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kernel.patches/3.2.34/wrapfs-v3.2.2-45-ga5296eb.patch

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Initial patches commit
2012-11-24 17:08:51 +01:00
diff --git a/Documentation/filesystems/00-INDEX b/Documentation/filesystems/00-INDEX
index 8c624a1..b8822ed 100644
--- a/Documentation/filesystems/00-INDEX
+++ b/Documentation/filesystems/00-INDEX
@@ -114,6 +114,8 @@ vfat.txt
- info on using the VFAT filesystem used in Windows NT and Windows 95
vfs.txt
- overview of the Virtual File System
+wrapfs.txt
+ - info and mount options for the stackable wrapper file system
xfs.txt
- info and mount options for the XFS filesystem.
xip.txt
diff --git a/Documentation/filesystems/wrapfs.txt b/Documentation/filesystems/wrapfs.txt
new file mode 100644
index 0000000..f61879a
--- /dev/null
+++ b/Documentation/filesystems/wrapfs.txt
@@ -0,0 +1,165 @@
+Wrapfs: a null-layer (aka wrapper) stackable file system
+
+Maintainer: Erez Zadok <ezk AT cs DOT stonybrook DOT edu>
+Web Site: <http://wrapfs.filesystems.org/>
+
+------------------------------------------------------------------------------
+MOTIVATION:
+
+Wrapfs is a small null-layer stackable file system, similar to BSD's Nullfs.
+Wrapfs is small, under 1800 lines of code. Compare that to, say, eCryptfs
+and Unionfs, each of which are over 10,000 LoC. As such, Wrapfs is simple
+and easy to read and understand. Wrapfs is useful for several reasons:
+
+1. Many people like to experiment with in-kernel file system ideas as a
+ prototype; Wrapfs is an ideal small template from which one could modify
+ the code to create new file system functionality incrementally.
+
+2. As a platform to test and debug generic stacking problems in other Linux
+ stackable file systems (e.g., ecryptfs).
+
+3. As a way to test VFS enhancements to better support stacking in Linux.
+
+4. Wrapfs is a very useful instructional tool, often used as a starting
+ point for course assignments, for people who want a small example of who
+ the Linux VFS works, or for those who want to learn to write new Linux
+ file systems.
+
+Various versions of Wrapfs appeared as part of the "fistgen" package since
+1994, and have been used by numerous users world-wide. For a more detailed
+history of Wrapfs, and list of most of its known users, see the section
+marked "HISTORY" below.
+
+------------------------------------------------------------------------------
+OPERATION:
+
+This is a brief description of how Wrapfs operates. For more information,
+see the full paper published in Linux Expo 1999, titled "A Stackable File
+System Interface For Linux":
+
+ <http://www.fsl.cs.sunysb.edu/docs/linux-stacking/linux.pdf>
+
+The basic function of a stackable file system is to pass an operation and
+its arguments to the lower-level file system. For every VFS object (inode,
+dentry, file, superblock, etc.), Wrapfs keeps a one-to-one mapping of a
+Wrapfs-level object to the lower one. We call the Wrapfs object the "upper"
+one, and the one below we call the "lower" one. Wrapfs stores these
+mappings as simple pointers inside the private field of the existing VFS
+objects (e.g., dentry->d_fsdata, sb->s_fs_info, and a container for inodes).
+
+There are two kinds of stackable operations: those that create new VFS
+objects and those that don't.
+
+The following distilled code snippet shows a method which doesn't create a
+new object. The method just has to pass it to the lower layer and propagate
+any errors back up the VFS:
+
+int wrapfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+ int err;
+ struct inode *lower_dir;
+ struct dentry *lower_dentry;
+ lower_dir = get_lower_inode(dir);
+ lower_dentry = get_lower_dentry(dentry);
+ err = lower_dir->i_op->unlink(lower_dir, lower_dentry);
+ return err;
+}
+
+The following code snippet shows a method which creates a new object. After
+a lower object gets created, Wrapfs has to also create its own object, and
+make the pointer connections between the upper and lower objects (the latter
+is done via a helper routine called "interpose"):
+
+int wrapfs_create(struct inode *dir, struct dentry *dentry, int mode)
+{
+ int err;
+ struct dentry *lower_dentry;
+ struct inode *lower_dir;
+ lower_dir = wrapfs_lower_inode(dir);
+ lower_dentry = wrapfs_lower_dentry(dentry);
+ err = vfs_create(lower_dir, lower_dentry, mode);
+ if (!err)
+ err = wrapfs_interpose(dentry, dir->i_sb);
+ return err;
+}
+
+The wrapfs_unlink code snippet above can be easily modified to change the
+behavior of unlink(2). For example, if an ->unlink operation is changed to
+->rename, this could become the basis for an "undo" file system; or if the
+lower_dentry's name gets encrypted before calling the lower ->unlink, this
+could be part of an encryption file system.
+
+------------------------------------------------------------------------------
+USAGE:
+
+First, you have to have some pre-existing directory already mounted from any
+other file system, say /some/lower/path. Then, to mount wrapfs in
+/mnt/wrapfs, on that lower directory, issue this command:
+
+# mount -t wrapfs /some/lower/path /mnt/wrapfs
+
+To access the files via Wrapfs, use the mount point /mnt/wrapfs.
+
+------------------------------------------------------------------------------
+CAVEATS:
+
+Stacking on NFS. Wrapfs has been tested with LTP, racer, fsx, parallel
+compile, and more. It's been tested on top of ext2, ext3, xfs, reiserfs,
+and tmpfs -- and passed all tests. However, on top of nfs3, wrapfs has to
+treat silly-deleted files as if they don't exist: in ->unlink, if we try to
+vfs_unlink an NFS silly-deleted file, NFS returns EBUSY; so we simply ignore
+it and return 0 (success) to the VFS. NFS will delete this file later on
+anyway. As the VFS also has special handling for silly-deleted files, this
+isn't unusual. A cleaner way to handle this in the future is if the VFS
+were to handle silly-deleted (aka "delayed-delete") files entirely at the
+VFS.
+
+------------------------------------------------------------------------------
+HISTORY:
+
+Wrapfs was developed initially in 1994 for Linux 2.1, as part of Erez
+Zadok's graduate work at Columbia University. It was designed to be a
+flexible null-layer, pass-through, stackable file system, from which other
+file systems would be developed and even instantiated automatically using a
+high-level language. One of the first file systems developed from Wrapfs
+was a simple encryption file system called Cryptfs (eCryptfs is based on
+Cryptfs). Other examples include Gzipfs, a stackable compression file
+system, and Unionfs, a stackable unification file system. Wrapfs was
+integrated into a larger package called fistgen (see www.filesystems.org),
+and ported to FreeBSD and Solaris. Wrapfs and fistgen continued to be
+maintained for newer versions of kernels, but remained largely standalone
+until recently: this release of Wrapfs for Linux represents a clean version
+written from scratch.
+
+Over the past 15+ years, versions of Wrapfs had been used by many users and
+companies. At one point or another, the following groups have used stacking
+code based on Wrapfs.
+
+1. PROJECTS: eCryptfs, Unionfs, mini_fo, Aufs, FindFS, StoreCompress,
+ TestFS, ToPAS, and MFS.
+
+2. COMPANIES AND RESEARCH LABS: Bell Labs's Plan 9 group, EMC,
+ Hewlett-Packard, IBM Research Almaden, IBM Research Austin, Red Hat,
+ SuSE, Sun Microsystems, Veritas, Booyaka, CalSoft (India), Computer Farm,
+ Deutsche Bank (Germany), DreamWorks LLC, Eli Lilly and Company, FAME
+ Information Services, GMX AG (Germany), IBM global services (India), IDA
+ Center for Communications Research, Indra Networks, Inc., Kavi
+ Corporation, Mendepie, Mitsubishi Electric (Japan), Mobile-Mind, Monster
+ Labs, Morning Network (Russia), NeST Technologies, Packet General
+ Networks, Inc., Outstep Technologies, Reflective Systems Group, River
+ Styx Internet, SARAI Net, Saint-Petersburg Official Web Site (Russia),
+ Shadow Island Games, TISCover (Germany), Trymedia Systems, Uber Admin,
+ Videsh Sanchar Nigam Limited (India), Wanadoo (France), and iNsu
+ Innovations.
+
+3. UNIVERSITIES: Georgia Institute of Technology, Stanford University, UC
+ Berkeley, UCLA, University of Maryland, College Park, University of
+ Michigan, Ben Gurion University (Israel), Clarkson University, Clemson
+ University, Deutsches Elektronen Synchrotron (Germany), Electronics and
+ Telecommunications Research Institute (South Korea), Indian Institute of
+ Technology (India), National Taiwan University, Pune University (India),
+ The College of William \& Mary, Trinity College (Ireland), Universitaet
+ Frankfurt am Main (Germany), University Hospital Olomouc (Czech
+ Republic), and University of Salermo (Italy).
