archive/auto-enable-journal_async_commit

   1 ext4: automatically enable journal_async_commit on ext4 file systems
   2
   3 Now that we have cleaned up journal_async_commit, it's safe to enable
   4 it all the time.  But we only want to do so if ext4-specific INCOMPAT
   5 features are enabled, since otherwise we will prevent the filesystem
   6 from being mounted using ext3.
   7
   8 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
   9
  10 ---
  11  Documentation/filesystems/ext4.txt |   11 ++++++++---
  12  fs/ext4/super.c                    |   29 ++++++++++++++++++++++++++---
  13  2 files changed, 34 insertions(+), 6 deletions(-)
  14
  15 diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
  16 index 6ab9442..713f5d5 100644
  17 --- a/Documentation/filesystems/ext4.txt
  18 +++ b/Documentation/filesystems/ext4.txt
  19 @@ -140,9 +140,14 @@ journal_checksum   Enable checksumming of the journal transactions.
  20                         compatible change and will be ignored by older kernels.
  21
  22  journal_async_commit   Commit block can be written to disk without waiting
  23 -                       for descriptor blocks. If enabled older kernels cannot
  24 -                       mount the device. This will enable 'journal_checksum'
  25 -                       internally.
  26 +                       for descriptor blocks.  This will enable
  27 +                       'journal_checksum' internally.  This mount
  28 +                       option will be automatically enabled if
  29 +                       ext4-specific INCOMPAT features are present in
  30 +                       the file system.
  31 +
  32 +nojournal_async_commit Disable the journal_async_commit option, even
  33 +                       for ext4 filesystems.
  34
  35  journal=update         Update the ext4 file system's journal to the current
  36                         format.
  37 diff --git a/fs/ext4/super.c b/fs/ext4/super.c
  38 index 9706981..d719551 100644
  39 --- a/fs/ext4/super.c
  40 +++ b/fs/ext4/super.c
  41 @@ -203,6 +203,15 @@ void ext4_itable_unused_set(struct super_block *sb,
  42                 bg->bg_itable_unused_hi = cpu_to_le16(count >> 16);
  43  }
  44
  45 +/*
  46 + * If ext4 filesystem features are enabled, then enable async_commits
  47 + * by default.
  48 + */
  49 +#define ASYNC_COMMIT_DEFAULT(sb) (EXT4_HAS_INCOMPAT_FEATURE(sb, \
  50 +                                       (EXT4_FEATURE_INCOMPAT_EXTENTS| \
  51 +                                        EXT4_FEATURE_INCOMPAT_64BIT| \
  52 +                                        EXT4_FEATURE_INCOMPAT_FLEX_BG)))
  53 +
  54
  55  /* Just increment the non-pointer handle value */
  56  static handle_t *ext4_get_nojournal(void)
  57 @@ -1020,9 +1029,15 @@ static int ext4_show_options(struct seq_file *seq, struct vfsmount *vfs)
  58          */
  59         seq_puts(seq, ",barrier=");
  60         seq_puts(seq, test_opt(sb, BARRIER) ? "1" : "0");
  61 -       if (test_opt(sb, JOURNAL_ASYNC_COMMIT))
  62 -               seq_puts(seq, ",journal_async_commit");
  63 -       else if (test_opt(sb, JOURNAL_CHECKSUM))
  64 +       if (ASYNC_COMMIT_DEFAULT(sb)) {
  65 +               if (!test_opt(sb, JOURNAL_ASYNC_COMMIT))
  66 +                       seq_puts(seq, ",nojournal_async_commit");
  67 +       } else {
  68 +               if (test_opt(sb, JOURNAL_ASYNC_COMMIT))
  69 +                       seq_puts(seq, ",journal_async_commit");
  70 +       }
  71 +       if (test_opt(sb, JOURNAL_CHECKSUM) &&
  72 +           !test_opt(sb, JOURNAL_ASYNC_COMMIT))
  73                 seq_puts(seq, ",journal_checksum");
  74         if (test_opt(sb, I_VERSION))
  75                 seq_puts(seq, ",i_version");
  76 @@ -1239,6 +1254,7 @@ enum {
  77         Opt_commit, Opt_min_batch_time, Opt_max_batch_time,
  78         Opt_journal_update, Opt_journal_dev,
  79         Opt_journal_checksum, Opt_journal_async_commit,
  80 +       Opt_nojournal_async_commit,
  81         Opt_abort, Opt_data_journal, Opt_data_ordered, Opt_data_writeback,
  82         Opt_data_err_abort, Opt_data_err_ignore,
  83         Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
  84 @@ -1285,6 +1301,7 @@ static const match_table_t tokens = {
  85         {Opt_journal_dev, "journal_dev=%u"},
  86         {Opt_journal_checksum, "journal_checksum"},
  87         {Opt_journal_async_commit, "journal_async_commit"},
  88 +       {Opt_nojournal_async_commit, "nojournal_async_commit"},
  89         {Opt_abort, "abort"},
  90         {Opt_data_journal, "data=journal"},
  91         {Opt_data_ordered, "data=ordered"},
  92 @@ -1559,6 +1576,9 @@ static int parse_options(char *options, struct super_block *sb,
  93                         set_opt(sb, JOURNAL_ASYNC_COMMIT);
  94                         set_opt(sb, JOURNAL_CHECKSUM);
  95                         break;
  96 +               case Opt_nojournal_async_commit:
  97 +                       clear_opt(sb, JOURNAL_ASYNC_COMMIT);
  98 +                       break;
  99                 case Opt_noload:
 100                         set_opt(sb, NOLOAD);
 101                         break;
 102 @@ -3161,6 +3181,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 103             ((def_mount_opts & EXT4_DEFM_NODELALLOC) == 0))
 104                 set_opt(sb, DELALLOC);
 105
 106 +       if (ASYNC_COMMIT_DEFAULT(sb))
 107 +               set_opt(sb, JOURNAL_ASYNC_COMMIT);
 108 +
 109         if (!parse_options((char *) sbi->s_es->s_mount_opts, sb,
 110                            &journal_devnum, &journal_ioprio, NULL, 0)) {
 111                 ext4_msg(sb, KERN_WARNING,