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-rw-r--r--fs/Kconfig1
-rw-r--r--fs/Makefile1
-rw-r--r--fs/overlayfs/Kconfig4
-rw-r--r--fs/overlayfs/Makefile7
-rw-r--r--fs/overlayfs/copy_up.c385
-rw-r--r--fs/overlayfs/dir.c597
-rw-r--r--fs/overlayfs/inode.c384
-rw-r--r--fs/overlayfs/overlayfs.h64
-rw-r--r--fs/overlayfs/readdir.c566
-rw-r--r--fs/overlayfs/super.c611
10 files changed, 2620 insertions, 0 deletions
diff --git a/fs/Kconfig b/fs/Kconfig
index f95ae3a027f..e0c5d4326ce 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -67,6 +67,7 @@ source "fs/quota/Kconfig"
source "fs/autofs4/Kconfig"
source "fs/fuse/Kconfig"
+source "fs/overlayfs/Kconfig"
config CUSE
tristate "Character device in Userspace support"
diff --git a/fs/Makefile b/fs/Makefile
index 2fb97793467..fcd9788adfb 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -106,6 +106,7 @@ obj-$(CONFIG_QNX6FS_FS) += qnx6/
obj-$(CONFIG_AUTOFS4_FS) += autofs4/
obj-$(CONFIG_ADFS_FS) += adfs/
obj-$(CONFIG_FUSE_FS) += fuse/
+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs/
obj-$(CONFIG_UDF_FS) += udf/
obj-$(CONFIG_SUN_OPENPROMFS) += openpromfs/
obj-$(CONFIG_OMFS_FS) += omfs/
diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig
new file mode 100644
index 00000000000..c4517da01fa
--- /dev/null
+++ b/fs/overlayfs/Kconfig
@@ -0,0 +1,4 @@
+config OVERLAYFS_FS
+ tristate "Overlay filesystem support"
+ help
+ Add support for overlay filesystem.
diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile
new file mode 100644
index 00000000000..8f91889480d
--- /dev/null
+++ b/fs/overlayfs/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for the overlay filesystem.
+#
+
+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o
+
+overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
new file mode 100644
index 00000000000..87dbeee0a14
--- /dev/null
+++ b/fs/overlayfs/copy_up.c
@@ -0,0 +1,385 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * 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 <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/splice.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+#include <linux/uaccess.h>
+#include <linux/sched.h>
+#include "overlayfs.h"
+
+#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
+
+static int ovl_copy_up_xattr(struct dentry *old, struct dentry *new)
+{
+ ssize_t list_size, size;
+ char *buf, *name, *value;
+ int error;
+
+ if (!old->d_inode->i_op->getxattr ||
+ !new->d_inode->i_op->getxattr)
+ return 0;
+
+ list_size = vfs_listxattr(old, NULL, 0);
+ if (list_size <= 0) {
+ if (list_size == -EOPNOTSUPP)
+ return 0;
+ return list_size;
+ }
+
+ buf = kzalloc(list_size, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ error = -ENOMEM;
+ value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);
+ if (!value)
+ goto out;
+
+ list_size = vfs_listxattr(old, buf, list_size);
+ if (list_size <= 0) {
+ error = list_size;
+ goto out_free_value;
+ }
+
+ for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
+ size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);
+ if (size <= 0) {
+ error = size;
+ goto out_free_value;
+ }
+ error = vfs_setxattr(new, name, value, size, 0);
+ if (error)
+ goto out_free_value;
+ }
+
+out_free_value:
+ kfree(value);
+out:
+ kfree(buf);
+ return error;
+}
+
+static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
+{
+ struct file *old_file;
+ struct file *new_file;
+ int error = 0;
+
+ if (len == 0)
+ return 0;
+
+ old_file = ovl_path_open(old, O_RDONLY);
+ if (IS_ERR(old_file))
+ return PTR_ERR(old_file);
+
+ new_file = ovl_path_open(new, O_WRONLY);
+ if (IS_ERR(new_file)) {
+ error = PTR_ERR(new_file);
+ goto out_fput;
+ }
+
+ /* FIXME: copy up sparse files efficiently */
+ while (len) {
+ loff_t offset = new_file->f_pos;
+ size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
+ long bytes;
+
+ if (len < this_len)
+ this_len = len;
+
+ if (signal_pending_state(TASK_KILLABLE, current)) {
+ error = -EINTR;
+ break;
+ }
+
+ bytes = do_splice_direct(old_file, &offset, new_file, this_len,
+ SPLICE_F_MOVE);
+ if (bytes <= 0) {
+ error = bytes;
+ break;
+ }
+
+ len -= bytes;
+ }
+
+ fput(new_file);
+out_fput:
+ fput(old_file);
+ return error;
+}
+
+static char *ovl_read_symlink(struct dentry *realdentry)
+{
+ int res;
+ char *buf;
+ struct inode *inode = realdentry->d_inode;
+ mm_segment_t old_fs;
+
+ res = -EINVAL;
+ if (!inode->i_op->readlink)
+ goto err;
+
+ res = -ENOMEM;
+ buf = (char *) __get_free_page(GFP_KERNEL);
+ if (!buf)
+ goto err;
+
+ old_fs = get_fs();
+ set_fs(get_ds());
+ /* The cast to a user pointer is valid due to the set_fs() */
+ res = inode->i_op->readlink(realdentry,
+ (char __user *)buf, PAGE_SIZE - 1);
+ set_fs(old_fs);
+ if (res < 0) {
+ free_page((unsigned long) buf);
+ goto err;
+ }
+ buf[res] = '\0';
+
+ return buf;
+
+err:
+ return ERR_PTR(res);
+}
+
+static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
+{
+ struct iattr attr = {
+ .ia_valid =
+ ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
+ .ia_atime = stat->atime,
+ .ia_mtime = stat->mtime,
+ };
+
+ return notify_change(upperdentry, &attr);
+}
+
+static int ovl_set_mode(struct dentry *upperdentry, umode_t mode)
+{
+ struct iattr attr = {
+ .ia_valid = ATTR_MODE,
+ .ia_mode = mode,
+ };
+
+ return notify_change(upperdentry, &attr);
+}
+
+static int ovl_copy_up_locked(struct dentry *upperdir, struct dentry *dentry,
+ struct path *lowerpath, struct kstat *stat,
+ const char *link)
+{
+ int err;
+ struct path newpath;
+ umode_t mode = stat->mode;
+
+ /* Can't properly set mode on creation because of the umask */
+ stat->mode &= S_IFMT;
+
+ ovl_path_upper(dentry, &newpath);
+ WARN_ON(newpath.dentry);
+ newpath.dentry = ovl_upper_create(upperdir, dentry, stat, link);
+ if (IS_ERR(newpath.dentry))
+ return PTR_ERR(newpath.dentry);
+
+ if (S_ISREG(stat->mode)) {
+ err = ovl_copy_up_data(lowerpath, &newpath, stat->size);
+ if (err)
+ goto err_remove;
+ }
+
+ err = ovl_copy_up_xattr(lowerpath->dentry, newpath.dentry);
+ if (err)
+ goto err_remove;
+
+ mutex_lock(&newpath.dentry->d_inode->i_mutex);
+ if (!S_ISLNK(stat->mode))
+ err = ovl_set_mode(newpath.dentry, mode);
+ if (!err)
+ err = ovl_set_timestamps(newpath.dentry, stat);
+ mutex_unlock(&newpath.dentry->d_inode->i_mutex);
+ if (err)
+ goto err_remove;
+
+ ovl_dentry_update(dentry, newpath.dentry);
+
+ /*
+ * Easiest way to get rid of the lower dentry reference is to
+ * drop this dentry. This is neither needed nor possible for
+ * directories.
+ */
+ if (!S_ISDIR(stat->mode))
+ d_drop(dentry);
+
+ return 0;
+
+err_remove:
+ if (S_ISDIR(stat->mode))
+ vfs_rmdir(upperdir->d_inode, newpath.dentry);
+ else
+ vfs_unlink(upperdir->d_inode, newpath.dentry);
+
+ dput(newpath.dentry);
+
+ return err;
+}
+
+/*
+ * Copy up a single dentry
+ *
+ * Directory renames only allowed on "pure upper" (already created on
+ * upper filesystem, never copied up). Directories which are on lower or
+ * are merged may not be renamed. For these -EXDEV is returned and
+ * userspace has to deal with it. This means, when copying up a
+ * directory we can rely on it and ancestors being stable.
+ *
+ * Non-directory renames start with copy up of source if necessary. The
+ * actual rename will only proceed once the copy up was successful. Copy
+ * up uses upper parent i_mutex for exclusion. Since rename can change
+ * d_parent it is possible that the copy up will lock the old parent. At
+ * that point the file will have already been copied up anyway.
