Commit 24b58424 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

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: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent c09eef30

fs/ext4/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -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

fs/ext4/super.c

+58 −0
Original line number Diff line number Diff line
@@ -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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