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>

fs/stat.c

@@ -401,9 +401,9 @@ SYSCALL_DEFINE4(fstatat64, int, dfd, char __user *, filename,
 }
 #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 @@ void inode_add_bytes(struct inode *inode, loff_t bytes)
 		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);
 }
 

include/linux/fs.h

@@ -2297,6 +2297,7 @@ extern const struct inode_operations page_symlink_inode_operations;
 extern int generic_readlink(struct dentry *, char __user *, int);
 extern void generic_fillattr(struct inode *, struct kstat *);
 extern int vfs_getattr(struct vfsmount *, struct dentry *, struct kstat *);
+void __inode_add_bytes(struct inode *inode, loff_t bytes);
 void inode_add_bytes(struct inode *inode, loff_t bytes);
 void inode_sub_bytes(struct inode *inode, loff_t bytes);
 loff_t inode_get_bytes(struct inode *inode);