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authorTheodore Ts'o <tytso@mit.edu>2009-12-07 14:08:51 -0500
committerTheodore Ts'o <tytso@mit.edu>2009-12-07 14:08:51 -0500
commit24b584240a0006ea7436cd35f5e8983eb76f1e6f (patch)
tree8b14be4ebcc93301bc63b061ecf89a16f114a31c
parentc09eef305dd43846360944ad072f051f964fa383 (diff)
downloadblackbird-op-linux-24b584240a0006ea7436cd35f5e8983eb76f1e6f.tar.gz
blackbird-op-linux-24b584240a0006ea7436cd35f5e8983eb76f1e6f.zip
ext4: Use ext4 file system driver for ext2/ext3 file system mounts
Add a new config option, CONFIG_EXT4_USE_FOR_EXT23 which if enabled, will cause ext4 to be used for either ext2 or ext3 file system mounts when ext2 or ext3 is not enabled in the configuration. This allows minimalist kernel fanatics to drop to file system drivers from their compiled kernel with out losing functionality. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
-rw-r--r--fs/ext4/Kconfig10
-rw-r--r--fs/ext4/super.c58
2 files changed, 68 insertions, 0 deletions
diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig
index 9f2d45d75b1a..a6b4e93833d6 100644
--- a/fs/ext4/Kconfig
+++ b/fs/ext4/Kconfig
@@ -26,6 +26,16 @@ config EXT4_FS
If unsure, say N.
+config EXT4_USE_FOR_EXT23
+ bool "Use ext4 for ext2/ext3 file systems"
+ depends on !EXT3_FS || !EXT2_FS
+ default y
+ help
+ Allow the ext4 file system driver code to be used for ext2 or
+ ext3 file system mounts. This allows users to reduce their
+ compiled kernel size by using one file system driver for
+ ext2, ext3, and ext4 file systems.
+
config EXT4_FS_XATTR
bool "Ext4 extended attributes"
depends on EXT4_FS
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5a2db612950b..30476daf966e 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3960,6 +3960,58 @@ static int ext4_get_sb(struct file_system_type *fs_type, int flags,
return get_sb_bdev(fs_type, flags, dev_name, data, ext4_fill_super,mnt);
}
+#if !defined(CONTIG_EXT2_FS) && defined(CONFIG_EXT4_USE_FOR_EXT23)
+static struct file_system_type ext2_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "ext2",
+ .get_sb = ext4_get_sb,
+ .kill_sb = kill_block_super,
+ .fs_flags = FS_REQUIRES_DEV,
+};
+
+static inline void register_as_ext2(void)
+{
+ int err = register_filesystem(&ext2_fs_type);
+ if (err)
+ printk(KERN_WARNING
+ "EXT4-fs: Unable to register as ext2 (%d)\n", err);
+}
+
+static inline void unregister_as_ext2(void)
+{
+ unregister_filesystem(&ext2_fs_type);
+}
+#else
+static inline void register_as_ext2(void) { }
+static inline void unregister_as_ext2(void) { }
+#endif
+
+#if !defined(CONTIG_EXT3_FS) && defined(CONFIG_EXT4_USE_FOR_EXT23)
+static struct file_system_type ext3_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "ext3",
+ .get_sb = ext4_get_sb,
+ .kill_sb = kill_block_super,
+ .fs_flags = FS_REQUIRES_DEV,
+};
+
+static inline void register_as_ext3(void)
+{
+ int err = register_filesystem(&ext3_fs_type);
+ if (err)
+ printk(KERN_WARNING
+ "EXT4-fs: Unable to register as ext3 (%d)\n", err);
+}
+
+static inline void unregister_as_ext3(void)
+{
+ unregister_filesystem(&ext3_fs_type);
+}
+#else
+static inline void register_as_ext3(void) { }
+static inline void unregister_as_ext3(void) { }
+#endif
+
static struct file_system_type ext4_fs_type = {
.owner = THIS_MODULE,
.name = "ext4",
@@ -3989,11 +4041,15 @@ static int __init init_ext4_fs(void)
err = init_inodecache();
if (err)
goto out1;
+ register_as_ext2();
+ register_as_ext3();
err = register_filesystem(&ext4_fs_type);
if (err)
goto out;
return 0;
out:
+ unregister_as_ext2();
+ unregister_as_ext3();
destroy_inodecache();
out1:
exit_ext4_xattr();
@@ -4009,6 +4065,8 @@ out4:
static void __exit exit_ext4_fs(void)
{
+ unregister_as_ext2();
+ unregister_as_ext3();
unregister_filesystem(&ext4_fs_type);
destroy_inodecache();
exit_ext4_xattr();
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