+ */
+static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
+ struct path *lowerpath, struct kstat *stat)
+{
+ int err;
+ struct kstat pstat;
+ struct path parentpath;
+ struct dentry *upperdir;
+ const struct cred *old_cred;
+ struct cred *override_cred;
+ char *link = NULL;
+
+ ovl_path_upper(parent, &parentpath);
+ upperdir = parentpath.dentry;
+
+ err = vfs_getattr(parentpath.mnt, parentpath.dentry, &pstat);
+ if (err)
+ return err;
+
+ if (S_ISLNK(stat->mode)) {
+ link = ovl_read_symlink(lowerpath->dentry);
+ if (IS_ERR(link))
+ return PTR_ERR(link);
+ }
+
+ err = -ENOMEM;
+ override_cred = prepare_creds();
+ if (!override_cred)
+ goto out_free_link;
+
+ override_cred->fsuid = stat->uid;
+ override_cred->fsgid = stat->gid;
+ /*
+ * CAP_SYS_ADMIN for copying up extended attributes
+ * CAP_DAC_OVERRIDE for create
+ * CAP_FOWNER for chmod, timestamp update
+ * CAP_FSETID for chmod
+ * CAP_MKNOD for mknod
+ */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
+ cap_raise(override_cred->cap_effective, CAP_FSETID);
+ cap_raise(override_cred->cap_effective, CAP_MKNOD);
+ old_cred = override_creds(override_cred);
+
+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
+ if (ovl_path_type(dentry) != OVL_PATH_LOWER) {
+ err = 0;
+ } else {
+ err = ovl_copy_up_locked(upperdir, dentry, lowerpath,
+ stat, link);
+ if (!err) {
+ /* Restore timestamps on parent (best effort) */
+ ovl_set_timestamps(upperdir, &pstat);
+ }
+ }
+
+ mutex_unlock(&upperdir->d_inode->i_mutex);
+
+ revert_creds(old_cred);
+ put_cred(override_cred);
+
+out_free_link:
+ if (link)
+ free_page((unsigned long) link);
+
+ return err;
+}
+
+int ovl_copy_up(struct dentry *dentry)
+{
+ int err;
+
+ err = 0;
+ while (!err) {
+ struct dentry *next;
+ struct dentry *parent;
+ struct path lowerpath;
+ struct kstat stat;
+ enum ovl_path_type type = ovl_path_type(dentry);
+
+ if (type != OVL_PATH_LOWER)
+ break;
+
+ next = dget(dentry);
+ /* find the topmost dentry not yet copied up */
+ for (;;) {
+ parent = dget_parent(next);
+
+ type = ovl_path_type(parent);
+ if (type != OVL_PATH_LOWER)
+ break;
+
+ dput(next);
+ next = parent;
+ }
+
+ ovl_path_lower(next, &lowerpath);
+ err = vfs_getattr(lowerpath.mnt, lowerpath.dentry, &stat);
+ if (!err)
+ err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
+
+ dput(parent);
+ dput(next);
+ }
+
+ return err;
+}
+
+/* Optimize by not copying up the file first and truncating later */
+int ovl_copy_up_truncate(struct dentry *dentry, loff_t size)
+{
+ int err;
+ struct kstat stat;
+ struct path lowerpath;
+ struct dentry *parent = dget_parent(dentry);
+
+ err = ovl_copy_up(parent);
+ if (err)
+ goto out_dput_parent;
+
+ ovl_path_lower(dentry, &lowerpath);
+ err = vfs_getattr(lowerpath.mnt, lowerpath.dentry, &stat);
+ if (err)
+ goto out_dput_parent;
+
+ if (size < stat.size)
+ stat.size = size;
+
+ err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
+
+out_dput_parent:
+ dput(parent);
+ return err;
+}
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
new file mode 100644
index 00000000000..00aa6d99cb6
--- /dev/null
+++ b/fs/overlayfs/dir.c
@@ -0,0 +1,597 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * 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 <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+#include <linux/cred.h>
+#include "overlayfs.h"
+
+static const char *ovl_whiteout_symlink = "(overlay-whiteout)";
+
+static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry)
+{
+ int err;
+ struct dentry *newdentry;
+ const struct cred *old_cred;
+ struct cred *override_cred;
+
+ /* FIXME: recheck lower dentry to see if whiteout is really needed */
+
+ err = -ENOMEM;
+ override_cred = prepare_creds();
+ if (!override_cred)
+ goto out;
+
+ /*
+ * CAP_SYS_ADMIN for setxattr
+ * CAP_DAC_OVERRIDE for symlink creation
+ * CAP_FOWNER for unlink in sticky directory
+ */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
+ override_cred->fsuid = 0;
+ override_cred->fsgid = 0;
+ old_cred = override_creds(override_cred);
+
+ newdentry = lookup_one_len(dentry->d_name.name, upperdir,
+ dentry->d_name.len);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out_put_cred;
+
+ /* Just been removed within the same locked region */
+ WARN_ON(newdentry->d_inode);
+
+ err = vfs_symlink(upperdir->d_inode, newdentry, ovl_whiteout_symlink);
+ if (err)
+ goto out_dput;
+
+ ovl_dentry_version_inc(dentry->d_parent);
+
+ err = vfs_setxattr(newdentry, ovl_whiteout_xattr, "y", 1, 0);
+ if (err)
+ vfs_unlink(upperdir->d_inode, newdentry);
+
+out_dput:
+ dput(newdentry);
+out_put_cred:
+ revert_creds(old_cred);
+ put_cred(override_cred);
+out:
+ if (err) {
+ /*
+ * There's no way to recover from failure to whiteout.
+ * What should we do? Log a big fat error and... ?
+ */
+ printk(KERN_ERR "overlayfs: ERROR - failed to whiteout '%s'\n",
+ dentry->d_name.name);
+ }
+
+ return err;
+}
+
+static struct dentry *ovl_lookup_create(struct dentry *upperdir,
+ struct dentry *template)
+{
+ int err;
+ struct dentry *newdentry;
+ struct qstr *name = &template->d_name;
+
+ newdentry = lookup_one_len(name->name, upperdir, name->len);
+ if (IS_ERR(newdentry))
+ return newdentry;
+
+ if (newdentry->d_inode) {
+ const struct cred *old_cred;
+ struct cred *override_cred;
+
+ /* No need to check whiteout if lower parent is non-existent */
+ err = -EEXIST;
+ if (!ovl_dentry_lower(template->d_parent))
+ goto out_dput;
+
+ if (!S_ISLNK(newdentry->d_inode->i_mode))
+ goto out_dput;
+
+ err = -ENOMEM;
+ override_cred = prepare_creds();
+ if (!override_cred)
+ goto out_dput;
+
+ /*
+ * CAP_SYS_ADMIN for getxattr
+ * CAP_FOWNER for unlink in sticky directory
+ */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
+ old_cred = override_creds(override_cred);
+
+ err = -EEXIST;
+ if (ovl_is_whiteout(newdentry))
+ err = vfs_unlink(upperdir->d_inode, newdentry);
+
+ revert_creds(old_cred);
+ put_cred(override_cred);
+ if (err)
+ goto out_dput;
+
+ dput(newdentry);
+ newdentry = lookup_one_len(name->name, upperdir, name->len);
+ if (IS_ERR(newdentry)) {
+ ovl_whiteout(upperdir, template);
+ return newdentry;
+ }
+
+ /*
+ * Whiteout just been successfully removed, parent
+ * i_mutex is still held, there's no way the lookup
+ * could return positive.
+ */
+ WARN_ON(newdentry->d_inode);
+ }
+
+ return newdentry;
+
+out_dput:
+ dput(newdentry);
+ return ERR_PTR(err);
+}
+
+struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
+ struct kstat *stat, const char *link)
+{
+ int err;
+ struct dentry *newdentry;
+ struct inode *dir = upperdir->d_inode;
+
+ newdentry = ovl_lookup_create(upperdir, dentry);
+ if (IS_ERR(newdentry))
+ goto out;
+
+ switch (stat->mode & S_IFMT) {
+ case S_IFREG:
+ err = vfs_create(dir, newdentry, stat->mode, NULL);
+ break;
+
+ case S_IFDIR:
+ err = vfs_mkdir(dir, newdentry, stat->mode);
+ break;
+
+ case S_IFCHR:
+ case S_IFBLK:
+ case S_IFIFO:
+ case S_IFSOCK:
+ err = vfs_mknod(dir, newdentry, stat->mode, stat->rdev);
+ break;
+
+ case S_IFLNK:
+ err = vfs_symlink(dir, newdentry, link);
+ break;
+
+ default:
+ err = -EPERM;
+ }
+ if (err) {
+ if (ovl_dentry_is_opaque(dentry))
+ ovl_whiteout(upperdir, dentry);
+ dput(newdentry);
+ newdentry = ERR_PTR(err);
+ } else if (WARN_ON(!newdentry->d_inode)) {
+ /*
+ * Not quite sure if non-instantiated dentry is legal or not.
+ * VFS doesn't seem to care so check and warn here.
