Wu Fengguang <fengguang.wu@xxxxxxxxx> writes:
> * the ra fields can be accessed concurrently in a racy way.
> --- linux.orig/mm/fadvise.c 2009-12-30 13:02:03.000000000 +0800
> +++ linux/mm/fadvise.c 2009-12-30 13:23:05.000000000 +0800
> @@ -77,12 +77,14 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, lof
> switch (advice) {
> case POSIX_FADV_NORMAL:
> file->f_ra.ra_pages = bdi->ra_pages;
> + file->f_ra.flags &= ~RA_FLAG_RANDOM;
> break;
> case POSIX_FADV_RANDOM:
> - file->f_ra.ra_pages = 0;
> + file->f_ra.flags |= RA_FLAG_RANDOM;
What prevents this from racing with a parallel readahead
state modification, losing the bits?
-Andi
--
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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