+
+------------------------------------------------------------------------------
diff --git a/MAINTAINERS b/MAINTAINERS
index f986e7d..1aecfdb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7374,6 +7374,16 @@ F: include/linux/workqueue.h
F: kernel/workqueue.c
F: Documentation/workqueue.txt
+WRAPFS
+P: Erez Zadok
+M: ezk@cs.sunysb.edu
+L: wrapfs@filesystems.org
+W: http://wrapfs.filesystems.org/
+T: git git.kernel.org/pub/scm/linux/kernel/git/ezk/wrapfs.git
+S: Maintained
+F: Documentation/filesystems/wrapfs.txt
+F: fs/wrapfs/
+
X.25 NETWORK LAYER
M: Andrew Hendry <andrew.hendry@gmail.com>
L: linux-x25@vger.kernel.org
diff --git a/fs/Kconfig b/fs/Kconfig
index 6ad58a5..73699ed 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -194,6 +194,7 @@ if MISC_FILESYSTEMS
source "fs/adfs/Kconfig"
source "fs/affs/Kconfig"
source "fs/ecryptfs/Kconfig"
+source "fs/wrapfs/Kconfig"
source "fs/hfs/Kconfig"
source "fs/hfsplus/Kconfig"
source "fs/befs/Kconfig"
diff --git a/fs/Makefile b/fs/Makefile
index d2c3353..36daa5e 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -82,6 +82,7 @@ obj-$(CONFIG_ISO9660_FS) += isofs/
obj-$(CONFIG_HFSPLUS_FS) += hfsplus/ # Before hfs to find wrapped HFS+
obj-$(CONFIG_HFS_FS) += hfs/
obj-$(CONFIG_ECRYPT_FS) += ecryptfs/
+obj-$(CONFIG_WRAP_FS) += wrapfs/
obj-$(CONFIG_VXFS_FS) += freevxfs/
obj-$(CONFIG_NFS_FS) += nfs/
obj-$(CONFIG_EXPORTFS) += exportfs/
diff --git a/fs/wrapfs/Kconfig b/fs/wrapfs/Kconfig
new file mode 100644
index 0000000..d790ccd
--- /dev/null
+++ b/fs/wrapfs/Kconfig
@@ -0,0 +1,9 @@
+config WRAP_FS
+ tristate "Wrapfs stackable file system (EXPERIMENTAL)"
+ depends on EXPERIMENTAL
+ help
+ Wrapfs is a stackable file system which simply passes its
+ operations to the lower layer. It is designed as a useful
+ template for developing or debugging other stackable file systems,
+ and more (see Documentation/filesystems/wrapfs.txt). See
+ <http://wrapfs.filesystems.org/> for details.
diff --git a/fs/wrapfs/Makefile b/fs/wrapfs/Makefile
new file mode 100644
index 0000000..f318d11
--- /dev/null
+++ b/fs/wrapfs/Makefile
@@ -0,0 +1,7 @@
+WRAPFS_VERSION="0.1"
+
+EXTRA_CFLAGS += -DWRAPFS_VERSION=\"$(WRAPFS_VERSION)\"
+
+obj-$(CONFIG_WRAP_FS) += wrapfs.o
+
+wrapfs-y := dentry.o file.o inode.o main.o super.o lookup.o mmap.o
diff --git a/fs/wrapfs/dentry.c b/fs/wrapfs/dentry.c
new file mode 100644
index 0000000..b173153
--- /dev/null
+++ b/fs/wrapfs/dentry.c
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009 Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "wrapfs.h"
+
+/*
+ * returns: -ERRNO if error (returned to user)
+ * 0: tell VFS to invalidate dentry
+ * 1: dentry is valid
+ */
+static int wrapfs_d_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
+ struct path lower_path, saved_path;
+ struct dentry *lower_dentry;
+ int err = 1;
+
+ if (nd && nd->flags & LOOKUP_RCU)
+ return -ECHILD;
+
+ wrapfs_get_lower_path(dentry, &lower_path);
+ lower_dentry = lower_path.dentry;
+ if (!lower_dentry->d_op || !lower_dentry->d_op->d_revalidate)
+ goto out;
+ pathcpy(&saved_path, &nd->path);
+ pathcpy(&nd->path, &lower_path);
+ err = lower_dentry->d_op->d_revalidate(lower_dentry, nd);
+ pathcpy(&nd->path, &saved_path);
+out:
+ wrapfs_put_lower_path(dentry, &lower_path);
+ return err;
+}
+
+static void wrapfs_d_release(struct dentry *dentry)
+{
+ /* release and reset the lower paths */
+ wrapfs_put_reset_lower_path(dentry);
+ free_dentry_private_data(dentry);
+ return;
+}
+
+const struct dentry_operations wrapfs_dops = {
+ .d_revalidate = wrapfs_d_revalidate,
+ .d_release = wrapfs_d_release,
+};
diff --git a/fs/wrapfs/file.c b/fs/wrapfs/file.c
new file mode 100644
index 0000000..7a7fe1e
--- /dev/null
+++ b/fs/wrapfs/file.c
@@ -0,0 +1,298 @@
+/*
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009 Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "wrapfs.h"
+
+static ssize_t wrapfs_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ int err;
+ struct file *lower_file;
+ struct dentry *dentry = file->f_path.dentry;
+
+ lower_file = wrapfs_lower_file(file);
+ err = vfs_read(lower_file, buf, count, ppos);
+ /* update our inode atime upon a successful lower read */
+ if (err >= 0)
+ fsstack_copy_attr_atime(dentry->d_inode,
+ lower_file->f_path.dentry->d_inode);
+
+ return err;
+}
+
+static ssize_t wrapfs_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ int err = 0;
+ struct file *lower_file;
+ struct dentry *dentry = file->f_path.dentry;
+
+ lower_file = wrapfs_lower_file(file);
+ err = vfs_write(lower_file, buf, count, ppos);
+ /* update our inode times+sizes upon a successful lower write */
+ if (err >= 0) {
+ fsstack_copy_inode_size(dentry->d_inode,
+ lower_file->f_path.dentry->d_inode);
+ fsstack_copy_attr_times(dentry->d_inode,
+ lower_file->f_path.dentry->d_inode);
+ }
+
+ return err;
+}
+
+static int wrapfs_readdir(struct file *file, void *dirent, filldir_t filldir)
+{
+ int err = 0;
+ struct file *lower_file = NULL;
+ struct dentry *dentry = file->f_path.dentry;
+
+ lower_file = wrapfs_lower_file(file);
+ err = vfs_readdir(lower_file, filldir, dirent);
+ file->f_pos = lower_file->f_pos;
+ if (err >= 0) /* copy the atime */
+ fsstack_copy_attr_atime(dentry->d_inode,
+ lower_file->f_path.dentry->d_inode);
+ return err;
+}
+
+static long wrapfs_unlocked_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ long err = -ENOTTY;
+ struct file *lower_file;
+
+ lower_file = wrapfs_lower_file(file);
+
+ /* XXX: use vfs_ioctl if/when VFS exports it */
+ if (!lower_file || !lower_file->f_op)
+ goto out;
+ if (lower_file->f_op->unlocked_ioctl)
+ err = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
+
+out:
+ return err;
+}
+
+#ifdef CONFIG_COMPAT
+static long wrapfs_compat_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ long err = -ENOTTY;
+ struct file *lower_file;
+
+ lower_file = wrapfs_lower_file(file);
+
+ /* XXX: use vfs_ioctl if/when VFS exports it */
+ if (!lower_file || !lower_file->f_op)
+ goto out;
+ if (lower_file->f_op->compat_ioctl)
+ err = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
+
+out:
+ return err;
+}
+#endif
+
+static int wrapfs_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ int err = 0;
+ bool willwrite;
+ struct file *lower_file;
+ const struct vm_operations_struct *saved_vm_ops = NULL;
+
+ /* this might be deferred to mmap's writepage */
+ willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags);
+
+ /*
+ * File systems which do not implement ->writepage may use
+ * generic_file_readonly_mmap as their ->mmap op. If you call
+ * generic_file_readonly_mmap with VM_WRITE, you'd get an -EINVAL.
+ * But we cannot call the lower ->mmap op, so we can't tell that
+ * writeable mappings won't work. Therefore, our only choice is to
+ * check if the lower file system supports the ->writepage, and if
+ * not, return EINVAL (the same error that
+ * generic_file_readonly_mmap returns in that case).
+ */
+ lower_file = wrapfs_lower_file(file);
+ if (willwrite && !lower_file->f_mapping->a_ops->writepage) {
+ err = -EINVAL;
+ printk(KERN_ERR "wrapfs: lower file system does not "
+ "support writeable mmap\n");
+ goto out;
+ }
+
+ /*
+ * find and save lower vm_ops.
