Commit f8e08a84 authored by Al Viro's avatar Al Viro Committed by Linus Torvalds
Browse files

[PATCH] reiserfs endianness: sanitize reiserfs_key union 



Since we only access reiserfs_key ->u.k_offset_v2 guts in four helper
functions, we are free to sanitize those, as long as

- layout of the structure is unchanged (it's on-disk object)

- behaviour of these helpers is same as before.

Patch kills the mess with endianness-dependent bitfields and replaces them
with a single __le64.  Helpers are switched to straightforward shift/and/or.

Benefits:

- exact same definitions for little- and big-endian architectures; no ifdefs
  in sight.

- generate the same code on little-endian and improved on big-endian.

- doesn't rely on lousy bitfields handling in gcc codegenerator.

- happens to be standard C (unsigned long long is not a valid type for a
  bitfield; it's a gccism and not well-implemented one, at that).

Signed-off-by: default avatarAl Viro <viro@parcelfarce.linux.theplanet.co.uk>
Cc: <reiserfs-dev@namesys.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 6b9f5829

include/linux/reiserfs_fs.h

+7 −35
Original line number Diff line number Diff line
@@ -381,57 +381,29 @@ struct offset_v1 { 
} __attribute__ ((__packed__));



struct offset_v2 {

#ifdef __LITTLE_ENDIAN

	    /* little endian version */

	    __u64 k_offset:60;

	    __u64 k_type: 4;

#else

	    /* big endian version */

	    __u64 k_type: 4;

	    __u64 k_offset:60;

#endif

	__le64 v;

} __attribute__ ((__packed__));



#ifndef __LITTLE_ENDIAN

typedef union {

    struct offset_v2 offset_v2;

    __u64 linear;

} __attribute__ ((__packed__)) offset_v2_esafe_overlay;



static inline __u16 offset_v2_k_type( const struct offset_v2 *v2 )

{

    offset_v2_esafe_overlay tmp = *(const offset_v2_esafe_overlay *)v2;

    tmp.linear = le64_to_cpu( tmp.linear );

    return (tmp.offset_v2.k_type <= TYPE_MAXTYPE)?tmp.offset_v2.k_type:TYPE_ANY;

	__u8 type = le64_to_cpu(v2->v) >> 60;

	return (type <= TYPE_MAXTYPE)?type:TYPE_ANY;

}

 

static inline void set_offset_v2_k_type( struct offset_v2 *v2, int type )

{

    offset_v2_esafe_overlay *tmp = (offset_v2_esafe_overlay *)v2;

    tmp->linear = le64_to_cpu(tmp->linear);

    tmp->offset_v2.k_type = type;

    tmp->linear = cpu_to_le64(tmp->linear);

	v2->v = (v2->v & cpu_to_le64(~0ULL>>4)) | cpu_to_le64((__u64)type<<60);

}

 

static inline loff_t offset_v2_k_offset( const struct offset_v2 *v2 )

{

    offset_v2_esafe_overlay tmp = *(const offset_v2_esafe_overlay *)v2;

    tmp.linear = le64_to_cpu( tmp.linear );

    return tmp.offset_v2.k_offset;

	return le64_to_cpu(v2->v) & (~0ULL>>4);

}



static inline void set_offset_v2_k_offset( struct offset_v2 *v2, loff_t offset ){

    offset_v2_esafe_overlay *tmp = (offset_v2_esafe_overlay *)v2;

    tmp->linear = le64_to_cpu(tmp->linear);

    tmp->offset_v2.k_offset = offset;

    tmp->linear = cpu_to_le64(tmp->linear);

	offset &= (~0ULL>>4);

	v2->v = (v2->v & cpu_to_le64(15ULL<<60)) | cpu_to_le64(offset);

}

#else

# define offset_v2_k_type(v2)           ((v2)->k_type)

# define set_offset_v2_k_type(v2,val)   (offset_v2_k_type(v2) = (val))

# define offset_v2_k_offset(v2)         ((v2)->k_offset)

# define set_offset_v2_k_offset(v2,val) (offset_v2_k_offset(v2) = (val))

#endif



/* Key of an item determines its location in the S+tree, and

   is composed of 4 components */

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