block: misc fixes and improvements

index 3a43c1d..5a1511e 100644
@@ -285,9 +285,7 @@ static int printk_partition(struct device *dev, void *data)
  */
 void __init printk_all_partitions(void)
 {
-	mutex_lock(&block_class_lock);
 	class_for_each_device(&block_class, NULL, NULL, printk_partition);
-	mutex_unlock(&block_class_lock);
 }
 
 #ifdef CONFIG_PROC_FS

@@ -311,7 +309,6 @@ static void *part_start(struct seq_file *part, loff_t *pos)
 	if (!n)
 		seq_puts(part, "major minor  #blocks  name\n\n");
 
-	mutex_lock(&block_class_lock);
 	dev = class_find_device(&block_class, NULL, &n, find_start);
 	if (dev)
 		return dev_to_disk(dev);

@@ -338,7 +335,6 @@ static void *part_next(struct seq_file *part, void *v, loff_t *pos)
 
 static void part_stop(struct seq_file *part, void *v)
 {
-	mutex_unlock(&block_class_lock);
 }
 
 static int show_partition(struct seq_file *part, void *v)

@@ -571,7 +567,6 @@ static void *diskstats_start(struct seq_file *part, loff_t *pos)
 	struct device *dev;
 	loff_t n = *pos;
 
-	mutex_lock(&block_class_lock);
 	dev = class_find_device(&block_class, NULL, &n, find_start);
 	if (dev)
 		return dev_to_disk(dev);

@@ -592,7 +587,6 @@ static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
 
 static void diskstats_stop(struct seq_file *part, void *v)
 {
-	mutex_unlock(&block_class_lock);
 }
 
 static int diskstats_show(struct seq_file *s, void *v)

@@ -711,14 +705,12 @@ dev_t blk_lookup_devt(const char *name, int part)
 	dev_t devt = MKDEV(0, 0);
 	struct find_block find;
 
-	mutex_lock(&block_class_lock);
 	find.name = name;
 	find.part = part;
 	dev = class_find_device(&block_class, NULL, (void *)&find, match_id);
 	if (dev)
 		devt = MKDEV(MAJOR(dev->devt),
 			     MINOR(dev->devt) + part);
-	mutex_unlock(&block_class_lock);
 
 	return devt;
 }

index 375c579..c722de0 100644
@@ -68,8 +68,6 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
 		case BLKPG_DEL_PARTITION:
 			if (!disk->part[part-1])
 				return -ENXIO;
-			if (disk->part[part - 1]->nr_sects == 0)
-				return -ENXIO;
 			bdevp = bdget_disk(disk, part);
 			if (!bdevp)
 				return -ENOMEM;

index 7d6b34e..1b1808e 100644
@@ -325,8 +325,6 @@ void delete_partition(struct gendisk *disk, int part)
 
 	if (!p)
 		return;
-	if (!p->nr_sects)
-		return;
 	disk->part[part-1] = NULL;
 	p->start_sect = 0;
 	p->nr_sects = 0;

index decc8f1..3a43c1d 100644
@@ -238,7 +238,7 @@ static int printk_partition(struct device *dev, void *data)
 	int n;
 
 	if (dev->type != &disk_type)
-		goto exit;
+		return 0;
 
 	sgp = dev_to_disk(dev);
 	/*

@@ -246,7 +246,7 @@ static int printk_partition(struct device *dev, void *data)
 	 */
 	if (get_capacity(sgp) == 0 ||
 	    (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
-		goto exit;
+		return 0;
 
 	/*
 	 * Note, unlike /proc/partitions, I am showing the numbers in

@@ -266,15 +266,15 @@ static int printk_partition(struct device *dev, void *data)
 	/* now show the partitions */
 	for (n = 0; n < sgp->minors - 1; ++n) {
 		if (sgp->part[n] == NULL)
-			goto exit;
+			continue;
 		if (sgp->part[n]->nr_sects == 0)
-			goto exit;
+			continue;
 		printk("  %02x%02x %10llu %s\n",
 			sgp->major, n + 1 + sgp->first_minor,
 			(unsigned long long)sgp->part[n]->nr_sects >> 1,
 			disk_name(sgp, n + 1, buf));
 	}
-exit:
+
 	return 0;
 }
 

@@ -294,11 +294,11 @@ void __init printk_all_partitions(void)
 /* iterator */
 static int find_start(struct device *dev, void *data)
 {
-	loff_t k = *(loff_t *)data;
+	loff_t *k = (loff_t *)data;
 
 	if (dev->type != &disk_type)
 		return 0;
-	if (!k--)
+	if (!(*k)--)
 		return 1;
 	return 0;
 }

