target/linux/generic/patches-2.6.32/040-use_ext4_for_ext23.patch

   1 From 24b584240a0006ea7436cd35f5e8983eb76f1e6f Mon Sep 17 00:00:00 2001
   2 From: Theodore Ts'o <tytso@mit.edu>
   3 Date: Mon, 7 Dec 2009 14:08:51 -0500
   4 Subject: [PATCH] ext4: Use ext4 file system driver for ext2/ext3 file system mounts
   5
   6 Add a new config option, CONFIG_EXT4_USE_FOR_EXT23 which if enabled,
   7 will cause ext4 to be used for either ext2 or ext3 file system mounts
   8 when ext2 or ext3 is not enabled in the configuration.
   9
  10 This allows minimalist kernel fanatics to drop to file system drivers
  11 from their compiled kernel with out losing functionality.
  12
  13 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  14 ---
  15  fs/ext4/Kconfig |   10 +++++++++
  16  fs/ext4/super.c |   58 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
  17  2 files changed, 68 insertions(+), 0 deletions(-)
  18
  19 --- a/fs/ext4/Kconfig
  20 +++ b/fs/ext4/Kconfig
  21 @@ -26,6 +26,16 @@ config EXT4_FS
  22
  23           If unsure, say N.
  24
  25 +config EXT4_USE_FOR_EXT23
  26 +       bool "Use ext4 for ext2/ext3 file systems"
  27 +       depends on !EXT3_FS || !EXT2_FS
  28 +       default y
  29 +       help
  30 +         Allow the ext4 file system driver code to be used for ext2 or
  31 +         ext3 file system mounts.  This allows users to reduce their
  32 +         compiled kernel size by using one file system driver for
  33 +         ext2, ext3, and ext4 file systems.
  34 +
  35  config EXT4_FS_XATTR
  36         bool "Ext4 extended attributes"
  37         depends on EXT4_FS
  38 --- a/fs/ext4/super.c
  39 +++ b/fs/ext4/super.c
  40 @@ -3994,6 +3994,58 @@ static int ext4_get_sb(struct file_syste
  41         return get_sb_bdev(fs_type, flags, dev_name, data, ext4_fill_super,mnt);
  42  }
  43
  44 +#if !defined(CONTIG_EXT2_FS) && defined(CONFIG_EXT4_USE_FOR_EXT23)
  45 +static struct file_system_type ext2_fs_type = {
  46 +       .owner          = THIS_MODULE,
  47 +       .name           = "ext2",
  48 +       .get_sb         = ext4_get_sb,
  49 +       .kill_sb        = kill_block_super,
  50 +       .fs_flags       = FS_REQUIRES_DEV,
  51 +};
  52 +
  53 +static inline void register_as_ext2(void)
  54 +{
  55 +       int err = register_filesystem(&ext2_fs_type);
  56 +       if (err)
  57 +               printk(KERN_WARNING
  58 +                      "EXT4-fs: Unable to register as ext2 (%d)\n", err);
  59 +}
  60 +
  61 +static inline void unregister_as_ext2(void)
  62 +{
  63 +       unregister_filesystem(&ext2_fs_type);
  64 +}
  65 +#else
  66 +static inline void register_as_ext2(void) { }
  67 +static inline void unregister_as_ext2(void) { }
  68 +#endif
  69 +
  70 +#if !defined(CONTIG_EXT3_FS) && defined(CONFIG_EXT4_USE_FOR_EXT23)
  71 +static struct file_system_type ext3_fs_type = {
  72 +       .owner          = THIS_MODULE,
  73 +       .name           = "ext3",
  74 +       .get_sb         = ext4_get_sb,
  75 +       .kill_sb        = kill_block_super,
  76 +       .fs_flags       = FS_REQUIRES_DEV,
  77 +};
  78 +
  79 +static inline void register_as_ext3(void)
  80 +{
  81 +       int err = register_filesystem(&ext3_fs_type);
  82 +       if (err)
  83 +               printk(KERN_WARNING
  84 +                      "EXT4-fs: Unable to register as ext3 (%d)\n", err);
  85 +}
  86 +
  87 +static inline void unregister_as_ext3(void)
  88 +{
  89 +       unregister_filesystem(&ext3_fs_type);
  90 +}
  91 +#else
  92 +static inline void register_as_ext3(void) { }
  93 +static inline void unregister_as_ext3(void) { }
  94 +#endif
  95 +
  96  static struct file_system_type ext4_fs_type = {
  97         .owner          = THIS_MODULE,
  98         .name           = "ext4",
  99 @@ -4024,11 +4076,15 @@ static int __init init_ext4_fs(void)
 100         err = init_inodecache();
 101         if (err)
 102                 goto out1;
 103 +       register_as_ext2();
 104 +       register_as_ext3();
 105         err = register_filesystem(&ext4_fs_type);
 106         if (err)
 107                 goto out;
 108         return 0;
 109  out:
 110 +       unregister_as_ext2();
 111 +       unregister_as_ext3();
 112         destroy_inodecache();
 113  out1:
 114         exit_ext4_xattr();
 115 @@ -4044,6 +4100,8 @@ out4:
 116
 117  static void __exit exit_ext4_fs(void)
 118  {
 119 +       unregister_as_ext2();
 120 +       unregister_as_ext3();
 121         unregister_filesystem(&ext4_fs_type);
 122         destroy_inodecache();
 123         exit_ext4_xattr();