dont-show-jbd-data-option-if-defaulted

   1 ext4: don't show data=<mode> option if defaulted
   2
   3 From: Tyson Nottingham <tgnottingham@gmail.com>
   4
   5 Previously, mount -l would show data=<mode> even if the ext4 default
   6 journaling mode was being used. Change this to be consistent with the
   7 rest of the options.
   8
   9 Ext4 already did the right thing when the journaling mode being used
  10 matched the one specified in the superblock's default mount options. The
  11 reason it failed to do the right thing for the ext4 defaults is that,
  12 when set, they were never included in sbi->s_def_mount_opt (unlike the
  13 superblock's defaults, which were).
  14
  15 Signed-off-by: Tyson Nottingham <tgnottingham@gmail.com>
  16 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  17 ---
  18
  19 Before:
  20
  21 (Without any default journaling mode configured in superblock or mount
  22 option, ext4 will use its own default, which is ordered in this case.)
  23
  24 $ sudo mount -o loop=$(losetup -f) image.ext4 mnt
  25 $ grep data /proc/fs/ext4/loop0/options
  26 data=ordered
  27 $ mount -l | grep image
  28 /home/tgnottingham/image.ext4 on /home/tgnottingham/mnt type ext4 (rw,relatime,data=ordered)
  29
  30 data=ordered is still displayed, even though the ext4 default was used.
  31
  32
  33 After:
  34
  35 $ sudo mount -o loop=$(losetup -f) image.ext4 mnt
  36 $ grep data /proc/fs/ext4/loop0/options
  37 data=ordered
  38 $ mount -l | grep image
  39 /home/tgnottingham/image.ext4 on /home/tgnottingham/mnt type ext4 (rw,relatime)
  40
  41 data=ordered is not displayed, since it was the default.
  42
  43 tgnottingham@kernel-dev:~$ sudo mount -o loop=$(losetup -f),data=journal image.ext4 mnt
  44 $ grep data /proc/fs/ext4/loop0/options
  45 data=journal
  46 $ mount -l | grep image
  47 /home/tgnottingham/image.ext4 on /home/tgnottingham/mnt type ext4 (rw,relatime,nodelalloc,data=journal)
  48
  49 data=journal is displayed, since it was not the default.
  50
  51
  52 Default mount options stored in superblock were tested but not shown.
  53
  54 ---
  55  fs/ext4/super.c | 7 +++++--
  56  1 file changed, 5 insertions(+), 2 deletions(-)
  57
  58 diff --git a/fs/ext4/super.c b/fs/ext4/super.c
  59 index 7437ed0..7fbe7f4 100644
  60 --- a/fs/ext4/super.c
  61 +++ b/fs/ext4/super.c
  62 @@ -4091,10 +4091,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
  63                  * cope, else JOURNAL_DATA
  64                  */
  65                 if (jbd2_journal_check_available_features
  66 -                   (sbi->s_journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE))
  67 +                   (sbi->s_journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)) {
  68                         set_opt(sb, ORDERED_DATA);
  69 -               else
  70 +                       sbi->s_def_mount_opt |= EXT4_MOUNT_ORDERED_DATA;
  71 +               } else {
  72                         set_opt(sb, JOURNAL_DATA);
  73 +                       sbi->s_def_mount_opt |= EXT4_MOUNT_JOURNAL_DATA;
  74 +               }
  75                 break;
  76
  77         case EXT4_MOUNT_ORDERED_DATA:
  78 --
  79 2.7.4
  80
  81