2 files changed, 53 insertions, 32 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 72e0a2887cb7..2f2873b9a041 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -929,6 +929,7 @@ static int do_open(struct block_device *bdev, struct file *file, int for_part)
 {
         struct module *owner = NULL;
         struct gendisk *disk;
+        struct hd_struct *part = NULL;
         int ret;
         int partno;
         int perm = 0;
@@ -978,7 +979,6 @@ static int do_open(struct block_device *bdev, struct file *file, int for_part)
                         if (bdev->bd_invalidated)
                                 rescan_partitions(disk, bdev);
                 } else {
-                        struct hd_struct *p;
                         struct block_device *whole;
                         whole = bdget_disk(disk, 0);
                         ret = -ENOMEM;
@@ -989,16 +989,16 @@ static int do_open(struct block_device *bdev, struct file *file, int for_part)
                         if (ret)
                                 goto out_first;
                         bdev->bd_contains = whole;
-                        p = disk->part[partno - 1];
+                        part = disk_get_part(disk, partno);
                         bdev->bd_inode->i_data.backing_dev_info =
                            whole->bd_inode->i_data.backing_dev_info;
-                        if (!(disk->flags & GENHD_FL_UP) || !p || !p->nr_sects) {
+                        if (!(disk->flags & GENHD_FL_UP) ||
+                            !part || !part->nr_sects) {
                                 ret = -ENXIO;
                                 goto out_first;
                         }
-                        kobject_get(&p->dev.kobj);
-                        bdev->bd_part = p;
-                        bd_set_size(bdev, (loff_t) p->nr_sects << 9);
+                        bdev->bd_part = part;
+                        bd_set_size(bdev, (loff_t)part->nr_sects << 9);
                 }
         } else {
                 put_disk(disk);
@@ -1027,6 +1027,7 @@ out_first:
                 __blkdev_put(bdev->bd_contains, 1);
         bdev->bd_contains = NULL;
         put_disk(disk);
+        disk_put_part(part);
         module_put(owner);
 out:
         mutex_unlock(&bdev->bd_mutex);
@@ -1119,7 +1120,7 @@ static int __blkdev_put(struct block_device *bdev, int for_part)
                 module_put(owner);
 
                 if (bdev->bd_contains != bdev) {
-                        kobject_put(&bdev->bd_part->dev.kobj);
+                        disk_put_part(bdev->bd_part);
                         bdev->bd_part = NULL;
                 }
                 bdev->bd_disk = NULL;
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index e77fa144a07d..96c8bf41e455 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -314,19 +314,29 @@ static inline void disk_sysfs_add_subdirs(struct gendisk *disk)
         kobject_put(k);
 }
 
+static void delete_partition_rcu_cb(struct rcu_head *head)
+{
+        struct hd_struct *part = container_of(head, struct hd_struct, rcu_head);
+
+        part->start_sect = 0;
+        part->nr_sects = 0;
+        part_stat_set_all(part, 0);
+        put_device(&part->dev);
+}
+
 void delete_partition(struct gendisk *disk, int partno)
 {
-        struct hd_struct *p = disk->part[partno - 1];
+        struct hd_struct *part;
 
-        if (!p)
+        part = disk->__part[partno-1];
+        if (!part)
                 return;
-        disk->part[partno - 1] = NULL;
-        p->start_sect = 0;
-        p->nr_sects = 0;
-        part_stat_set_all(p, 0);
-        kobject_put(p->holder_dir);
-        device_del(&p->dev);
-        put_device(&p->dev);
+
+        rcu_assign_pointer(disk->__part[partno-1], NULL);
+        kobject_put(part->holder_dir);
+        device_del(&part->dev);
+
+        call_rcu(&part->rcu_head, delete_partition_rcu_cb);
 }
 
 static ssize_t whole_disk_show(struct device *dev,
@@ -343,7 +353,7 @@ int add_partition(struct gendisk *disk, int partno,
         struct hd_struct *p;
         int err;
 
-        if (disk->part[partno - 1])
+        if (disk->__part[partno - 1])
                 return -EBUSY;
 
         p = kzalloc(sizeof(*p), GFP_KERNEL);
@@ -391,7 +401,8 @@ int add_partition(struct gendisk *disk, int partno,
         }
 
         /* everything is up and running, commence */
-        disk->part[partno - 1] = p;
+        INIT_RCU_HEAD(&p->rcu_head);
+        rcu_assign_pointer(disk->__part[partno - 1], p);
 
         /* suppress uevent if the disk supresses it */
         if (!disk->dev.uevent_suppress)
@@ -414,9 +425,9 @@ out_put:
 void register_disk(struct gendisk *disk)
 {
         struct block_device *bdev;
+        struct disk_part_iter piter;
+        struct hd_struct *part;
         char *s;
-        int i;
-        struct hd_struct *p;
         int err;
 
         disk->dev.parent = disk->driverfs_dev;
@@ -466,16 +477,16 @@ exit:
         kobject_uevent(&disk->dev.kobj, KOBJ_ADD);
 
         /* announce possible partitions */
-        for (i = 0; i < disk_max_parts(disk); i++) {
-                p = disk->part[i];
-                if (!p || !p->nr_sects)
-                        continue;
-                kobject_uevent(&p->dev.kobj, KOBJ_ADD);
-        }
+        disk_part_iter_init(&piter, disk, 0);
+        while ((part = disk_part_iter_next(&piter)))
+                kobject_uevent(&part->dev.kobj, KOBJ_ADD);
+        disk_part_iter_exit(&piter);
 }
 
 int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
 {
+        struct disk_part_iter piter;
+        struct hd_struct *part;
         struct parsed_partitions *state;
         int p, res;
 
@@ -485,8 +496,12 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
         if (res)
                 return res;
         bdev->bd_invalidated = 0;
-        for (p = 1; p <= disk_max_parts(disk); p++)
-                delete_partition(disk, p);
+
+        disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
+        while ((part = disk_part_iter_next(&piter)))
+                delete_partition(disk, part->partno);
+        disk_part_iter_exit(&piter);
+
         if (disk->fops->revalidate_disk)
                 disk->fops->revalidate_disk(disk);
         if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
@@ -545,13 +560,18 @@ EXPORT_SYMBOL(read_dev_sector);
 
 void del_gendisk(struct gendisk *disk)
 {
-        int p;
+        struct disk_part_iter piter;
+        struct hd_struct *part;
 
         /* invalidate stuff */
-        for (p = disk_max_parts(disk); p > 0; p--) {
-                invalidate_partition(disk, p);
-                delete_partition(disk, p);
+        disk_part_iter_init(&piter, disk,
+                             DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
+        while ((part = disk_part_iter_next(&piter))) {
+                invalidate_partition(disk, part->partno);
+                delete_partition(disk, part->partno);
         }
+        disk_part_iter_exit(&piter);
+
         invalidate_partition(disk, 0);
         disk->capacity = 0;
         disk->flags &= ~GENHD_FL_UP;