From: Guo Chao <yan@linux.vnet.ibm.com>
Date: Thu, 21 Feb 2013 23:16:42 +0000 (-0800)
Subject: block: use i_size_write() in bd_set_size()
X-Git-Tag: v3.2.41~5
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c1a782a5c7a83f4aa3239533619e93b1fc3ab79d;p=thirdparty%2Fkernel%2Fstable.git

block: use i_size_write() in bd_set_size()

commit d646a02a9d44d1421f273ae3923d97b47b918176 upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 613edd8822dd7..833dddb5d6597 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1064,7 +1064,9 @@ 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;