1 files changed, 211 insertions, 126 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index b98765f6f77f..e75d48c0421a 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -296,12 +296,9 @@ static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
 	BUG_ON(atomic_read(&conf->active_stripes)==0);
 	if (test_bit(STRIPE_HANDLE, &sh->state)) {
 		if (test_bit(STRIPE_DELAYED, &sh->state) &&
-		    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
+		    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 			list_add_tail(&sh->lru, &conf->delayed_list);
-			if (atomic_read(&conf->preread_active_stripes)
-			    < IO_THRESHOLD)
-				md_wakeup_thread(conf->mddev->thread);
-		} else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
+		else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 			   sh->bm_seq - conf->seq_write > 0)
 			list_add_tail(&sh->lru, &conf->bitmap_list);
 		else {
@@ -2898,31 +2895,102 @@ static int want_replace(struct stripe_head *sh, int disk_idx)
  * Returns 1 when no more member devices need to be checked, otherwise returns
  * 0 to tell the loop in handle_stripe_fill to continue
  */
-static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
-		       int disk_idx, int disks)
+
+static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
+			   int disk_idx, int disks)
 {
 	struct r5dev *dev = &sh->dev[disk_idx];
 	struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
 				  &sh->dev[s->failed_num[1]] };
+	int i;
+
+
+	if (test_bit(R5_LOCKED, &dev->flags) ||
+	    test_bit(R5_UPTODATE, &dev->flags))
+		/* No point reading this as we already have it or have
+		 * decided to get it.
+		 */
+		return 0;
+
+	if (dev->toread ||
+	    (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
+		/* We need this block to directly satisfy a request */
+		return 1;
+
+	if (s->syncing || s->expanding ||
+	    (s->replacing && want_replace(sh, disk_idx)))
+		/* When syncing, or expanding we read everything.
+		 * When replacing, we need the replaced block.
+		 */
+		return 1;
+
+	if ((s->failed >= 1 && fdev[0]->toread) ||
+	    (s->failed >= 2 && fdev[1]->toread))
+		/* If we want to read from a failed device, then
+		 * we need to actually read every other device.
+		 */
+		return 1;
+
+	/* Sometimes neither read-modify-write nor reconstruct-write
+	 * cycles can work.  In those cases we read every block we
+	 * can.  Then the parity-update is certain to have enough to
+	 * work with.
+	 * This can only be a problem when we need to write something,
+	 * and some device has failed.  If either of those tests
+	 * fail we need look no further.
+	 */
+	if (!s->failed || !s->to_write)
+		return 0;
+
+	if (test_bit(R5_Insync, &dev->flags) &&
+	    !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
+		/* Pre-reads at not permitted until after short delay
+		 * to gather multiple requests.  However if this
+		 * device is no Insync, the block could only be be computed
+		 * and there is no need to delay that.
+		 */
+		return 0;
+
+	for (i = 0; i < s->failed; i++) {
+		if (fdev[i]->towrite &&
+		    !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
+		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
+			/* If we have a partial write to a failed
+			 * device, then we will need to reconstruct
+			 * the content of that device, so all other
+			 * devices must be read.
+			 */
+			return 1;
+	}
+
+	/* If we are forced to do a reconstruct-write, either because
+	 * the current RAID6 implementation only supports that, or
+	 * or because parity cannot be trusted and we are currently
+	 * recovering it, there is extra need to be careful.
+	 * If one of the devices that we would need to read, because
+	 * it is not being overwritten (and maybe not written at all)
+	 * is missing/faulty, then we need to read everything we can.
+	 */
+	if (sh->raid_conf->level != 6 &&
+	    sh->sector < sh->raid_conf->mddev->recovery_cp)
+		/* reconstruct-write isn't being forced */
+		return 0;
+	for (i = 0; i < s->failed; i++) {
+		if (!test_bit(R5_UPTODATE, &fdev[i]->flags) &&
+		    !test_bit(R5_OVERWRITE, &fdev[i]->flags))
+			return 1;
+	}
+
+	return 0;
+}
+
+static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
+		       int disk_idx, int disks)
+{
+	struct r5dev *dev = &sh->dev[disk_idx];
 