@@ -312,7 +312,7 @@ static void *part_start(struct seq_file *part, loff_t *pos)
 		seq_puts(part, "major minor  #blocks  name\n\n");
 
 	mutex_lock(&block_class_lock);
-	dev = class_find_device(&block_class, NULL, (void *)pos, find_start);
+	dev = class_find_device(&block_class, NULL, &n, find_start);
 	if (dev)
 		return dev_to_disk(dev);
 	return NULL;

@@ -569,9 +569,10 @@ static struct device_type disk_type = {
 static void *diskstats_start(struct seq_file *part, loff_t *pos)
 {
 	struct device *dev;
+	loff_t n = *pos;
 
 	mutex_lock(&block_class_lock);
-	dev = class_find_device(&block_class, NULL, (void *)pos, find_start);
+	dev = class_find_device(&block_class, NULL, &n, find_start);
 	if (dev)
 		return dev_to_disk(dev);
 	return NULL;

index 5a1511e..e9d60fd 100644
@@ -228,113 +228,113 @@ struct gendisk *get_gendisk(dev_t devt, int *part)
 }
 
 /*
- * print a partitions - intended for places where the root filesystem can't be
- * mounted and thus to give the victim some idea of what went wrong
- */
-static int printk_partition(struct device *dev, void *data)
-{
-	struct gendisk *sgp;
-	char buf[BDEVNAME_SIZE];
-	int n;
-
-	if (dev->type != &disk_type)
-		return 0;
-
-	sgp = dev_to_disk(dev);
-	/*
-	 * Don't show empty devices or things that have been surpressed
-	 */
-	if (get_capacity(sgp) == 0 ||
-	    (sgp->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
-		return 0;
-
-	/*
-	 * Note, unlike /proc/partitions, I am showing the numbers in
-	 * hex - the same format as the root= option takes.
-	 */
-	printk("%02x%02x %10llu %s",
-		sgp->major, sgp->first_minor,
-		(unsigned long long)get_capacity(sgp) >> 1,
-		disk_name(sgp, 0, buf));
-	if (sgp->driverfs_dev != NULL &&
-	    sgp->driverfs_dev->driver != NULL)
-		printk(" driver: %s\n",
-			sgp->driverfs_dev->driver->name);
-	else
-		printk(" (driver?)\n");
-
-	/* now show the partitions */
-	for (n = 0; n < sgp->minors - 1; ++n) {
-		if (sgp->part[n] == NULL)
-			continue;
-		if (sgp->part[n]->nr_sects == 0)
-			continue;
-		printk("  %02x%02x %10llu %s\n",
-			sgp->major, n + 1 + sgp->first_minor,
-			(unsigned long long)sgp->part[n]->nr_sects >> 1,
-			disk_name(sgp, n + 1, buf));
-	}
-
-	return 0;
-}
-
-/*
  * print a full list of all partitions - intended for places where the root
  * filesystem can't be mounted and thus to give the victim some idea of what
  * went wrong
  */
 void __init printk_all_partitions(void)
 {
-	class_for_each_device(&block_class, NULL, NULL, printk_partition);
+	struct class_dev_iter iter;
+	struct device *dev;
+
+	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
+	while ((dev = class_dev_iter_next(&iter))) {
+		struct gendisk *disk = dev_to_disk(dev);
+		char buf[BDEVNAME_SIZE];
+		int n;
+
+		/*
+		 * Don't show empty devices or things that have been
+		 * surpressed
+		 */
+		if (get_capacity(disk) == 0 ||
+		    (disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
+			continue;
+
+		/*
+		 * Note, unlike /proc/partitions, I am showing the
+		 * numbers in hex - the same format as the root=
+		 * option takes.
+		 */
+		printk("%02x%02x %10llu %s",
+		       disk->major, disk->first_minor,
+		       (unsigned long long)get_capacity(disk) >> 1,
+		       disk_name(disk, 0, buf));
+		if (disk->driverfs_dev != NULL &&
+		    disk->driverfs_dev->driver != NULL)
+			printk(" driver: %s\n",
+			       disk->driverfs_dev->driver->name);
+		else
+			printk(" (driver?)\n");
+
+		/* now show the partitions */
+		for (n = 0; n < disk->minors - 1; ++n) {
+			if (disk->part[n] == NULL)
+				continue;
+			if (disk->part[n]->nr_sects == 0)
+				continue;
+			printk("  %02x%02x %10llu %s\n",
+			       disk->major, n + 1 + disk->first_minor,
+			       (unsigned long long)disk->part[n]->nr_sects >> 1,
+			       disk_name(disk, n + 1, buf));
+		}
+	}
+	class_dev_iter_exit(&iter);
 }
 