+ */
+ dput(newdentry);
+ newdentry = ERR_PTR(-ENOENT);
+ }
+
+out:
+ return newdentry;
+
+}
+
+static int ovl_set_opaque(struct dentry *upperdentry)
+{
+ int err;
+ const struct cred *old_cred;
+ struct cred *override_cred;
+
+ override_cred = prepare_creds();
+ if (!override_cred)
+ return -ENOMEM;
+
+ /* CAP_SYS_ADMIN for setxattr of "trusted" namespace */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ old_cred = override_creds(override_cred);
+ err = vfs_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0);
+ revert_creds(old_cred);
+ put_cred(override_cred);
+
+ return err;
+}
+
+static int ovl_remove_opaque(struct dentry *upperdentry)
+{
+ int err;
+ const struct cred *old_cred;
+ struct cred *override_cred;
+
+ override_cred = prepare_creds();
+ if (!override_cred)
+ return -ENOMEM;
+
+ /* CAP_SYS_ADMIN for removexattr of "trusted" namespace */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ old_cred = override_creds(override_cred);
+ err = vfs_removexattr(upperdentry, ovl_opaque_xattr);
+ revert_creds(old_cred);
+ put_cred(override_cred);
+
+ return err;
+}
+
+static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
+ struct kstat *stat)
+{
+ int err;
+ enum ovl_path_type type;
+ struct path realpath;
+
+ type = ovl_path_real(dentry, &realpath);
+ err = vfs_getattr(realpath.mnt, realpath.dentry, stat);
+ if (err)
+ return err;
+
+ stat->dev = dentry->d_sb->s_dev;
+ stat->ino = dentry->d_inode->i_ino;
+
+ /*
+ * It's probably not worth it to count subdirs to get the
+ * correct link count. nlink=1 seems to pacify 'find' and
+ * other utilities.
+ */
+ if (type == OVL_PATH_MERGE)
+ stat->nlink = 1;
+
+ return 0;
+}
+
+static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
+ const char *link)
+{
+ int err;
+ struct dentry *newdentry;
+ struct dentry *upperdir;
+ struct inode *inode;
+ struct kstat stat = {
+ .mode = mode,
+ .rdev = rdev,
+ };
+
+ err = -ENOMEM;
+ inode = ovl_new_inode(dentry->d_sb, mode, dentry->d_fsdata);
+ if (!inode)
+ goto out;
+
+ err = ovl_copy_up(dentry->d_parent);
+ if (err)
+ goto out_iput;
+
+ upperdir = ovl_dentry_upper(dentry->d_parent);
+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
+
+ newdentry = ovl_upper_create(upperdir, dentry, &stat, link);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out_unlock;
+
+ ovl_dentry_version_inc(dentry->d_parent);
+ if (ovl_dentry_is_opaque(dentry) && S_ISDIR(mode)) {
+ err = ovl_set_opaque(newdentry);
+ if (err) {
+ vfs_rmdir(upperdir->d_inode, newdentry);
+ ovl_whiteout(upperdir, dentry);
+ goto out_dput;
+ }
+ }
+ ovl_dentry_update(dentry, newdentry);
+ d_instantiate(dentry, inode);
+ inode = NULL;
+ newdentry = NULL;
+ err = 0;
+
+out_dput:
+ dput(newdentry);
+out_unlock:
+ mutex_unlock(&upperdir->d_inode->i_mutex);
+out_iput:
+ iput(inode);
+out:
+ return err;
+}
+
+static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+ struct nameidata *nd)
+{
+ return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
+}
+
+static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+ return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
+}
+
+static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
+ dev_t rdev)
+{
+ return ovl_create_object(dentry, mode, rdev, NULL);
+}
+
+static int ovl_symlink(struct inode *dir, struct dentry *dentry,
+ const char *link)
+{
+ return ovl_create_object(dentry, S_IFLNK, 0, link);
+}
+
+static int ovl_do_remove(struct dentry *dentry, bool is_dir)
+{
+ int err;
+ enum ovl_path_type type;
+ struct path realpath;
+ struct dentry *upperdir;
+
+ err = ovl_copy_up(dentry->d_parent);
+ if (err)
+ return err;
+
+ upperdir = ovl_dentry_upper(dentry->d_parent);
+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
+ type = ovl_path_real(dentry, &realpath);
+ if (type != OVL_PATH_LOWER) {
+ err = -ESTALE;
+ if (realpath.dentry->d_parent != upperdir)
+ goto out_d_drop;
+
+ /* FIXME: create whiteout up front and rename to target */
+
+ if (is_dir)
+ err = vfs_rmdir(upperdir->d_inode, realpath.dentry);
+ else
+ err = vfs_unlink(upperdir->d_inode, realpath.dentry);
+ if (err)
+ goto out_d_drop;
+
+ ovl_dentry_version_inc(dentry->d_parent);
+ }
+
+ if (type != OVL_PATH_UPPER || ovl_dentry_is_opaque(dentry))
+ err = ovl_whiteout(upperdir, dentry);
+
+ /*
+ * Keeping this dentry hashed would mean having to release
+ * upperpath/lowerpath, which could only be done if we are the
+ * sole user of this dentry. Too tricky... Just unhash for
+ * now.
+ */
+out_d_drop:
+ d_drop(dentry);
+ mutex_unlock(&upperdir->d_inode->i_mutex);
+
+ return err;
+}
+
+static int ovl_unlink(struct inode *dir, struct dentry *dentry)
+{
+ return ovl_do_remove(dentry, false);
+}
+
+
+static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ int err;
+ enum ovl_path_type type;
+
+ type = ovl_path_type(dentry);
+ if (type != OVL_PATH_UPPER) {
+ err = ovl_check_empty_and_clear(dentry, type);
+ if (err)
+ return err;
+ }
+
+ return ovl_do_remove(dentry, true);
+}
+
+static int ovl_link(struct dentry *old, struct inode *newdir,
+ struct dentry *new)
+{
+ int err;
+ struct dentry *olddentry;
+ struct dentry *newdentry;
+ struct dentry *upperdir;
+
+ err = ovl_copy_up(old);
+ if (err)
+ goto out;
+
+ err = ovl_copy_up(new->d_parent);
+ if (err)
+ goto out;
+
+ upperdir = ovl_dentry_upper(new->d_parent);
+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
+ newdentry = ovl_lookup_create(upperdir, new);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out_unlock;
+
+ olddentry = ovl_dentry_upper(old);
+ err = vfs_link(olddentry, upperdir->d_inode, newdentry);
+ if (!err) {
+ if (WARN_ON(!newdentry->d_inode)) {
+ dput(newdentry);
+ err = -ENOENT;
+ goto out_unlock;
+ }
+
+ ovl_dentry_version_inc(new->d_parent);
+ ovl_dentry_update(new, newdentry);
+
+ ihold(old->d_inode);
+ d_instantiate(new, old->d_inode);
+ } else {
+ if (ovl_dentry_is_opaque(new))
+ ovl_whiteout(upperdir, new);
+ dput(newdentry);
+ }
+out_unlock:
+ mutex_unlock(&upperdir->d_inode->i_mutex);
+out:
+ return err;
+
+}
+
+static int ovl_rename(struct inode *olddir, struct dentry *old,
+ struct inode *newdir, struct dentry *new)
+{
+ int err;
+ enum ovl_path_type old_type;
+ enum ovl_path_type new_type;
+ struct dentry *old_upperdir;
+ struct dentry *new_upperdir;
+ struct dentry *olddentry;
+ struct dentry *newdentry;
+ struct dentry *trap;
+ bool old_opaque;
+ bool new_opaque;
+ bool new_create = false;
+ bool is_dir = S_ISDIR(old->d_inode->i_mode);
+
+ /* Don't copy up directory trees */
+ old_type = ovl_path_type(old);
+ if (old_type != OVL_PATH_UPPER && is_dir)
+ return -EXDEV;
+
+ if (new->d_inode) {
+ new_type = ovl_path_type(new);
+
+ if (new_type == OVL_PATH_LOWER && old_type == OVL_PATH_LOWER) {
+ if (ovl_dentry_lower(old)->d_inode ==
+ ovl_dentry_lower(new)->d_inode)
+ return 0;
+ }
+ if (new_type != OVL_PATH_LOWER && old_type != OVL_PATH_LOWER) {
+ if (ovl_dentry_upper(old)->d_inode ==
+ ovl_dentry_upper(new)->d_inode)
+ return 0;
+ }
+
+ if (new_type != OVL_PATH_UPPER &&
+ S_ISDIR(new->d_inode->i_mode)) {
+ err = ovl_check_empty_and_clear(new, new_type);
+ if (err)
+ return err;
+ }
+ } else {
+ new_type = OVL_PATH_UPPER;
+ }
+
+ err = ovl_copy_up(old);
+ if (err)
+ return err;
+
+ err = ovl_copy_up(new->d_parent);
+ if (err)
+ return err;
+
+ old_upperdir = ovl_dentry_upper(old->d_parent);
+ new_upperdir = ovl_dentry_upper(new->d_parent);
+
+ trap = lock_rename(new_upperdir, old_upperdir);
+
+ olddentry = ovl_dentry_upper(old);
+ newdentry = ovl_dentry_upper(new);
+ if (newdentry) {
+ dget(newdentry);
+ } else {
+ new_create = true;
+ newdentry = ovl_lookup_create(new_upperdir, new);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out_unlock;
