ext4: don't show mount options in /proc/mounts if there is no journal

After creating an ext4 file system without a journal:

  # mke2fs -t ext4 -O ^has_journal /dev/sda
  # mount -t ext4 /dev/sda /test

the /proc/mounts will show:
"/dev/sda /test ext4 rw,relatime,user_xattr,acl,barrier=1,data=writeback 0 0"
which can fool users into thinking that the fs is using writeback mode.

So don't set the writeback option when the journal has not been
enabled; we don't depend on the writeback option being set, since
ext4_should_writeback_data() in ext4_jbd2.h tests to see if the
journal is not present before returning true.

Reported-by: Robin Dong <sanbai@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index ed5e80ef48c46a6018203708ed3250fa64d2bffa..fdce4eebce0cef4f9ca22dc4d551ba3f7878c62a 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3485,7 +3485,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
                goto failed_mount_wq;
        } else {
                clear_opt(sb, DATA_FLAGS);
-               set_opt(sb, WRITEBACK_DATA);
                sbi->s_journal = NULL;
                needs_recovery = 0;
                goto no_journal;