[PATCH] Btrfs: don't ignore log btree writeback errors

[PATCH] Btrfs: don't ignore log btree writeback errors

[Filipe Manana]

If an error happens during writeback of log btree extents, make sure the
error is returned to the caller (fsync), so that it takes proper action
(commit current transaction) instead of writing a superblock that points
to log btrees with all or some nodes that weren't durably persisted.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/tree-log.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 6d58d72..c8274d3 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2599,12 +2599,14 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 	index2 = root_log_ctx.log_transid % 2;
 	if (atomic_read(&log_root_tree->log_commit[index2])) {
 		blk_finish_plug(&plug);
-		btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
+		ret = btrfs_wait_marked_extents(log, &log->dirty_log_pages,
+						mark);
 		wait_log_commit(trans, log_root_tree,
 				root_log_ctx.log_transid);
 		btrfs_free_logged_extents(log, log_transid);
 		mutex_unlock(&log_root_tree->log_mutex);
-		ret = root_log_ctx.log_ret;
+		if (!ret)
+			ret = root_log_ctx.log_ret;
 		goto out;
 	}
 	ASSERT(root_log_ctx.log_transid == log_root_tree->log_transid);
@@ -2641,10 +2643,17 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
 		mutex_unlock(&log_root_tree->log_mutex);
 		goto out_wake_log_root;
 	}
-	btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
-	btrfs_wait_marked_extents(log_root_tree,
-				  &log_root_tree->dirty_log_pages,
-				  EXTENT_NEW | EXTENT_DIRTY);
+	ret = btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
+	if (!ret)
+		ret = btrfs_wait_marked_extents(log_root_tree,
+						&log_root_tree->dirty_log_pages,
+						EXTENT_NEW | EXTENT_DIRTY);
+	if (ret) {
+		btrfs_set_log_full_commit(root->fs_info, trans);
+		btrfs_free_logged_extents(log, log_transid);
+		mutex_unlock(&log_root_tree->log_mutex);
+		goto out_wake_log_root;
+	}
 	btrfs_wait_logged_extents(log, log_transid);
 
 	btrfs_set_super_log_root(root->fs_info->super_for_commit,
-- 
1.9.1

Re: [PATCH] Btrfs: don't ignore log btree writeback errors

[Holger Hoffstätte]

On Thu, 13 Nov 2014 16:59:53 +0000, Filipe Manana wrote:

> If an error happens during writeback of log btree extents, make sure the
> error is returned to the caller (fsync), so that it takes proper action
> (commit current transaction) instead of writing a superblock that points
> to log btrees with all or some nodes that weren't durably persisted.
> 
> Signed-off-by: Filipe Manana <fdmanana@suse.com>
> ---
>  fs/btrfs/tree-log.c | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
> index 6d58d72..c8274d3 100644
> --- a/fs/btrfs/tree-log.c
> +++ b/fs/btrfs/tree-log.c
> @@ -2599,12 +2599,14 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
>  	index2 = root_log_ctx.log_transid % 2;
>  	if (atomic_read(&log_root_tree->log_commit[index2])) {
>  		blk_finish_plug(&plug);
> -		btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
> +		ret = btrfs_wait_marked_extents(log, &log->dirty_log_pages,
> +						mark);
>  		wait_log_commit(trans, log_root_tree,
>  				root_log_ctx.log_transid);
>  		btrfs_free_logged_extents(log, log_transid);
>  		mutex_unlock(&log_root_tree->log_mutex);
> -		ret = root_log_ctx.log_ret;
> +		if (!ret)
> +			ret = root_log_ctx.log_ret;
>  		goto out;
>  	}
>  	ASSERT(root_log_ctx.log_transid == log_root_tree->log_transid);

This first hunk didn't apply to my 3.14.x tree that is 99.999% in sync with
btrfs-3.18+, as a line is missing from the context. See:

https://git.kernel.org/cgit/linux/kernel/git/mason/linux-btrfs.git/tree/fs/btrfs/tree-log.c?h=for-linus#n2605

Any idea where that missing btrfs_free_logged_extents() went?

cheers
Holger

Re: [PATCH] Btrfs: don't ignore log btree writeback errors

[Holger Hoffstätte]

On Thu, 13 Nov 2014 17:33:19 +0000, Holger Hoffstätte wrote:

