From: Eric Sandeen <sandeen@redhat.com>
Date: Tue, 18 Dec 2007 12:06:24 -0600
Subject: [fs] ecryptfs: stacking functions from upstream vfs
Message-id: 47680C20.9010202@redhat.com
O-Subject: [RHEL 5.2 PATCH] 2/15: stacking filesystem functions from upstream vfs
Bugzilla: 228341

Filesystem stacking code from upstream (2.6.24-rc4)

 fs/Makefile              |    3 ++-
 fs/stack.c               |   42 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/fs_stack.h |   31 +++++++++++++++++++++++++++++++
 3 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/fs/Makefile b/fs/Makefile
index 10b629b..e6b3fc3 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -10,7 +10,8 @@ obj-y :=	open.o read_write.o file_table.o buffer.o  bio.o super.o \
 		ioctl.o readdir.o select.o fifo.o locks.o dcache.o inode.o \
 		attr.o bad_inode.o file.o filesystems.o namespace.o aio.o \
 		seq_file.o xattr.o libfs.o fs-writeback.o mpage.o direct-io.o \
-		ioprio.o pnode.o drop_caches.o splice.o sync.o
+		ioprio.o pnode.o drop_caches.o splice.o sync.o \
+		stack.o
 
 obj-$(CONFIG_INOTIFY)		+= inotify.o
 obj-$(CONFIG_INOTIFY_USER)	+= inotify_user.o
diff --git a/fs/stack.c b/fs/stack.c
new file mode 100644
index 0000000..67716f6
--- /dev/null
+++ b/fs/stack.c
@@ -0,0 +1,42 @@
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/fs_stack.h>
+
+/* does _NOT_ require i_mutex to be held.
+ *
+ * This function cannot be inlined since i_size_{read,write} is rather
+ * heavy-weight on 32-bit systems
+ */
+void fsstack_copy_inode_size(struct inode *dst, const struct inode *src)
+{
+	i_size_write(dst, i_size_read((struct inode *)src));
+	dst->i_blocks = src->i_blocks;
+}
+EXPORT_SYMBOL_GPL(fsstack_copy_inode_size);
+
+/* copy all attributes; get_nlinks is optional way to override the i_nlink
+ * copying
+ */
+void fsstack_copy_attr_all(struct inode *dest, const struct inode *src,
+				int (*get_nlinks)(struct inode *))
+{
+	dest->i_mode = src->i_mode;
+	dest->i_uid = src->i_uid;
+	dest->i_gid = src->i_gid;
+	dest->i_rdev = src->i_rdev;
+	dest->i_atime = src->i_atime;
+	dest->i_mtime = src->i_mtime;
+	dest->i_ctime = src->i_ctime;
+	dest->i_blkbits = src->i_blkbits;
+	dest->i_flags = src->i_flags;
+
+	/*
+	 * Update the nlinks AFTER updating the above fields, because the
+	 * get_links callback may depend on them.
+	 */
+	if (!get_nlinks)
+		dest->i_nlink = src->i_nlink;
+	else
+		dest->i_nlink = (*get_nlinks)(dest);
+}
+EXPORT_SYMBOL_GPL(fsstack_copy_attr_all);
diff --git a/include/linux/fs_stack.h b/include/linux/fs_stack.h
new file mode 100644
index 0000000..bb516ce
--- /dev/null
+++ b/include/linux/fs_stack.h
@@ -0,0 +1,31 @@
+#ifndef _LINUX_FS_STACK_H
+#define _LINUX_FS_STACK_H
+
+/* This file defines generic functions used primarily by stackable
+ * filesystems; none of these functions require i_mutex to be held.
+ */
+
+#include <linux/fs.h>
+
+/* externs for fs/stack.c */
+extern void fsstack_copy_attr_all(struct inode *dest, const struct inode *src,
+				int (*get_nlinks)(struct inode *));
+
+extern void fsstack_copy_inode_size(struct inode *dst, const struct inode *src);
+
+/* inlines */
+static inline void fsstack_copy_attr_atime(struct inode *dest,
+					   const struct inode *src)
+{
+	dest->i_atime = src->i_atime;
+}
+
+static inline void fsstack_copy_attr_times(struct inode *dest,
+					   const struct inode *src)
+{
+	dest->i_atime = src->i_atime;
+	dest->i_mtime = src->i_mtime;
+	dest->i_ctime = src->i_ctime;
+}
+
+#endif /* _LINUX_FS_STACK_H */