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Date: Fri, 1 Aug 2014 08:40:17 +0200
From: Andreas Dilger <adilger@...ger.ca>
To: Azat Khuzhin <a3at.mail@...il.com>
Cc: Eric Sandeen <sandeen@...hat.com>,
"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
"tytso@....edu" <tytso@....edu>,
"darrick.wong@...cle.com" <darrick.wong@...cle.com>
Subject: Re: [PATCH 3/4 v3] tune2fs: update journal super block when changing UUID for fs.
I already fixed that in my recent patch:
http://marc.info/?l=linux-ext4&m=140667665421773&w=2
Cheers, Andreas
> On Jul 31, 2014, at 17:45, Azat Khuzhin <a3at.mail@...il.com> wrote:
>
>> On Thu, Jul 31, 2014 at 10:16:44AM -0500, Eric Sandeen wrote:
>>> On 7/28/14, 2:43 AM, Azat Khuzhin wrote:
>>> Using -U option you can change the UUID for fs, however it will not work
>>> for journal device, since it have a copy of this UUID inside jsb (i.e.
>>> journal super block). So copy UUID on change into that block.
>>>
>>> Here is the initial thread:
>>> http://comments.gmane.org/gmane.comp.file-systems.ext4/44532
>>>
>>> You can reproduce this by executing following commands:
>>> $ fallocate -l100M /tmp/dev
>>> $ fallocate -l100M /tmp/journal
>>> $ sudo /sbin/losetup /dev/loop1 /tmp/dev
>>> $ sudo /sbin/losetup /dev/loop0 /tmp/journal
>>> $ mke2fs -O journal_dev /tmp/journal
>>> $ tune2fs -U da1f2ed0-60f6-aaaa-92fd-738701418523 /tmp/journal
>>> $ sudo mke2fs -t ext4 -J device=/dev/loop0 /dev/loop1
>>> $ dumpe2fs -h /tmp/dev | fgrep UUID
>>> dumpe2fs 1.43-WIP (18-May-2014)
>>> Filesystem UUID: 8a776be9-12eb-411f-8e88-b873575ecfb6
>>> Journal UUID: e3d02151-e776-4865-af25-aecb7291e8e5
>>> $ sudo e2fsck /dev/vdc
>>> e2fsck 1.43-WIP (18-May-2014)
>>> External journal does not support this filesystem
>>>
>>> /dev/loop1: ********** WARNING: Filesystem still has errors **********
>>>
>>> Reported-by: Chin Tzung Cheng <chintzung@...il.com>
>>> Signed-off-by: Azat Khuzhin <a3at.mail@...il.com>
>>> Reviewed-by: Andreas Dilger <adilger@...ger.ca>
>>> ---
>>> misc/tune2fs.c | 74 ++++++++++++++++++++++++++++++++++++++++++++--------------
>>> 1 file changed, 56 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/misc/tune2fs.c b/misc/tune2fs.c
>>> index 1df655a..74e57ae 100644
>>> --- a/misc/tune2fs.c
>>> +++ b/misc/tune2fs.c
>>> @@ -175,6 +175,38 @@ static __u32 clear_ok_features[3] = {
>>> EXT4_FEATURE_RO_COMPAT_GDT_CSUM
>>> };
>>>
>>> +/**
>>> + * Try to get journal super block if any
>>> + */
>>> +static int get_journal_sb(ext2_filsys jfs, char buf[SUPERBLOCK_SIZE])
>>> +{
>>> + int retval;
>>> + int start;
>>> + journal_superblock_t *jsb;
>>> +
>>> + if (!(jfs->super->s_feature_incompat &
>>> + EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
>>> + return EXT2_ET_UNSUPP_FEATURE;
>>> + }
>>> +
>>> + /* Get the journal superblock */
>>> + if ((retval = io_channel_read_blk64(jfs->io,
>>> + ext2fs_journal_sb_start(jfs->blocksize), -SUPERBLOCK_SIZE, buf))) {
>>> + com_err(program_name, retval, "%s",
>>> + _("while reading journal superblock"));
>>> + return retval;
>>> + }
>>> +
>>> + jsb = (journal_superblock_t *) buf;
>>> + if ((jsb->s_header.h_magic != (unsigned)ntohl(JFS_MAGIC_NUMBER)) ||
>>> + (jsb->s_header.h_blocktype != (unsigned)ntohl(JFS_SUPERBLOCK_V2))) {
>>> + fputs(_("Journal superblock not found!\n"), stderr);
>>> + return EXT2_ET_BAD_MAGIC;
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +
>>> /*
>>> * Remove an external journal from the filesystem
>>> */
>>> @@ -218,29 +250,15 @@ static int remove_journal_device(ext2_filsys fs)
>>> _("while trying to open external journal"));
>>> goto no_valid_journal;
>>> }
>>> - if (!(jfs->super->s_feature_incompat &
>>> - EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)) {
>>> - fprintf(stderr, _("%s is not a journal device.\n"),
>>> - journal_path);
>>> - goto no_valid_journal;
>>> - }
>>>
>>> - start = ext2fs_journal_sb_start(fs->blocksize);
>>
>> This is already committed (which is why Coverity whined about it), but:
>> removing this assignment causes an uninitialized use of "start" later
>> in this function:
>>
>> /* Write back the journal superblock */
>> if ((retval = io_channel_write_blk64(jfs->io, start,
>> -SUPERBLOCK_SIZE, buf)))
>>
>> -Eric
>
> Hi Eric,
>
> Thanks for catching this.
> Patch in attachment must fix this issue.
>
> I maked with -Wall to catch more bugs like this.
> And there is one more note:
> expected ‘char *’ but argument is of type ‘__u8 *’
> journal_user()
> I will send a patch later.
>
>
> From 903f251e1ebce3d666a8b2af04b812d4f6751056 Mon Sep 17 00:00:00 2001
> From: Azat Khuzhin <a3at.mail@...il.com>
> Date: Thu, 31 Jul 2014 19:26:16 +0400
> Subject: [PATCH] tune2fs: initialize start block in remove_journal_device()
>
> ---
> misc/tune2fs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/misc/tune2fs.c b/misc/tune2fs.c
> index 0c1feb1..044daaf 100644
> --- a/misc/tune2fs.c
> +++ b/misc/tune2fs.c
> @@ -181,7 +181,6 @@ static __u32 clear_ok_features[3] = {
> static int get_journal_sb(ext2_filsys jfs, char buf[SUPERBLOCK_SIZE])
> {
> int retval;
> - int start;
> journal_superblock_t *jsb;
>
> if (!(jfs->super->s_feature_incompat &
> @@ -286,6 +285,7 @@ static int remove_journal_device(ext2_filsys fs)
> jsb->s_nr_users = htonl(nr_users);
>
> /* Write back the journal superblock */
> + start = ext2fs_journal_sb_start(jfs->blocksize);
> if ((retval = io_channel_write_blk64(jfs->io, start,
> -SUPERBLOCK_SIZE, buf))) {
> com_err(program_name, retval,
> --
> 2.0.1
>
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