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[PATCH 05/13] xfs: add CRC infrastructure

To: xfs@xxxxxxxxxxx
Subject: [PATCH 05/13] xfs: add CRC infrastructure
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Tue, 10 Feb 2009 15:22:46 -0500
References: <20090210202241.546501000@xxxxxxxxxxxxxxxxxxxxxx>
User-agent: quilt/0.47-1
 - add a mount feature bit for CRC enabled filesystems
 - add some helpers for generating and verifying the CRCs
 - add a copy_uuid helper
 - add a pre-io callback to xfs_buf for calculating the CRCs

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


Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Index: xfs/fs/xfs/Kconfig
===================================================================
--- xfs.orig/fs/xfs/Kconfig     2009-02-03 16:52:11.665916316 +0100
+++ xfs/fs/xfs/Kconfig  2009-02-05 19:04:41.218218577 +0100
@@ -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
Index: xfs/fs/xfs/linux-2.6/xfs_linux.h
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_linux.h       2009-02-05 17:53:06.742088475 
+0100
+++ xfs/fs/xfs/linux-2.6/xfs_linux.h    2009-02-05 19:04:31.269945065 +0100
@@ -72,6 +72,7 @@
 #include <linux/random.h>
 #include <linux/ctype.h>
 #include <linux/writeback.h>
+#include <linux/crc32c.h>
 
 #include <asm/page.h>
 #include <asm/div64.h>
Index: xfs/fs/xfs/xfs_sb.h
===================================================================
--- xfs.orig/fs/xfs/xfs_sb.h    2009-02-03 16:52:12.358436358 +0100
+++ xfs/fs/xfs/xfs_sb.h 2009-02-05 19:04:31.272973243 +0100
@@ -80,10 +80,12 @@ struct xfs_mount;
 #define XFS_SB_VERSION2_RESERVED4BIT   0x00000004
 #define XFS_SB_VERSION2_ATTR2BIT       0x00000008      /* Inline attr rework */
 #define XFS_SB_VERSION2_PARENTBIT      0x00000010      /* parent pointers */
+#define XFS_SB_VERSION2_CRCBIT         0x00000020      /* metadata has CRCs */
 
 #define        XFS_SB_VERSION2_OKREALFBITS     \
        (XFS_SB_VERSION2_LAZYSBCOUNTBIT | \
-        XFS_SB_VERSION2_ATTR2BIT)
+        XFS_SB_VERSION2_ATTR2BIT | \
+        XFS_SB_VERSION2_CRCBIT)
 #define        XFS_SB_VERSION2_OKSASHFBITS     \
        (0)
 #define XFS_SB_VERSION2_OKREALBITS     \
@@ -495,6 +497,12 @@ static inline void xfs_sb_version_remove
                sbp->sb_versionnum &= ~XFS_SB_VERSION_MOREBITSBIT;
 }
 
+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
  */
Index: xfs/fs/xfs/linux-2.6/xfs_buf.c
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_buf.c 2009-02-05 17:53:06.643944544 +0100
+++ xfs/fs/xfs/linux-2.6/xfs_buf.c      2009-02-05 19:04:31.273973789 +0100
@@ -1108,6 +1108,14 @@ _xfs_buf_ioapply(
                     (bp->b_flags & XBF_READ_AHEAD) ? READA : READ;
        }
 
+       /*
+        * call out to buffer specific pre-write I/O functions. Used for
+        * validation of buffers and CRC calculations prior to I/O issue.
+        */
+       if (bp->b_io_callback && (bp->b_flags & XBF_WRITE))
+               bp->b_io_callback(bp);
+
+
        /* Special code path for reading a sub page size buffer in --
         * we populate up the whole page, and hence the other metadata
         * in the same page.  This optimization is only valid when the
Index: xfs/fs/xfs/linux-2.6/xfs_buf.h
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_buf.h 2009-01-21 21:03:27.825295146 +0100
+++ xfs/fs/xfs/linux-2.6/xfs_buf.h      2009-02-05 19:04:31.273973789 +0100
@@ -174,6 +174,8 @@ typedef struct xfs_buf {
        unsigned int            b_offset;       /* page offset in first page */
        struct page             **b_pages;      /* array of page pointers */
        struct page             *b_page_array[XB_PAGES]; /* inline pages */
+       void                    (*b_io_callback)(struct xfs_buf *);
+                                               /* pre-write I/O callback */
 #ifdef XFS_BUF_LOCK_TRACKING
        int                     b_last_holder;
 #endif
@@ -236,6 +238,16 @@ static inline int xfs_buf_geterror(xfs_b
 /* Buffer Utility Routines */
 extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
 