+ }
+
+ err = -ESTALE;
+ if (olddentry->d_parent != old_upperdir)
+ goto out_dput;
+ if (newdentry->d_parent != new_upperdir)
+ goto out_dput;
+ if (olddentry == trap)
+ goto out_dput;
+ if (newdentry == trap)
+ goto out_dput;
+
+ old_opaque = ovl_dentry_is_opaque(old);
+ new_opaque = ovl_dentry_is_opaque(new) || new_type != OVL_PATH_UPPER;
+
+ if (is_dir && !old_opaque && new_opaque) {
+ err = ovl_set_opaque(olddentry);
+ if (err)
+ goto out_dput;
+ }
+
+ err = vfs_rename(old_upperdir->d_inode, olddentry,
+ new_upperdir->d_inode, newdentry);
+
+ if (err) {
+ if (new_create && ovl_dentry_is_opaque(new))
+ ovl_whiteout(new_upperdir, new);
+ if (is_dir && !old_opaque && new_opaque)
+ ovl_remove_opaque(olddentry);
+ goto out_dput;
+ }
+
+ if (old_type != OVL_PATH_UPPER || old_opaque)
+ err = ovl_whiteout(old_upperdir, old);
+ if (is_dir && old_opaque && !new_opaque)
+ ovl_remove_opaque(olddentry);
+
+ if (old_opaque != new_opaque)
+ ovl_dentry_set_opaque(old, new_opaque);
+
+ ovl_dentry_version_inc(old->d_parent);
+ ovl_dentry_version_inc(new->d_parent);
+
+out_dput:
+ dput(newdentry);
+out_unlock:
+ unlock_rename(new_upperdir, old_upperdir);
+ return err;
+}
+
+const struct inode_operations ovl_dir_inode_operations = {
+ .lookup = ovl_lookup,
+ .mkdir = ovl_mkdir,
+ .symlink = ovl_symlink,
+ .unlink = ovl_unlink,
+ .rmdir = ovl_rmdir,
+ .rename = ovl_rename,
+ .link = ovl_link,
+ .setattr = ovl_setattr,
+ .create = ovl_create,
+ .mknod = ovl_mknod,
+ .permission = ovl_permission,
+ .getattr = ovl_dir_getattr,
+ .setxattr = ovl_setxattr,
+ .getxattr = ovl_getxattr,
+ .listxattr = ovl_listxattr,
+ .removexattr = ovl_removexattr,
+};
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
new file mode 100644
index 00000000000..c220ea745f2
--- /dev/null
+++ b/fs/overlayfs/inode.c
@@ -0,0 +1,384 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * 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 <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include "overlayfs.h"
+
+int ovl_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ struct dentry *upperdentry;
+ int err;
+
+ if ((attr->ia_valid & ATTR_SIZE) && !ovl_dentry_upper(dentry))
+ err = ovl_copy_up_truncate(dentry, attr->ia_size);
+ else
+ err = ovl_copy_up(dentry);
+ if (err)
+ return err;
+
+ upperdentry = ovl_dentry_upper(dentry);
+
+ if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
+ attr->ia_valid &= ~ATTR_MODE;
+
+ mutex_lock(&upperdentry->d_inode->i_mutex);
+ err = notify_change(upperdentry, attr);
+ mutex_unlock(&upperdentry->d_inode->i_mutex);
+
+ return err;
+}
+
+static int ovl_getattr(struct vfsmount *mnt, struct dentry *dentry,
+ struct kstat *stat)
+{
+ struct path realpath;
+
+ ovl_path_real(dentry, &realpath);
+ return vfs_getattr(realpath.mnt, realpath.dentry, stat);
+}
+
+int ovl_permission(struct inode *inode, int mask)
+{
+ struct ovl_entry *oe;
+ struct dentry *alias = NULL;
+ struct inode *realinode;
+ struct dentry *realdentry;
+ bool is_upper;
+ int err;
+
+ if (S_ISDIR(inode->i_mode)) {
+ oe = inode->i_private;
+ } else if (mask & MAY_NOT_BLOCK) {
+ return -ECHILD;
+ } else {
+ /*
+ * For non-directories find an alias and get the info
+ * from there.
+ */
+ spin_lock(&inode->i_lock);
+ if (WARN_ON(list_empty(&inode->i_dentry))) {
+ spin_unlock(&inode->i_lock);
+ return -ENOENT;
+ }
+ alias = list_entry(inode->i_dentry.next,
+ struct dentry, d_alias);
+ dget(alias);
+ spin_unlock(&inode->i_lock);
+ oe = alias->d_fsdata;
+ }
+
+ realdentry = ovl_entry_real(oe, &is_upper);
+
+ /* Careful in RCU walk mode */
+ realinode = ACCESS_ONCE(realdentry->d_inode);
+ if (!realinode) {
+ WARN_ON(!(mask & MAY_NOT_BLOCK));
+ err = -ENOENT;
+ goto out_dput;
+ }
+
+ if (mask & MAY_WRITE) {
+ umode_t mode = realinode->i_mode;
+
+ /*
+ * Writes will always be redirected to upper layer, so
+ * ignore lower layer being read-only.
+ *
+ * If the overlay itself is read-only then proceed
+ * with the permission check, don't return EROFS.
+ * This will only happen if this is the lower layer of
+ * another overlayfs.
+ *
+ * If upper fs becomes read-only after the overlay was
+ * constructed return EROFS to prevent modification of
+ * upper layer.
+ */
+ err = -EROFS;
+ if (is_upper && !IS_RDONLY(inode) && IS_RDONLY(realinode) &&
+ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
+ goto out_dput;
+
+ /*
+ * Nobody gets write access to an immutable file.
+ */
+ err = -EACCES;
+ if (IS_IMMUTABLE(realinode))
+ goto out_dput;
+ }
+
+ if (realinode->i_op->permission)
+ err = realinode->i_op->permission(realinode, mask);
+ else
+ err = generic_permission(realinode, mask);
+out_dput:
+ dput(alias);
+ return err;
+}
+
+
+struct ovl_link_data {
+ struct dentry *realdentry;
+ void *cookie;
+};
+
+static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ void *ret;
+ struct dentry *realdentry;
+ struct inode *realinode;
+
+ realdentry = ovl_dentry_real(dentry);
+ realinode = realdentry->d_inode;
+
+ if (WARN_ON(!realinode->i_op->follow_link))
+ return ERR_PTR(-EPERM);
+
+ ret = realinode->i_op->follow_link(realdentry, nd);
+ if (IS_ERR(ret))
+ return ret;
+
+ if (realinode->i_op->put_link) {
+ struct ovl_link_data *data;
+
+ data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL);
+ if (!data) {
+ realinode->i_op->put_link(realdentry, nd, ret);
+ return ERR_PTR(-ENOMEM);
+ }
+ data->realdentry = realdentry;
+ data->cookie = ret;
+
+ return data;
+ } else {
+ return NULL;
+ }
+}
+
+static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c)
+{
+ struct inode *realinode;
+ struct ovl_link_data *data = c;
+
+ if (!data)
+ return;
+
+ realinode = data->realdentry->d_inode;
+ realinode->i_op->put_link(data->realdentry, nd, data->cookie);
+ kfree(data);
+}
+
+static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
+{
+ struct path realpath;
+ struct inode *realinode;
+
+ ovl_path_real(dentry, &realpath);
+ realinode = realpath.dentry->d_inode;
+
+ if (!realinode->i_op->readlink)
+ return -EINVAL;
+
+ touch_atime(&realpath);
+
+ return realinode->i_op->readlink(realpath.dentry, buf, bufsiz);
+}
+
+
+static bool ovl_is_private_xattr(const char *name)
+{
+ return strncmp(name, "trusted.overlay.", 14) == 0;
+}
+
+int ovl_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ int err;
+ struct dentry *upperdentry;
+
+ if (ovl_is_private_xattr(name))
+ return -EPERM;
+
+ err = ovl_copy_up(dentry);
+ if (err)
+ return err;
+
+ upperdentry = ovl_dentry_upper(dentry);
+ return vfs_setxattr(upperdentry, name, value, size, flags);
+}
+
+ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
+ void *value, size_t size)
+{
+ if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
+ ovl_is_private_xattr(name))
+ return -ENODATA;
+
+ return vfs_getxattr(ovl_dentry_real(dentry), name, value, size);
+}
+
+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
+{
+ ssize_t res;
+ int off;
+
+ res = vfs_listxattr(ovl_dentry_real(dentry), list, size);
+ if (res <= 0 || size == 0)
+ return res;
+
+ if (ovl_path_type(dentry->d_parent) != OVL_PATH_MERGE)
+ return res;
+
+ /* filter out private xattrs */
+ for (off = 0; off < res;) {
+ char *s = list + off;
+ size_t slen = strlen(s) + 1;
+
+ BUG_ON(off + slen > res);
+
+ if (ovl_is_private_xattr(s)) {
+ res -= slen;
+ memmove(s, s + slen, res - off);
+ } else {
+ off += slen;
+ }
+ }
+
+ return res;
+}
+
+int ovl_removexattr(struct dentry *dentry, const char *name)
+{
+ int err;
+ struct path realpath;
+ enum ovl_path_type type;
+
+ if (ovl_path_type(dentry->d_parent) == OVL_PATH_MERGE &&
+ ovl_is_private_xattr(name))
+ return -ENODATA;
+
+ type = ovl_path_real(dentry, &realpath);
+ if (type == OVL_PATH_LOWER) {