+ *
+ * XXX: the VFS should have a cleaner way of finding the lower vm_ops
+ */
+ if (!WRAPFS_F(file)->lower_vm_ops) {
+ err = lower_file->f_op->mmap(lower_file, vma);
+ if (err) {
+ printk(KERN_ERR "wrapfs: lower mmap failed %d\n", err);
+ goto out;
+ }
+ saved_vm_ops = vma->vm_ops; /* save: came from lower ->mmap */
+ err = do_munmap(current->mm, vma->vm_start,
+ vma->vm_end - vma->vm_start);
+ if (err) {
+ printk(KERN_ERR "wrapfs: do_munmap failed %d\n", err);
+ goto out;
+ }
+ }
+
+ /*
+ * Next 3 lines are all I need from generic_file_mmap. I definitely
+ * don't want its test for ->readpage which returns -ENOEXEC.
+ */
+ file_accessed(file);
+ vma->vm_ops = &wrapfs_vm_ops;
+ vma->vm_flags |= VM_CAN_NONLINEAR;
+
+ file->f_mapping->a_ops = &wrapfs_aops; /* set our aops */
+ if (!WRAPFS_F(file)->lower_vm_ops) /* save for our ->fault */
+ WRAPFS_F(file)->lower_vm_ops = saved_vm_ops;
+
+out:
+ return err;
+}
+
+static int wrapfs_open(struct inode *inode, struct file *file)
+{
+ int err = 0;
+ struct file *lower_file = NULL;
+ struct path lower_path;
+
+ /* don't open unhashed/deleted files */
+ if (d_unhashed(file->f_path.dentry)) {
+ err = -ENOENT;
+ goto out_err;
+ }
+
+ file->private_data =
+ kzalloc(sizeof(struct wrapfs_file_info), GFP_KERNEL);
+ if (!WRAPFS_F(file)) {
+ err = -ENOMEM;
+ goto out_err;
+ }
+
+ /* open lower object and link wrapfs's file struct to lower's */
+ wrapfs_get_lower_path(file->f_path.dentry, &lower_path);
+ lower_file = dentry_open(lower_path.dentry, lower_path.mnt,
+ file->f_flags, current_cred());
+ if (IS_ERR(lower_file)) {
+ err = PTR_ERR(lower_file);
+ lower_file = wrapfs_lower_file(file);
+ if (lower_file) {
+ wrapfs_set_lower_file(file, NULL);
+ fput(lower_file); /* fput calls dput for lower_dentry */
+ }
+ } else {
+ wrapfs_set_lower_file(file, lower_file);
+ }
+
+ if (err)
+ kfree(WRAPFS_F(file));
+ else
+ fsstack_copy_attr_all(inode, wrapfs_lower_inode(inode));
+out_err:
+ return err;
+}
+
+static int wrapfs_flush(struct file *file, fl_owner_t id)
+{
+ int err = 0;
+ struct file *lower_file = NULL;
+
+ lower_file = wrapfs_lower_file(file);
+ if (lower_file && lower_file->f_op && lower_file->f_op->flush)
+ err = lower_file->f_op->flush(lower_file, id);
+
+ return err;
+}
+
+/* release all lower object references & free the file info structure */
+static int wrapfs_file_release(struct inode *inode, struct file *file)
+{
+ struct file *lower_file;
+
+ lower_file = wrapfs_lower_file(file);
+ if (lower_file) {
+ wrapfs_set_lower_file(file, NULL);
+ fput(lower_file);
+ }
+
+ kfree(WRAPFS_F(file));
+ return 0;
+}
+
+static int wrapfs_fsync(struct file *file, loff_t start, loff_t end,
+ int datasync)
+{
+ int err;
+ struct file *lower_file;
+ struct path lower_path;
+ struct dentry *dentry = file->f_path.dentry;
+
+ err = generic_file_fsync(file, start, end, datasync);
+ if (err)
+ goto out;
+ lower_file = wrapfs_lower_file(file);
+ wrapfs_get_lower_path(dentry, &lower_path);
+ err = vfs_fsync_range(lower_file, start, end, datasync);
+ wrapfs_put_lower_path(dentry, &lower_path);
+out:
+ return err;
+}
+
+static int wrapfs_fasync(int fd, struct file *file, int flag)
+{
+ int err = 0;
+ struct file *lower_file = NULL;
+
+ lower_file = wrapfs_lower_file(file);
+ if (lower_file->f_op && lower_file->f_op->fasync)
+ err = lower_file->f_op->fasync(fd, lower_file, flag);
+
+ return err;
+}
+
+const struct file_operations wrapfs_main_fops = {
+ .llseek = generic_file_llseek,
+ .read = wrapfs_read,
+ .write = wrapfs_write,
+ .unlocked_ioctl = wrapfs_unlocked_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = wrapfs_compat_ioctl,
+#endif
+ .mmap = wrapfs_mmap,
+ .open = wrapfs_open,
+ .flush = wrapfs_flush,
+ .release = wrapfs_file_release,
+ .fsync = wrapfs_fsync,
+ .fasync = wrapfs_fasync,
+};
+
+/* trimmed directory options */
+const struct file_operations wrapfs_dir_fops = {
+ .llseek = generic_file_llseek,
+ .read = generic_read_dir,
+ .readdir = wrapfs_readdir,
+ .unlocked_ioctl = wrapfs_unlocked_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = wrapfs_compat_ioctl,
+#endif
+ .open = wrapfs_open,
+ .release = wrapfs_file_release,
+ .flush = wrapfs_flush,
+ .fsync = wrapfs_fsync,
+ .fasync = wrapfs_fasync,
+};
diff --git a/fs/wrapfs/inode.c b/fs/wrapfs/inode.c
new file mode 100644
index 0000000..1dc3645
--- /dev/null
+++ b/fs/wrapfs/inode.c
@@ -0,0 +1,514 @@
+/*
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009 Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "wrapfs.h"
+
+static int wrapfs_create(struct inode *dir, struct dentry *dentry,
+ int mode, struct nameidata *nd)
+{
+ int err = 0;
+ struct dentry *lower_dentry;
+ struct dentry *lower_parent_dentry = NULL;
+ struct path lower_path, saved_path;
+
+ wrapfs_get_lower_path(dentry, &lower_path);
+ lower_dentry = lower_path.dentry;
+ lower_parent_dentry = lock_parent(lower_dentry);
+
+ err = mnt_want_write(lower_path.mnt);
+ if (err)
+ goto out_unlock;
+
+ pathcpy(&saved_path, &nd->path);
+ pathcpy(&nd->path, &lower_path);
+ err = vfs_create(lower_parent_dentry->d_inode, lower_dentry, mode, nd);
+ pathcpy(&nd->path, &saved_path);
+ if (err)
+ goto out;
+
+ err = wrapfs_interpose(dentry, dir->i_sb, &lower_path);
+ if (err)
+ goto out;
+ fsstack_copy_attr_times(dir, wrapfs_lower_inode(dir));
+ fsstack_copy_inode_size(dir, lower_parent_dentry->d_inode);
+
+out:
+ mnt_drop_write(lower_path.mnt);
+out_unlock:
+ unlock_dir(lower_parent_dentry);
+ wrapfs_put_lower_path(dentry, &lower_path);
+ return err;
+}
+
+static int wrapfs_link(struct dentry *old_dentry, struct inode *dir,
+ struct dentry *new_dentry)
+{
+ struct dentry *lower_old_dentry;
+ struct dentry *lower_new_dentry;
+ struct dentry *lower_dir_dentry;
+ u64 file_size_save;
+ int err;
+ struct path lower_old_path, lower_new_path;
+
+ file_size_save = i_size_read(old_dentry->d_inode);
+ wrapfs_get_lower_path(old_dentry, &lower_old_path);
+ wrapfs_get_lower_path(new_dentry, &lower_new_path);
+ lower_old_dentry = lower_old_path.dentry;
+ lower_new_dentry = lower_new_path.dentry;
+ lower_dir_dentry = lock_parent(lower_new_dentry);
+
+ err = mnt_want_write(lower_new_path.mnt);
+ if (err)
+ goto out_unlock;
+
+ err = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
+ lower_new_dentry);
+ if (err || !lower_new_dentry->d_inode)
+ goto out;
+
+ err = wrapfs_interpose(new_dentry, dir->i_sb, &lower_new_path);
+ if (err)
+ goto out;
+ fsstack_copy_attr_times(dir, lower_new_dentry->d_inode);
+ fsstack_copy_inode_size(dir, lower_new_dentry->d_inode);
+ set_nlink(old_dentry->d_inode,
+ wrapfs_lower_inode(old_dentry->d_inode)->i_nlink);
+ i_size_write(new_dentry->d_inode, file_size_save);
+out:
+ mnt_drop_write(lower_new_path.mnt);
+out_unlock:
+ unlock_dir(lower_dir_dentry);
+ wrapfs_put_lower_path(old_dentry, &lower_old_path);
+ wrapfs_put_lower_path(new_dentry, &lower_new_path);
+ return err;
+}
+
+static int wrapfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+ int err;
+ struct dentry *lower_dentry;
+ struct inode *lower_dir_inode = wrapfs_lower_inode(dir);
+ struct dentry *lower_dir_dentry;
+ struct path lower_path;
+
+ wrapfs_get_lower_path(dentry, &lower_path);
+ lower_dentry = lower_path.dentry;
+ dget(lower_dentry);
+ lower_dir_dentry = lock_parent(lower_dentry);
+
+ err = mnt_want_write(lower_path.mnt);
+ if (err)
+ goto out_unlock;
+ err = vfs_unlink(lower_dir_inode, lower_dentry);
+
+ /*
+ * Note: unlinking on top of NFS can cause silly-renamed files.
