1 files changed, 66 insertions, 2 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 38e721b..b3c1d3d 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -116,6 +116,8 @@ EXPORT_SYMBOL(invalidate_bdev);
 
 int set_blocksize(struct block_device *bdev, int size)
 {
+	struct address_space *mapping;
+
 	/* Size must be a power of two, and between 512 and PAGE_SIZE */
 	if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
 		return -EINVAL;
@@ -124,6 +126,19 @@ int set_blocksize(struct block_device *bdev, int size)
 	if (size < bdev_logical_block_size(bdev))
 		return -EINVAL;
 
+	/* Prevent starting I/O or mapping the device */
+	percpu_down_write(&bdev->bd_block_size_semaphore);
+
+	/* Check that the block device is not memory mapped */
+	mapping = bdev->bd_inode->i_mapping;
+	mutex_lock(&mapping->i_mmap_mutex);
+	if (mapping_mapped(mapping)) {
+		mutex_unlock(&mapping->i_mmap_mutex);
+		percpu_up_write(&bdev->bd_block_size_semaphore);
+		return -EBUSY;
+	}
+	mutex_unlock(&mapping->i_mmap_mutex);
+
 	/* Don't change the size if it is same as current */
 	if (bdev->bd_block_size != size) {
 		sync_blockdev(bdev);
@@ -131,6 +146,9 @@ int set_blocksize(struct block_device *bdev, int size)
 		bdev->bd_inode->i_blkbits = blksize_bits(size);
 		kill_bdev(bdev);
 	}
+
+	percpu_up_write(&bdev->bd_block_size_semaphore);
+
 	return 0;
 }
 
@@ -441,6 +459,12 @@ static struct inode *bdev_alloc_inode(struct super_block *sb)
 	struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
 	if (!ei)
 		return NULL;
+
+	if (unlikely(percpu_init_rwsem(&ei->bdev.bd_block_size_semaphore))) {
+		kmem_cache_free(bdev_cachep, ei);
+		return NULL;
+	}
+
 	return &ei->vfs_inode;
 }
 
@@ -449,6 +473,8 @@ static void bdev_i_callback(struct rcu_head *head)
 	struct inode *inode = container_of(head, struct inode, i_rcu);
 	struct bdev_inode *bdi = BDEV_I(inode);
 
+	percpu_free_rwsem(&bdi->bdev.bd_block_size_semaphore);
+
 	kmem_cache_free(bdev_cachep, bdi);
 }
 
@@ -1567,6 +1593,22 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 	return blkdev_ioctl(bdev, mode, cmd, arg);
 }
 
+ssize_t blkdev_aio_read(struct kiocb *iocb, const struct iovec *iov,
+			unsigned long nr_segs, loff_t pos)
+{
+	ssize_t ret;
+	struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
+
+	percpu_down_read(&bdev->bd_block_size_semaphore);
+
+	ret = generic_file_aio_read(iocb, iov, nr_segs, pos);
+
+	percpu_up_read(&bdev->bd_block_size_semaphore);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(blkdev_aio_read);
+
 /*
  * Write data to the block device.  Only intended for the block device itself
  * and the raw driver which basically is a fake block device.
@@ -1578,12 +1620,16 @@ ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
 			 unsigned long nr_segs, loff_t pos)
 {
 	struct file *file = iocb->ki_filp;
+	struct block_device *bdev = I_BDEV(file->f_mapping->host);
 	struct blk_plug plug;
 	ssize_t ret;
 
 	BUG_ON(iocb->ki_pos != pos);
 
 	blk_start_plug(&plug);
+
+	percpu_down_read(&bdev->bd_block_size_semaphore);
+
 	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 	if (ret > 0 || ret == -EIOCBQUEUED) {
 		ssize_t err;
@@ -1592,11 +1638,29 @@ ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
 		if (err < 0 && ret > 0)
 			ret = err;
 	}
+
+	percpu_up_read(&bdev->bd_block_size_semaphore);
+
 	blk_finish_plug(&plug);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(blkdev_aio_write);
 
+static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	int ret;
+	struct block_device *bdev = I_BDEV(file->f_mapping->host);
+
+	percpu_down_read(&bdev->bd_block_size_semaphore);
+
+	ret = generic_file_mmap(file, vma);
+
+	percpu_up_read(&bdev->bd_block_size_semaphore);
+
+	return ret;
+}
+
 /*
  * Try to release a page associated with block device when the system
  * is under memory pressure.
@@ -1627,9 +1691,9 @@ const struct file_operations def_blk_fops = {
 	.llseek		= block_llseek,
 	.read		= do_sync_read,
 	.write		= do_sync_write,
-  	.aio_read	= generic_file_aio_read,
+  	.aio_read	= blkdev_aio_read,
 	.aio_write	= blkdev_aio_write,
-	.mmap		= generic_file_mmap,
+	.mmap		= blkdev_mmap,
 	.fsync		= blkdev_fsync,
 	.unlocked_ioctl	= block_ioctl,
 #ifdef CONFIG_COMPAT