+ err = vfs_getxattr(realpath.dentry, name, NULL, 0);
+ if (err < 0)
+ return err;
+
+ err = ovl_copy_up(dentry);
+ if (err)
+ return err;
+
+ ovl_path_upper(dentry, &realpath);
+ }
+
+ return vfs_removexattr(realpath.dentry, name);
+}
+
+static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
+ struct dentry *realdentry)
+{
+ if (type != OVL_PATH_LOWER)
+ return false;
+
+ if (special_file(realdentry->d_inode->i_mode))
+ return false;
+
+ if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
+ return false;
+
+ return true;
+}
+
+static struct file *ovl_open(struct dentry *dentry, struct file *file,
+ const struct cred *cred)
+{
+ int err;
+ struct path realpath;
+ enum ovl_path_type type;
+
+ type = ovl_path_real(dentry, &realpath);
+ if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) {
+ if (file->f_flags & O_TRUNC)
+ err = ovl_copy_up_truncate(dentry, 0);
+ else
+ err = ovl_copy_up(dentry);
+ if (err)
+ return ERR_PTR(err);
+
+ ovl_path_upper(dentry, &realpath);
+ }
+
+ return vfs_open(&realpath, file, cred);
+}
+
+static const struct inode_operations ovl_file_inode_operations = {
+ .setattr = ovl_setattr,
+ .permission = ovl_permission,
+ .getattr = ovl_getattr,
+ .setxattr = ovl_setxattr,
+ .getxattr = ovl_getxattr,
+ .listxattr = ovl_listxattr,
+ .removexattr = ovl_removexattr,
+ .open = ovl_open,
+};
+
+static const struct inode_operations ovl_symlink_inode_operations = {
+ .setattr = ovl_setattr,
+ .follow_link = ovl_follow_link,
+ .put_link = ovl_put_link,
+ .readlink = ovl_readlink,
+ .getattr = ovl_getattr,
+ .setxattr = ovl_setxattr,
+ .getxattr = ovl_getxattr,
+ .listxattr = ovl_listxattr,
+ .removexattr = ovl_removexattr,
+};
+
+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
+ struct ovl_entry *oe)
+{
+ struct inode *inode;
+
+ inode = new_inode(sb);
+ if (!inode)
+ return NULL;
+
+ mode &= S_IFMT;
+
+ inode->i_ino = get_next_ino();
+ inode->i_mode = mode;
+ inode->i_flags |= S_NOATIME | S_NOCMTIME;
+
+ switch (mode) {
+ case S_IFDIR:
+ inode->i_private = oe;
+ inode->i_op = &ovl_dir_inode_operations;
+ inode->i_fop = &ovl_dir_operations;
+ break;
+
+ case S_IFLNK:
+ inode->i_op = &ovl_symlink_inode_operations;
+ break;
+
+ case S_IFREG:
+ case S_IFSOCK:
+ case S_IFBLK:
+ case S_IFCHR:
+ case S_IFIFO:
+ inode->i_op = &ovl_file_inode_operations;
+ break;
+
+ default:
+ WARN(1, "illegal file type: %i\n", mode);
+ inode = NULL;
+ }
+
+ return inode;
+
+}
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
new file mode 100644
index 00000000000..1dd05f76604
--- /dev/null
+++ b/fs/overlayfs/overlayfs.h
@@ -0,0 +1,64 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * 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.
+ */
+
+struct ovl_entry;
+
+enum ovl_path_type {
+ OVL_PATH_UPPER,
+ OVL_PATH_MERGE,
+ OVL_PATH_LOWER,
+};
+
+extern const char *ovl_opaque_xattr;
+extern const char *ovl_whiteout_xattr;
+extern const struct dentry_operations ovl_dentry_operations;
+
+enum ovl_path_type ovl_path_type(struct dentry *dentry);
+u64 ovl_dentry_version_get(struct dentry *dentry);
+void ovl_dentry_version_inc(struct dentry *dentry);
+void ovl_path_upper(struct dentry *dentry, struct path *path);
+void ovl_path_lower(struct dentry *dentry, struct path *path);
+enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
+struct dentry *ovl_dentry_upper(struct dentry *dentry);
+struct dentry *ovl_dentry_lower(struct dentry *dentry);
+struct dentry *ovl_dentry_real(struct dentry *dentry);
+struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper);
+bool ovl_dentry_is_opaque(struct dentry *dentry);
+void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque);
+bool ovl_is_whiteout(struct dentry *dentry);
+void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry);
+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
+ struct nameidata *nd);
+struct file *ovl_path_open(struct path *path, int flags);
+
+struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
+ struct kstat *stat, const char *link);
+
+/* readdir.c */
+extern const struct file_operations ovl_dir_operations;
+int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type);
+
+/* inode.c */
+int ovl_setattr(struct dentry *dentry, struct iattr *attr);
+int ovl_permission(struct inode *inode, int mask);
+int ovl_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags);
+ssize_t ovl_getxattr(struct dentry *dentry, const char *name,
+ void *value, size_t size);
+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
+int ovl_removexattr(struct dentry *dentry, const char *name);
+
+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
+ struct ovl_entry *oe);
+/* dir.c */
+extern const struct inode_operations ovl_dir_inode_operations;
+
+/* copy_up.c */
+int ovl_copy_up(struct dentry *dentry);
+int ovl_copy_up_truncate(struct dentry *dentry, loff_t size);
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
new file mode 100644
index 00000000000..0797efbc7be
--- /dev/null
+++ b/fs/overlayfs/readdir.c
@@ -0,0 +1,566 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * 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 <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/namei.h>
+#include <linux/file.h>
+#include <linux/xattr.h>
+#include <linux/rbtree.h>
+#include <linux/security.h>
+#include <linux/cred.h>
+#include "overlayfs.h"
+
+struct ovl_cache_entry {
+ const char *name;
+ unsigned int len;
+ unsigned int type;
+ u64 ino;
+ bool is_whiteout;
+ struct list_head l_node;
+ struct rb_node node;
+};
+
+struct ovl_readdir_data {
+ struct rb_root *root;
+ struct list_head *list;
+ struct list_head *middle;
+ struct dentry *dir;
+ int count;
+ int err;
+};
+
+struct ovl_dir_file {
+ bool is_real;
+ bool is_cached;
+ struct list_head cursor;
+ u64 cache_version;
+ struct list_head cache;
+ struct file *realfile;
+};
+
+static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
+{
+ return container_of(n, struct ovl_cache_entry, node);
+}
+
+static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
+ const char *name, int len)
+{
+ struct rb_node *node = root->rb_node;
+ int cmp;
+
+ while (node) {
+ struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
+
+ cmp = strncmp(name, p->name, len);
+ if (cmp > 0)
+ node = p->node.rb_right;
+ else if (cmp < 0 || len < p->len)
+ node = p->node.rb_left;
+ else
+ return p;
+ }
+
+ return NULL;
+}
+
+static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,
+ u64 ino, unsigned int d_type)
+{
+ struct ovl_cache_entry *p;
+
+ p = kmalloc(sizeof(*p) + len + 1, GFP_KERNEL);
+ if (p) {
+ char *name_copy = (char *) (p + 1);
+ memcpy(name_copy, name, len);
+ name_copy[len] = '\0';
+ p->name = name_copy;
+ p->len = len;
+ p->type = d_type;
+ p->ino = ino;
+ p->is_whiteout = false;
+ }
+
+ return p;
+}
+
+static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
+ const char *name, int len, u64 ino,
+ unsigned int d_type)
+{
+ struct rb_node **newp = &rdd->root->rb_node;
+ struct rb_node *parent = NULL;
+ struct ovl_cache_entry *p;
+
+ while (*newp) {
+ int cmp;
+ struct ovl_cache_entry *tmp;
+
+ parent = *newp;
+ tmp = ovl_cache_entry_from_node(*newp);
+ cmp = strncmp(name, tmp->name, len);
+ if (cmp > 0)
+ newp = &tmp->node.rb_right;
+ else if (cmp < 0 || len < tmp->len)
+ newp = &tmp->node.rb_left;
+ else
+ return 0;
+ }
+
+ p = ovl_cache_entry_new(name, len, ino, d_type);
+ if (p == NULL)
+ return -ENOMEM;
+
+ list_add_tail(&p->l_node, rdd->list);
+ rb_link_node(&p->node, parent, newp);
+ rb_insert_color(&p->node, rdd->root);
+
+ return 0;
+}
+
+static int ovl_fill_lower(void *buf, const char *name, int namelen,
+ loff_t offset, u64 ino, unsigned int d_type)
+{
+ struct ovl_readdir_data *rdd = buf;
