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: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>

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: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
Christoph Hellwig · Ben Myers
1 parent 1813dd6405
Showing 5 changed files with 78 additions and 0 deletions Side-by-side Diff
fs/xfs/Kconfig
fs/xfs/uuid.h
fs/xfs/xfs_cksum.h
fs/xfs/xfs_linux.h
fs/xfs/xfs_sb.h
@@ -2,6 +2,7 @@
 	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
@@ -26,5 +26,11 @@
 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 @@
 #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	| \
@@ -501,6 +502,12 @@
 {
 	return xfs_sb_version_hasmorebits(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));
 }
  
 /*
...	...	@@ -2,6 +2,7 @@
2	2	tristate "XFS filesystem support"
3	3	depends on BLOCK
4	4	select EXPORTFS
	5	+ select LIBCRC32C
5	6	help
6	7	XFS is a high performance journaling filesystem which originated
7	8	on the SGI IRIX platform. It is completely multi-threaded, can
...	...	@@ -26,5 +26,11 @@
26	26	extern int uuid_equal(uuid_t uuid1, uuid_t uuid2);
27	27	extern void uuid_getnodeuniq(uuid_t *uuid, int fsid [2]);
28	28
	29	+static inline void
	30	+uuid_copy(uuid_t dst, uuid_t src)
	31	+{
	32	+ memcpy(dst, src, sizeof(uuid_t));
	33	+}
	34	+
29	35	#endif /* __XFS_SUPPORT_UUID_H__ */
	1	+#ifndef _XFS_CKSUM_H
	2	+#define _XFS_CKSUM_H 1
	3	+
	4	+#define XFS_CRC_SEED (~(__uint32_t)0)
	5	+
	6	+/*
	7	+ * Calculate the intermediate checksum for a buffer that has the CRC field
	8	+ * inside it. The offset of the 32bit crc fields is passed as the
	9	+ * cksum_offset parameter.
	10	+ */
	11	+static inline __uint32_t
	12	+xfs_start_cksum(char *buffer, size_t length, unsigned long cksum_offset)
	13	+{
	14	+ __uint32_t zero = 0;
	15	+ __uint32_t crc;
	16	+
	17	+ /* Calculate CRC up to the checksum. */
	18	+ crc = crc32c(XFS_CRC_SEED, buffer, cksum_offset);
	19	+
	20	+ /* Skip checksum field */
	21	+ crc = crc32c(crc, &zero, sizeof(__u32));
	22	+
	23	+ /* Calculate the rest of the CRC. */
	24	+ return crc32c(crc, &buffer[cksum_offset + sizeof(__be32)],
	25	+ length - (cksum_offset + sizeof(__be32)));
	26	+}
	27	+
	28	+/*
	29	+ * Convert the intermediate checksum to the final ondisk format.
	30	+ *
	31	+ * The CRC32c calculation uses LE format even on BE machines, but returns the
	32	+ * result in host endian format. Hence we need to byte swap it back to LE format
	33	+ * so that it is consistent on disk.
	34	+ */
	35	+static inline __le32
	36	+xfs_end_cksum(__uint32_t crc)
	37	+{
	38	+ return ~cpu_to_le32(crc);
	39	+}
	40	+
	41	+/*
	42	+ * Helper to generate the checksum for a buffer.
	43	+ */
	44	+static inline void
	45	+xfs_update_cksum(char *buffer, size_t length, unsigned long cksum_offset)
	46	+{
	47	+ __uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset);
	48	+
	49	+ (__le32 )(buffer + cksum_offset) = xfs_end_cksum(crc);
	50	+}
	51	+
	52	+/*
	53	+ * Helper to verify the checksum for a buffer.
	54	+ */
	55	+static inline int
	56	+xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset)
	57	+{
	58	+ __uint32_t crc = xfs_start_cksum(buffer, length, cksum_offset);
	59	+
	60	+ return (__le32 )(buffer + cksum_offset) == xfs_end_cksum(crc);
	61	+}
	62	+
	63	+#endif /* _XFS_CKSUM_H */
...	...	@@ -44,6 +44,7 @@
44	44	#include <linux/kernel.h>
45	45	#include <linux/blkdev.h>
46	46	#include <linux/slab.h>
	47	+#include <linux/crc32c.h>
47	48	#include <linux/module.h>
48	49	#include <linux/mutex.h>
49	50	#include <linux/file.h>
...	...	@@ -81,6 +81,7 @@
81	81	#define XFS_SB_VERSION2_ATTR2BIT 0x00000008 /* Inline attr rework */
82	82	#define XFS_SB_VERSION2_PARENTBIT 0x00000010 /* parent pointers */
83	83	#define XFS_SB_VERSION2_PROJID32BIT 0x00000080 /* 32 bit project id */
	84	+#define XFS_SB_VERSION2_CRCBIT 0x00000100 /* metadata CRCs */
84	85
85	86	#define XFS_SB_VERSION2_OKREALFBITS \
86	87	(XFS_SB_VERSION2_LAZYSBCOUNTBIT \| \
...	...	@@ -501,6 +502,12 @@
501	502	{
502	503	return xfs_sb_version_hasmorebits(sbp) &&
503	504	(sbp->sb_features2 & XFS_SB_VERSION2_PROJID32BIT);
	505	+}
	506	+
	507	+static inline int xfs_sb_version_hascrc(xfs_sb_t *sbp)
	508	+{
	509	+ return (xfs_sb_version_hasmorebits(sbp) &&
	510	+ (sbp->sb_features2 & XFS_SB_VERSION2_CRCBIT));
504	511	}
505	512
506	513	/*