 	/* is the data in this block needed, and can we get it? */
-	if (!test_bit(R5_LOCKED, &dev->flags) &&
-	    !test_bit(R5_UPTODATE, &dev->flags) &&
-	    (dev->toread ||
-	     (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
-	     s->syncing || s->expanding ||
-	     (s->replacing && want_replace(sh, disk_idx)) ||
-	     (s->failed >= 1 && fdev[0]->toread) ||
-	     (s->failed >= 2 && fdev[1]->toread) ||
-	     (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
-	      (!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) &&
-	      !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
-	     ((sh->raid_conf->level == 6 ||
-	       sh->sector >= sh->raid_conf->mddev->recovery_cp)
-	      && s->failed && s->to_write &&
-	      (s->to_write - s->non_overwrite <
-	       sh->raid_conf->raid_disks - sh->raid_conf->max_degraded) &&
-	      (!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))))) {
+	if (need_this_block(sh, s, disk_idx, disks)) {
 		/* we would like to get this block, possibly by computing it,
 		 * otherwise read it if the backing disk is insync
 		 */
@@ -3102,7 +3170,8 @@ static void handle_stripe_dirtying(struct r5conf *conf,
 	 * generate correct data from the parity.
 	 */
 	if (conf->max_degraded == 2 ||
-	    (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
+	    (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
+	     s->failed == 0)) {
 		/* Calculate the real rcw later - for now make it
 		 * look like rcw is cheaper
 		 */
@@ -4081,7 +4150,7 @@ static void activate_bit_delay(struct r5conf *conf,
 	}
 }
 
-int md_raid5_congested(struct mddev *mddev, int bits)
+static int raid5_congested(struct mddev *mddev, int bits)
 {
 	struct r5conf *conf = mddev->private;
 
@@ -4098,24 +4167,14 @@ int md_raid5_congested(struct mddev *mddev, int bits)
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(md_raid5_congested);
-
-static int raid5_congested(void *data, int bits)
-{
-	struct mddev *mddev = data;
-
-	return mddev_congested(mddev, bits) ||
-		md_raid5_congested(mddev, bits);
-}
 
 /* We want read requests to align with chunks where possible,
  * but write requests don't need to.
  */
-static int raid5_mergeable_bvec(struct request_queue *q,
+static int raid5_mergeable_bvec(struct mddev *mddev,
 				struct bvec_merge_data *bvm,
 				struct bio_vec *biovec)
 {
-	struct mddev *mddev = q->queuedata;
 	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 	int max;
 	unsigned int chunk_sectors = mddev->chunk_sectors;
@@ -5296,11 +5355,14 @@ static void raid5d(struct md_thread *thread)
 static ssize_t
 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
 {
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf;
+	int ret = 0;
+	spin_lock(&mddev->lock);
+	conf = mddev->private;
 	if (conf)
-		return sprintf(page, "%d\n", conf->max_nr_stripes);
-	else
-		return 0;
+		ret = sprintf(page, "%d\n", conf->max_nr_stripes);
+	spin_unlock(&mddev->lock);
+	return ret;
 }
 
 int
@@ -5339,21 +5401,25 @@ EXPORT_SYMBOL(raid5_set_cache_size);
 static ssize_t
 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
 {
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf;
 	unsigned long new;
 	int err;
 
 	if (len >= PAGE_SIZE)
 		return -EINVAL;
-	if (!conf)
-		return -ENODEV;
-
 	if (kstrtoul(page, 10, &new))
 		return -EINVAL;
-	err = raid5_set_cache_size(mddev, new);
+	err = mddev_lock(mddev);
 	if (err)
 		return err;
-	return len;
+	conf = mddev->private;
+	if (!conf)
+		err = -ENODEV;
+	else
+		err = raid5_set_cache_size(mddev, new);
+	mddev_unlock(mddev);
+
+	return err ?: len;
 }
 
 static struct md_sysfs_entry
@@ -5364,29 +5430,40 @@ raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
 static ssize_t
 raid5_show_preread_threshold(struct mddev *mddev, char *page)
 {
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf;
+	int ret = 0;
+	spin_lock(&mddev->lock);
+	conf = mddev->private;
 	if (conf)
-		return sprintf(page, "%d\n", conf->bypass_threshold);
-	else
-		return 0;
+		ret = sprintf(page, "%d\n", conf->bypass_threshold);
+	spin_unlock(&mddev->lock);
+	return ret;
 }
 
