[dm-devel] dm log: struct log_write_super and padding (was: Re: dm: add log writes target)
Geert Uytterhoeven
geert at linux-m68k.org
Sat Apr 18 22:16:05 UTC 2015
On Sat, Apr 18, 2015 at 2:34 PM, Linux Kernel Mailing List
<linux-kernel at vger.kernel.org> wrote:
> Gitweb: http://git.kernel.org/linus/;a=commit;h=0e9cebe724597a76ab1b0ebc0a21e16f7db11b47
> Commit: 0e9cebe724597a76ab1b0ebc0a21e16f7db11b47
> --- /dev/null
> +++ b/drivers/md/dm-log-writes.c
> @@ -0,0 +1,825 @@
> +/*
> + * Basic info about the log for userspace.
> + */
> +struct log_write_super {
> + __le64 magic;
> + __le64 version;
> + __le64 nr_entries;
> + __le32 sectorsize;
Should there be an explicit padding of 4 bytes?
Does anything assume that sizeof(struct log_write_super) is always 4 * 8?
On architectures where the natural alignment of 64-bit quantities is less
than 8 bytes, sizeof(struct log_write_super) is smaller than 32 bytes
(e.g. on m68k it's 28).
> +};
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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