs_ioctl_dev_info_args to preset missing btrfs
devices.

The new member is added in the original padding area so the ioctl API is
not affected but user headers needs to be updated.

Cc: Anand Jain <Anand.Jain@oracle.com>
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 fs/btrfs/ioctl.c           | 3 +++
 include/uapi/linux/btrfs.h | 5 ++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 7680a40..1920f24 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2610,6 +2610,9 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)
 	di_args->devid = dev->devid;
 	di_args->bytes_used = dev->bytes_used;
 	di_args->total_bytes = dev->total_bytes;
+	di_args->flags = BTRFS_IOCTL_DEV_INFO_FLAG_SET;
+	if (dev->missing)
+		di_args->flags |= BTRFS_IOCTL_DEV_INFO_MISSING;
 	memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
 	if (dev->name) {
 		struct rcu_string *name;
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index b4d6909..5eb1f03 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -168,12 +168,15 @@ struct btrfs_ioctl_dev_replace_args {
 	__u64 spare[64];
 };
 
+#define BTRFS_IOCTL_DEV_INFO_MISSING			(1ULL<<0)
+#define BTRFS_IOCTL_DEV_INFO_FLAG_SET			(1ULL<<63)
 struct btrfs_ioctl_dev_info_args {
 	__u64 devid;				/* in/out */
 	__u8 uuid[BTRFS_UUID_SIZE];		/* in/out */
 	__u64 bytes_used;			/* out */
 	__u64 total_bytes;			/* out */
-	__u64 unused[379];			/* pad to 4k */
+	__u64 flags;				/* out */
+	__u64 unused[378];			/* pad to 4k */
 	__u8 path[BTRFS_DEVICE_PATH_NAME_MAX];	/* out */
 };
 
-- 
1.9.2

Re: [RFC PATCH 0/2] Kernel space btrfs missing device detection.

[Goffredo Baroncelli]

Hi,

instead of extending the BTRFS_IOCTL_DEV_INFO ioctl, why do not add a field under /sys/fs/btrfs/<UUID>/ ? Something like /sys/fs/btrfs/<UUID>/missing_device

BR
G.Baroncelli

On 05/06/2014 08:33 AM, Qu Wenruo wrote:
> Original btrfs will not detection any missing device since there is
> no notification mechanism for fs layer to detect missing device in
> block layer.
> 
> However we don't really need to notify fs layer upon dev remove,
> probing in dev_info/rm_dev ioctl is good enough since they are the
> only two ioctls caring about missing device.
> 
> This patchset will do ioctl time missing dev detection and return
> device missing status in dev_info ioctl using a new member in
> btrfs_ioctl_dev_info_args with a backward compatible method.
> 
> Cc: Anand Jain <Anand.Jain@oracle.com> Qu Wenruo (2): btrfs: Add
> missing device check in dev_info/rm_dev ioctl btrfs: Add new member
> of btrfs_ioctl_dev_info_args.
> 
> fs/btrfs/ioctl.c           |  4 ++++ fs/btrfs/volumes.c         | 25
> ++++++++++++++++++++++++- fs/btrfs/volumes.h         |  2 ++ 
> include/uapi/linux/btrfs.h |  5 ++++- 4 files changed, 34
> insertions(+), 2 deletions(-)
> 


-- 
gpg @keyserver.linux.it: Goffredo Baroncelli (kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D  17B2 0EDA 9B37 8B82 E0B5

Re: [RFC PATCH 0/2] Kernel space btrfs missing device detection.

[Qu Wenruo]

-------- Original Message --------
Subject: Re: [RFC PATCH 0/2] Kernel space btrfs missing device detection.
From: Goffredo Baroncelli <kreijack@libero.it>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>, linux-btrfs@vger.kernel.org
Date: 2014年05月07日 02:10
> Hi,
>
> instead of extending the BTRFS_IOCTL_DEV_INFO ioctl, why do not add a field under /sys/fs/btrfs/<UUID>/ ? Something like /sys/fs/btrfs/<UUID>/missing_device
>
> BR
> G.Baroncelli
I think that is also a good idea. I'll try to add it later.

Thanks
Qu

>
> On 05/06/2014 08:33 AM, Qu Wenruo wrote:
>> Original btrfs will not detection any missing device since there is
>> no notification mechanism for fs layer to detect missing device in
>> block layer.
>>
>> However we don't really need to notify fs layer upon dev remove,
>> probing in dev_info/rm_dev ioctl is good enough since they are the
>> only two ioctls caring about missing device.
>>
>> This patchset will do ioctl time missing dev detection and return
>> device missing status in dev_info ioctl using a new member in
>> btrfs_ioctl_dev_info_args with a backward compatible method.
>>
>> Cc: Anand Jain <Anand.Jain@oracle.com> Qu Wenruo (2): btrfs: Add
>> missing device check in dev_info/rm_dev ioctl btrfs: Add new member
>> of btrfs_ioctl_dev_info_args.
>>
>> fs/btrfs/ioctl.c           |  4 ++++ fs/btrfs/volumes.c         | 25
>> ++++++++++++++++++++++++- fs/btrfs/volumes.h         |  2 ++
>> include/uapi/linux/btrfs.h |  5 ++++- 4 files changed, 34
>> insertions(+), 2 deletions(-)
>>
>