-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 5/27/14, 12:10 PM, Chris Mason wrote:
> On 05/26/2014 09:35 PM, Jeff Mahoney wrote:
>> We are currently allocating space_info objects in an array when
>> we allocate space_info. When a user does something like:
>>
>> # btrfs balance start -mconvert=raid1 -dconvert=raid1 /mnt #
>> btrfs balance start -mconvert=single -dconvert=single /mnt -f #
>> btrfs balance start -mconvert=raid1 -dconvert=raid1 /
>>
>> We can end up with memory corruption since the kobject hasn't
>> been reinitialized properly and the name pointer was left set.
>>
>> The rationale behind allocating them statically was to avoid
>> creating a separate kobject container that just contained the
>> raid type. It used the index in the array to determine the
>> index.
>>
>> Ultimately, though, this wastes more memory than it saves in all
>> but the most complex scenarios and introduces kobject lifetime
>> questions.
>>
>> This patch allocates the kobjects dynamically instead. Note that
>> we also remove the kobject_get/put of the parent kobject since
>> kobject_add and kobject_del do that internally.
>
> Thanks Jeff, one small thing below:
>
>> --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@
>> -8352,17 +8351,26 @@ static void __link_block_group(struct bt
>> up_write(&space_info->groups_sem);
>>
>> if (first) { - struct kobject *kobj =
>> &space_info->block_group_kobjs[index]; + struct raid_kobject
>> *rkobj; int ret;
>>
>> - kobject_get(&space_info->kobj); /* put in release */ -
>> ret =
>> kobject_add(kobj, &space_info->kobj, "%s", -
>> get_raid_name(index)); + rkobj = kzalloc(sizeof(*rkobj),
>> GFP_KERNEL);
> ^^^^^^^^^^^^
>
> GFP_NOFS? We've got a transaction running here.
Sigh. Yep.
- -Jeff
- --
Jeff Mahoney
SUSE Labs
-----BEGIN PGP SIGNATURE-----
Version: GnuPG/MacGPG2 v2.0.22 (Darwin)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=C73I
-----END PGP SIGNATURE-----
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
