wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/xattr.c b/fs/xattr.c
index d5dd6c8..07d0e47 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -129,7 +129,7 @@
 	if (error)
 		return error;
 
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	error = security_inode_setxattr(dentry, name, value, size, flags);
 	if (error)
 		goto out;
@@ -137,7 +137,7 @@
 	error = __vfs_setxattr_noperm(dentry, name, value, size, flags);
 
 out:
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	return error;
 }
 EXPORT_SYMBOL_GPL(vfs_setxattr);
@@ -277,7 +277,7 @@
 	if (error)
 		return error;
 
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	error = security_inode_removexattr(dentry, name);
 	if (error)
 		goto out;
@@ -290,7 +290,7 @@
 	}
 
 out:
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	return error;
 }
 EXPORT_SYMBOL_GPL(vfs_removexattr);