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Commit bc02e869 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Ben Myers
Browse files

xfs: add CRC infrastructure 



 - add a mount feature bit for CRC enabled filesystems
 - add some helpers for generating and verifying the CRCs
 - add a copy_uuid helper

The checksumming helpers are loosely based on similar ones in sctp,
all other bits come from Dave Chinner.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarMark Tinguely <tinguely@sgi.com>
Signed-off-by: default avatarBen Myers <bpm@sgi.com>
parent 1813dd64

fs/xfs/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ config XFS_FS 
	tristate "XFS filesystem support"

	depends on BLOCK

	select EXPORTFS

	select LIBCRC32C

	help

	  XFS is a high performance journaling filesystem which originated

	  on the SGI IRIX platform.  It is completely multi-threaded, can

fs/xfs/uuid.h

+6 −0
Original line number Diff line number Diff line
@@ -26,4 +26,10 @@ extern int uuid_is_nil(uuid_t *uuid); 
extern int uuid_equal(uuid_t *uuid1, uuid_t *uuid2);

extern void uuid_getnodeuniq(uuid_t *uuid, int fsid [2]);



static inline void

uuid_copy(uuid_t *dst, uuid_t *src)

{

	memcpy(dst, src, sizeof(uuid_t));

}



#endif	/* __XFS_SUPPORT_UUID_H__ */

fs/xfs/xfs_cksum.h

0 → 100644
+63 −0
Original line number Diff line number Diff line 
#ifndef _XFS_CKSUM_H

#define _XFS_CKSUM_H 1



#define XFS_CRC_SEED	(~(__uint32_t)0)



/*

 * Calculate the intermediate checksum for a buffer that has the CRC field

 * inside it.  The offset of the 32bit crc fields is passed as the

 * cksum_offset parameter.

 */

static inline __uint32_t

xfs_start_cksum(char *buffer, size_t length, unsigned long cksum_offset)

{

	__uint32_t zero = 0;

	__uint32_t crc;



	/* Calculate CRC up to the checksum. */

	crc = crc32c(XFS_CRC_SEED, buffer, cksum_offset);



	/* Skip checksum field */

	crc = crc32c(crc, &zero, sizeof(__u32));



	/* Calculate the rest of the CRC. */

	return crc32c(crc, &buffer[cksum_offset + sizeof(__be32)],

		      length - (cksum_offset + sizeof(__be32)));

}



/*

 * Convert the intermediate checksum to the final ondisk format.

 *

 * The CRC32c calculation uses LE format even on BE machines, but returns the

 * result in host endian format. Hence we need to byte swap it back to LE format

 * so that it is consistent on disk.

 */

static inline __le32

xfs_end_cksum(__uint32_t crc)

{

	return ~cpu_to_le32(crc);

}



/*

 * Helper to generate the checksum for a buffer.

 */

static inline void

xfs_update_cksum(char *buffer, size_t length, unsigned long cksum_offset)

{

	__uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset);



	*(__le32 *)(buffer + cksum_offset) = xfs_end_cksum(crc);

}



/*

 * Helper to verify the checksum for a buffer.

 */

static inline int

xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset)

{

	__uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset);



	return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);

}



#endif /* _XFS_CKSUM_H */

fs/xfs/xfs_linux.h

+1 −0
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ 
#include <linux/kernel.h>

#include <linux/blkdev.h>

#include <linux/slab.h>

#include <linux/crc32c.h>

#include <linux/module.h>

#include <linux/mutex.h>

#include <linux/file.h>

fs/xfs/xfs_sb.h

+7 −0
Original line number Diff line number Diff line
@@ -81,6 +81,7 @@ struct xfs_mount; 
#define XFS_SB_VERSION2_ATTR2BIT	0x00000008	/* Inline attr rework */

#define XFS_SB_VERSION2_PARENTBIT	0x00000010	/* parent pointers */

#define XFS_SB_VERSION2_PROJID32BIT	0x00000080	/* 32 bit project id */

#define XFS_SB_VERSION2_CRCBIT		0x00000100	/* metadata CRCs */



#define	XFS_SB_VERSION2_OKREALFBITS	\

	(XFS_SB_VERSION2_LAZYSBCOUNTBIT	| \
@@ -503,6 +504,12 @@ static inline int xfs_sb_version_hasprojid32bit(xfs_sb_t *sbp) 
		(sbp->sb_features2 & XFS_SB_VERSION2_PROJID32BIT);

}



static inline int xfs_sb_version_hascrc(xfs_sb_t *sbp)

{

	return (xfs_sb_version_hasmorebits(sbp) &&

		(sbp->sb_features2 & XFS_SB_VERSION2_CRCBIT));

}



/*

 * end of superblock version macros

 */