Re: [PATCH] linux/magic.h for magic numbers

From: Ian Kent
Date: Tue Sep 12 2006 - 04:20:05 EST


On Sat, 9 Sep 2006, Jeff Garzik wrote:

>
> An IRC discussion sparked a memory: most filesystems really don't
> need to put anything at all in include/linux. Excluding API-ish
> filesystems like procfs, just about the only filesystem symbols that
> get exported outside of __KERNEL__ are the *_SUPER_MAGIC symbols,
> and similar symbols.
>
> After seeing the useful attributes of linux/poison.h, I propose a
> similar linux/magic.h.
>
> We can see from the patch below that this permitted the deletion of a
> couple headers, where the *_SUPER_MAGIC symbol was the only thing in the
> entire header.
>
> Other non-filesystem-related magic numbers could get moved here
> eventually, if maintainers so desire, but I wanted to start off with the
> obvious low-hanging fruit.
>

Would be good to include autofs in this lot.

Defined in linux/autofs/autofs_i.h
Defined in linux/autofs4/autofs_i.h

as

#define AUTOFS_SUPER_MAGIC 0x0187

> The 'magic' branch of
> git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/misc-2.6.git
>
> contains the following update:
>
> fs/affs/affs.h | 1 -
> fs/affs/super.c | 1 +
> fs/hpfs/hpfs_fn.h | 1 -
> fs/hpfs/super.c | 1 +
> fs/openpromfs/inode.c | 1 +
> include/linux/adfs_fs.h | 2 +-
> include/linux/affs_fs.h | 7 -------
> include/linux/coda_psdev.h | 4 ++--
> include/linux/efs_fs_sb.h | 3 +--
> include/linux/ext2_fs.h | 6 +-----
> include/linux/ext3_fs.h | 6 +-----
> include/linux/hpfs_fs.h | 8 --------
> include/linux/iso_fs.h | 6 +++---
> include/linux/jffs2.h | 4 ++--
> include/linux/magic.h | 36 ++++++++++++++++++++++++++++++++++++
> include/linux/minix_fs.h | 6 ++----
> include/linux/msdos_fs.h | 4 ++--
> include/linux/ncp_fs.h | 5 +----
> include/linux/nfs_fs.h | 6 +-----
> include/linux/openprom_fs.h | 10 ----------
> include/linux/proc_fs.h | 3 +--
> include/linux/qnx4_fs.h | 2 +-
> include/linux/reiserfs_fs.h | 10 ++--------
> include/linux/smb.h | 3 +--
> include/linux/usbdevice_fs.h | 3 +--
> 25 files changed, 62 insertions(+), 77 deletions(-)
>
> diff --git a/fs/affs/affs.h b/fs/affs/affs.h
> index 0ddd4cc..1dc8438 100644
> --- a/fs/affs/affs.h
> +++ b/fs/affs/affs.h
> @@ -1,7 +1,6 @@
> #include <linux/types.h>
> #include <linux/fs.h>
> #include <linux/buffer_head.h>
> -#include <linux/affs_fs.h>
> #include <linux/amigaffs.h>
>
> /* AmigaOS allows file names with up to 30 characters length.
