1 files changed, 66 insertions, 2 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 38e721b35d45..b3c1d3dae77d 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