diff options
| author | Darrick J. Wong <darrick.wong@oracle.com> | 2019-11-20 11:32:55 -0800 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2019-11-20 22:58:55 -0500 |
| commit | 3f21d8239567e890b4c41cd69a617ba10cd98f75 (patch) | |
| tree | 543e68c6904be0c63c4f76bfd1ee4891a7bc6bf0 | |
| parent | 446483e39862d57717fe89190d502bbba0371147 (diff) | |
| download | e2fsprogs-3f21d8239567e890b4c41cd69a617ba10cd98f75.tar.gz | |
tune2fs: prohibit toggling uninit_bg on live filesystems
An internal customer followed an erroneous AskUbuntu article[1] to try to
change the UUID of a live ext4 filesystem. The article claims that you
can work around tune2fs' "cannot change UUID on live fs" error by
disabling uninit_bg, changing the UUID, and re-enabling the feature.
This led to metadata corruption because tune2fs' journal descriptor
rewrite races with regular filesystem writes. Therefore, prevent
administrators from turning on or off uninit_bg on a mounted fs.
[1] https://askubuntu.com/questions/132079/how-do-i-change-uuid-of-a-disk-to-whatever-i-want/195839#459097
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | misc/tune2fs.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/misc/tune2fs.c b/misc/tune2fs.c index 7d2d38d7d..301cf3880 100644 --- a/misc/tune2fs.c +++ b/misc/tune2fs.c @@ -1308,6 +1308,12 @@ mmp_error: if (FEATURE_ON(E2P_FEATURE_RO_INCOMPAT, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) { + if (mount_flags & EXT2_MF_MOUNTED) { + fputs(_("Cannot enable uninit_bg on a mounted " + "filesystem!\n"), stderr); + exit(1); + } + /* Do not enable uninit_bg when metadata_csum enabled */ if (ext2fs_has_feature_metadata_csum(fs->super)) ext2fs_clear_feature_gdt_csum(fs->super); @@ -1317,6 +1323,12 @@ mmp_error: if (FEATURE_OFF(E2P_FEATURE_RO_INCOMPAT, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) { + if (mount_flags & EXT2_MF_MOUNTED) { + fputs(_("Cannot disable uninit_bg on a mounted " + "filesystem!\n"), stderr); + exit(1); + } + err = disable_uninit_bg(fs, EXT4_FEATURE_RO_COMPAT_GDT_CSUM); if (err) |