Don't let users change metadata_csum on a mounted filesystem because
there's no way to tell the kernel to turn on the feature; there's no
way to prevent the kernel from rewriting on-disk structures while
tune2fs is also rewriting them; and there's no way to tell the kernel
to reload them after tune2fs is finished.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
misc/tune2fs.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index ecbdea0..7fee870 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -1110,6 +1110,9 @@ mmp_error:
EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {
if (check_fsck_needed(fs))
exit(1);
+ if (mount_flags & EXT2_MF_MOUNTED)
+ fputs(_("Cannot enable metadata_csum on a mounted "
+ "filesystem!\n"), stderr);
rewrite_checksums = 1;
/* metadata_csum supersedes uninit_bg */
fs->super->s_feature_ro_compat &=
@@ -1132,6 +1135,9 @@ mmp_error:
EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {
if (check_fsck_needed(fs))
exit(1);
+ if (mount_flags & EXT2_MF_MOUNTED)
+ fputs(_("Cannot disable metadata_csum on a mounted "
+ "filesystem!\n"), stderr);
rewrite_checksums = 1;
/*
* If we're turning off metadata_csum and not turning on
--
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