Re: [PATCH] Re: fs corruption with invalidate_buffers()

From: Linus Torvalds (torvalds@transmeta.com)
Date: Thu Dec 21 2000 - 20:01:00 EST


On Fri, 22 Dec 2000, Jan Niehusmann wrote:
>
> The test I did initially was the following:
>
> if(!atomic_read(&bh->b_count) &&
> (destroy_dirty_buffers || !buffer_dirty(bh))
> && ! (bh->b_page && bh->b_page->mapping)
> )
>
> That is, I was explicitely checking for a mapped page. It worked well, too.
> Is this more reasonable?

I'd suggest just doing this instead (warning: cut-and-paste in xterm, so
white-space damage):

        --- linux/fs/buffer.c.old Wed Dec 20 17:50:56 2000
        +++ linux/fs/buffer.c Thu Dec 21 16:42:11 2000
        @@ -639,8 +639,13 @@
                                continue;
                        for (i = nr_buffers_type[nlist]; i > 0 ; bh = bh_next, i--) {
                                bh_next = bh->b_next_free;
        +
        + /* Another device? */
                                if (bh->b_dev != dev)
                                        continue;
        + /* Part of a mapping? */
        + if (bh->b_page->mapping)
        + continue;
                                if (buffer_locked(bh)) {
                                        atomic_inc(&bh->b_count);
                                        spin_unlock(&lru_list_lock);

which just ignores mapped buffers entirely (and doesn't test for
bh->b_page being non-NULL, because that shouldn't be allowed anyway).

                Linus

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