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> --- Here is the RFC patch for this, I'm not sure about the check for *is this journal device or not*, so I will glad to see some comments. Thanks. misc/tune2fs.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/misc/tune2fs.c b/misc/tune2fs.c index d95cc3d..ffa07f6 100644 --- a/misc/tune2fs.c +++ b/misc/tune2fs.c @@ -2411,6 +2411,10 @@ int main(int argc, char **argv) struct ext2_super_block *sb; io_manager io_ptr, io_ptr_orig = NULL; int rc = 0; + /** For journal dev */ + journal_superblock_t *jsb; + int jsb_start; + char buf[1024]; #ifdef ENABLE_NLS setlocale(LC_MESSAGES, ""); @@ -2736,6 +2740,26 @@ retry_open: ext2fs_group_desc_csum_set(fs, i); fs->flags &= ~EXT2_FLAG_SUPER_ONLY; } + + /* If this is a journal dev, we need to copy UUID into jsb */ + jsb_start = 1; + if (fs->blocksize == 1024) + jsb_start++; + if ((rc = io_channel_read_blk64(fs->io, jsb_start, -1024, buf))) { + goto closefs; + } + 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(_("Need to update journal superblock.\n"), stdout); + memcpy(jsb->s_uuid, sb->s_uuid, sizeof(sb->s_uuid)); + + /* Writeback the journal superblock */ + if ((rc = io_channel_write_blk64(fs->io, jsb_start, -1024, buf))) { + goto closefs; + } + } + ext2fs_mark_super_dirty(fs); if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super, EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) -- 2.0.0 -- 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