+ struct ovl_cache_entry *p;
+
+ rdd->count++;
+ p = ovl_cache_entry_find(rdd->root, name, namelen);
+ if (p) {
+ list_move_tail(&p->l_node, rdd->middle);
+ } else {
+ p = ovl_cache_entry_new(name, namelen, ino, d_type);
+ if (p == NULL)
+ rdd->err = -ENOMEM;
+ else
+ list_add_tail(&p->l_node, rdd->middle);
+ }
+
+ return rdd->err;
+}
+
+static void ovl_cache_free(struct list_head *list)
+{
+ struct ovl_cache_entry *p;
+ struct ovl_cache_entry *n;
+
+ list_for_each_entry_safe(p, n, list, l_node)
+ kfree(p);
+
+ INIT_LIST_HEAD(list);
+}
+
+static int ovl_fill_upper(void *buf, const char *name, int namelen,
+ loff_t offset, u64 ino, unsigned int d_type)
+{
+ struct ovl_readdir_data *rdd = buf;
+
+ rdd->count++;
+ return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
+}
+
+static inline int ovl_dir_read(struct path *realpath,
+ struct ovl_readdir_data *rdd, filldir_t filler)
+{
+ struct file *realfile;
+ int err;
+
+ realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
+ if (IS_ERR(realfile))
+ return PTR_ERR(realfile);
+
+ do {
+ rdd->count = 0;
+ rdd->err = 0;
+ err = vfs_readdir(realfile, filler, rdd);
+ if (err >= 0)
+ err = rdd->err;
+ } while (!err && rdd->count);
+ fput(realfile);
+
+ return 0;
+}
+
+static void ovl_dir_reset(struct file *file)
+{
+ struct ovl_dir_file *od = file->private_data;
+ enum ovl_path_type type = ovl_path_type(file->f_path.dentry);
+
+ if (ovl_dentry_version_get(file->f_path.dentry) != od->cache_version) {
+ list_del_init(&od->cursor);
+ ovl_cache_free(&od->cache);
+ od->is_cached = false;
+ }
+ WARN_ON(!od->is_real && type != OVL_PATH_MERGE);
+ if (od->is_real && type == OVL_PATH_MERGE) {
+ fput(od->realfile);
+ od->realfile = NULL;
+ od->is_real = false;
+ }
+}
+
+static int ovl_dir_mark_whiteouts(struct ovl_readdir_data *rdd)
+{
+ struct ovl_cache_entry *p;
+ struct dentry *dentry;
+ const struct cred *old_cred;
+ struct cred *override_cred;
+
+ override_cred = prepare_creds();
+ if (!override_cred) {
+ ovl_cache_free(rdd->list);
+ return -ENOMEM;
+ }
+
+ /*
+ * CAP_SYS_ADMIN for getxattr
+ * CAP_DAC_OVERRIDE for lookup
+ */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+ old_cred = override_creds(override_cred);
+
+ mutex_lock(&rdd->dir->d_inode->i_mutex);
+ list_for_each_entry(p, rdd->list, l_node) {
+ if (p->type != DT_LNK)
+ continue;
+
+ dentry = lookup_one_len(p->name, rdd->dir, p->len);
+ if (IS_ERR(dentry))
+ continue;
+
+ p->is_whiteout = ovl_is_whiteout(dentry);
+ dput(dentry);
+ }
+ mutex_unlock(&rdd->dir->d_inode->i_mutex);
+
+ revert_creds(old_cred);
+ put_cred(override_cred);
+
+ return 0;
+}
+
+static inline int ovl_dir_read_merged(struct path *upperpath,
+ struct path *lowerpath,
+ struct ovl_readdir_data *rdd)
+{
+ int err;
+ struct rb_root root = RB_ROOT;
+ struct list_head middle;
+
+ rdd->root = &root;
+ if (upperpath->dentry) {
+ rdd->dir = upperpath->dentry;
+ err = ovl_dir_read(upperpath, rdd, ovl_fill_upper);
+ if (err)
+ goto out;
+
+ err = ovl_dir_mark_whiteouts(rdd);
+ if (err)
+ goto out;
+ }
+ /*
+ * Insert lowerpath entries before upperpath ones, this allows
+ * offsets to be reasonably constant
+ */
+ list_add(&middle, rdd->list);
+ rdd->middle = &middle;
+ err = ovl_dir_read(lowerpath, rdd, ovl_fill_lower);
+ list_del(&middle);
+out:
+ rdd->root = NULL;
+
+ return err;
+}
+
+static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
+{
+ struct list_head *l;
+ loff_t off;
+
+ l = od->cache.next;
+ for (off = 0; off < pos; off++) {
+ if (l == &od->cache)
+ break;
+ l = l->next;
+ }
+ list_move_tail(&od->cursor, l);
+}
+
+static int ovl_readdir(struct file *file, void *buf, filldir_t filler)
+{
+ struct ovl_dir_file *od = file->private_data;
+ int res;
+
+ if (!file->f_pos)
+ ovl_dir_reset(file);
+
+ if (od->is_real) {
+ res = vfs_readdir(od->realfile, filler, buf);
+ file->f_pos = od->realfile->f_pos;
+
+ return res;
+ }
+
+ if (!od->is_cached) {
+ struct path lowerpath;
+ struct path upperpath;
+ struct ovl_readdir_data rdd = { .list = &od->cache };
+
+ ovl_path_lower(file->f_path.dentry, &lowerpath);
+ ovl_path_upper(file->f_path.dentry, &upperpath);
+
+ res = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd);
+ if (res) {
+ ovl_cache_free(rdd.list);
+ return res;
+ }
+
+ od->cache_version = ovl_dentry_version_get(file->f_path.dentry);
+ od->is_cached = true;
+
+ ovl_seek_cursor(od, file->f_pos);
+ }
+
+ while (od->cursor.next != &od->cache) {
+ int over;
+ loff_t off;
+ struct ovl_cache_entry *p;
+
+ p = list_entry(od->cursor.next, struct ovl_cache_entry, l_node);
+ off = file->f_pos;
+ if (!p->is_whiteout) {
+ over = filler(buf, p->name, p->len, off, p->ino,
+ p->type);
+ if (over)
+ break;
+ }
+ file->f_pos++;
+ list_move(&od->cursor, &p->l_node);
+ }
+
+ return 0;
+}
+
+static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
+{
+ loff_t res;
+ struct ovl_dir_file *od = file->private_data;
+
+ mutex_lock(&file->f_dentry->d_inode->i_mutex);
+ if (!file->f_pos)
+ ovl_dir_reset(file);
+
+ if (od->is_real) {
+ res = vfs_llseek(od->realfile, offset, origin);
+ file->f_pos = od->realfile->f_pos;
+ } else {
+ res = -EINVAL;
+
+ switch (origin) {
+ case SEEK_CUR:
+ offset += file->f_pos;
+ break;
+ case SEEK_SET:
+ break;
+ default:
+ goto out_unlock;
+ }
+ if (offset < 0)
+ goto out_unlock;
+
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ if (od->is_cached)
+ ovl_seek_cursor(od, offset);
+ }
+ res = offset;
+ }
+out_unlock:
+ mutex_unlock(&file->f_dentry->d_inode->i_mutex);
+
+ return res;
+}
+
+static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
+ int datasync)
+{
+ struct ovl_dir_file *od = file->private_data;
+
+ /* May need to reopen directory if it got copied up */
+ if (!od->realfile) {
+ struct path upperpath;
+
+ ovl_path_upper(file->f_path.dentry, &upperpath);
+ od->realfile = ovl_path_open(&upperpath, O_RDONLY);
+ if (IS_ERR(od->realfile))
+ return PTR_ERR(od->realfile);
+ }
+
+ return vfs_fsync_range(od->realfile, start, end, datasync);
+}
+
+static int ovl_dir_release(struct inode *inode, struct file *file)
+{
+ struct ovl_dir_file *od = file->private_data;
+
+ list_del(&od->cursor);
+ ovl_cache_free(&od->cache);
+ if (od->realfile)
+ fput(od->realfile);
+ kfree(od);
+
+ return 0;
+}
+
+static int ovl_dir_open(struct inode *inode, struct file *file)
+{
+ struct path realpath;
+ struct file *realfile;
+ struct ovl_dir_file *od;
+ enum ovl_path_type type;
+
+ od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
+ if (!od)
+ return -ENOMEM;
+
+ type = ovl_path_real(file->f_path.dentry, &realpath);
+ realfile = ovl_path_open(&realpath, file->f_flags);
+ if (IS_ERR(realfile)) {
+ kfree(od);
+ return PTR_ERR(realfile);
+ }
+ INIT_LIST_HEAD(&od->cache);
+ INIT_LIST_HEAD(&od->cursor);
+ od->is_cached = false;
+ od->realfile = realfile;
+ od->is_real = (type != OVL_PATH_MERGE);
+ file->private_data = od;
+
+ return 0;
+}
+
+const struct file_operations ovl_dir_operations = {
+ .read = generic_read_dir,
+ .open = ovl_dir_open,
+ .readdir = ovl_readdir,
+ .llseek = ovl_dir_llseek,
+ .fsync = ovl_dir_fsync,
+ .release = ovl_dir_release,
+};
+
+static int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
+{
+ int err;
+ struct path lowerpath;
+ struct path upperpath;
+ struct ovl_cache_entry *p;
+ struct ovl_readdir_data rdd = { .list = list };
+
+ ovl_path_upper(dentry, &upperpath);
+ ovl_path_lower(dentry, &lowerpath);
+
+ err = ovl_dir_read_merged(&upperpath, &lowerpath, &rdd);
+ if (err)
+ return err;
+
+ err = 0;
+
+ list_for_each_entry(p, list, l_node) {
+ if (p->is_whiteout)
+ continue;
+
+ if (p->name[0] == '.') {
+ if (p->len == 1)
+ continue;
+ if (p->len == 2 && p->name[1] == '.')