> diff --git a/fs/affs/super.c b/fs/affs/super.c
> index 5200f49..1735201 100644
> --- a/fs/affs/super.c
> +++ b/fs/affs/super.c
> @@ -14,6 +14,7 @@ #include <linux/module.h>
> #include <linux/init.h>
> #include <linux/statfs.h>
> #include <linux/parser.h>
> +#include <linux/magic.h>
> #include "affs.h"
>
> extern struct timezone sys_tz;
> diff --git a/fs/hpfs/hpfs_fn.h b/fs/hpfs/hpfs_fn.h
> index f687d54..32ab51e 100644
> --- a/fs/hpfs/hpfs_fn.h
> +++ b/fs/hpfs/hpfs_fn.h
> @@ -12,7 +12,6 @@
> #include <linux/mutex.h>
> #include <linux/pagemap.h>
> #include <linux/buffer_head.h>
> -#include <linux/hpfs_fs.h>
> #include <linux/slab.h>
> #include <linux/smp_lock.h>
>
> diff --git a/fs/hpfs/super.c b/fs/hpfs/super.c
> index f798480..8fe51c3 100644
> --- a/fs/hpfs/super.c
> +++ b/fs/hpfs/super.c
> @@ -11,6 +11,7 @@ #include <linux/module.h>
> #include <linux/parser.h>
> #include <linux/init.h>
> #include <linux/statfs.h>
> +#include <linux/magic.h>
>
> /* Mark the filesystem dirty, so that chkdsk checks it when os/2 booted */
>
> diff --git a/fs/openpromfs/inode.c b/fs/openpromfs/inode.c
> index 93a56bd..a6ad105 100644
> --- a/fs/openpromfs/inode.c
> +++ b/fs/openpromfs/inode.c
> @@ -12,6 +12,7 @@ #include <linux/openprom_fs.h>
> #include <linux/init.h>
> #include <linux/slab.h>
> #include <linux/seq_file.h>
> +#include <linux/magic.h>
>
> #include <asm/openprom.h>
> #include <asm/oplib.h>
> diff --git a/include/linux/adfs_fs.h b/include/linux/adfs_fs.h
> index 4a5d50c..ef788c2 100644
> --- a/include/linux/adfs_fs.h
> +++ b/include/linux/adfs_fs.h
> @@ -2,6 +2,7 @@ #ifndef _ADFS_FS_H
> #define _ADFS_FS_H
>
> #include <linux/types.h>
> +#include <linux/magic.h>
>
> /*
> * Disc Record at disc address 0xc00
> @@ -38,7 +39,6 @@ #define ADFS_DISCRECORD (0xc00)
> #define ADFS_DR_OFFSET (0x1c0)
> #define ADFS_DR_SIZE 60
> #define ADFS_DR_SIZE_BITS (ADFS_DR_SIZE << 3)
> -#define ADFS_SUPER_MAGIC 0xadf5
>
> #ifdef __KERNEL__
> #include <linux/adfs_fs_i.h>
> diff --git a/include/linux/affs_fs.h b/include/linux/affs_fs.h
> deleted file mode 100644
> index c57b5ee..0000000
> --- a/include/linux/affs_fs.h
> +++ /dev/null
> @@ -1,7 +0,0 @@
> -#ifndef _AFFS_FS_H
> -#define _AFFS_FS_H
> -/*
> - * The affs filesystem constants/structures
> - */
> -#define AFFS_SUPER_MAGIC 0xadff
> -#endif
> diff --git a/include/linux/coda_psdev.h b/include/linux/coda_psdev.h
> index 98f6c52..b541bb3 100644
> --- a/include/linux/coda_psdev.h
> +++ b/include/linux/coda_psdev.h
> @@ -1,11 +1,11 @@
> #ifndef __CODA_PSDEV_H
> #define __CODA_PSDEV_H
>
> +#include <linux/magic.h>
> +
> #define CODA_PSDEV_MAJOR 67
> #define MAX_CODADEVS 5 /* how many do we allow */
>
> -#define CODA_SUPER_MAGIC 0x73757245
> -
> struct kstatfs;
>
> struct coda_sb_info
> diff --git a/include/linux/efs_fs_sb.h b/include/linux/efs_fs_sb.h
> index c76088b..ff1945e 100644
> --- a/include/linux/efs_fs_sb.h
> +++ b/include/linux/efs_fs_sb.h