+ * Trying to delete such files results in EBUSY from NFS
+ * below. Silly-renamed files will get deleted by NFS later on, so
+ * we just need to detect them here and treat such EBUSY errors as
+ * if the upper file was successfully deleted.
+ */
+ if (err == -EBUSY && lower_dentry->d_flags & DCACHE_NFSFS_RENAMED)
+ err = 0;
+ if (err)
+ goto out;
+ fsstack_copy_attr_times(dir, lower_dir_inode);
+ fsstack_copy_inode_size(dir, lower_dir_inode);
+ set_nlink(dentry->d_inode,
+ wrapfs_lower_inode(dentry->d_inode)->i_nlink);
+ dentry->d_inode->i_ctime = dir->i_ctime;
+ d_drop(dentry); /* this is needed, else LTP fails (VFS won't do it) */
+out:
+ mnt_drop_write(lower_path.mnt);
+out_unlock:
+ unlock_dir(lower_dir_dentry);
+ dput(lower_dentry);
+ wrapfs_put_lower_path(dentry, &lower_path);
+ return err;
+}
+
+static int wrapfs_symlink(struct inode *dir, struct dentry *dentry,
+ const char *symname)
+{
+ int err = 0;
+ struct dentry *lower_dentry;
+ struct dentry *lower_parent_dentry = NULL;
+ struct path lower_path;
+
+ wrapfs_get_lower_path(dentry, &lower_path);
+ lower_dentry = lower_path.dentry;
+ lower_parent_dentry = lock_parent(lower_dentry);
+
+ err = mnt_want_write(lower_path.mnt);
+ if (err)
+ goto out_unlock;
+ err = vfs_symlink(lower_parent_dentry->d_inode, lower_dentry, symname);
+ if (err)
+ goto out;
+ err = wrapfs_interpose(dentry, dir->i_sb, &lower_path);
+ if (err)
+ goto out;
+ fsstack_copy_attr_times(dir, wrapfs_lower_inode(dir));
+ fsstack_copy_inode_size(dir, lower_parent_dentry->d_inode);
+
+out:
+ mnt_drop_write(lower_path.mnt);
+out_unlock:
+ unlock_dir(lower_parent_dentry);
+ wrapfs_put_lower_path(dentry, &lower_path);
+ return err;
+}
+
+static int wrapfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+ int err = 0;
+ struct dentry *lower_dentry;
+ struct dentry *lower_parent_dentry = NULL;
+ struct path lower_path;
+
+ wrapfs_get_lower_path(dentry, &lower_path);
+ lower_dentry = lower_path.dentry;
+ lower_parent_dentry = lock_parent(lower_dentry);
+
+ err = mnt_want_write(lower_path.mnt);
+ if (err)
+ goto out_unlock;
+ err = vfs_mkdir(lower_parent_dentry->d_inode, lower_dentry, mode);
+ if (err)
+ goto out;
+
+ err = wrapfs_interpose(dentry, dir->i_sb, &lower_path);
+ if (err)
+ goto out;
+
+ fsstack_copy_attr_times(dir, wrapfs_lower_inode(dir));
+ fsstack_copy_inode_size(dir, lower_parent_dentry->d_inode);
+ /* update number of links on parent directory */
+ set_nlink(dir, wrapfs_lower_inode(dir)->i_nlink);
+
+out:
+ mnt_drop_write(lower_path.mnt);
+out_unlock:
+ unlock_dir(lower_parent_dentry);
+ wrapfs_put_lower_path(dentry, &lower_path);
+ return err;
+}
+
+static int wrapfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ struct dentry *lower_dentry;
+ struct dentry *lower_dir_dentry;
+ int err;
+ struct path lower_path;
+
+ wrapfs_get_lower_path(dentry, &lower_path);
+ lower_dentry = lower_path.dentry;
+ lower_dir_dentry = lock_parent(lower_dentry);
+
+ err = mnt_want_write(lower_path.mnt);
+ if (err)
+ goto out_unlock;
+ err = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
+ if (err)
+ goto out;
+
+ d_drop(dentry); /* drop our dentry on success (why not VFS's job?) */
+ if (dentry->d_inode)
+ clear_nlink(dentry->d_inode);
+ fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
+ fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
+ set_nlink(dir, lower_dir_dentry->d_inode->i_nlink);
+
+out:
+ mnt_drop_write(lower_path.mnt);
+out_unlock:
+ unlock_dir(lower_dir_dentry);
+ wrapfs_put_lower_path(dentry, &lower_path);
+ return err;
+}
+
+static int wrapfs_mknod(struct inode *dir, struct dentry *dentry, int mode,
+ dev_t dev)
+{
+ int err = 0;
+ struct dentry *lower_dentry;
+ struct dentry *lower_parent_dentry = NULL;
+ struct path lower_path;
+
+ wrapfs_get_lower_path(dentry, &lower_path);
+ lower_dentry = lower_path.dentry;
+ lower_parent_dentry = lock_parent(lower_dentry);
+
+ err = mnt_want_write(lower_path.mnt);
+ if (err)
+ goto out_unlock;
+ err = vfs_mknod(lower_parent_dentry->d_inode, lower_dentry, mode, dev);
+ if (err)
+ goto out;
+
+ err = wrapfs_interpose(dentry, dir->i_sb, &lower_path);
+ if (err)
+ goto out;
+ fsstack_copy_attr_times(dir, wrapfs_lower_inode(dir));
+ fsstack_copy_inode_size(dir, lower_parent_dentry->d_inode);
+
+out:
+ mnt_drop_write(lower_path.mnt);
+out_unlock:
+ unlock_dir(lower_parent_dentry);
+ wrapfs_put_lower_path(dentry, &lower_path);
+ return err;
+}
+
+/*
+ * The locking rules in wrapfs_rename are complex. We could use a simpler
+ * superblock-level name-space lock for renames and copy-ups.
+ */
+static int wrapfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ int err = 0;
+ struct dentry *lower_old_dentry = NULL;
+ struct dentry *lower_new_dentry = NULL;
+ struct dentry *lower_old_dir_dentry = NULL;
+ struct dentry *lower_new_dir_dentry = NULL;
+ struct dentry *trap = NULL;
+ struct path lower_old_path, lower_new_path;
+
+ wrapfs_get_lower_path(old_dentry, &lower_old_path);
+ wrapfs_get_lower_path(new_dentry, &lower_new_path);
+ lower_old_dentry = lower_old_path.dentry;
+ lower_new_dentry = lower_new_path.dentry;
+ lower_old_dir_dentry = dget_parent(lower_old_dentry);
+ lower_new_dir_dentry = dget_parent(lower_new_dentry);
+
+ trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+ /* source should not be ancestor of target */
+ if (trap == lower_old_dentry) {
+ err = -EINVAL;
+ goto out;
+ }
+ /* target should not be ancestor of source */
+ if (trap == lower_new_dentry) {
+ err = -ENOTEMPTY;
+ goto out;
+ }
+
+ err = mnt_want_write(lower_old_path.mnt);
+ if (err)
+ goto out;
+ err = mnt_want_write(lower_new_path.mnt);
+ if (err)
+ goto out_drop_old_write;
+
+ err = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
+ lower_new_dir_dentry->d_inode, lower_new_dentry);
+ if (err)
+ goto out_err;
+
+ fsstack_copy_attr_all(new_dir, lower_new_dir_dentry->d_inode);
+ fsstack_copy_inode_size(new_dir, lower_new_dir_dentry->d_inode);
+ if (new_dir != old_dir) {
+ fsstack_copy_attr_all(old_dir,
+ lower_old_dir_dentry->d_inode);
+ fsstack_copy_inode_size(old_dir,
+ lower_old_dir_dentry->d_inode);
+ }
+
+out_err:
+ mnt_drop_write(lower_new_path.mnt);
+out_drop_old_write:
+ mnt_drop_write(lower_old_path.mnt);
+out:
+ unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
+ dput(lower_old_dir_dentry);
+ dput(lower_new_dir_dentry);
+ wrapfs_put_lower_path(old_dentry, &lower_old_path);
+ wrapfs_put_lower_path(new_dentry, &lower_new_path);
+ return err;
+}
+
+static int wrapfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
+{
+ int err;
+ struct dentry *lower_dentry;
+ struct path lower_path;
+
+ wrapfs_get_lower_path(dentry, &lower_path);
+ lower_dentry = lower_path.dentry;
+ if (!lower_dentry->d_inode->i_op ||
+ !lower_dentry->d_inode->i_op->readlink) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ err = lower_dentry->d_inode->i_op->readlink(lower_dentry,
+ buf, bufsiz);
+ if (err < 0)
+ goto out;
+ fsstack_copy_attr_atime(dentry->d_inode, lower_dentry->d_inode);
+
+out:
+ wrapfs_put_lower_path(dentry, &lower_path);
+ return err;
+}
+
+static void *wrapfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ char *buf;
+ int len = PAGE_SIZE, err;
+ mm_segment_t old_fs;
+
+ /* This is freed by the put_link method assuming a successful call. */
+ buf = kmalloc(len, GFP_KERNEL);
+ if (!buf) {
+ buf = ERR_PTR(-ENOMEM);
+ goto out;
+ }
+
+ /* read the symlink, and then we will follow it */
+ old_fs = get_fs();
+ set_fs(KERNEL_DS);
+ err = wrapfs_readlink(dentry, buf, len);
+ set_fs(old_fs);
+ if (err < 0) {
+ kfree(buf);
+ buf = ERR_PTR(err);
+ } else {
+ buf[err] = '\0';
+ }
+out:
+ nd_set_link(nd, buf);
+ return NULL;
+}
+
+/* this @nd *IS* still used */
+static void wrapfs_put_link(struct dentry *dentry, struct nameidata *nd,
+ void *cookie)
+{
+ char *buf = nd_get_link(nd);
+ if (!IS_ERR(buf)) /* free the char* */
+ kfree(buf);
+}
+
+static int wrapfs_permission(struct inode *inode, int mask)
+{
+ struct inode *lower_inode;
+ int err;
+
+ lower_inode = wrapfs_lower_inode(inode);
+ err = inode_permission(lower_inode, mask);
+ return err;
+}
+
+static int wrapfs_setattr(struct dentry *dentry, struct iattr *ia)
+{
+ int err = 0;
+ struct dentry *lower_dentry;
+ struct inode *inode;
+ struct inode *lower_inode;
+ struct path lower_path;
+ struct iattr lower_ia;
+
+ inode = dentry->d_inode;
+
+ /*
+ * Check if user has permission to change inode. We don't check if
+ * this user can change the lower inode: that should happen when
+ * calling notify_change on the lower inode.