+ continue;
+ }
+ err = -ENOTEMPTY;
+ break;
+ }
+
+ return err;
+}
+
+static int ovl_remove_whiteouts(struct dentry *dir, struct list_head *list)
+{
+ struct path upperpath;
+ struct dentry *upperdir;
+ struct ovl_cache_entry *p;
+ const struct cred *old_cred;
+ struct cred *override_cred;
+ int err;
+
+ ovl_path_upper(dir, &upperpath);
+ upperdir = upperpath.dentry;
+
+ override_cred = prepare_creds();
+ if (!override_cred)
+ return -ENOMEM;
+
+ /*
+ * CAP_DAC_OVERRIDE for lookup and unlink
+ * CAP_SYS_ADMIN for setxattr of "trusted" namespace
+ * CAP_FOWNER for unlink in sticky directory
+ */
+ cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ cap_raise(override_cred->cap_effective, CAP_FOWNER);
+ old_cred = override_creds(override_cred);
+
+ err = vfs_setxattr(upperdir, ovl_opaque_xattr, "y", 1, 0);
+ if (err)
+ goto out_revert_creds;
+
+ mutex_lock_nested(&upperdir->d_inode->i_mutex, I_MUTEX_PARENT);
+ list_for_each_entry(p, list, l_node) {
+ struct dentry *dentry;
+ int ret;
+
+ if (!p->is_whiteout)
+ continue;
+
+ dentry = lookup_one_len(p->name, upperdir, p->len);
+ if (IS_ERR(dentry)) {
+ printk(KERN_WARNING
+ "overlayfs: failed to lookup whiteout %.*s: %li\n",
+ p->len, p->name, PTR_ERR(dentry));
+ continue;
+ }
+ ret = vfs_unlink(upperdir->d_inode, dentry);
+ dput(dentry);
+ if (ret)
+ printk(KERN_WARNING
+ "overlayfs: failed to unlink whiteout %.*s: %i\n",
+ p->len, p->name, ret);
+ }
+ mutex_unlock(&upperdir->d_inode->i_mutex);
+
+out_revert_creds:
+ revert_creds(old_cred);
+ put_cred(override_cred);
+
+ return err;
+}
+
+int ovl_check_empty_and_clear(struct dentry *dentry, enum ovl_path_type type)
+{
+ int err;
+ LIST_HEAD(list);
+
+ err = ovl_check_empty_dir(dentry, &list);
+ if (!err && type == OVL_PATH_MERGE)
+ err = ovl_remove_whiteouts(dentry, &list);
+
+ ovl_cache_free(&list);
+
+ return err;
+}
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
new file mode 100644
index 00000000000..0aaa4c29546
--- /dev/null
+++ b/fs/overlayfs/super.c
@@ -0,0 +1,611 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * 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 <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+#include <linux/mount.h>
+#include <linux/slab.h>
+#include <linux/parser.h>
+#include <linux/module.h>
+#include <linux/cred.h>
+#include <linux/sched.h>
+#include "overlayfs.h"
+
+MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
+MODULE_DESCRIPTION("Overlay filesystem");
+MODULE_LICENSE("GPL");
+
+struct ovl_fs {
+ struct vfsmount *upper_mnt;
+ struct vfsmount *lower_mnt;
+};
+
+struct ovl_entry {
+ /*
+ * Keep "double reference" on upper dentries, so that
+ * d_delete() doesn't think it's OK to reset d_inode to NULL.
+ */
+ struct dentry *__upperdentry;
+ struct dentry *lowerdentry;
+ union {
+ struct {
+ u64 version;
+ bool opaque;
+ };
+ struct rcu_head rcu;
+ };
+};
+
+const char *ovl_whiteout_xattr = "trusted.overlay.whiteout";
+const char *ovl_opaque_xattr = "trusted.overlay.opaque";
+
+
+enum ovl_path_type ovl_path_type(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ if (oe->__upperdentry) {
+ if (oe->lowerdentry && S_ISDIR(dentry->d_inode->i_mode))
+ return OVL_PATH_MERGE;
+ else
+ return OVL_PATH_UPPER;
+ } else {
+ return OVL_PATH_LOWER;
+ }
+}
+
+static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
+{
+ struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry);
+ smp_read_barrier_depends();
+ return upperdentry;
+}
+
+void ovl_path_upper(struct dentry *dentry, struct path *path)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ path->mnt = ofs->upper_mnt;
+ path->dentry = ovl_upperdentry_dereference(oe);
+}
+
+void ovl_path_lower(struct dentry *dentry, struct path *path)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ path->mnt = ofs->lower_mnt;
+ path->dentry = oe->lowerdentry;
+}
+
+enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
+{
+
+ enum ovl_path_type type = ovl_path_type(dentry);
+
+ if (type == OVL_PATH_LOWER)
+ ovl_path_lower(dentry, path);
+ else
+ ovl_path_upper(dentry, path);
+
+ return type;
+}
+
+struct dentry *ovl_dentry_upper(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ return ovl_upperdentry_dereference(oe);
+}
+
+struct dentry *ovl_dentry_lower(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ return oe->lowerdentry;
+}
+
+struct dentry *ovl_dentry_real(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ struct dentry *realdentry;
+
+ realdentry = ovl_upperdentry_dereference(oe);
+ if (!realdentry)
+ realdentry = oe->lowerdentry;
+
+ return realdentry;
+}
+
+struct dentry *ovl_entry_real(struct ovl_entry *oe, bool *is_upper)
+{
+ struct dentry *realdentry;
+
+ realdentry = ovl_upperdentry_dereference(oe);
+ if (realdentry) {
+ *is_upper = true;
+ } else {
+ realdentry = oe->lowerdentry;
+ *is_upper = false;
+ }
+ return realdentry;
+}
+
+bool ovl_dentry_is_opaque(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ return oe->opaque;
+}
+
+void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ oe->opaque = opaque;
+}
+
+void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ WARN_ON(!mutex_is_locked(&upperdentry->d_parent->d_inode->i_mutex));
+ WARN_ON(oe->__upperdentry);
+ BUG_ON(!upperdentry->d_inode);
+ smp_wmb();
+ oe->__upperdentry = dget(upperdentry);
+}
+
+void ovl_dentry_version_inc(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
+ oe->version++;
+}
+
+u64 ovl_dentry_version_get(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ WARN_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
+ return oe->version;
+}
+
+bool ovl_is_whiteout(struct dentry *dentry)
+{
+ int res;
+ char val;
+
+ if (!dentry)
+ return false;
+ if (!dentry->d_inode)
+ return false;
+ if (!S_ISLNK(dentry->d_inode->i_mode))
+ return false;
+
+ res = vfs_getxattr(dentry, ovl_whiteout_xattr, &val, 1);
+ if (res == 1 && val == 'y')
+ return true;
+
+ return false;
+}
+
+static bool ovl_is_opaquedir(struct dentry *dentry)
+{
+ int res;
+ char val;
+
+ if (!S_ISDIR(dentry->d_inode->i_mode))
+ return false;
+
+ res = vfs_getxattr(dentry, ovl_opaque_xattr, &val, 1);
+ if (res == 1 && val == 'y')
+ return true;
+
+ return false;
+}
+
+static void ovl_entry_free(struct rcu_head *head)
+{
+ struct ovl_entry *oe = container_of(head, struct ovl_entry, rcu);
+ kfree(oe);
+}
+
+static void ovl_dentry_release(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ if (oe) {
+ dput(oe->__upperdentry);
+ dput(oe->__upperdentry);
+ dput(oe->lowerdentry);
+ call_rcu(&oe->rcu, ovl_entry_free);
+ }
+}
+
+const struct dentry_operations ovl_dentry_operations = {
+ .d_release = ovl_dentry_release,
+};
+
+static struct ovl_entry *ovl_alloc_entry(void)
+{
+ return kzalloc(sizeof(struct ovl_entry), GFP_KERNEL);
+}
+
+static inline struct dentry *ovl_lookup_real(struct dentry *dir,
+ struct qstr *name)
+{
+ struct dentry *dentry;
+
+ mutex_lock(&dir->d_inode->i_mutex);
+ dentry = lookup_one_len(name->name, dir, name->len);
+ mutex_unlock(&dir->d_inode->i_mutex);
+
+ if (IS_ERR(dentry)) {
+ if (PTR_ERR(dentry) == -ENOENT)
+ dentry = NULL;
+ } else if (!dentry->d_inode) {
+ dput(dentry);
+ dentry = NULL;
+ }
+ return dentry;
+}
+
+static int ovl_do_lookup(struct dentry *dentry)
+{
+ struct ovl_entry *oe;
+ struct dentry *upperdir;
+ struct dentry *lowerdir;
+ struct dentry *upperdentry = NULL;
+ struct dentry *lowerdentry = NULL;
+ struct inode *inode = NULL;
+ int err;
+
+ err = -ENOMEM;