 #ifdef CONFIG_PROC_FS
 /* iterator */
-static int find_start(struct device *dev, void *data)
+static void *disk_seqf_start(struct seq_file *seqf, loff_t *pos)
 {
-	loff_t *k = (loff_t *)data;
+	loff_t skip = *pos;
+	struct class_dev_iter *iter;
+	struct device *dev;
 
-	if (dev->type != &disk_type)
-		return 0;
-	if (!(*k)--)
-		return 1;
-	return 0;
+	iter = kmalloc(GFP_KERNEL, sizeof(*iter));
+	if (!iter)
+		return ERR_PTR(-ENOMEM);
+
+	seqf->private = iter;
+	class_dev_iter_init(iter, &block_class, NULL, &disk_type);
+	do {
+		dev = class_dev_iter_next(iter);
+		if (!dev)
+			return NULL;
+	} while (skip--);
+
+	return dev_to_disk(dev);
 }
 
-static void *part_start(struct seq_file *part, loff_t *pos)
+static void *disk_seqf_next(struct seq_file *seqf, void *v, loff_t *pos)
 {
 	struct device *dev;
-	loff_t n = *pos;
-
-	if (!n)
-		seq_puts(part, "major minor  #blocks  name\n\n");
 
-	dev = class_find_device(&block_class, NULL, &n, find_start);
+	(*pos)++;
+	dev = class_dev_iter_next(seqf->private);
 	if (dev)
 		return dev_to_disk(dev);
 	return NULL;
 }
 
-static int find_next(struct device *dev, void *data)
+static void disk_seqf_stop(struct seq_file *seqf, void *v)
 {
-	if (dev->type == &disk_type)
-		return 1;
-	return 0;
-}
+	struct class_dev_iter *iter = seqf->private;
 
-static void *part_next(struct seq_file *part, void *v, loff_t *pos)
-{
-	struct gendisk *gp = v;
-	struct device *dev;
-	++*pos;
-	dev = class_find_device(&block_class, &gp->dev, NULL, find_next);
-	if (dev)
-		return dev_to_disk(dev);
-	return NULL;
+	/* stop is called even after start failed :-( */
+	if (iter) {
+		class_dev_iter_exit(iter);
+		kfree(iter);
+	}
 }
 
-static void part_stop(struct seq_file *part, void *v)
+static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
 {
+	static void *p;
+
+	p = disk_seqf_start(seqf, pos);
+	if (!IS_ERR(p) && p)
+		seq_puts(part, "major minor  #blocks  name\n\n");
+	return p;
 }
 
 static int show_partition(struct seq_file *part, void *v)

@@ -370,9 +370,9 @@ static int show_partition(struct seq_file *part, void *v)
 }
 
 const struct seq_operations partitions_op = {
-	.start	= part_start,
-	.next	= part_next,
-	.stop	= part_stop,
+	.start	= show_partition_start,
+	.next	= disk_seqf_next,
+	.stop	= disk_seqf_stop,
 	.show	= show_partition
 };
 #endif

@@ -561,34 +561,6 @@ static struct device_type disk_type = {
  * The output looks suspiciously like /proc/partitions with a bunch of
  * extra fields.
  */
-
-static void *diskstats_start(struct seq_file *part, loff_t *pos)
-{
-	struct device *dev;
-	loff_t n = *pos;
-
-	dev = class_find_device(&block_class, NULL, &n, find_start);
-	if (dev)
-		return dev_to_disk(dev);
-	return NULL;
-}
-
-static void *diskstats_next(struct seq_file *part, void *v, loff_t *pos)
-{
-	struct gendisk *gp = v;
-	struct device *dev;
-
-	++*pos;
-	dev = class_find_device(&block_class, &gp->dev, NULL, find_next);
-	if (dev)
-		return dev_to_disk(dev);
-	return NULL;
-}
-
-static void diskstats_stop(struct seq_file *part, void *v)
-{
-}
-
 static int diskstats_show(struct seq_file *s, void *v)
 {
 	struct gendisk *gp = v;

@@ -650,9 +622,9 @@ static int diskstats_show(struct seq_file *s, void *v)
 }
 
 const struct seq_operations diskstats_op = {
-	.start	= diskstats_start,
-	.next	= diskstats_next,
-	.stop	= diskstats_stop,
+	.start	= disk_seqf_start,
+	.next	= disk_seqf_next,
+	.stop	= disk_seqf_stop,
 	.show	= diskstats_show
 };
 #endif /* CONFIG_PROC_FS */

@@ -680,38 +652,23 @@ void genhd_media_change_notify(struct gendisk *disk)
 EXPORT_SYMBOL_GPL(genhd_media_change_notify);
 #endif  /*  0  */
 
