From 6b992ff25658367089db4a82666e232b65d55eae Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Thu, 30 Oct 2014 10:53:16 -0400
Subject: [PATCH] ext4: disallow changing journal_csum option during remount
ext4 does not permit changing the metadata or journal checksum feature
flag while mounted. Until we decide to support that, don't allow a
remount to change the journal_csum flag (right now we silently fail to
change anything).
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
fs/ext4/super.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5c11e2153e365..96059e0ef1653 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4845,6 +4845,14 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
goto restore_opts;
}
+ if ((old_opts.s_mount_opt & EXT4_MOUNT_JOURNAL_CHECKSUM) ^
+ test_opt(sb, JOURNAL_CHECKSUM)) {
+ ext4_msg(sb, KERN_ERR, "changing journal_checksum "
+ "during remount not supported");
+ err = -EINVAL;
+ goto restore_opts;
+ }
+
if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA) {
if (test_opt2(sb, EXPLICIT_DELALLOC)) {
ext4_msg(sb, KERN_ERR, "can't mount with "
--
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