+ */
+ err = inode_change_ok(inode, ia);
+ if (err)
+ goto out_err;
+
+ wrapfs_get_lower_path(dentry, &lower_path);
+ lower_dentry = lower_path.dentry;
+ lower_inode = wrapfs_lower_inode(inode);
+
+ /* prepare our own lower struct iattr (with the lower file) */
+ memcpy(&lower_ia, ia, sizeof(lower_ia));
+ if (ia->ia_valid & ATTR_FILE)
+ lower_ia.ia_file = wrapfs_lower_file(ia->ia_file);
+
+ /*
+ * If shrinking, first truncate upper level to cancel writing dirty
+ * pages beyond the new eof; and also if its' maxbytes is more
+ * limiting (fail with -EFBIG before making any change to the lower
+ * level). There is no need to vmtruncate the upper level
+ * afterwards in the other cases: we fsstack_copy_inode_size from
+ * the lower level.
+ */
+ if (ia->ia_valid & ATTR_SIZE) {
+ err = inode_newsize_ok(inode, ia->ia_size);
+ if (err)
+ goto out;
+ truncate_setsize(inode, ia->ia_size);
+ }
+
+ /*
+ * mode change is for clearing setuid/setgid bits. Allow lower fs
+ * to interpret this in its own way.
+ */
+ if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
+ lower_ia.ia_valid &= ~ATTR_MODE;
+
+ /* notify the (possibly copied-up) lower inode */
+ /*
+ * Note: we use lower_dentry->d_inode, because lower_inode may be
+ * unlinked (no inode->i_sb and i_ino==0. This happens if someone
+ * tries to open(), unlink(), then ftruncate() a file.
+ */
+ mutex_lock(&lower_dentry->d_inode->i_mutex);
+ err = notify_change(lower_dentry, &lower_ia); /* note: lower_ia */
+ mutex_unlock(&lower_dentry->d_inode->i_mutex);
+ if (err)
+ goto out;
+
+ /* get attributes from the lower inode */
+ fsstack_copy_attr_all(inode, lower_inode);
+ /*
+ * Not running fsstack_copy_inode_size(inode, lower_inode), because
+ * VFS should update our inode size, and notify_change on
+ * lower_inode should update its size.
+ */
+
+out:
+ wrapfs_put_lower_path(dentry, &lower_path);
+out_err:
+ return err;
+}
+
+const struct inode_operations wrapfs_symlink_iops = {
+ .readlink = wrapfs_readlink,
+ .permission = wrapfs_permission,
+ .follow_link = wrapfs_follow_link,
+ .setattr = wrapfs_setattr,
+ .put_link = wrapfs_put_link,
+};
+
+const struct inode_operations wrapfs_dir_iops = {
+ .create = wrapfs_create,
+ .lookup = wrapfs_lookup,
+ .link = wrapfs_link,
+ .unlink = wrapfs_unlink,
+ .symlink = wrapfs_symlink,
+ .mkdir = wrapfs_mkdir,
+ .rmdir = wrapfs_rmdir,
+ .mknod = wrapfs_mknod,
+ .rename = wrapfs_rename,
+ .permission = wrapfs_permission,
+ .setattr = wrapfs_setattr,
+};
+
+const struct inode_operations wrapfs_main_iops = {
+ .permission = wrapfs_permission,
+ .setattr = wrapfs_setattr,
+};
diff --git a/fs/wrapfs/lookup.c b/fs/wrapfs/lookup.c
new file mode 100644
index 0000000..325b2ba
--- /dev/null
+++ b/fs/wrapfs/lookup.c
@@ -0,0 +1,304 @@
+/*
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009 Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "wrapfs.h"
+
+/* The dentry cache is just so we have properly sized dentries */
+static struct kmem_cache *wrapfs_dentry_cachep;
+
+int wrapfs_init_dentry_cache(void)
+{
+ wrapfs_dentry_cachep =
+ kmem_cache_create("wrapfs_dentry",
+ sizeof(struct wrapfs_dentry_info),
+ 0, SLAB_RECLAIM_ACCOUNT, NULL);
+
+ return wrapfs_dentry_cachep ? 0 : -ENOMEM;
+}
+
+void wrapfs_destroy_dentry_cache(void)
+{
+ if (wrapfs_dentry_cachep)
+ kmem_cache_destroy(wrapfs_dentry_cachep);
+}
+
+void free_dentry_private_data(struct dentry *dentry)
+{
+ if (!dentry || !dentry->d_fsdata)
+ return;
+ kmem_cache_free(wrapfs_dentry_cachep, dentry->d_fsdata);
+ dentry->d_fsdata = NULL;
+}
+
+/* allocate new dentry private data */
+int new_dentry_private_data(struct dentry *dentry)
+{
+ struct wrapfs_dentry_info *info = WRAPFS_D(dentry);
+
+ /* use zalloc to init dentry_info.lower_path */
+ info = kmem_cache_zalloc(wrapfs_dentry_cachep, GFP_ATOMIC);
+ if (!info)
+ return -ENOMEM;
+
+ spin_lock_init(&info->lock);
+ dentry->d_fsdata = info;
+
+ return 0;
+}
+
+static int wrapfs_inode_test(struct inode *inode, void *candidate_lower_inode)
+{
+ struct inode *current_lower_inode = wrapfs_lower_inode(inode);
+ if (current_lower_inode == (struct inode *)candidate_lower_inode)
+ return 1; /* found a match */
+ else
+ return 0; /* no match */
+}
+
+static int wrapfs_inode_set(struct inode *inode, void *lower_inode)
+{
+ /* we do actual inode initialization in wrapfs_iget */
+ return 0;
+}
+
+struct inode *wrapfs_iget(struct super_block *sb, struct inode *lower_inode)
+{
+ struct wrapfs_inode_info *info;
+ struct inode *inode; /* the new inode to return */
+ int err;
+
+ inode = iget5_locked(sb, /* our superblock */
+ /*
+ * hashval: we use inode number, but we can
+ * also use "(unsigned long)lower_inode"
+ * instead.