> On Thu, 13 Nov 2014 16:59:53 +0000, Filipe Manana wrote:
> 
>> If an error happens during writeback of log btree extents, make sure the
>> error is returned to the caller (fsync), so that it takes proper action
>> (commit current transaction) instead of writing a superblock that points
>> to log btrees with all or some nodes that weren't durably persisted.
>> 
>> Signed-off-by: Filipe Manana <fdmanana@suse.com>
>> ---
>>  fs/btrfs/tree-log.c | 21 +++++++++++++++------
>>  1 file changed, 15 insertions(+), 6 deletions(-)
>> 
>> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
>> index 6d58d72..c8274d3 100644
>> --- a/fs/btrfs/tree-log.c
>> +++ b/fs/btrfs/tree-log.c
>> @@ -2599,12 +2599,14 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
>>  	index2 = root_log_ctx.log_transid % 2;
>>  	if (atomic_read(&log_root_tree->log_commit[index2])) {
>>  		blk_finish_plug(&plug);
>> -		btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
>> +		ret = btrfs_wait_marked_extents(log, &log->dirty_log_pages,
>> +						mark);
>>  		wait_log_commit(trans, log_root_tree,
>>  				root_log_ctx.log_transid);
>>  		btrfs_free_logged_extents(log, log_transid);
>>  		mutex_unlock(&log_root_tree->log_mutex);
>> -		ret = root_log_ctx.log_ret;
>> +		if (!ret)
>> +			ret = root_log_ctx.log_ret;
>>  		goto out;
>>  	}
>>  	ASSERT(root_log_ctx.log_transid == log_root_tree->log_transid);
> 
> This first hunk didn't apply to my 3.14.x tree that is 99.999% in sync with
> btrfs-3.18+, as a line is missing from the context. See:
> 
> https://git.kernel.org/cgit/linux/kernel/git/mason/linux-btrfs.git/tree/fs/btrfs/tree-log.c?h=for-linus#n2605
> 
> Any idea where that missing btrfs_free_logged_extents() went?

Found it: it went away with Josef's recent patch on Nov 6:
"Btrfs: make sure we wait on logged extents when fsycning two subvols"
(http://permalink.gmane.org/gmane.comp.file-systems.btrfs/40005)

..which I have applied. boohoo.

That patch also adds another call to btrfs_wait_marked_extents(), which should
then probably also have its return value handled?

thanks,
Holger

Re: [PATCH] Btrfs: don't ignore log btree writeback errors

[Filipe David Manana]

On Thu, Nov 13, 2014 at 5:43 PM, Holger Hoffstätte
<holger.hoffstaette@googlemail.com> wrote:
> On Thu, 13 Nov 2014 17:33:19 +0000, Holger Hoffstätte wrote:
>
>> On Thu, 13 Nov 2014 16:59:53 +0000, Filipe Manana wrote:
>>
>>> If an error happens during writeback of log btree extents, make sure the
>>> error is returned to the caller (fsync), so that it takes proper action
>>> (commit current transaction) instead of writing a superblock that points
>>> to log btrees with all or some nodes that weren't durably persisted.
>>>
>>> Signed-off-by: Filipe Manana <fdmanana@suse.com>
>>> ---
>>>  fs/btrfs/tree-log.c | 21 +++++++++++++++------
>>>  1 file changed, 15 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
>>> index 6d58d72..c8274d3 100644
>>> --- a/fs/btrfs/tree-log.c
>>> +++ b/fs/btrfs/tree-log.c
>>> @@ -2599,12 +2599,14 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
>>>      index2 = root_log_ctx.log_transid % 2;
>>>      if (atomic_read(&log_root_tree->log_commit[index2])) {
>>>              blk_finish_plug(&plug);
>>> -            btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
>>> +            ret = btrfs_wait_marked_extents(log, &log->dirty_log_pages,
>>> +                                            mark);
>>>              wait_log_commit(trans, log_root_tree,
>>>                              root_log_ctx.log_transid);
>>>              btrfs_free_logged_extents(log, log_transid);
>>>              mutex_unlock(&log_root_tree->log_mutex);
>>> -            ret = root_log_ctx.log_ret;
>>> +            if (!ret)
>>> +                    ret = root_log_ctx.log_ret;
>>>              goto out;
>>>      }
>>>      ASSERT(root_log_ctx.log_transid == log_root_tree->log_transid);
>>
>> This first hunk didn't apply to my 3.14.x tree that is 99.999% in sync with
>> btrfs-3.18+, as a line is missing from the context. See:
>>
>> https://git.kernel.org/cgit/linux/kernel/git/mason/linux-btrfs.git/tree/fs/btrfs/tree-log.c?h=for-linus#n2605
>>
>> Any idea where that missing btrfs_free_logged_extents() went?
>
> Found it: it went away with Josef's recent patch on Nov 6:
> "Btrfs: make sure we wait on logged extents when fsycning two subvols"
> (http://permalink.gmane.org/gmane.comp.file-systems.btrfs/40005)
>
> ..which I have applied. boohoo.
>
> That patch also adds another call to btrfs_wait_marked_extents(), which should
> then probably also have its return value handled?

No, it's a different call - btrfs_wait_logged_extents().

>
> thanks,
> Holger
>
> --
> 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



-- 
Filipe David Manana,

"Reasonable men adapt themselves to the world.
 Unreasonable men adapt the world to themselves.
 That's why all progress depends on unreasonable men."

