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Commit 615f996f authored by David Woodhouse's avatar David Woodhouse Committed by Chris Mason
Browse files

Switch btrfs_name_hash() to crc32c 



Date: Tue, 19 Aug 2008 19:21:57 +0100
Using a 64-bit hash as the readdir cookie is just asking for trouble.
And gets it, when we try to export the file system by NFS.

Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 76fcef19

fs/btrfs/Makefile

+1 −1
Original line number Original line Diff line number Diff line
@@ -3,7 +3,7 @@ ifneq ($(KERNELRELEASE),) 




obj-m  := btrfs.o

obj-m  := btrfs.o

btrfs-y := super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \

btrfs-y := super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \

	   hash.o file-item.o inode-item.o inode-map.o disk-io.o \

	   file-item.o inode-item.o inode-map.o disk-io.o \

	   transaction.o bit-radix.o inode.o file.o tree-defrag.o \

	   transaction.o bit-radix.o inode.o file.o tree-defrag.o \

	   extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \

	   extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \

	   extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \

	   extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \

fs/btrfs/hash.c

deleted100644 → 0
+0 −112
Original line number Original line Diff line number Diff line 
/*

 * Copyright (C) 2007 Oracle.  All rights reserved.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public

 * License v2 as published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 *

 * You should have received a copy of the GNU General Public

 * License along with this program; if not, write to the

 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 * Boston, MA 021110-1307, USA.

 */



/*

 *  Original copy from:

 *  linux/fs/ext3/hash.c

 *

 * Copyright (C) 2002 by Theodore Ts'o

 *

 * This file is released under the GPL v2.

 *

 * This file may be redistributed under the terms of the GNU Public

 * License.

 */



#include <linux/types.h>

#include "hash.h"

#define DELTA 0x9E3779B9



static void TEA_transform(__u32 buf[2], __u32 const in[])

{

	__u32	sum = 0;

	__u32	b0 = buf[0], b1 = buf[1];

	__u32	a = in[0], b = in[1], c = in[2], d = in[3];

	int	n = 16;



	do {

		sum += DELTA;

		b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);

		b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);

	} while(--n);



	buf[0] += b0;

	buf[1] += b1;

}



static void str2hashbuf(const char *msg, int len, __u32 *buf, int num)

{

	__u32	pad, val;

	int	i;



	pad = (__u32)len | ((__u32)len << 8);

	pad |= pad << 16;



	val = pad;

	if (len > num*4)

		len = num * 4;

	for (i=0; i < len; i++) {

		if ((i % 4) == 0)

			val = pad;

		val = msg[i] + (val << 8);

		if ((i % 4) == 3) {

			*buf++ = val;

			val = pad;

			num--;

		}

	}

	if (--num >= 0)

		*buf++ = val;

	while (--num >= 0)

		*buf++ = pad;

}



u64 btrfs_name_hash(const char *name, int len)

{

	__u32	hash;

	__u32	minor_hash = 0;

	const char	*p;

	__u32		in[8], buf[4];

	u64		hash_result;



	if (len == 1 && *name == '.') {

		return 1;

	} else if (len == 2 && name[0] == '.' && name[1] == '.') {

		return 2;

	}



	/* Initialize the default seed for the hash checksum functions */

	buf[0] = 0x67452301;

	buf[1] = 0xefcdab89;

	buf[2] = 0x98badcfe;

	buf[3] = 0x10325476;



	p = name;

	while (len > 0) {

		str2hashbuf(p, len, in, 4);

		TEA_transform(buf, in);

		len -= 16;

		p += 16;

	}

	hash = buf[0];

	minor_hash = buf[1];

	hash_result = buf[0];

	hash_result <<= 32;

	hash_result |= buf[1];

	return hash_result;

}

fs/btrfs/hash.h

+6 −1
Original line number Original line Diff line number Diff line
@@ -18,5 +18,10 @@ 




#ifndef __HASH__

#ifndef __HASH__

#define __HASH__

#define __HASH__

u64 btrfs_name_hash(const char *name, int len);



#include "crc32c.h"

static inline u64 btrfs_name_hash(const char *name, int len)

{

	return btrfs_crc32c((u32)~1, name, len);

}

#endif
 
#endif