+ */
+ lower_inode->i_ino, /* hashval */
+ wrapfs_inode_test, /* inode comparison function */
+ wrapfs_inode_set, /* inode init function */
+ lower_inode); /* data passed to test+set fxns */
+ if (!inode) {
+ err = -EACCES;
+ iput(lower_inode);
+ return ERR_PTR(err);
+ }
+ /* if found a cached inode, then just return it */
+ if (!(inode->i_state & I_NEW))
+ return inode;
+
+ /* initialize new inode */
+ info = WRAPFS_I(inode);
+
+ inode->i_ino = lower_inode->i_ino;
+ if (!igrab(lower_inode)) {
+ err = -ESTALE;
+ return ERR_PTR(err);
+ }
+ wrapfs_set_lower_inode(inode, lower_inode);
+
+ inode->i_version++;
+
+ /* use different set of inode ops for symlinks & directories */
+ if (S_ISDIR(lower_inode->i_mode))
+ inode->i_op = &wrapfs_dir_iops;
+ else if (S_ISLNK(lower_inode->i_mode))
+ inode->i_op = &wrapfs_symlink_iops;
+ else
+ inode->i_op = &wrapfs_main_iops;
+
+ /* use different set of file ops for directories */
+ if (S_ISDIR(lower_inode->i_mode))
+ inode->i_fop = &wrapfs_dir_fops;
+ else
+ inode->i_fop = &wrapfs_main_fops;
+
+ inode->i_mapping->a_ops = &wrapfs_aops;
+
+ inode->i_atime.tv_sec = 0;
+ inode->i_atime.tv_nsec = 0;
+ inode->i_mtime.tv_sec = 0;
+ inode->i_mtime.tv_nsec = 0;
+ inode->i_ctime.tv_sec = 0;
+ inode->i_ctime.tv_nsec = 0;
+
+ /* properly initialize special inodes */
+ if (S_ISBLK(lower_inode->i_mode) || S_ISCHR(lower_inode->i_mode) ||
+ S_ISFIFO(lower_inode->i_mode) || S_ISSOCK(lower_inode->i_mode))
+ init_special_inode(inode, lower_inode->i_mode,
+ lower_inode->i_rdev);
+
+ /* all well, copy inode attributes */
+ fsstack_copy_attr_all(inode, lower_inode);
+ fsstack_copy_inode_size(inode, lower_inode);
+
+ unlock_new_inode(inode);
+ return inode;
+}
+
+/*
+ * Connect a wrapfs inode dentry/inode with several lower ones. This is
+ * the classic stackable file system "vnode interposition" action.
+ *
+ * @dentry: wrapfs's dentry which interposes on lower one
+ * @sb: wrapfs's super_block
+ * @lower_path: the lower path (caller does path_get/put)
+ */
+int wrapfs_interpose(struct dentry *dentry, struct super_block *sb,
+ struct path *lower_path)
+{
+ int err = 0;
+ struct inode *inode;
+ struct inode *lower_inode;
+ struct super_block *lower_sb;
+
+ lower_inode = lower_path->dentry->d_inode;
+ lower_sb = wrapfs_lower_super(sb);
+
+ /* check that the lower file system didn't cross a mount point */
+ if (lower_inode->i_sb != lower_sb) {
+ err = -EXDEV;
+ goto out;
+ }
+
+ /*
+ * We allocate our new inode below by calling wrapfs_iget,
+ * which will initialize some of the new inode's fields
+ */
+
+ /* inherit lower inode number for wrapfs's inode */
+ inode = wrapfs_iget(sb, lower_inode);
+ if (IS_ERR(inode)) {
+ err = PTR_ERR(inode);
+ goto out;
+ }
+
+ d_add(dentry, inode);
+
+out:
+ return err;
+}
+
+/*
+ * Main driver function for wrapfs's lookup.
+ *
+ * Returns: NULL (ok), ERR_PTR if an error occurred.
+ * Fills in lower_parent_path with <dentry,mnt> on success.
+ */
+static struct dentry *__wrapfs_lookup(struct dentry *dentry, int flags,
+ struct path *lower_parent_path)
+{
+ int err = 0;
+ struct vfsmount *lower_dir_mnt;
+ struct dentry *lower_dir_dentry = NULL;
+ struct dentry *lower_dentry;
+ const char *name;
+ struct path lower_path;
+ struct qstr this;
+
+ /* must initialize dentry operations */
+ d_set_d_op(dentry, &wrapfs_dops);
+
+ if (IS_ROOT(dentry))
+ goto out;
+
+ name = dentry->d_name.name;
+
+ /* now start the actual lookup procedure */
+ lower_dir_dentry = lower_parent_path->dentry;
+ lower_dir_mnt = lower_parent_path->mnt;
+
+ /* Use vfs_path_lookup to check if the dentry exists or not */
+ err = vfs_path_lookup(lower_dir_dentry, lower_dir_mnt, name, 0,
+ &lower_path);
+
+ /* no error: handle positive dentries */
+ if (!err) {
+ wrapfs_set_lower_path(dentry, &lower_path);
+ err = wrapfs_interpose(dentry, dentry->d_sb, &lower_path);
+ if (err) /* path_put underlying path on error */
+ wrapfs_put_reset_lower_path(dentry);
+ goto out;
+ }
+
+ /*
+ * We don't consider ENOENT an error, and we want to return a
+ * negative dentry.
+ */
+ if (err && err != -ENOENT)
+ goto out;
+
+ /* instatiate a new negative dentry */
+ this.name = name;
+ this.len = strlen(name);
+ this.hash = full_name_hash(this.name, this.len);
+ lower_dentry = d_lookup(lower_dir_dentry, &this);
+ if (lower_dentry)
+ goto setup_lower;
+
+ lower_dentry = d_alloc(lower_dir_dentry, &this);
+ if (!lower_dentry) {
+ err = -ENOMEM;
+ goto out;
+ }
+ d_add(lower_dentry, NULL); /* instantiate and hash */
+
+setup_lower:
+ lower_path.dentry = lower_dentry;
+ lower_path.mnt = mntget(lower_dir_mnt);
+ wrapfs_set_lower_path(dentry, &lower_path);
+
+ /*
+ * If the intent is to create a file, then don't return an error, so
+ * the VFS will continue the process of making this negative dentry
+ * into a positive one.
+ */
+ if (flags & (LOOKUP_CREATE|LOOKUP_RENAME_TARGET))
+ err = 0;
+
+out:
+ return ERR_PTR(err);
+}
+
+struct dentry *wrapfs_lookup(struct inode *dir, struct dentry *dentry,
+ struct nameidata *nd)
+{
+ struct dentry *ret, *parent;
+ struct path lower_parent_path;
+ int err = 0;
+
+ BUG_ON(!nd);
+ parent = dget_parent(dentry);
+
+ wrapfs_get_lower_path(parent, &lower_parent_path);
+
+ /* allocate dentry private data. We free it in ->d_release */
+ err = new_dentry_private_data(dentry);
+ if (err) {
+ ret = ERR_PTR(err);
+ goto out;
+ }
+ ret = __wrapfs_lookup(dentry, nd->flags, &lower_parent_path);
+ if (IS_ERR(ret))
+ goto out;
+ if (ret)
+ dentry = ret;
+ if (dentry->d_inode)
+ fsstack_copy_attr_times(dentry->d_inode,
+ wrapfs_lower_inode(dentry->d_inode));
+ /* update parent directory's atime */
+ fsstack_copy_attr_atime(parent->d_inode,
+ wrapfs_lower_inode(parent->d_inode));
+
+out:
+ wrapfs_put_lower_path(parent, &lower_parent_path);
+ dput(parent);
+ return ret;
+}
diff --git a/fs/wrapfs/main.c b/fs/wrapfs/main.c
new file mode 100644
index 0000000..130aca6
--- /dev/null
+++ b/fs/wrapfs/main.c
@@ -0,0 +1,173 @@
+/*
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009 Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "wrapfs.h"
+#include <linux/module.h>
+
+/*
+ * There is no need to lock the wrapfs_super_info's rwsem as there is no
+ * way anyone can have a reference to the superblock at this point in time.
+ */
+static int wrapfs_read_super(struct super_block *sb, void *raw_data, int silent)
+{
+ int err = 0;
+ struct super_block *lower_sb;
+ struct path lower_path;
+ char *dev_name = (char *) raw_data;
+ struct inode *inode;
+
+ if (!dev_name) {
+ printk(KERN_ERR
+ "wrapfs: read_super: missing dev_name argument\n");
+ err = -EINVAL;
+ goto out;
+ }
+
+ /* parse lower path */
+ err = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
+ &lower_path);
+ if (err) {
+ printk(KERN_ERR "wrapfs: error accessing "
+ "lower directory '%s'\n", dev_name);
+ goto out;
+ }
+
+ /* allocate superblock private data */
+ sb->s_fs_info = kzalloc(sizeof(struct wrapfs_sb_info), GFP_KERNEL);
+ if (!WRAPFS_SB(sb)) {
+ printk(KERN_CRIT "wrapfs: read_super: out of memory\n");
+ err = -ENOMEM;
+ goto out_free;
+ }
+
+ /* set the lower superblock field of upper superblock */
+ lower_sb = lower_path.dentry->d_sb;
+ atomic_inc(&lower_sb->s_active);
+ wrapfs_set_lower_super(sb, lower_sb);
+
+ /* inherit maxbytes from lower file system */
+ sb->s_maxbytes = lower_sb->s_maxbytes;
+
+ /*
+ * Our c/m/atime granularity is 1 ns because we may stack on file
+ * systems whose granularity is as good.