+/*
+ * Set the function that should be called immediately prior
+ * to a write I/O being issued on this buffer.
+ */
+static inline void
+xfs_buf_set_io_callback(xfs_buf_t *bp, void (*func)(xfs_buf_t *))
+{
+       bp->b_io_callback = func;
+}
+
 /* Pinning Buffer Storage in Memory */
 extern void xfs_buf_pin(xfs_buf_t *);
 extern void xfs_buf_unpin(xfs_buf_t *);
Index: xfs/fs/xfs/support/uuid.c
===================================================================
--- xfs.orig/fs/xfs/support/uuid.c      2009-01-21 21:03:27.838294778 +0100
+++ xfs/fs/xfs/support/uuid.c   2009-02-05 19:04:31.274944514 +0100
@@ -72,6 +72,12 @@ uuid_equal(uuid_t *uuid1, uuid_t *uuid2)
        return memcmp(uuid1, uuid2, sizeof(uuid_t)) ? 0 : 1;
 }
 
+void
+uuid_copy(uuid_t *dst, uuid_t *src)
+{
+       memcpy(dst, src, sizeof(uuid_t));
+}
+
 /*
  * Given a 128-bit uuid, return a 64-bit value by adding the top and bottom
  * 64-bit words.  NOTE: This function can not be changed EVER.  Although
Index: xfs/fs/xfs/support/uuid.h
===================================================================
--- xfs.orig/fs/xfs/support/uuid.h      2009-01-21 21:03:27.838294778 +0100
+++ xfs/fs/xfs/support/uuid.h   2009-02-05 19:04:31.279944870 +0100
@@ -25,6 +25,7 @@ typedef struct {
 extern void uuid_create_nil(uuid_t *uuid);
 extern int uuid_is_nil(uuid_t *uuid);
 extern int uuid_equal(uuid_t *uuid1, uuid_t *uuid2);
+extern void uuid_copy(uuid_t *dst, uuid_t *src);
 extern void uuid_getnodeuniq(uuid_t *uuid, int fsid [2]);
 extern __uint64_t uuid_hash64(uuid_t *uuid);
 extern int uuid_table_insert(uuid_t *uuid);
Index: xfs/fs/xfs/xfs_cksum.h
===================================================================
--- /dev/null   1970-01-01 00:00:00.000000000 +0000
+++ xfs/fs/xfs/xfs_cksum.h      2009-02-05 19:04:31.282972630 +0100
@@ -0,0 +1,62 @@
+#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.
+ *
+ * Note that crc32c is already endianess agnostic, so no additional
+ * byte swap is needed.
+ */
+static inline __be32
+xfs_end_cksum(__uint32_t crc)
+{
+       return (__force __be32)~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);
+
+       *(__be32 *)(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 *(__be32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
+}
+
+#endif /* _XFS_CKSUM_H */
Index: xfs/fs/xfs/xfs_mount.c
===================================================================
--- xfs.orig/fs/xfs/xfs_mount.c 2009-02-05 17:53:07.338944053 +0100
+++ xfs/fs/xfs/xfs_mount.c      2009-02-05 19:04:31.286943944 +0100
@@ -569,6 +569,11 @@ xfs_mount_common(xfs_mount_t *mp, xfs_sb
        ASSERT(sbp->sb_inodesize ==  256 || sbp->sb_inodesize ==  512 ||
               sbp->sb_inodesize == 1024 || sbp->sb_inodesize == 2048);
 
+       if (xfs_sb_version_hascrc(sbp))
+               printk("XFS: using CRCs\n");
+       else
+               printk("XFS: not using CRCs\n");
+
        mp->m_agfrotor = mp->m_agirotor = 0;
        spin_lock_init(&mp->m_agirotor_lock);
        mp->m_maxagi = mp->m_sb.sb_agcount;

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