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From:   Naohiro Aota <Naohiro.Aota@wdc.com>
To:     Josef Bacik <josef@toxicpanda.com>
CC:     "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
        David Sterba <dsterba@suse.com>, Chris Mason <clm@fb.com>,
        Qu Wenruo <wqu@suse.com>, Nikolay Borisov <nborisov@suse.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Hannes Reinecke <hare@suse.com>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
        Damien Le Moal <Damien.LeMoal@wdc.com>,
        =?iso-8859-1?Q?Matias_Bj=F8rling?= <mb@lightnvm.io>,
        Johannes Thumshirn <jthumshirn@suse.de>,
        Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH 03/19] btrfs: Check and enable HMZONED mode
Thread-Topic: [PATCH 03/19] btrfs: Check and enable HMZONED mode
Thread-Index: AQHVHTKBzmgdNkH+W06mgCGzH1JPPA==
Date:   Tue, 18 Jun 2019 06:43:52 +0000
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On 2019/06/13 22:57, Josef Bacik wrote:=0A=
> On Fri, Jun 07, 2019 at 10:10:09PM +0900, Naohiro Aota wrote:=0A=
>> HMZONED mode cannot be used together with the RAID5/6 profile for now.=
=0A=
>> Introduce the function btrfs_check_hmzoned_mode() to check this. This=0A=
>> function will also check if HMZONED flag is enabled on the file system a=
nd=0A=
>> if the file system consists of zoned devices with equal zone size.=0A=
>>=0A=
>> Additionally, as updates to the space cache are in-place, the space cach=
e=0A=
>> cannot be located over sequential zones and there is no guarantees that =
the=0A=
>> device will have enough conventional zones to store this cache. Resolve=
=0A=
>> this problem by disabling completely the space cache.  This does not=0A=
>> introduces any problems with sequential block groups: all the free space=
 is=0A=
>> located after the allocation pointer and no free space before the pointe=
r.=0A=
>> There is no need to have such cache.=0A=
>>=0A=
>> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>=0A=
>> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>=0A=
>> ---=0A=
>>   fs/btrfs/ctree.h       |  3 ++=0A=
>>   fs/btrfs/dev-replace.c |  7 +++=0A=
>>   fs/btrfs/disk-io.c     |  7 +++=0A=
>>   fs/btrfs/super.c       | 12 ++---=0A=
>>   fs/btrfs/volumes.c     | 99 ++++++++++++++++++++++++++++++++++++++++++=
=0A=
>>   fs/btrfs/volumes.h     |  1 +=0A=
>>   6 files changed, 124 insertions(+), 5 deletions(-)=0A=
>>=0A=
>> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h=0A=
>> index b81c331b28fa..6c00101407e4 100644=0A=
>> --- a/fs/btrfs/ctree.h=0A=
>> +++ b/fs/btrfs/ctree.h=0A=
>> @@ -806,6 +806,9 @@ struct btrfs_fs_info {=0A=
>>   	struct btrfs_root *uuid_root;=0A=
>>   	struct btrfs_root *free_space_root;=0A=
>>   =0A=
>> +	/* Zone size when in HMZONED mode */=0A=
>> +	u64 zone_size;=0A=
>> +=0A=
>>   	/* the log root tree is a directory of all the other log roots */=0A=
>>   	struct btrfs_root *log_root_tree;=0A=
>>   =0A=
>> diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c=0A=
>> index ee0989c7e3a9..fbe5ea2a04ed 100644=0A=
>> --- a/fs/btrfs/dev-replace.c=0A=
>> +++ b/fs/btrfs/dev-replace.c=0A=
>> @@ -201,6 +201,13 @@ static int btrfs_init_dev_replace_tgtdev(struct btr=
fs_fs_info *fs_info,=0A=
>>   		return PTR_ERR(bdev);=0A=
>>   	}=0A=
>>   =0A=
>> +	if ((bdev_zoned_model(bdev) =3D=3D BLK_ZONED_HM &&=0A=
>> +	     !btrfs_fs_incompat(fs_info, HMZONED)) ||=0A=
>> +	    (!bdev_is_zoned(bdev) && btrfs_fs_incompat(fs_info, HMZONED))) {=
=0A=
> =0A=
> You do this in a few places, turn this into a helper please.=0A=
> =0A=
>> +		ret =3D -EINVAL;=0A=
>> +		goto error;=0A=
>> +	}=0A=
>> +=0A=
>>   	filemap_write_and_wait(bdev->bd_inode->i_mapping);=0A=
>>   =0A=
>>   	devices =3D &fs_info->fs_devices->devices;=0A=
>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c=0A=
>> index 663efce22d98..7c1404c76768 100644=0A=
>> --- a/fs/btrfs/disk-io.c=0A=
>> +++ b/fs/btrfs/disk-io.c=0A=
>> @@ -3086,6 +3086,13 @@ int open_ctree(struct super_block *sb,=0A=
>>   =0A=
>>   	btrfs_free_extra_devids(fs_devices, 1);=0A=
>>   =0A=
>> +	ret =3D btrfs_check_hmzoned_mode(fs_info);=0A=
>> +	if (ret) {=0A=
>> +		btrfs_err(fs_info, "failed to init hmzoned mode: %d",=0A=
>> +				ret);=0A=
>> +		goto fail_block_groups;=0A=
>> +	}=0A=
>> +=0A=
>>   	ret =3D btrfs_sysfs_add_fsid(fs_devices, NULL);=0A=
>>   	if (ret) {=0A=
>>   		btrfs_err(fs_info, "failed to init sysfs fsid interface: %d",=0A=
>> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c=0A=
>> index 2c66d9ea6a3b..740a701f16c5 100644=0A=
>> --- a/fs/btrfs/super.c=0A=
>> +++ b/fs/btrfs/super.c=0A=
>> @@ -435,11 +435,13 @@ int btrfs_parse_options(struct btrfs_fs_info *info=
, char *options,=0A=
>>   	bool saved_compress_force;=0A=
>>   	int no_compress =3D 0;=0A=
>>   =0A=
>> -	cache_gen =3D btrfs_super_cache_generation(info->super_copy);=0A=
>> -	if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))=0A=
>> -		btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);=0A=
>> -	else if (cache_gen)=0A=
>> -		btrfs_set_opt(info->mount_opt, SPACE_CACHE);=0A=
>> +	if (!btrfs_fs_incompat(info, HMZONED)) {=0A=
>> +		cache_gen =3D btrfs_super_cache_generation(info->super_copy);=0A=
>> +		if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))=0A=
>> +			btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);=0A=
>> +		else if (cache_gen)=0A=
>> +			btrfs_set_opt(info->mount_opt, SPACE_CACHE);=0A=
>> +	}=0A=
>>   =0A=
> =0A=
> This disables the free space tree as well as the cache, sounds like you o=
nly=0A=
> need to disable the free space cache?  Thanks,=0A=
=0A=
Right. We can still use the free space tree on HMZONED. I'll fix in the nex=
t version.=0A=
Thanks=0A=
=0A=