block: use i_size_write() in bd_set_size()

blkdev_ioctl(GETBLKSIZE) uses i_size_read() to read size of block device.
If we update block size directly, reader may see intermediate result in
some machines and configurations.  Use i_size_write() instead.

Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Guo Chao <yan@linux.vnet.ibm.com>
Cc: M. Hindess <hindessm@uk.ibm.com>
Cc: Nikanth Karthikesan <knikanth@suse.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 172f8491a2bd..82b7c9ad29ac 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1032,7 +1032,9 @@ void bd_set_size(struct block_device *bdev, loff_t size)
 {
         unsigned bsize = bdev_logical_block_size(bdev);
 
-        bdev->bd_inode->i_size = size;
+        mutex_lock(&bdev->bd_inode->i_mutex);
+        i_size_write(bdev->bd_inode, size);
+        mutex_unlock(&bdev->bd_inode->i_mutex);
         while (bsize < PAGE_CACHE_SIZE) {
                 if (size & bsize)
                         break;