+ */
+ sb->s_time_gran = 1;
+
+ sb->s_op = &wrapfs_sops;
+
+ /* get a new inode and allocate our root dentry */
+ inode = wrapfs_iget(sb, lower_path.dentry->d_inode);
+ if (IS_ERR(inode)) {
+ err = PTR_ERR(inode);
+ goto out_sput;
+ }
+ sb->s_root = d_alloc_root(inode);
+ if (!sb->s_root) {
+ err = -ENOMEM;
+ goto out_iput;
+ }
+ d_set_d_op(sb->s_root, &wrapfs_dops);
+
+ /* link the upper and lower dentries */
+ sb->s_root->d_fsdata = NULL;
+ err = new_dentry_private_data(sb->s_root);
+ if (err)
+ goto out_freeroot;
+
+ /* if get here: cannot have error */
+
+ /* set the lower dentries for s_root */
+ wrapfs_set_lower_path(sb->s_root, &lower_path);
+
+ /*
+ * No need to call interpose because we already have a positive
+ * dentry, which was instantiated by d_alloc_root. Just need to
+ * d_rehash it.
+ */
+ d_rehash(sb->s_root);
+ if (!silent)
+ printk(KERN_INFO
+ "wrapfs: mounted on top of %s type %s\n",
+ dev_name, lower_sb->s_type->name);
+ goto out; /* all is well */
+
+ /* no longer needed: free_dentry_private_data(sb->s_root); */
+out_freeroot:
+ dput(sb->s_root);
+out_iput:
+ iput(inode);
+out_sput:
+ /* drop refs we took earlier */
+ atomic_dec(&lower_sb->s_active);
+ kfree(WRAPFS_SB(sb));
+ sb->s_fs_info = NULL;
+out_free:
+ path_put(&lower_path);
+
+out:
+ return err;
+}
+
+struct dentry *wrapfs_mount(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *raw_data)
+{
+ void *lower_path_name = (void *) dev_name;
+
+ return mount_nodev(fs_type, flags, lower_path_name,
+ wrapfs_read_super);
+}
+
+static struct file_system_type wrapfs_fs_type = {
+ .owner = THIS_MODULE,
+ .name = WRAPFS_NAME,
+ .mount = wrapfs_mount,
+ .kill_sb = generic_shutdown_super,
+ .fs_flags = FS_REVAL_DOT,
+};
+
+static int __init init_wrapfs_fs(void)
+{
+ int err;
+
+ pr_info("Registering wrapfs " WRAPFS_VERSION "\n");
+
+ err = wrapfs_init_inode_cache();
+ if (err)
+ goto out;
+ err = wrapfs_init_dentry_cache();
+ if (err)
+ goto out;
+ err = register_filesystem(&wrapfs_fs_type);
+out:
+ if (err) {
+ wrapfs_destroy_inode_cache();
+ wrapfs_destroy_dentry_cache();
+ }
+ return err;
+}
+
+static void __exit exit_wrapfs_fs(void)
+{
+ wrapfs_destroy_inode_cache();
+ wrapfs_destroy_dentry_cache();
+ unregister_filesystem(&wrapfs_fs_type);
+ pr_info("Completed wrapfs module unload\n");
+}
+
+MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University"
+ " (http://www.fsl.cs.sunysb.edu/)");
+MODULE_DESCRIPTION("Wrapfs " WRAPFS_VERSION
+ " (http://wrapfs.filesystems.org/)");
+MODULE_LICENSE("GPL");
+
+module_init(init_wrapfs_fs);
+module_exit(exit_wrapfs_fs);
diff --git a/fs/wrapfs/mmap.c b/fs/wrapfs/mmap.c
new file mode 100644
index 0000000..c224fc3
--- /dev/null
+++ b/fs/wrapfs/mmap.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009 Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "wrapfs.h"
+
+static int wrapfs_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ int err;
+ struct file *file, *lower_file;
+ const struct vm_operations_struct *lower_vm_ops;
+ struct vm_area_struct lower_vma;
+
+ memcpy(&lower_vma, vma, sizeof(struct vm_area_struct));
+ file = lower_vma.vm_file;
+ lower_vm_ops = WRAPFS_F(file)->lower_vm_ops;
+ BUG_ON(!lower_vm_ops);
+
+ lower_file = wrapfs_lower_file(file);
+ /*
+ * XXX: vm_ops->fault may be called in parallel. Because we have to
+ * resort to temporarily changing the vma->vm_file to point to the
+ * lower file, a concurrent invocation of wrapfs_fault could see a
+ * different value. In this workaround, we keep a different copy of
+ * the vma structure in our stack, so we never expose a different
+ * value of the vma->vm_file called to us, even temporarily. A
+ * better fix would be to change the calling semantics of ->fault to
+ * take an explicit file pointer.
+ */
+ lower_vma.vm_file = lower_file;
+ err = lower_vm_ops->fault(&lower_vma, vmf);
+ return err;
+}
+
+/*
+ * XXX: the default address_space_ops for wrapfs is empty. We cannot set
+ * our inode->i_mapping->a_ops to NULL because too many code paths expect
+ * the a_ops vector to be non-NULL.
+ */
+const struct address_space_operations wrapfs_aops = {
+ /* empty on purpose */
+};
+
+const struct vm_operations_struct wrapfs_vm_ops = {
+ .fault = wrapfs_fault,
+};
diff --git a/fs/wrapfs/super.c b/fs/wrapfs/super.c
new file mode 100644
index 0000000..89d277d
--- /dev/null
+++ b/fs/wrapfs/super.c
@@ -0,0 +1,168 @@
+/*
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009 Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "wrapfs.h"
+
+/*
+ * The inode cache is used with alloc_inode for both our inode info and the
+ * vfs inode.
+ */
+static struct kmem_cache *wrapfs_inode_cachep;
+
+/* final actions when unmounting a file system */
+static void wrapfs_put_super(struct super_block *sb)
+{
+ struct wrapfs_sb_info *spd;
+ struct super_block *s;
+
+ spd = WRAPFS_SB(sb);
+ if (!spd)
+ return;
+
+ /* decrement lower super references */
+ s = wrapfs_lower_super(sb);
+ wrapfs_set_lower_super(sb, NULL);
+ atomic_dec(&s->s_active);
+
+ kfree(spd);
+ sb->s_fs_info = NULL;
+}
+
+static int wrapfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+ int err;
+ struct path lower_path;
+
+ wrapfs_get_lower_path(dentry, &lower_path);
+ err = vfs_statfs(&lower_path, buf);
+ wrapfs_put_lower_path(dentry, &lower_path);
+
+ /* set return buf to our f/s to avoid confusing user-level utils */
+ buf->f_type = WRAPFS_SUPER_MAGIC;
+
+ return err;
+}
+
+/*
+ * @flags: numeric mount options
+ * @options: mount options string
+ */
+static int wrapfs_remount_fs(struct super_block *sb, int *flags, char *options)
+{
+ int err = 0;
+
+ /*
+ * The VFS will take care of "ro" and "rw" flags among others. We
+ * can safely accept a few flags (RDONLY, MANDLOCK), and honor
+ * SILENT, but anything else left over is an error.
+ */
+ if ((*flags & ~(MS_RDONLY | MS_MANDLOCK | MS_SILENT)) != 0) {
+ printk(KERN_ERR
+ "wrapfs: remount flags 0x%x unsupported\n", *flags);
+ err = -EINVAL;
+ }
+
+ return err;
+}
+
+/*
+ * Called by iput() when the inode reference count reached zero
+ * and the inode is not hashed anywhere. Used to clear anything
+ * that needs to be, before the inode is completely destroyed and put
+ * on the inode free list.
+ */
+static void wrapfs_evict_inode(struct inode *inode)
+{
+ struct inode *lower_inode;
+
+ truncate_inode_pages(&inode->i_data, 0);
+ end_writeback(inode);
+ /*
+ * Decrement a reference to a lower_inode, which was incremented
+ * by our read_inode when it was created initially.
+ */
+ lower_inode = wrapfs_lower_inode(inode);
+ wrapfs_set_lower_inode(inode, NULL);
+ iput(lower_inode);
+}
+
+static struct inode *wrapfs_alloc_inode(struct super_block *sb)
+{
+ struct wrapfs_inode_info *i;
+
+ i = kmem_cache_alloc(wrapfs_inode_cachep, GFP_KERNEL);
+ if (!i)
+ return NULL;
+
+ /* memset everything up to the inode to 0 */
+ memset(i, 0, offsetof(struct wrapfs_inode_info, vfs_inode));
+
+ i->vfs_inode.i_version = 1;
+ return &i->vfs_inode;
+}
+
+static void wrapfs_destroy_inode(struct inode *inode)
+{
+ kmem_cache_free(wrapfs_inode_cachep, WRAPFS_I(inode));
+}
+
+/* wrapfs inode cache constructor */
+static void init_once(void *obj)
+{
+ struct wrapfs_inode_info *i = obj;
+
+ inode_init_once(&i->vfs_inode);
+}
+
+int wrapfs_init_inode_cache(void)
+{
+ int err = 0;
+
+ wrapfs_inode_cachep =
+ kmem_cache_create("wrapfs_inode_cache",
+ sizeof(struct wrapfs_inode_info), 0,
+ SLAB_RECLAIM_ACCOUNT, init_once);
+ if (!wrapfs_inode_cachep)
+ err = -ENOMEM;
+ return err;
+}
+
+/* wrapfs inode cache destructor */
+void wrapfs_destroy_inode_cache(void)
+{
+ if (wrapfs_inode_cachep)
+ kmem_cache_destroy(wrapfs_inode_cachep);
+}
+
+/*
+ * Used only in nfs, to kill any pending RPC tasks, so that subsequent
+ * code can actually succeed and won't leave tasks that need handling.
