[Aufs 22/25] aufs branch for loopback block device

J. R. Okajima
2009-03-09T03:31:28Z

support and test loopback block device as a branch

Signed-off-by: J. R. Okajima <hooanon05@yahoo.co.jp>
---
fs/aufs/loop.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
fs/aufs/loop.h | 41 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 87 insertions(+), 0 deletions(-)
create mode 100644 fs/aufs/loop.c
create mode 100644 fs/aufs/loop.h

diff --git a/fs/aufs/loop.c b/fs/aufs/loop.c
new file mode 100644
index 0000000..84a940f
--- /dev/null
+++ b/fs/aufs/loop.c
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * support for loopback block device as a branch
+ */
+
+#include <linux/loop.h>
+#include "aufs.h"
+
+/*
+ * test if two lower dentries have overlapping branches.
+ */
+int au_test_loopback_overlap(struct super_block *sb, struct dentry *h_d1,
+ struct dentry *h_d2)
+{
+ struct inode *h_inode;
+ struct loop_device *l;
+
+ h_inode = h_d1->d_inode;
+ if (MAJOR(h_inode->i_sb->s_dev) != LOOP_MAJOR)
+ return 0;
+
+ l = h_inode->i_sb->s_bdev->bd_disk->private_data;
+ h_d1 = l->lo_backing_file->f_dentry;
+ /* h_d1 can be local NFS. in this case aufs cannot detect the loop */
+ if (unlikely(h_d1->d_sb == sb))
+ return 1;
+ return !!au_test_subdir(h_d1, h_d2);
+}
+
+/* true if a kernel thread named 'loop[0-9].*' accesses a file */
+int au_test_loopback_kthread(void)
+{
+ const char c = current->comm[4];
+
+ return current->mm == NULL
+ && '0' <= c && c <= '9'
+ && strncmp(current->comm, "loop", 4) == 0;
+}
diff --git a/fs/aufs/loop.h b/fs/aufs/loop.h
new file mode 100644
index 0000000..1c0ee40
--- /dev/null
+++ b/fs/aufs/loop.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2005-2009 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/*
+ * support for loopback mount as a branch
+ */
+
+#ifndef __AUFS_LOOP_H__
+#define __AUFS_LOOP_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+
+#ifdef CONFIG_AUFS_BDEV_LOOP
+/* loop.c */
+int au_test_loopback_overlap(struct super_block *sb, struct dentry *h_d1,
+ struct dentry *h_d2);
+int au_test_loopback_kthread(void);
+#else
+static inline
+int au_test_loopback_overlap(struct super_block *sb, struct dentry *h_d1,
+ struct dentry *h_d2)
+{
+ return 0;
+}
+
+static inline int au_test_loopback_kthread(void)
+{
+ return 0;
+}
+#endif /* BLK_DEV_LOOP */
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_LOOP_H__ */
--
1.6.1.284.g5dc13