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/fat/file.c b/fs/fat/file.c
index 43d3475..f701856 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -24,9 +24,9 @@
 {
 	u32 attr;
 
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	attr = fat_make_attrs(inode);
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 
 	return put_user(attr, user_attr);
 }
@@ -47,7 +47,7 @@
 	err = mnt_want_write_file(file);
 	if (err)
 		goto out;
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 
 	/*
 	 * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
@@ -109,7 +109,7 @@
 	fat_save_attrs(inode, attr);
 	mark_inode_dirty(inode);
 out_unlock_inode:
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	mnt_drop_write_file(file);
 out:
 	return err;
@@ -246,7 +246,7 @@
 	if (!S_ISREG(inode->i_mode))
 		return -EOPNOTSUPP;
 
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	if (mode & FALLOC_FL_KEEP_SIZE) {
 		ondisksize = inode->i_blocks << 9;
 		if ((offset + len) <= ondisksize)
@@ -272,7 +272,7 @@
 	}
 
 error:
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 	return err;
 }