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SubjectRe: [PATCH 1/2] md/raid5: avoid duplicate code
On Fri, May 08, 2015 at 03:28:00PM +1000, NeilBrown wrote:
> On Wed, 6 May 2015 17:45:49 +0800 Yuanhan Liu <yuanhan.liu@linux.intel.com>
> wrote:
>
> > Move the code that put one idle sh(hot in cache, but happens to be
> > zero referenced) back to active stage to __find_stripe(). Because
> > that's what need to do every time you invoke __find_stripe().
> >
> > Moving it there avoids duplicate code, as well as makes a bit more
> > sense, IMO, as it tells a whole story now.
>
> Thanks for this. It is a good cleanup.
>
> However I don't want to make any new changes to the RAID5 code until I find a
> couple of bugs that I'm hunting. So I won't apply it just yet.
> Remind me in a couple of weeks if I seem to have forgotten.

Got it. Thanks.


--yliu
>
> >
> > Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> > ---
> > drivers/md/raid5.c | 50 ++++++++++++++++++--------------------------------
> > 1 file changed, 18 insertions(+), 32 deletions(-)
> >
> > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> > index 77dfd72..e7fa818 100644
> > --- a/drivers/md/raid5.c
> > +++ b/drivers/md/raid5.c
> > @@ -567,8 +567,25 @@ static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
> >
> > pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
> > hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
> > - if (sh->sector == sector && sh->generation == generation)
> > + if (sh->sector == sector && sh->generation == generation) {
> > + if (!atomic_inc_not_zero(&sh->count)) {
> > + spin_lock(&conf->device_lock);
> > + if (!atomic_read(&sh->count)) {
> > + if (!test_bit(STRIPE_HANDLE, &sh->state))
> > + atomic_inc(&conf->active_stripes);
> > + BUG_ON(list_empty(&sh->lru) &&
> > + !test_bit(STRIPE_EXPANDING, &sh->state));
> > + list_del_init(&sh->lru);
> > + if (sh->group) {
> > + sh->group->stripes_cnt--;
> > + sh->group = NULL;
> > + }
> > + }
> > + atomic_inc(&sh->count);
> > + spin_unlock(&conf->device_lock);
> > + }
> > return sh;
> > + }
> > pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
> > return NULL;
> > }
> > @@ -698,21 +715,6 @@ get_active_stripe(struct r5conf *conf, sector_t sector,
> > init_stripe(sh, sector, previous);
> > atomic_inc(&sh->count);
> > }
> > - } else if (!atomic_inc_not_zero(&sh->count)) {
> > - spin_lock(&conf->device_lock);
> > - if (!atomic_read(&sh->count)) {
> > - if (!test_bit(STRIPE_HANDLE, &sh->state))
> > - atomic_inc(&conf->active_stripes);
> > - BUG_ON(list_empty(&sh->lru) &&
> > - !test_bit(STRIPE_EXPANDING, &sh->state));
> > - list_del_init(&sh->lru);
> > - if (sh->group) {
> > - sh->group->stripes_cnt--;
> > - sh->group = NULL;
> > - }
> > - }
> > - atomic_inc(&sh->count);
> > - spin_unlock(&conf->device_lock);
> > }
> > } while (sh == NULL);
> >
> > @@ -771,22 +773,6 @@ static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh
> > hash = stripe_hash_locks_hash(head_sector);
> > spin_lock_irq(conf->hash_locks + hash);
> > head = __find_stripe(conf, head_sector, conf->generation);
> > - if (head && !atomic_inc_not_zero(&head->count)) {
> > - spin_lock(&conf->device_lock);
> > - if (!atomic_read(&head->count)) {
> > - if (!test_bit(STRIPE_HANDLE, &head->state))
> > - atomic_inc(&conf->active_stripes);
> > - BUG_ON(list_empty(&head->lru) &&
> > - !test_bit(STRIPE_EXPANDING, &head->state));
> > - list_del_init(&head->lru);
> > - if (head->group) {
> > - head->group->stripes_cnt--;
> > - head->group = NULL;
> > - }
> > - }
> > - atomic_inc(&head->count);
> > - spin_unlock(&conf->device_lock);
> > - }
> > spin_unlock_irq(conf->hash_locks + hash);
> >
> > if (!head)
>




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