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

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
......@@ -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
......
......@@ -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__ */
#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 */
......@@ -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>
......
......@@ -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
*/
......
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