On Thursday March 16, akpm@xxxxxxxx wrote:
> NeilBrown <neilb@xxxxxxx> wrote:
> >
> > +static int resize_stripes(raid5_conf_t *conf, int newsize)
> > +{
> > + /* make all the stripes able to hold 'newsize' devices.
> > + * New slots in each stripe get 'page' set to a new page.
> > + * We allocate all the new stripes first, then if that succeeds,
> > + * copy everything across.
> > + * Finally we add new pages. This could fail, but we leave
> > + * the stripe cache at it's new size, just with some pages empty.
> > + *
> > + * We use GFP_NOIO allocations as IO to the raid5 is blocked
> > + * at some points in this operation.
> > + */
> > + struct stripe_head *osh, *nsh;
> > + struct list_head newstripes, oldstripes;
>
> You can use LIST_HEAD() here, avoid the separate INIT_LIST_HEAD().
>
I guess.....
I have to have the declaration "miles" from where I use the variable.
Do I have to have the initialisation equally far? Ok, I'll do that..
>
> > + struct disk_info *ndisks;
> > + int err = 0;
> > + kmem_cache_t *sc;
> > + int i;
> > +
> > + if (newsize <= conf->pool_size)
> > + return 0; /* never bother to shrink */
> > +
> > + sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
> > + sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
> > + 0, 0, NULL, NULL);
>
> kmem_cache_create() internally does a GFP_KERNEL allocation.
>
> > + if (!sc)
> > + return -ENOMEM;
> > + INIT_LIST_HEAD(&newstripes);
> > + for (i = conf->max_nr_stripes; i; i--) {
> > + nsh = kmem_cache_alloc(sc, GFP_NOIO);
>
> So either this can use GFP_KERNEL, or we have a problem.
Good point.... Maybe the comment about GFP_NOIO just needs to be
improved.
We cannot risk waiting on IO after the
/* OK, we have enough stripes, start collecting inactive
* stripes and copying them over
*/
comment, up to the second last while loop, that starts
while(!list_empty(&newstripes)) {
Before the comment, which where the kmem_cache_create is, is OK.
Thanks!
NeilBrown
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