> @@ -9,8 +9,7 @@
> #ifndef __EFS_FS_SB_H__
> #define __EFS_FS_SB_H__
>
> -/* statfs() magic number for EFS */
> -#define EFS_SUPER_MAGIC 0x414A53
> +#include <linux/magic.h>
>
> /* EFS superblock magic numbers */
> #define EFS_MAGIC 0x072959
> diff --git a/include/linux/ext2_fs.h b/include/linux/ext2_fs.h
> index facf34e..33a1aa1 100644
> --- a/include/linux/ext2_fs.h
> +++ b/include/linux/ext2_fs.h
> @@ -17,6 +17,7 @@ #ifndef _LINUX_EXT2_FS_H
> #define _LINUX_EXT2_FS_H
>
> #include <linux/types.h>
> +#include <linux/magic.h>
>
> /*
> * The second extended filesystem constants/structures
> @@ -63,11 +64,6 @@ #define EXT2_UNDEL_DIR_INO 6 /* Undelet
> /* First non-reserved inode for old ext2 filesystems */
> #define EXT2_GOOD_OLD_FIRST_INO 11
>
> -/*
> - * The second extended file system magic number
> - */
> -#define EXT2_SUPER_MAGIC 0xEF53
> -
> #ifdef __KERNEL__
> #include <linux/ext2_fs_sb.h>
> static inline struct ext2_sb_info *EXT2_SB(struct super_block *sb)
> diff --git a/include/linux/ext3_fs.h b/include/linux/ext3_fs.h
> index 9f9cce7..0eed918 100644
> --- a/include/linux/ext3_fs.h
> +++ b/include/linux/ext3_fs.h
> @@ -17,6 +17,7 @@ #ifndef _LINUX_EXT3_FS_H
> #define _LINUX_EXT3_FS_H
>
> #include <linux/types.h>
> +#include <linux/magic.h>
>
> /*
> * The second extended filesystem constants/structures
> @@ -67,11 +68,6 @@ #define EXT3_JOURNAL_INO 8 /* Journal i
> #define EXT3_GOOD_OLD_FIRST_INO 11
>
> /*
> - * The second extended file system magic number
> - */
> -#define EXT3_SUPER_MAGIC 0xEF53
> -
> -/*
> * Maximal count of links to a file
> */
> #define EXT3_LINK_MAX 32000
> diff --git a/include/linux/hpfs_fs.h b/include/linux/hpfs_fs.h
> deleted file mode 100644
> index a5028dd..0000000
> --- a/include/linux/hpfs_fs.h
> +++ /dev/null
> @@ -1,8 +0,0 @@
> -#ifndef _LINUX_HPFS_FS_H
> -#define _LINUX_HPFS_FS_H
> -
> -/* HPFS magic number (word 0 of block 16) */
> -
> -#define HPFS_SUPER_MAGIC 0xf995e849
> -
> -#endif
> diff --git a/include/linux/iso_fs.h b/include/linux/iso_fs.h
> index 4796787..4688ac4 100644
> --- a/include/linux/iso_fs.h
> +++ b/include/linux/iso_fs.h
> @@ -2,6 +2,8 @@ #ifndef _ISOFS_FS_H
> #define _ISOFS_FS_H
>
> #include <linux/types.h>
> +#include <linux/magic.h>
> +
> /*
> * The isofs filesystem constants/structures
> */
> @@ -160,6 +162,4 @@ #define ISOFS_BLOCK_SIZE 2048
> #define ISOFS_BUFFER_SIZE(INODE) ((INODE)->i_sb->s_blocksize)
> #define ISOFS_BUFFER_BITS(INODE) ((INODE)->i_sb->s_blocksize_bits)
>
> -#define ISOFS_SUPER_MAGIC 0x9660
> -
> -#endif
> +#endif /* _ISOFS_FS_H */
> diff --git a/include/linux/jffs2.h b/include/linux/jffs2.h
> index c9c7607..840631f 100644
> --- a/include/linux/jffs2.h
> +++ b/include/linux/jffs2.h
> @@ -15,12 +15,12 @@
> #ifndef __LINUX_JFFS2_H__
> #define __LINUX_JFFS2_H__
>
> +#include <linux/magic.h>
> +
> /* You must include something which defines the C99 uintXX_t types.
