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Subject: Re: [PATCH] ext2fs: add ext2fs_read_sb that returns superblock
From:   =?utf-8?B?0JHQu9Cw0LPQvtC00LDRgNC10L3QutC+INCQ0YDRgtGR0Lw=?= 
        <artem.blagodarenko@gmail.com>
In-Reply-To: <FED4628E-3B0D-45C7-92A6-FCBB71F187B0@dilger.ca>
Date:   Thu, 3 Oct 2019 18:58:12 +0300
Cc:     linux-ext4 <linux-ext4@vger.kernel.org>, adilger.kernel@dilger.ca
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Message-Id: <4CE33DD0-C911-4D3B-B46F-C19EAC34F9A9@gmail.com>
References: <20190905110110.32627-1-c17828@cray.com>
 <1B7DFCD4-F274-4A7A-B7FC-04566308322F@gmail.com>
 <FED4628E-3B0D-45C7-92A6-FCBB71F187B0@dilger.ca>
To:     Andreas Dilger <adilger@dilger.ca>
Sender: linux-ext4-owner@vger.kernel.org
Precedence: bulk

Thanks.

Sorry, not good new call time for me, but I can join occasionally.
I joined today, but too late.

Best regards,
Artem Blagodarenko.

> On 3 Oct 2019, at 18:55, Andreas Dilger <adilger@dilger.ca> wrote:
>=20
> We just discussed this on the ext4 developer concall today, and Ted is =
looking into it.=20
>=20
> Cheers, Andreas
>=20
>> On Oct 3, 2019, at 09:47, =D0=91=D0=BB=D0=B0=D0=B3=D0=BE=D0=B4=D0=B0=D1=
=80=D0=B5=D0=BD=D0=BA=D0=BE =D0=90=D1=80=D1=82=D1=91=D0=BC =
<artem.blagodarenko@gmail.com> wrote:
>>=20
>> Hello,
>>=20
>> Does anybody wants to give any feedback for this?
>> e2label became really faster on large partitions with this patch. =
Probably it can be useful.
>>=20
>> Ted, what do you think?
>>=20
>> Thanks,
>> Artem Blagodarenko.
>>=20
>>=20
>>=20
>>> On 5 Sep 2019, at 14:01, Artem Blagodarenko =
<artem.blagodarenko@gmail.com> wrote:
>>>=20
>>> tune2fs is used to make e2label duties.  ext2fs_open2() reads group
>>> descriptors which are not used during disk label obtaining, but =
takes
>>> a lot of time on large partitions.
>>>=20
>>> This patch adds ext2fs_read_sb(), there only initialized superblock
>>> is returned This saves time dramatically.
>>>=20
>>> Signed-off-by: Artem Blagodarenko <c17828@cray.com>
>>> Cray-bug-id: LUS-5777
>>> ---
>>> lib/ext2fs/ext2fs.h |  2 ++
>>> lib/ext2fs/openfs.c | 16 ++++++++++++++++
>>> misc/tune2fs.c      | 23 +++++++++++++++--------
>>> 3 files changed, 33 insertions(+), 8 deletions(-)
>>>=20
>>> diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
>>> index 59fd9742..3a63b74d 100644
>>> --- a/lib/ext2fs/ext2fs.h
>>> +++ b/lib/ext2fs/ext2fs.h
>>> @@ -1630,6 +1630,8 @@ extern int ext2fs_journal_sb_start(int =
blocksize);
>>> extern errcode_t ext2fs_open(const char *name, int flags, int =
superblock,
>>>                unsigned int block_size, io_manager manager,
>>>                ext2_filsys *ret_fs);
>>> +extern errcode_t ext2fs_read_sb(const char *name, io_manager =
manager,
>>> +                struct ext2_super_block * super);
>>> extern errcode_t ext2fs_open2(const char *name, const char =
*io_options,
>>>                 int flags, int superblock,
>>>                 unsigned int block_size, io_manager manager,
>>> diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
>>> index 51b54a44..95f45d84 100644
>>> --- a/lib/ext2fs/openfs.c
>>> +++ b/lib/ext2fs/openfs.c
>>> @@ -99,6 +99,22 @@ static void block_sha_map_free_entry(void *data)
>>>   return;
>>> }
>>>=20
>>> +errcode_t ext2fs_read_sb(const char *name, io_manager manager,
>>> +             struct ext2_super_block * super)
>>> +{
>>> +    io_channel    io;
>>> +    errcode_t    retval =3D 0;
>>> +
>>> +    retval =3D manager->open(name, 0, &io);
>>> +    if (!retval) {
>>> +        retval =3D io_channel_read_blk(io, 1, -SUPERBLOCK_SIZE,
>>> +                     super);
>>> +        io_channel_close(io);
>>> +    }
>>> +
>>> +    return retval;
>>> +}
>>> +
>>> /*
>>> *  Note: if superblock is non-zero, block-size must also be =
non-zero.
>>> *    Superblock and block_size can be zero to use the default size.
>>> diff --git a/misc/tune2fs.c b/misc/tune2fs.c
>>> index 7d2d38d7..fea607e1 100644
>>> --- a/misc/tune2fs.c
>>> +++ b/misc/tune2fs.c
>>> @@ -2879,6 +2879,21 @@ int tune2fs_main(int argc, char **argv)
>>> #endif
>>>       io_ptr =3D unix_io_manager;
>>>=20
>>> +    if (print_label) {
>>> +        /* For e2label emulation */
>>> +        struct ext2_super_block sb;
>>> +
>>> +        /* Read only superblock. Nothing else metters.*/
>>> +        retval =3D ext2fs_read_sb(device_name, io_ptr, &sb);
>>> +        if (!retval) {
>>> +            printf("%.*s\n", (int) sizeof(sb.s_volume_name),
>>> +                   sb.s_volume_name);
>>> +        }
>>> +
>>> +        remove_error_table(&et_ext2_error_table);
>>> +        return retval;
>>> +    }
>>> +
>>> retry_open:
>>>   if ((open_flag & EXT2_FLAG_RW) =3D=3D 0 || f_flag)
>>>       open_flag |=3D EXT2_FLAG_SKIP_MMP;
>>> @@ -2972,14 +2987,6 @@ retry_open:
>>>   sb =3D fs->super;
>>>   fs->flags &=3D ~EXT2_FLAG_MASTER_SB_ONLY;
>>>=20
>>> -    if (print_label) {
>>> -        /* For e2label emulation */
>>> -        printf("%.*s\n", (int) sizeof(sb->s_volume_name),
>>> -               sb->s_volume_name);
>>> -        remove_error_table(&et_ext2_error_table);
>>> -        goto closefs;
>>> -    }
>>> -
>>>   retval =3D ext2fs_check_if_mounted(device_name, &mount_flags);
>>>   if (retval) {
>>>       com_err("ext2fs_check_if_mount", retval,
>>> --=20
>>> 2.14.3
>>>=20
>>=20