[PATCH 2/2] ovl: fix building as a module
From: Miklos Szeredi
Date: Tue Apr 19 2011 - 05:43:45 EST
From: Miklos Szeredi <mszeredi@xxxxxxx>
Didn't test module building after splitting up the source. So it
broke. Now it's fixed.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
---
fs/overlayfs/Makefile | 4 +-
fs/overlayfs/overlayfs.c | 596 ----------------------------------------------
fs/overlayfs/super.c | 596 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 599 insertions(+), 597 deletions(-)
delete mode 100644 fs/overlayfs/overlayfs.c
create mode 100644 fs/overlayfs/super.c
diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile
index a7ebbf0..8f91889 100644
--- a/fs/overlayfs/Makefile
+++ b/fs/overlayfs/Makefile
@@ -2,4 +2,6 @@
# Makefile for the overlay filesystem.
#
-obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o inode.o dir.o readdir.o copy_up.o
+obj-$(CONFIG_OVERLAYFS_FS) += overlayfs.o
+
+overlayfs-objs := super.o inode.o dir.o readdir.o copy_up.o
diff --git a/fs/overlayfs/overlayfs.c b/fs/overlayfs/overlayfs.c
deleted file mode 100644
index a9a09a6..0000000
--- a/fs/overlayfs/overlayfs.c
+++ /dev/null
@@ -1,596 +0,0 @@
-/*
- *
- * 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 "overlayfs.h"
-
-MODULE_AUTHOR("Miklos Szeredi <miklos@xxxxxxxxxx>");
-MODULE_DESCRIPTION("Overlay filesystem");
-MODULE_LICENSE("GPL");
-
-struct ovl_fs {
- struct vfsmount *upper_mnt;
- struct vfsmount *lower_mnt;
-};
-
-struct ovl_entry {
- 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);
- smp_wmb();
- oe->__upperdentry = 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->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 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;
-}
-
-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 = 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;
-}
-
-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);
-}
-
-/**
- * ovl_statfs
- * @sb: The overlayfs super block
- * @buf: The struct kstatfs to fill in with stats
- *
- * Get the filesystem statistics. As writes always target the upper layer
- * filesystem pass the statfs to the same filesystem.
- */
-static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
-{
- struct dentry *root_dentry = dentry->d_sb->s_root;
- struct path path;
- ovl_path_upper(root_dentry, &path);
-
- if (!path.dentry->d_sb->s_op->statfs)
- return -ENOSYS;
- return path.dentry->d_sb->s_op->statfs(path.dentry, buf);
-}
-
-static const struct super_operations ovl_super_operations = {
- .put_super = ovl_put_super,
- .remount_fs = ovl_remount_fs,
- .statfs = ovl_statfs,
-};
-
-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;
-
- root_inode = ovl_new_inode(sb, S_IFDIR, oe);
- if (!root_inode)
- goto out_free_oe;
-
- err = kern_path(config.upperdir, LOOKUP_FOLLOW, &upperpath);
- if (err)
- goto out_put_root;
-
- 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;
- }
-
- if (!(sb->s_flags & MS_RDONLY)) {
- err = mnt_want_write(ufs->upper_mnt);
- if (err)
- goto out_put_lower_mnt;
- }
-
- err = -ENOMEM;
- root_dentry = d_alloc_root(root_inode);
- if (!root_dentry)
- goto out_drop_write;
-
- mntput(upperpath.mnt);
- mntput(lowerpath.mnt);
-
- oe->__upperdentry = 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_put_root:
- iput(root_inode);
-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);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
new file mode 100644
index 0000000..a9a09a6
--- /dev/null
+++ b/fs/overlayfs/super.c
@@ -0,0 +1,596 @@
+/*
+ *
+ * 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 "overlayfs.h"
+
+MODULE_AUTHOR("Miklos Szeredi <miklos@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Overlay filesystem");
+MODULE_LICENSE("GPL");
+
+struct ovl_fs {
+ struct vfsmount *upper_mnt;
+ struct vfsmount *lower_mnt;
+};
+
+struct ovl_entry {
+ 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);
+ smp_wmb();
+ oe->__upperdentry = 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->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 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;
+}
+
+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 = 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;
+}
+
+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);
+}
+
+/**
+ * ovl_statfs
+ * @sb: The overlayfs super block
+ * @buf: The struct kstatfs to fill in with stats
+ *
+ * Get the filesystem statistics. As writes always target the upper layer
+ * filesystem pass the statfs to the same filesystem.
+ */
+static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+ struct dentry *root_dentry = dentry->d_sb->s_root;
+ struct path path;
+ ovl_path_upper(root_dentry, &path);
+
+ if (!path.dentry->d_sb->s_op->statfs)
+ return -ENOSYS;
+ return path.dentry->d_sb->s_op->statfs(path.dentry, buf);
+}
+
+static const struct super_operations ovl_super_operations = {
+ .put_super = ovl_put_super,
+ .remount_fs = ovl_remount_fs,
+ .statfs = ovl_statfs,
+};
+
+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;
+
+ root_inode = ovl_new_inode(sb, S_IFDIR, oe);
+ if (!root_inode)
+ goto out_free_oe;
+
+ err = kern_path(config.upperdir, LOOKUP_FOLLOW, &upperpath);
+ if (err)
+ goto out_put_root;
+
+ 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;
+ }
+
+ if (!(sb->s_flags & MS_RDONLY)) {
+ err = mnt_want_write(ufs->upper_mnt);
+ if (err)
+ goto out_put_lower_mnt;
+ }
+
+ err = -ENOMEM;
+ root_dentry = d_alloc_root(root_inode);
+ if (!root_dentry)
+ goto out_drop_write;
+
+ mntput(upperpath.mnt);
+ mntput(lowerpath.mnt);
+
+ oe->__upperdentry = 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_put_root:
+ iput(root_inode);
+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);
--
1.7.1
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