> We don't do it from here because this file is used in too many
> different environments. */
>
> -#define JFFS2_SUPER_MAGIC 0x72b6
> -
> /* Values we may expect to find in the 'magic' field */
> #define JFFS2_OLD_MAGIC_BITMASK 0x1984
> #define JFFS2_MAGIC_BITMASK 0x1985
> diff --git a/include/linux/magic.h b/include/linux/magic.h
> new file mode 100644
> index 0000000..c4ade90
> --- /dev/null
> +++ b/include/linux/magic.h
> @@ -0,0 +1,36 @@
> +#ifndef __LINUX_MAGIC_H__
> +#define __LINUX_MAGIC_H__
> +
> +#define ADFS_SUPER_MAGIC 0xadf5
> +#define AFFS_SUPER_MAGIC 0xadff
> +#define CODA_SUPER_MAGIC 0x73757245
> +#define EFS_SUPER_MAGIC 0x414A53
> +#define EXT2_SUPER_MAGIC 0xEF53
> +#define EXT3_SUPER_MAGIC 0xEF53
> +#define HPFS_SUPER_MAGIC 0xf995e849
> +#define ISOFS_SUPER_MAGIC 0x9660
> +#define JFFS2_SUPER_MAGIC 0x72b6
> +
> +#define MINIX_SUPER_MAGIC 0x137F /* original minix fs */
> +#define MINIX_SUPER_MAGIC2 0x138F /* minix fs, 30 char names */
> +#define MINIX2_SUPER_MAGIC 0x2468 /* minix V2 fs */
> +#define MINIX2_SUPER_MAGIC2 0x2478 /* minix V2 fs, 30 char names */
> +
> +#define MSDOS_SUPER_MAGIC 0x4d44 /* MD */
> +#define NCP_SUPER_MAGIC 0x564c /* Guess, what 0x564c is :-) */
> +#define NFS_SUPER_MAGIC 0x6969
> +#define OPENPROM_SUPER_MAGIC 0x9fa1
> +#define PROC_SUPER_MAGIC 0x9fa0
> +#define QNX4_SUPER_MAGIC 0x002f /* qnx4 fs detection */
> +
> +#define REISERFS_SUPER_MAGIC 0x52654973 /* used by gcc */
> + /* used by file system utilities that
> + look at the superblock, etc. */
> +#define REISERFS_SUPER_MAGIC_STRING "ReIsErFs"
> +#define REISER2FS_SUPER_MAGIC_STRING "ReIsEr2Fs"
> +#define REISER2FS_JR_SUPER_MAGIC_STRING "ReIsEr3Fs"
> +
> +#define SMB_SUPER_MAGIC 0x517B
> +#define USBDEVICE_SUPER_MAGIC 0x9fa2
> +
> +#endif /* __LINUX_MAGIC_H__ */
> diff --git a/include/linux/minix_fs.h b/include/linux/minix_fs.h
> index 1ecc3cc..916e8f7 100644
> --- a/include/linux/minix_fs.h
> +++ b/include/linux/minix_fs.h
> @@ -1,6 +1,8 @@
> #ifndef _LINUX_MINIX_FS_H
> #define _LINUX_MINIX_FS_H
>
> +#include <linux/magic.h>
> +
> /*
> * The minix filesystem constants/structures
> */
> @@ -19,10 +21,6 @@ #define MINIX2_LINK_MAX 65530
>
> #define MINIX_I_MAP_SLOTS 8
> #define MINIX_Z_MAP_SLOTS 64
> -#define MINIX_SUPER_MAGIC 0x137F /* original minix fs */
> -#define MINIX_SUPER_MAGIC2 0x138F /* minix fs, 30 char names */
> -#define MINIX2_SUPER_MAGIC 0x2468 /* minix V2 fs */
> -#define MINIX2_SUPER_MAGIC2 0x2478 /* minix V2 fs, 30 char names */
> #define MINIX_VALID_FS 0x0001 /* Clean fs. */
> #define MINIX_ERROR_FS 0x0002 /* fs has errors. */
>
> diff --git a/include/linux/msdos_fs.h b/include/linux/msdos_fs.h
> index d9035c7..bae62d6 100644
> --- a/include/linux/msdos_fs.h
> +++ b/include/linux/msdos_fs.h
