2 files changed, 39 insertions, 0 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 4eeb69a8873..b721955d382 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -853,6 +853,34 @@ struct block_device *open_by_devnum(dev_t dev, unsigned mode)
 EXPORT_SYMBOL(open_by_devnum);
 
 /**
+ * check_disk_size_change - checks for disk size change and adjusts
+ *                          bdev size.
+ *
+ * @disk: struct gendisk to check
+ * @bdev: struct bdev to adjust.
+ *
+ * This routine checks to see if the bdev size does not match the disk size
+ * and adjusts it if it differs.
+ */
+void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
+{
+        loff_t disk_size, bdev_size;
+
+        disk_size = (loff_t)get_capacity(disk) << 9;
+        bdev_size = i_size_read(bdev->bd_inode);
+        if (disk_size != bdev_size) {
+                char name[BDEVNAME_SIZE];
+
+                disk_name(disk, 0, name);
+                printk(KERN_INFO
+                       "%s: detected capacity change from %lld to %lld\n",
+                       name, bdev_size, disk_size);
+                i_size_write(bdev->bd_inode, disk_size);
+        }
+}
+EXPORT_SYMBOL(check_disk_size_change);
+
+/**
  * revalidate_disk - wrapper for lower-level driver's revalidate_disk
  *                   call-back
  *
@@ -864,11 +892,20 @@ EXPORT_SYMBOL(open_by_devnum);
  */
 int revalidate_disk(struct gendisk *disk)
 {
+        struct block_device *bdev;
         int ret = 0;
 
         if (disk->fops->revalidate_disk)
                 ret = disk->fops->revalidate_disk(disk);
 
+        bdev = bdget_disk(disk, 0);
+        if (!bdev)
+                return ret;
+
+        mutex_lock(&bdev->bd_mutex);
+        check_disk_size_change(disk, bdev);
+        mutex_unlock(&bdev->bd_mutex);
+        bdput(bdev);
         return ret;
 }
 EXPORT_SYMBOL(revalidate_disk);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d63461f9798..32477e8872d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1722,6 +1722,8 @@ extern int fs_may_remount_ro(struct super_block *);
  */
 #define bio_data_dir(bio)       ((bio)->bi_rw & 1)
 
+extern void check_disk_size_change(struct gendisk *disk,
+                                   struct block_device *bdev);
 extern int revalidate_disk(struct gendisk *);
 extern int check_disk_change(struct block_device *);
 extern int __invalidate_device(struct block_device *);