| 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(); |
| 124 | |