> @@ -1,6 +1,8 @@
> #ifndef _LINUX_MSDOS_FS_H
> #define _LINUX_MSDOS_FS_H
>
> +#include <linux/magic.h>
> +
> /*
> * The MS-DOS filesystem constants/structures
> */
> @@ -18,8 +20,6 @@ #define CT_LE_W(v) cpu_to_le16(v)
> #define CT_LE_L(v) cpu_to_le32(v)
>
>
> -#define MSDOS_SUPER_MAGIC 0x4d44 /* MD */
> -
> #define MSDOS_ROOT_INO 1 /* == MINIX_ROOT_INO */
> #define MSDOS_DIR_BITS 5 /* log2(sizeof(struct msdos_dir_entry)) */
>
> diff --git a/include/linux/ncp_fs.h b/include/linux/ncp_fs.h
> index b208f0c..02e352b 100644
> --- a/include/linux/ncp_fs.h
> +++ b/include/linux/ncp_fs.h
> @@ -11,6 +11,7 @@ #define _LINUX_NCP_FS_H
> #include <linux/fs.h>
> #include <linux/in.h>
> #include <linux/types.h>
> +#include <linux/magic.h>
>
> #include <linux/ipx.h>
> #include <linux/ncp_no.h>
> @@ -185,10 +186,6 @@ struct ncp_entry_info {
> __u8 file_handle[6];
> };
>
> -/* Guess, what 0x564c is :-) */
> -#define NCP_SUPER_MAGIC 0x564c
> -
> -
> static inline struct ncp_server *NCP_SBP(struct super_block *sb)
> {
> return sb->s_fs_info;
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index 2474345..8ada5da 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -14,6 +14,7 @@ #include <linux/mm.h>
> #include <linux/pagemap.h>
> #include <linux/rwsem.h>
> #include <linux/wait.h>
> +#include <linux/magic.h>
>
> #include <linux/sunrpc/debug.h>
> #include <linux/sunrpc/auth.h>
> @@ -43,11 +44,6 @@ #define NFS_MAX_UDP_TIMEOUT (60*HZ)
> #define NFS_MAX_TCP_TIMEOUT (600*HZ)
>
> /*
> - * superblock magic number for NFS
> - */
> -#define NFS_SUPER_MAGIC 0x6969
> -
> -/*
> * These are the default flags for swap requests
> */
> #define NFS_RPC_SWAPFLAGS (RPC_TASK_SWAPPER|RPC_TASK_ROOTCREDS)
> diff --git a/include/linux/openprom_fs.h b/include/linux/openprom_fs.h
> deleted file mode 100644
> index a837aab..0000000
> --- a/include/linux/openprom_fs.h
> +++ /dev/null
> @@ -1,10 +0,0 @@
> -#ifndef _LINUX_OPENPROM_FS_H
> -#define _LINUX_OPENPROM_FS_H
> -
> -/*
> - * The openprom filesystem constants/structures
> - */
> -
> -#define OPENPROM_SUPER_MAGIC 0x9fa1
> -
> -#endif /* _LINUX_OPENPROM_FS_H */
> diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
> index 17e7578..3435ca3 100644
> --- a/include/linux/proc_fs.h
> +++ b/include/linux/proc_fs.h
> @@ -4,6 +4,7 @@ #define _LINUX_PROC_FS_H
> #include <linux/slab.h>
> #include <linux/fs.h>
> #include <linux/spinlock.h>
> +#include <linux/magic.h>
> #include <asm/atomic.h>
>
> /*
> @@ -24,8 +25,6 @@ enum {
> PROC_ROOT_INO = 1,
> };
>
> -#define PROC_SUPER_MAGIC 0x9fa0
> -
> /*
> * This is not completely implemented yet. The idea is to
> * create an in-memory tree (like the actual /proc filesystem
> diff --git a/include/linux/qnx4_fs.h b/include/linux/qnx4_fs.h
