[Btrfs-devel][PATCH]Minor fix for btrfs_csum_file_block.

[Chris Mason]

On Tue, 30 Oct 2007 07:13:46 +0800
"Yan Zheng" <yanzheng at 21cn.com> wrote:

> 2007/10/30, Chris Mason <chris.mason at oracle.com>:
> > I made one small change here:
> > > @@ -238,7 +236,7 @@ insert:
> > >       csum_offset = 0;
> > >       if (found_next) {
> > >               u64 tmp = min((u64)i_size_read(inode), next_offset);
> > > -             tmp -= offset + root->sectorsize - 1;
> > > +             tmp -= offset - root->sectorsize + 1;
> >                 tmp -= offset & ~((u64)root->sectorsize - 1);
> 
> 'offset' is already aligned to sector size,  so this line is
> equivalent to 'tmp -= offset'.   I think it's better change this line
> to 'tmp = tmp - offset + root->sectorsize - 1'

In this case, we're calculating the number of csums we're going to
insert, and so it should include the csum for the block we were
passed.  So, tmp -= offset is correct.  The extra alignment is mostly
paranoia.

-chris