block: fix disk->part[] dereferencing race

[linux-2.6-omap-h63xx.git] / fs / block_dev.c

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 72e0a2887cb723bdbc8e858497552475839dc664..2f2873b9a04109f1c16e5d8f7863f08f50341e59 100644 (file)
--- 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;