-struct find_block {
-	const char *name;
-	int part;
-};
-
-static int match_id(struct device *dev, void *data)
-{
-	struct find_block *find = data;
-
-	if (dev->type != &disk_type)
-		return 0;
-	if (strcmp(dev->bus_id, find->name) == 0) {
-		struct gendisk *disk = dev_to_disk(dev);
-		if (find->part < disk->minors)
-			return 1;
-	}
-	return 0;
-}
-
 dev_t blk_lookup_devt(const char *name, int part)
 {
-	struct device *dev;
 	dev_t devt = MKDEV(0, 0);
-	struct find_block find;
+	struct class_dev_iter iter;
+	struct device *dev;
 
-	find.name = name;
-	find.part = part;
-	dev = class_find_device(&block_class, NULL, (void *)&find, match_id);
-	if (dev)
-		devt = MKDEV(MAJOR(dev->devt),
-			     MINOR(dev->devt) + part);
+	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
+	while ((dev = class_dev_iter_next(&iter))) {
+		struct gendisk *disk = dev_to_disk(dev);
 
+		if (!strcmp(dev->bus_id, name) && part < disk->minors) {
+			devt = MKDEV(MAJOR(dev->devt),
+				     MINOR(dev->devt) + part);
+			break;
+		}
+	}
+	class_dev_iter_exit(&iter);
 	return devt;
 }
 EXPORT_SYMBOL(blk_lookup_devt);

index c722de0..eb046ae 100644
@@ -43,12 +43,9 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
 				    || pstart < 0 || plength < 0)
 					return -EINVAL;
 			}
-			/* partition number in use? */
+
 			mutex_lock(&bdev->bd_mutex);
-			if (disk->part[part - 1]) {
-				mutex_unlock(&bdev->bd_mutex);
-				return -EBUSY;
-			}
+
 			/* overlap? */
 			for (i = 0; i < disk->minors - 1; i++) {
 				struct hd_struct *s = disk->part[i];

index 1b1808e..43dbfab 100644
@@ -300,15 +300,6 @@ struct device_type part_type = {
 	.release	= part_release,
 };
 
-static inline void partition_sysfs_add_subdir(struct hd_struct *p)
-{
-	struct kobject *k;
-
-	k = kobject_get(&p->dev.kobj);
-	p->holder_dir = kobject_create_and_add("holders", k);
-	kobject_put(k);
-}
-
 static inline void disk_sysfs_add_subdirs(struct gendisk *disk)
 {
 	struct kobject *k;

@@ -347,13 +338,16 @@ int add_partition(struct gendisk *disk, int part, sector_t start, sector_t len,
 	struct hd_struct *p;
 	int err;
 
+	if (disk->part[part - 1])
+		return -EBUSY;
+
 	p = kzalloc(sizeof(*p), GFP_KERNEL);
 	if (!p)
 		return -ENOMEM;
 
 	if (!init_part_stats(p)) {
 		err = -ENOMEM;
-		goto out0;
+		goto out_free;
 	}
 	p->start_sect = start;
 	p->nr_sects = len;

@@ -372,34 +366,42 @@ int add_partition(struct gendisk *disk, int part, sector_t start, sector_t len,
 	p->dev.class = &block_class;
 	p->dev.type = &part_type;
 	p->dev.parent = &disk->dev;
-	disk->part[part-1] = p;
 
 	/* delay uevent until 'holders' subdir is created */
 	p->dev.uevent_suppress = 1;
 	err = device_add(&p->dev);
 	if (err)
-		goto out1;
-	partition_sysfs_add_subdir(p);
+		goto out_put;
+
+	err = -ENOMEM;
+	p->holder_dir = kobject_create_and_add("holders", &p->dev.kobj);
+	if (!p->holder_dir)
+		goto out_del;
+
 	p->dev.uevent_suppress = 0;
 	if (flags & ADDPART_FLAG_WHOLEDISK) {
 		err = device_create_file(&p->dev, &dev_attr_whole_disk);
 		if (err)
-			goto out2;
+			goto out_del;
 	}
 
+	/* everything is up and running, commence */
+	disk->part[part - 1] = p;
+
 	/* suppress uevent if the disk supresses it */
 	if (!disk->dev.uevent_suppress)
 		kobject_uevent(&p->dev.kobj, KOBJ_ADD);
 
 	return 0;
 
-out2:
+out_free:
+	kfree(p);
+	return err;
+out_del:
+	kobject_put(p->holder_dir);
 	device_del(&p->dev);
-out1:
+out_put:
 	put_device(&p->dev);
-	free_part_stats(p);
-out0:
-	kfree(p);
 	return err;
 }