md/raid5: use seqcount to protect access to shape in make_request.
make_request() access various shape parameters (raid_disks, chunk_size etc) which might be changed by raid5_start_reshape(). If the later is called at and awkward time during the form, the wrong stripe_head might be used. So introduce a 'seqcount' and after finding a stripe_head make sure there is no reason to expect that we got the wrong one. Signed-off-by: NeilBrown <neilb@suse.de>
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@ -4408,8 +4408,10 @@ static void make_request(struct mddev *mddev, struct bio * bi)
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for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
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for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
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DEFINE_WAIT(w);
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DEFINE_WAIT(w);
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int previous;
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int previous;
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int seq;
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retry:
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retry:
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seq = read_seqcount_begin(&conf->gen_lock);
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previous = 0;
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previous = 0;
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prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
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prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
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if (unlikely(conf->reshape_progress != MaxSector)) {
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if (unlikely(conf->reshape_progress != MaxSector)) {
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@ -4442,7 +4444,7 @@ static void make_request(struct mddev *mddev, struct bio * bi)
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previous,
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previous,
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&dd_idx, NULL);
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&dd_idx, NULL);
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pr_debug("raid456: make_request, sector %llu logical %llu\n",
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pr_debug("raid456: make_request, sector %llu logical %llu\n",
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(unsigned long long)new_sector,
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(unsigned long long)new_sector,
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(unsigned long long)logical_sector);
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(unsigned long long)logical_sector);
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sh = get_active_stripe(conf, new_sector, previous,
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sh = get_active_stripe(conf, new_sector, previous,
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@ -4471,6 +4473,13 @@ static void make_request(struct mddev *mddev, struct bio * bi)
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goto retry;
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goto retry;
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}
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}
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}
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}
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if (read_seqcount_retry(&conf->gen_lock, seq)) {
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/* Might have got the wrong stripe_head
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* by accident
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*/
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release_stripe(sh);
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goto retry;
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}
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if (rw == WRITE &&
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if (rw == WRITE &&
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logical_sector >= mddev->suspend_lo &&
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logical_sector >= mddev->suspend_lo &&
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@ -5437,6 +5446,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
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if (alloc_thread_groups(conf, 0))
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if (alloc_thread_groups(conf, 0))
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goto abort;
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goto abort;
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spin_lock_init(&conf->device_lock);
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spin_lock_init(&conf->device_lock);
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seqcount_init(&conf->gen_lock);
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init_waitqueue_head(&conf->wait_for_stripe);
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init_waitqueue_head(&conf->wait_for_stripe);
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init_waitqueue_head(&conf->wait_for_overlap);
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init_waitqueue_head(&conf->wait_for_overlap);
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INIT_LIST_HEAD(&conf->handle_list);
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INIT_LIST_HEAD(&conf->handle_list);
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@ -6249,6 +6259,7 @@ static int raid5_start_reshape(struct mddev *mddev)
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atomic_set(&conf->reshape_stripes, 0);
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atomic_set(&conf->reshape_stripes, 0);
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spin_lock_irq(&conf->device_lock);
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spin_lock_irq(&conf->device_lock);
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write_seqcount_begin(&conf->gen_lock);
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conf->previous_raid_disks = conf->raid_disks;
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conf->previous_raid_disks = conf->raid_disks;
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conf->raid_disks += mddev->delta_disks;
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conf->raid_disks += mddev->delta_disks;
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conf->prev_chunk_sectors = conf->chunk_sectors;
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conf->prev_chunk_sectors = conf->chunk_sectors;
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@ -6265,6 +6276,7 @@ static int raid5_start_reshape(struct mddev *mddev)
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else
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else
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conf->reshape_progress = 0;
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conf->reshape_progress = 0;
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conf->reshape_safe = conf->reshape_progress;
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conf->reshape_safe = conf->reshape_progress;
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write_seqcount_end(&conf->gen_lock);
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spin_unlock_irq(&conf->device_lock);
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spin_unlock_irq(&conf->device_lock);
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/* Add some new drives, as many as will fit.
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/* Add some new drives, as many as will fit.
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@ -400,6 +400,7 @@ struct r5conf {
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int prev_chunk_sectors;
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int prev_chunk_sectors;
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int prev_algo;
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int prev_algo;
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short generation; /* increments with every reshape */
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short generation; /* increments with every reshape */
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seqcount_t gen_lock; /* lock against generation changes */
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unsigned long reshape_checkpoint; /* Time we last updated
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unsigned long reshape_checkpoint; /* Time we last updated
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* metadata */
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* metadata */
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long long min_offset_diff; /* minimum difference between
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long long min_offset_diff; /* minimum difference between
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