Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=4d167f09375bd6c18447d3fcc18baaf3acd15fbc
Commit:     4d167f09375bd6c18447d3fcc18baaf3acd15fbc
Parent:     e11e93facc38fb264a5ff1e154ebb2f11dc5cffa
Author:     NeilBrown <[EMAIL PROTECTED]>
AuthorDate: Wed May 9 02:35:37 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Wed May 9 12:30:57 2007 -0700

    md: stop using csum_partial for checksum calculation in md
    
    If CONFIG_NET is not selected, csum_partial is not exported, so md.ko cannot
    use it.  We shouldn't really be using csum_partial anyway as it is an
    internal-to-networking interface.
    
    So replace it with C code to do the same thing.  Speed is not crucial here, 
so
    something simple and correct is best.
    
    Signed-off-by: Neil Brown <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 drivers/md/md.c |   31 +++++++++++++++++++++++++++++--
 1 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 64b35cb..bad3241 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -590,14 +590,41 @@ abort:
        return ret;
 }
 
+
+static u32 md_csum_fold(u32 csum)
+{
+       csum = (csum & 0xffff) + (csum >> 16);
+       return (csum & 0xffff) + (csum >> 16);
+}
+
 static unsigned int calc_sb_csum(mdp_super_t * sb)
 {
+       u64 newcsum = 0;
+       u32 *sb32 = (u32*)sb;
+       int i;
        unsigned int disk_csum, csum;
 
        disk_csum = sb->sb_csum;
        sb->sb_csum = 0;
-       csum = csum_partial((void *)sb, MD_SB_BYTES, 0);
+
+       for (i = 0; i < MD_SB_BYTES/4 ; i++)
+               newcsum += sb32[i];
+       csum = (newcsum & 0xffffffff) + (newcsum>>32);
+
+
+#ifdef CONFIG_ALPHA
+       /* This used to use csum_partial, which was wrong for several
+        * reasons including that different results are returned on
+        * different architectures.  It isn't critical that we get exactly
+        * the same return value as before (we always csum_fold before
+        * testing, and that removes any differences).  However as we
+        * know that csum_partial always returned a 16bit value on
+        * alphas, do a fold to maximise conformity to previous behaviour.
+        */
+       sb->sb_csum = md_csum_fold(disk_csum);
+#else
        sb->sb_csum = disk_csum;
+#endif
        return csum;
 }
 
@@ -685,7 +712,7 @@ static int super_90_load(mdk_rdev_t *rdev, mdk_rdev_t 
*refdev, int minor_version
        if (sb->raid_disks <= 0)
                goto abort;
 
-       if (csum_fold(calc_sb_csum(sb)) != csum_fold(sb->sb_csum)) {
+       if (md_csum_fold(calc_sb_csum(sb)) != md_csum_fold(sb->sb_csum)) {
                printk(KERN_WARNING "md: invalid superblock checksum on %s\n",
                        b);
                goto abort;
-
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