> index 27f49c8..0c7ac44 100644
> --- a/include/linux/qnx4_fs.h
> +++ b/include/linux/qnx4_fs.h
> @@ -11,6 +11,7 @@ #ifndef _LINUX_QNX4_FS_H
> #define _LINUX_QNX4_FS_H
>
> #include <linux/qnxtypes.h>
> +#include <linux/magic.h>
>
> #define QNX4_ROOT_INO 1
>
> @@ -25,7 +26,6 @@ #define QNX4_FILE_FSYSCLEAN 0x20
>
> #define QNX4_I_MAP_SLOTS 8
> #define QNX4_Z_MAP_SLOTS 64
> -#define QNX4_SUPER_MAGIC 0x002f /* qnx4 fs detection */
> #define QNX4_VALID_FS 0x0001 /* Clean fs. */
> #define QNX4_ERROR_FS 0x0002 /* fs has errors. */
> #define QNX4_BLOCK_SIZE 0x200 /* blocksize of 512 bytes */
> diff --git a/include/linux/reiserfs_fs.h b/include/linux/reiserfs_fs.h
> index daa2d83..28493ff 100644
> --- a/include/linux/reiserfs_fs.h
> +++ b/include/linux/reiserfs_fs.h
> @@ -12,6 +12,8 @@ #ifndef _LINUX_REISER_FS_H
> #define _LINUX_REISER_FS_H
>
> #include <linux/types.h>
> +#include <linux/magic.h>
> +
> #ifdef __KERNEL__
> #include <linux/slab.h>
> #include <linux/interrupt.h>
> @@ -227,14 +229,6 @@ #define is_block_in_log_or_reserved_area
> ((!is_reiserfs_jr(SB_DISK_SUPER_BLOCK(s)) ? \
> SB_ONDISK_JOURNAL_SIZE(s) + 1 : SB_ONDISK_RESERVED_FOR_JOURNAL(s)))
>
> - /* used by gcc */
> -#define REISERFS_SUPER_MAGIC 0x52654973
> - /* used by file system utilities that
> - look at the superblock, etc. */
> -#define REISERFS_SUPER_MAGIC_STRING "ReIsErFs"
> -#define REISER2FS_SUPER_MAGIC_STRING "ReIsEr2Fs"
> -#define REISER2FS_JR_SUPER_MAGIC_STRING "ReIsEr3Fs"
> -
> int is_reiserfs_3_5(struct reiserfs_super_block *rs);
> int is_reiserfs_3_6(struct reiserfs_super_block *rs);
> int is_reiserfs_jr(struct reiserfs_super_block *rs);
> diff --git a/include/linux/smb.h b/include/linux/smb.h
> index b016220..6df3b15 100644
> --- a/include/linux/smb.h
> +++ b/include/linux/smb.h
> @@ -10,6 +10,7 @@ #ifndef _LINUX_SMB_H
> #define _LINUX_SMB_H
>
> #include <linux/types.h>
> +#include <linux/magic.h>
>
> enum smb_protocol {
> SMB_PROTOCOL_NONE,
> @@ -101,8 +102,6 @@ enum smb_conn_state {
> CONN_RETRYING /* Currently trying to reconnect */
> };
>
> -#define SMB_SUPER_MAGIC 0x517B
> -
> #define SMB_HEADER_LEN 37 /* includes everything up to, but not
> * including smb_bcc */
>
> diff --git a/include/linux/usbdevice_fs.h b/include/linux/usbdevice_fs.h
> index 7b7aadb..617d8a1 100644
> --- a/include/linux/usbdevice_fs.h
> +++ b/include/linux/usbdevice_fs.h
> @@ -32,11 +32,10 @@ #ifndef _LINUX_USBDEVICE_FS_H
> #define _LINUX_USBDEVICE_FS_H
>
> #include <linux/types.h>
> +#include <linux/magic.h>
>
> /* --------------------------------------------------------------------- */
>
> -#define USBDEVICE_SUPER_MAGIC 0x9fa2
> -
> /* usbdevfs ioctl codes */
>
> struct usbdevfs_ctrltransfer {
> -
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