Re: [PATCH 06/14] audit: Factor out chunk replacement code

On Wed, Nov 7, 2018 at 4:55 AM Jan Kara <jack(a)suse.cz&gt; wrote: > On Tue 06-11-18 08:58:36, Paul Moore wrote: > > On Thu, Oct 18, 2018 at 3:27 PM Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > > > On 2018-10-17 12:14, Jan Kara wrote: > > > > Chunk replacement code is very similar for the cases where we grow or > > > > shrink chunk. Factor the code out into a common helper function. > > > > > > Noting just the switch from list_replace_init() to list_splice_init(). > > > > Yeah, I wasn't expecting to see that, maybe it will make sense as I > > work through the rest of the patchset. > > > > Jan, can you explain the reason behind the change? I'm a little > > nervous that this is simply hiding a problem (e.g. the list_empty() > > check in splice). > > The reason is very simple: replace_chunk() gets called from tag_chunk() > *after* we have possibly done: > > if (!tree->root) { > tree->root = chunk; > list_add(&tree->same_root, &chunk->trees); > } > > So new->trees is possibly non-empty and we need to preserve its contents. > That's why we need list_splice() and not plain list_replace(). After revisiting this a couple of time this week, I found my problem - I had reversed list_splice_init() in my mind and was worried that if the old->trees list was not empty we would end up not adding new->trees. Sorry about the noise. I've updated the audit/working-fsnotify_fixes with the latest patches, including the revised 12/14 sent as an attachment, and I'm going to test it over the weekend. If the kernel is still standing on Monday morning I'll merge it into audit/next. Thanks again.