+ */
+static void wrapfs_umount_begin(struct super_block *sb)
+{
+ struct super_block *lower_sb;
+
+ lower_sb = wrapfs_lower_super(sb);
+ if (lower_sb && lower_sb->s_op && lower_sb->s_op->umount_begin)
+ lower_sb->s_op->umount_begin(lower_sb);
+}
+
+const struct super_operations wrapfs_sops = {
+ .put_super = wrapfs_put_super,
+ .statfs = wrapfs_statfs,
+ .remount_fs = wrapfs_remount_fs,
+ .evict_inode = wrapfs_evict_inode,
+ .umount_begin = wrapfs_umount_begin,
+ .show_options = generic_show_options,
+ .alloc_inode = wrapfs_alloc_inode,
+ .destroy_inode = wrapfs_destroy_inode,
+ .drop_inode = generic_delete_inode,
+};
diff --git a/fs/wrapfs/wrapfs.h b/fs/wrapfs/wrapfs.h
new file mode 100644
index 0000000..25b5795
--- /dev/null
+++ b/fs/wrapfs/wrapfs.h
@@ -0,0 +1,204 @@
+/*
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009 Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _WRAPFS_H_
+#define _WRAPFS_H_
+
+#include <linux/dcache.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/seq_file.h>
+#include <linux/statfs.h>
+#include <linux/fs_stack.h>
+#include <linux/magic.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+
+/* the file system name */
+#define WRAPFS_NAME "wrapfs"
+
+/* wrapfs root inode number */
+#define WRAPFS_ROOT_INO 1
+
+/* useful for tracking code reachability */
+#define UDBG printk(KERN_DEFAULT "DBG:%s:%s:%d\n", __FILE__, __func__, __LINE__)
+
+/* operations vectors defined in specific files */
+extern const struct file_operations wrapfs_main_fops;
+extern const struct file_operations wrapfs_dir_fops;
+extern const struct inode_operations wrapfs_main_iops;
+extern const struct inode_operations wrapfs_dir_iops;
+extern const struct inode_operations wrapfs_symlink_iops;
+extern const struct super_operations wrapfs_sops;
+extern const struct dentry_operations wrapfs_dops;
+extern const struct address_space_operations wrapfs_aops, wrapfs_dummy_aops;
+extern const struct vm_operations_struct wrapfs_vm_ops;
+
+extern int wrapfs_init_inode_cache(void);
+extern void wrapfs_destroy_inode_cache(void);
+extern int wrapfs_init_dentry_cache(void);
+extern void wrapfs_destroy_dentry_cache(void);
+extern int new_dentry_private_data(struct dentry *dentry);
+extern void free_dentry_private_data(struct dentry *dentry);
+extern struct dentry *wrapfs_lookup(struct inode *dir, struct dentry *dentry,
+ struct nameidata *nd);
+extern struct inode *wrapfs_iget(struct super_block *sb,
+ struct inode *lower_inode);
+extern int wrapfs_interpose(struct dentry *dentry, struct super_block *sb,
+ struct path *lower_path);
+
+/* file private data */
+struct wrapfs_file_info {
+ struct file *lower_file;
+ const struct vm_operations_struct *lower_vm_ops;
+};
+
+/* wrapfs inode data in memory */
+struct wrapfs_inode_info {
+ struct inode *lower_inode;
+ struct inode vfs_inode;
+};
+
+/* wrapfs dentry data in memory */
+struct wrapfs_dentry_info {
+ spinlock_t lock; /* protects lower_path */
+ struct path lower_path;
+};
+
+/* wrapfs super-block data in memory */
+struct wrapfs_sb_info {
+ struct super_block *lower_sb;
+};
+
+/*
+ * inode to private data
+ *
+ * Since we use containers and the struct inode is _inside_ the
+ * wrapfs_inode_info structure, WRAPFS_I will always (given a non-NULL
+ * inode pointer), return a valid non-NULL pointer.
+ */
+static inline struct wrapfs_inode_info *WRAPFS_I(const struct inode *inode)
+{
+ return container_of(inode, struct wrapfs_inode_info, vfs_inode);
+}
+
+/* dentry to private data */
+#define WRAPFS_D(dent) ((struct wrapfs_dentry_info *)(dent)->d_fsdata)
+
+/* superblock to private data */
+#define WRAPFS_SB(super) ((struct wrapfs_sb_info *)(super)->s_fs_info)
+
+/* file to private Data */
+#define WRAPFS_F(file) ((struct wrapfs_file_info *)((file)->private_data))
+
+/* file to lower file */
+static inline struct file *wrapfs_lower_file(const struct file *f)
+{
+ return WRAPFS_F(f)->lower_file;
+}
+
+static inline void wrapfs_set_lower_file(struct file *f, struct file *val)
+{
+ WRAPFS_F(f)->lower_file = val;
+}
+
+/* inode to lower inode. */
+static inline struct inode *wrapfs_lower_inode(const struct inode *i)
+{
+ return WRAPFS_I(i)->lower_inode;
+}
+
+static inline void wrapfs_set_lower_inode(struct inode *i, struct inode *val)
+{
+ WRAPFS_I(i)->lower_inode = val;
+}
+
+/* superblock to lower superblock */
+static inline struct super_block *wrapfs_lower_super(
+ const struct super_block *sb)
+{
+ return WRAPFS_SB(sb)->lower_sb;
+}
+
+static inline void wrapfs_set_lower_super(struct super_block *sb,
+ struct super_block *val)
+{
+ WRAPFS_SB(sb)->lower_sb = val;
+}
+
+/* path based (dentry/mnt) macros */
+static inline void pathcpy(struct path *dst, const struct path *src)
+{
+ dst->dentry = src->dentry;
+ dst->mnt = src->mnt;
+}
+/* Returns struct path. Caller must path_put it. */
+static inline void wrapfs_get_lower_path(const struct dentry *dent,
+ struct path *lower_path)
+{
+ spin_lock(&WRAPFS_D(dent)->lock);
+ pathcpy(lower_path, &WRAPFS_D(dent)->lower_path);
+ path_get(lower_path);
+ spin_unlock(&WRAPFS_D(dent)->lock);
+ return;
+}
+static inline void wrapfs_put_lower_path(const struct dentry *dent,
+ struct path *lower_path)
+{
+ path_put(lower_path);
+ return;
+}
+static inline void wrapfs_set_lower_path(const struct dentry *dent,
+ struct path *lower_path)
+{
+ spin_lock(&WRAPFS_D(dent)->lock);
+ pathcpy(&WRAPFS_D(dent)->lower_path, lower_path);
+ spin_unlock(&WRAPFS_D(dent)->lock);
+ return;
+}
+static inline void wrapfs_reset_lower_path(const struct dentry *dent)
+{
+ spin_lock(&WRAPFS_D(dent)->lock);
+ WRAPFS_D(dent)->lower_path.dentry = NULL;
+ WRAPFS_D(dent)->lower_path.mnt = NULL;
+ spin_unlock(&WRAPFS_D(dent)->lock);
+ return;
+}
+static inline void wrapfs_put_reset_lower_path(const struct dentry *dent)
+{
+ struct path lower_path;
+ spin_lock(&WRAPFS_D(dent)->lock);
+ pathcpy(&lower_path, &WRAPFS_D(dent)->lower_path);
+ WRAPFS_D(dent)->lower_path.dentry = NULL;
+ WRAPFS_D(dent)->lower_path.mnt = NULL;
+ spin_unlock(&WRAPFS_D(dent)->lock);
+ path_put(&lower_path);
+ return;
+}
+
+/* locking helpers */
+static inline struct dentry *lock_parent(struct dentry *dentry)
+{
+ struct dentry *dir = dget_parent(dentry);
+ mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
+ return dir;
+}
+
+static inline void unlock_dir(struct dentry *dir)
+{
+ mutex_unlock(&dir->d_inode->i_mutex);
+ dput(dir);
+}
+#endif /* not _WRAPFS_H_ */
diff --git a/include/linux/magic.h b/include/linux/magic.h
index 2d4beab..8ef0170 100644
--- a/include/linux/magic.h
+++ b/include/linux/magic.h
@@ -50,6 +50,8 @@
#define REISER2FS_SUPER_MAGIC_STRING "ReIsEr2Fs"
#define REISER2FS_JR_SUPER_MAGIC_STRING "ReIsEr3Fs"
+#define WRAPFS_SUPER_MAGIC 0xb550ca10
+
#define SMB_SUPER_MAGIC 0x517B
#define USBDEVICE_SUPER_MAGIC 0x9fa2
#define CGROUP_SUPER_MAGIC 0x27e0eb
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