Add unlocked version of inode_add_bytes() function

Quota code requires unlocked version of this function. Off course
we can just copy-paste the code, but copy-pasting is always an evil.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/stat.c b/fs/stat.c
index 075694e..c4ecd52 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -401,9 +401,9 @@
 }
 #endif /* __ARCH_WANT_STAT64 */
 
-void inode_add_bytes(struct inode *inode, loff_t bytes)
+/* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
+void __inode_add_bytes(struct inode *inode, loff_t bytes)
 {
-	spin_lock(&inode->i_lock);
 	inode->i_blocks += bytes >> 9;
 	bytes &= 511;
 	inode->i_bytes += bytes;
@@ -411,6 +411,12 @@
 		inode->i_blocks++;
 		inode->i_bytes -= 512;
 	}
+}
+
+void inode_add_bytes(struct inode *inode, loff_t bytes)
+{
+	spin_lock(&inode->i_lock);
+	__inode_add_bytes(inode, bytes);
 	spin_unlock(&inode->i_lock);
 }