 static ssize_t
 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
 {
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf;
 	unsigned long new;
+	int err;
+
 	if (len >= PAGE_SIZE)
 		return -EINVAL;
-	if (!conf)
-		return -ENODEV;
-
 	if (kstrtoul(page, 10, &new))
 		return -EINVAL;
-	if (new > conf->max_nr_stripes)
-		return -EINVAL;
-	conf->bypass_threshold = new;
-	return len;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	conf = mddev->private;
+	if (!conf)
+		err = -ENODEV;
+	else if (new > conf->max_nr_stripes)
+		err = -EINVAL;
+	else
+		conf->bypass_threshold = new;
+	mddev_unlock(mddev);
+	return err ?: len;
 }
 
 static struct md_sysfs_entry
@@ -5398,39 +5475,48 @@ raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
 static ssize_t
 raid5_show_skip_copy(struct mddev *mddev, char *page)
 {
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf;
+	int ret = 0;
+	spin_lock(&mddev->lock);
+	conf = mddev->private;
 	if (conf)
-		return sprintf(page, "%d\n", conf->skip_copy);
-	else
-		return 0;
+		ret = sprintf(page, "%d\n", conf->skip_copy);
+	spin_unlock(&mddev->lock);
+	return ret;
 }
 
 static ssize_t
 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
 {
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf;
 	unsigned long new;
+	int err;
+
 	if (len >= PAGE_SIZE)
 		return -EINVAL;
-	if (!conf)
-		return -ENODEV;
-
 	if (kstrtoul(page, 10, &new))
 		return -EINVAL;
 	new = !!new;
-	if (new == conf->skip_copy)
-		return len;
 
-	mddev_suspend(mddev);
-	conf->skip_copy = new;
-	if (new)
-		mddev->queue->backing_dev_info.capabilities |=
-						BDI_CAP_STABLE_WRITES;
-	else
-		mddev->queue->backing_dev_info.capabilities &=
-						~BDI_CAP_STABLE_WRITES;
-	mddev_resume(mddev);
-	return len;
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	conf = mddev->private;
+	if (!conf)
+		err = -ENODEV;
+	else if (new != conf->skip_copy) {
+		mddev_suspend(mddev);
+		conf->skip_copy = new;
+		if (new)
+			mddev->queue->backing_dev_info.capabilities |=
+				BDI_CAP_STABLE_WRITES;
+		else
+			mddev->queue->backing_dev_info.capabilities &=
+				~BDI_CAP_STABLE_WRITES;
+		mddev_resume(mddev);
+	}
+	mddev_unlock(mddev);
+	return err ?: len;
 }
 
 static struct md_sysfs_entry
@@ -5454,11 +5540,14 @@ raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
 static ssize_t
 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
 {
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf;
+	int ret = 0;
+	spin_lock(&mddev->lock);
+	conf = mddev->private;
 	if (conf)
-		return sprintf(page, "%d\n", conf->worker_cnt_per_group);
-	else
-		return 0;
+		ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
+	spin_unlock(&mddev->lock);
+	return ret;
 }
 
 static int alloc_thread_groups(struct r5conf *conf, int cnt,
@@ -5468,7 +5557,7 @@ static int alloc_thread_groups(struct r5conf *conf, int cnt,
 static ssize_t
 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
 {
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf;
 	unsigned long new;
 	int err;
 	struct r5worker_group *new_groups, *old_groups;
@@ -5476,41 +5565,41 @@ raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
 
 	if (len >= PAGE_SIZE)
 		return -EINVAL;
-	if (!conf)
-		return -ENODEV;
-
 	if (kstrtoul(page, 10, &new))
 		return -EINVAL;
 
-	if (new == conf->worker_cnt_per_group)
-		return len;
-
-	mddev_suspend(mddev);
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	conf = mddev->private;
+	if (!conf)
+		err = -ENODEV;
+	else if (new != conf->worker_cnt_per_group) {
+		mddev_suspend(mddev);
 
-	old_groups = conf->worker_groups;
-	if (old_groups)
-		flush_workqueue(raid5_wq);
+		old_groups = conf->worker_groups;
+		if (old_groups)
+			flush_workqueue(raid5_wq);
 
