commit 9c2c1e9a3d12563c68d6817b609bbfec0af149cb
author Azat Khuzhin <a3at.mail@gmail.com> Mon Jul 28 11:43:25 2014 +0400
committer Theodore Ts'o <tytso@mit.edu> Mon Jul 28 20:21:59 2014 -0400
tree 2fec8f95790d1370f1e747a96da7c6f5d09a0585
parent 7dfefaf413bbd4f7f51e2664dc4911873236ffdd

tune2fs: update journal users while updating fs UUID (with external journal)

When we have fs with external journal device, and updating it's UUID, we
should update UUID in users list for that external journal device.

Before:
$ tune2fs -U clear /tmp/dev
tune2fs 1.42.10 (18-May-2014)
$ dumpe2fs /tmp/dev | fgrep UUID
dumpe2fs 1.42.10 (18-May-2014)
Filesystem UUID:          <none>
Journal UUID:             da1f2ed0-60f6-aaaa-92fd-738701418523
$ dumpe2fs /tmp/journal | fgrep users -A10
dumpe2fs 1.42.10 (18-May-2014)
Journal number of users:  2
Journal users:            0707762d-638e-4bc6-944e-ae8ee7a3359e
                          0ad849df-1041-4f0a-b1c1-2f949d6a1e37

After:
$ sudo tune2fs -U clear /tmp/dev
tune2fs 1.43-WIP (18-May-2014)
$ dumpe2fs /tmp/dev | fgrep UUID
dumpe2fs 1.42.10 (18-May-2014)
Filesystem UUID:          <none>
Journal UUID:             da1f2ed0-60f6-aaaa-92fd-738701418523
$ dumpe2fs /tmp/journal | fgrep users -A10
dumpe2fs 1.42.10 (18-May-2014)
Journal number of users:  2
Journal users:            0707762d-638e-4bc6-944e-ae8ee7a3359e
                          00000000-0000-0000-0000-000000000000

Also add some consts to avoid *magic numbers*:
- UUID_STR_SIZE
- UUID_SIZE
- JFS_USERS_MAX
- JFS_USERS_SIZE

Proposed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>