+ oe = ovl_alloc_entry();
+ if (!oe)
+ goto out;
+
+ upperdir = ovl_dentry_upper(dentry->d_parent);
+ lowerdir = ovl_dentry_lower(dentry->d_parent);
+
+ if (upperdir) {
+ upperdentry = ovl_lookup_real(upperdir, &dentry->d_name);
+ err = PTR_ERR(upperdentry);
+ if (IS_ERR(upperdentry))
+ goto out_put_dir;
+
+ if (lowerdir && upperdentry &&
+ (S_ISLNK(upperdentry->d_inode->i_mode) ||
+ S_ISDIR(upperdentry->d_inode->i_mode))) {
+ const struct cred *old_cred;
+ struct cred *override_cred;
+
+ err = -ENOMEM;
+ override_cred = prepare_creds();
+ if (!override_cred)
+ goto out_dput_upper;
+
+ /* CAP_SYS_ADMIN needed for getxattr */
+ cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
+ old_cred = override_creds(override_cred);
+
+ if (ovl_is_opaquedir(upperdentry)) {
+ oe->opaque = true;
+ } else if (ovl_is_whiteout(upperdentry)) {
+ dput(upperdentry);
+ upperdentry = NULL;
+ oe->opaque = true;
+ }
+ revert_creds(old_cred);
+ put_cred(override_cred);
+ }
+ }
+ if (lowerdir && !oe->opaque) {
+ lowerdentry = ovl_lookup_real(lowerdir, &dentry->d_name);
+ err = PTR_ERR(lowerdentry);
+ if (IS_ERR(lowerdentry))
+ goto out_dput_upper;
+ }
+
+ if (lowerdentry && upperdentry &&
+ (!S_ISDIR(upperdentry->d_inode->i_mode) ||
+ !S_ISDIR(lowerdentry->d_inode->i_mode))) {
+ dput(lowerdentry);
+ lowerdentry = NULL;
+ oe->opaque = true;
+ }
+
+ if (lowerdentry || upperdentry) {
+ struct dentry *realdentry;
+
+ realdentry = upperdentry ? upperdentry : lowerdentry;
+ err = -ENOMEM;
+ inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode,
+ oe);
+ if (!inode)
+ goto out_dput;
+ }
+
+ if (upperdentry)
+ oe->__upperdentry = dget(upperdentry);
+
+ if (lowerdentry)
+ oe->lowerdentry = lowerdentry;
+
+ dentry->d_fsdata = oe;
+ dentry->d_op = &ovl_dentry_operations;
+ d_add(dentry, inode);
+
+ return 0;
+
+out_dput:
+ dput(lowerdentry);
+out_dput_upper:
+ dput(upperdentry);
+out_put_dir:
+ kfree(oe);
+out:
+ return err;
+}
+
+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
+ struct nameidata *nd)
+{
+ int err = ovl_do_lookup(dentry);
+
+ if (err)
+ return ERR_PTR(err);
+
+ return NULL;
+}
+
+struct file *ovl_path_open(struct path *path, int flags)
+{
+ path_get(path);
+ return dentry_open(path->dentry, path->mnt, flags, current_cred());
+}
+
+static void ovl_put_super(struct super_block *sb)
+{
+ struct ovl_fs *ufs = sb->s_fs_info;
+
+ if (!(sb->s_flags & MS_RDONLY))
+ mnt_drop_write(ufs->upper_mnt);
+
+ mntput(ufs->upper_mnt);
+ mntput(ufs->lower_mnt);
+
+ kfree(ufs);
+}
+
+static int ovl_remount_fs(struct super_block *sb, int *flagsp, char *data)
+{
+ int flags = *flagsp;
+ struct ovl_fs *ufs = sb->s_fs_info;
+
+ /* When remounting rw or ro, we need to adjust the write access to the
+ * upper fs.
+ */
+ if (((flags ^ sb->s_flags) & MS_RDONLY) == 0)
+ /* No change to readonly status */
+ return 0;
+
+ if (flags & MS_RDONLY) {
+ mnt_drop_write(ufs->upper_mnt);
+ return 0;
+ } else
+ return mnt_want_write(ufs->upper_mnt);
+}
+
+static const struct super_operations ovl_super_operations = {
+ .put_super = ovl_put_super,
+ .remount_fs = ovl_remount_fs,
+};
+
+struct ovl_config {
+ char *lowerdir;
+ char *upperdir;
+};
+
+enum {
+ Opt_lowerdir,
+ Opt_upperdir,
+ Opt_err,
+};
+
+static const match_table_t ovl_tokens = {
+ {Opt_lowerdir, "lowerdir=%s"},
+ {Opt_upperdir, "upperdir=%s"},
+ {Opt_err, NULL}
+};
+
+static int ovl_parse_opt(char *opt, struct ovl_config *config)
+{
+ char *p;
+
+ config->upperdir = NULL;
+ config->lowerdir = NULL;
+
+ while ((p = strsep(&opt, ",")) != NULL) {
+ int token;
+ substring_t args[MAX_OPT_ARGS];
+
+ if (!*p)
+ continue;
+
+ token = match_token(p, ovl_tokens, args);
+ switch (token) {
+ case Opt_upperdir:
+ kfree(config->upperdir);
+ config->upperdir = match_strdup(&args[0]);
+ if (!config->upperdir)
+ return -ENOMEM;
+ break;
+
+ case Opt_lowerdir:
+ kfree(config->lowerdir);
+ config->lowerdir = match_strdup(&args[0]);
+ if (!config->lowerdir)
+ return -ENOMEM;
+ break;
+
+ default:
+ return -EINVAL;
+ }
+ }
+ return 0;
+}
+
+static int ovl_fill_super(struct super_block *sb, void *data, int silent)
+{
+ struct path lowerpath;
+ struct path upperpath;
+ struct inode *root_inode;
+ struct dentry *root_dentry;
+ struct ovl_entry *oe;
+ struct ovl_fs *ufs;
+ struct ovl_config config;
+ int err;
+
+ err = ovl_parse_opt((char *) data, &config);
+ if (err)
+ goto out;
+
+ err = -EINVAL;
+ if (!config.upperdir || !config.lowerdir) {
+ printk(KERN_ERR "overlayfs: missing upperdir or lowerdir\n");
+ goto out_free_config;
+ }
+
+ err = -ENOMEM;
+ ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL);
+ if (!ufs)
+ goto out_free_config;
+
+ oe = ovl_alloc_entry();
+ if (oe == NULL)
+ goto out_free_ufs;
+
+ err = kern_path(config.upperdir, LOOKUP_FOLLOW, &upperpath);
+ if (err)
+ goto out_free_oe;
+
+ err = kern_path(config.lowerdir, LOOKUP_FOLLOW, &lowerpath);
+ if (err)
+ goto out_put_upperpath;
+
+ err = -ENOTDIR;
+ if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) ||
+ !S_ISDIR(lowerpath.dentry->d_inode->i_mode))
+ goto out_put_lowerpath;
+
+ ufs->upper_mnt = clone_private_mount(&upperpath);
+ err = PTR_ERR(ufs->upper_mnt);
+ if (IS_ERR(ufs->upper_mnt)) {
+ printk(KERN_ERR "overlayfs: failed to clone upperpath\n");
+ goto out_put_lowerpath;
+ }
+
+ ufs->lower_mnt = clone_private_mount(&lowerpath);
+ err = PTR_ERR(ufs->lower_mnt);
+ if (IS_ERR(ufs->lower_mnt)) {
+ printk(KERN_ERR "overlayfs: failed to clone lowerpath\n");
+ goto out_put_upper_mnt;
+ }
+
+ /*
+ * Make lower_mnt R/O. That way fchmod/fchown on lower file
+ * will fail instead of modifying lower fs.
+ */
+ ufs->lower_mnt->mnt_flags |= MNT_READONLY;
+
+ /* If the upper fs is r/o, we mark overlayfs r/o too */
+ if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)
+ sb->s_flags |= MS_RDONLY;
+
+ if (!(sb->s_flags & MS_RDONLY)) {
+ err = mnt_want_write(ufs->upper_mnt);
+ if (err)
+ goto out_put_lower_mnt;
+ }
+
+ err = -ENOMEM;
+ root_inode = ovl_new_inode(sb, S_IFDIR, oe);
+ if (!root_inode)
+ goto out_drop_write;
+
+ root_dentry = d_make_root(root_inode);
+ if (!root_dentry)
+ goto out_drop_write;
+
+ mntput(upperpath.mnt);
+ mntput(lowerpath.mnt);
+
+ oe->__upperdentry = dget(upperpath.dentry);
+ oe->lowerdentry = lowerpath.dentry;
+
+ root_dentry->d_fsdata = oe;
+ root_dentry->d_op = &ovl_dentry_operations;
+
+ sb->s_op = &ovl_super_operations;
+ sb->s_root = root_dentry;
+ sb->s_fs_info = ufs;
+
+ return 0;
+
+out_drop_write:
+ if (!(sb->s_flags & MS_RDONLY))
+ mnt_drop_write(ufs->upper_mnt);
+out_put_lower_mnt:
+ mntput(ufs->lower_mnt);
+out_put_upper_mnt:
+ mntput(ufs->upper_mnt);
+out_put_lowerpath:
+ path_put(&lowerpath);
+out_put_upperpath:
+ path_put(&upperpath);
+out_free_oe:
+ kfree(oe);
+out_free_ufs:
+ kfree(ufs);
+out_free_config:
+ kfree(config.lowerdir);
+ kfree(config.upperdir);
+out:
+ return err;
+}
+
+static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *raw_data)
+{
+ return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
+}
+
+static struct file_system_type ovl_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "overlayfs",
+ .mount = ovl_mount,
+ .kill_sb = kill_anon_super,
+};
+
+static int __init ovl_init(void)
+{
+ return register_filesystem(&ovl_fs_type);
+}
+
+static void __exit ovl_exit(void)
+{
+ unregister_filesystem(&ovl_fs_type);
+}
+
+module_init(ovl_init);
+module_exit(ovl_exit);
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-18 21:35:37 +0000