Commit 4d167f09 authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
Browse files

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: default avatarNeil Brown <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent e11e93fa
......@@ -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);
/* 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);
sb->sb_csum = disk_csum;
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",
goto abort;
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