-	err = alloc_thread_groups(conf, new,
-				  &group_cnt, &worker_cnt_per_group,
-				  &new_groups);
-	if (!err) {
-		spin_lock_irq(&conf->device_lock);
-		conf->group_cnt = group_cnt;
-		conf->worker_cnt_per_group = worker_cnt_per_group;
-		conf->worker_groups = new_groups;
-		spin_unlock_irq(&conf->device_lock);
+		err = alloc_thread_groups(conf, new,
+					  &group_cnt, &worker_cnt_per_group,
+					  &new_groups);
+		if (!err) {
+			spin_lock_irq(&conf->device_lock);
+			conf->group_cnt = group_cnt;
+			conf->worker_cnt_per_group = worker_cnt_per_group;
+			conf->worker_groups = new_groups;
+			spin_unlock_irq(&conf->device_lock);
 
-		if (old_groups)
-			kfree(old_groups[0].workers);
-		kfree(old_groups);
+			if (old_groups)
+				kfree(old_groups[0].workers);
+			kfree(old_groups);
+		}
+		mddev_resume(mddev);
 	}
+	mddev_unlock(mddev);
 
-	mddev_resume(mddev);
-
-	if (err)
-		return err;
-	return len;
+	return err ?: len;
 }
 
 static struct md_sysfs_entry
@@ -6178,11 +6267,6 @@ static int run(struct mddev *mddev)
 		if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
 			mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
 
-		blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
-
-		mddev->queue->backing_dev_info.congested_data = mddev;
-		mddev->queue->backing_dev_info.congested_fn = raid5_congested;
-
 		chunk_size = mddev->chunk_sectors << 9;
 		blk_queue_io_min(mddev->queue, chunk_size);
 		blk_queue_io_opt(mddev->queue, chunk_size *
@@ -6260,17 +6344,12 @@ abort:
 	return -EIO;
 }
 
-static int stop(struct mddev *mddev)
+static void raid5_free(struct mddev *mddev, void *priv)
 {
-	struct r5conf *conf = mddev->private;
+	struct r5conf *conf = priv;
 
-	md_unregister_thread(&mddev->thread);
-	if (mddev->queue)
-		mddev->queue->backing_dev_info.congested_fn = NULL;
 	free_conf(conf);
-	mddev->private = NULL;
 	mddev->to_remove = &raid5_attrs_group;
-	return 0;
 }
 
 static void status(struct seq_file *seq, struct mddev *mddev)
@@ -7044,7 +7123,7 @@ static struct md_personality raid6_personality =
 	.owner		= THIS_MODULE,
 	.make_request	= make_request,
 	.run		= run,
-	.stop		= stop,
+	.free		= raid5_free,
 	.status		= status,
 	.error_handler	= error,
 	.hot_add_disk	= raid5_add_disk,
@@ -7058,6 +7137,8 @@ static struct md_personality raid6_personality =
 	.finish_reshape = raid5_finish_reshape,
 	.quiesce	= raid5_quiesce,
 	.takeover	= raid6_takeover,
+	.congested	= raid5_congested,
+	.mergeable_bvec	= raid5_mergeable_bvec,
 };
 static struct md_personality raid5_personality =
 {
@@ -7066,7 +7147,7 @@ static struct md_personality raid5_personality =
 	.owner		= THIS_MODULE,
 	.make_request	= make_request,
 	.run		= run,
-	.stop		= stop,
+	.free		= raid5_free,
 	.status		= status,
 	.error_handler	= error,
 	.hot_add_disk	= raid5_add_disk,
@@ -7080,6 +7161,8 @@ static struct md_personality raid5_personality =
 	.finish_reshape = raid5_finish_reshape,
 	.quiesce	= raid5_quiesce,
 	.takeover	= raid5_takeover,
+	.congested	= raid5_congested,
+	.mergeable_bvec	= raid5_mergeable_bvec,
 };
 
 static struct md_personality raid4_personality =
@@ -7089,7 +7172,7 @@ static struct md_personality raid4_personality =
 	.owner		= THIS_MODULE,
 	.make_request	= make_request,
 	.run		= run,
-	.stop		= stop,
+	.free		= raid5_free,
 	.status		= status,
 	.error_handler	= error,
 	.hot_add_disk	= raid5_add_disk,
@@ -7103,6 +7186,8 @@ static struct md_personality raid4_personality =
 	.finish_reshape = raid5_finish_reshape,
 	.quiesce	= raid5_quiesce,
 	.takeover	= raid4_takeover,
+	.congested	= raid5_congested,
+	.mergeable_bvec	= raid5_mergeable_bvec,
 };
 
 static int __init raid5_init(void)