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@xxxxxxxxx> > Signed-off-by: Azat Khuzhin <a3at.mail@xxxxxxxxx> > Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx> > --- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