Re: [PATCH] Btrfs: don't ignore log btree writeback errors

[Holger Hoffstätte]

On Thu, 13 Nov 2014 17:50:44 +0000, Filipe David Manana wrote:

[snip]

>>> This first hunk didn't apply to my 3.14.x tree that is 99.999% in sync with
>>> btrfs-3.18+, as a line is missing from the context. See:
>>>
>>> https://git.kernel.org/cgit/linux/kernel/git/mason/linux-btrfs.git/tree/fs/btrfs/tree-log.c?h=for-linus#n2605
>>>
>>> Any idea where that missing btrfs_free_logged_extents() went?
>>
>> Found it: it went away with Josef's recent patch on Nov 6:
>> "Btrfs: make sure we wait on logged extents when fsycning two subvols"
>> (http://permalink.gmane.org/gmane.comp.file-systems.btrfs/40005)
>>
>> ..which I have applied. boohoo.
>>
>> That patch also adds another call to btrfs_wait_marked_extents(), which should
>> then probably also have its return value handled?
> 
> No, it's a different call - btrfs_wait_logged_extents().

Of course, you are right. I can't read (it's late :)

cheers
-h

Re: [PATCH] Btrfs: don't ignore log btree writeback errors

[Filipe David Manana]

On Thu, Nov 13, 2014 at 5:33 PM, Holger Hoffstätte
<holger.hoffstaette@googlemail.com> wrote:
> On Thu, 13 Nov 2014 16:59:53 +0000, Filipe Manana wrote:
>
>> If an error happens during writeback of log btree extents, make sure the
>> error is returned to the caller (fsync), so that it takes proper action
>> (commit current transaction) instead of writing a superblock that points
>> to log btrees with all or some nodes that weren't durably persisted.
>>
>> Signed-off-by: Filipe Manana <fdmanana@suse.com>
>> ---
>>  fs/btrfs/tree-log.c | 21 +++++++++++++++------
>>  1 file changed, 15 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
>> index 6d58d72..c8274d3 100644
>> --- a/fs/btrfs/tree-log.c
>> +++ b/fs/btrfs/tree-log.c
>> @@ -2599,12 +2599,14 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
>>       index2 = root_log_ctx.log_transid % 2;
>>       if (atomic_read(&log_root_tree->log_commit[index2])) {
>>               blk_finish_plug(&plug);
>> -             btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
>> +             ret = btrfs_wait_marked_extents(log, &log->dirty_log_pages,
>> +                                             mark);
>>               wait_log_commit(trans, log_root_tree,
>>                               root_log_ctx.log_transid);
>>               btrfs_free_logged_extents(log, log_transid);
>>               mutex_unlock(&log_root_tree->log_mutex);
>> -             ret = root_log_ctx.log_ret;
>> +             if (!ret)
>> +                     ret = root_log_ctx.log_ret;
>>               goto out;
>>       }
>>       ASSERT(root_log_ctx.log_transid == log_root_tree->log_transid);
>
> This first hunk didn't apply to my 3.14.x tree that is 99.999% in sync with
> btrfs-3.18+, as a line is missing from the context. See:
>
> https://git.kernel.org/cgit/linux/kernel/git/mason/linux-btrfs.git/tree/fs/btrfs/tree-log.c?h=for-linus#n2605
>
> Any idea where that missing btrfs_free_logged_extents() went?

Probably because you picked the following patch:

https://patchwork.kernel.org/patch/5244311/

While Chris' integration/for-linus branches don't have the patch
included yet (nor do I in my local branch). Nevertheless, it's a
trivial conflict to solve, just leave Josef's changes and mine.

thanks

>
> cheers
> Holger
>
> --
> 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



-- 
Filipe David Manana,

"Reasonable men adapt themselves to the world.
 Unreasonable men adapt the world to themselves.
 That's why all progress depends on unreasonable men."

Re: [PATCH] Btrfs: don't ignore log btree writeback errors

[Holger Hoffstätte]

On Thu, 13 Nov 2014 17:47:51 +0000, Filipe David Manana wrote:

[snip]

> While Chris' integration/for-linus branches don't have the patch
> included yet (nor do I in my local branch). Nevertheless, it's a
> trivial conflict to solve, just leave Josef's changes and mine.

So if I read this correctly the combined patch should look like this,
right?

--snip--
-		btrfs_wait_marked_extents(log, &log->dirty_log_pages, mark);
+		ret = btrfs_wait_marked_extents(log, &log->dirty_log_pages,
+						mark);
		btrfs_wait_logged_extents(log, log_transid);
 		wait_log_commit(trans, log_root_tree,
 				root_log_ctx.log_transid);
 		mutex_unlock(&log_root_tree->log_mutex);
-		ret = root_log_ctx.log_ret;
+		if (!ret)
+			ret = root_log_ctx.log_ret;
 		goto out;
--snip--

This saves the ret, logs the extents, commits and then handles any
error.

-h