fs/overlayfs/overlayfs.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  *
  * Copyright (C) 2011 Novell Inc.
  */

 #include <linux/kernel.h>
 #include <linux/uuid.h>
 #include <linux/fs.h>
 #include "ovl_entry.h"

 #undef pr_fmt
 #define pr_fmt(fmt) "overlayfs: " fmt

 enum ovl_path_type {
 	__OVL_PATH_UPPER	= (1 << 0),
 	__OVL_PATH_MERGE	= (1 << 1),
 	__OVL_PATH_ORIGIN	= (1 << 2),
 };

 #define OVL_TYPE_UPPER(type)	((type) & __OVL_PATH_UPPER)
 #define OVL_TYPE_MERGE(type)	((type) & __OVL_PATH_MERGE)
 #define OVL_TYPE_ORIGIN(type)	((type) & __OVL_PATH_ORIGIN)

 #define OVL_XATTR_NAMESPACE "overlay."
 #define OVL_XATTR_TRUSTED_PREFIX XATTR_TRUSTED_PREFIX OVL_XATTR_NAMESPACE
 #define OVL_XATTR_USER_PREFIX XATTR_USER_PREFIX OVL_XATTR_NAMESPACE

 enum ovl_xattr {
 	OVL_XATTR_OPAQUE,
 	OVL_XATTR_REDIRECT,
 	OVL_XATTR_ORIGIN,
 	OVL_XATTR_IMPURE,
 	OVL_XATTR_NLINK,
 	OVL_XATTR_UPPER,
 	OVL_XATTR_METACOPY,
 };

 enum ovl_inode_flag {
 	/* Pure upper dir that may contain non pure upper entries */
 	OVL_IMPURE,
 	/* Non-merge dir that may contain whiteout entries */
 	OVL_WHITEOUTS,
 	OVL_INDEX,
 	OVL_UPPERDATA,
 	/* Inode number will remain constant over copy up. */
 	OVL_CONST_INO,
 };

 enum ovl_entry_flag {
 	OVL_E_UPPER_ALIAS,
 	OVL_E_OPAQUE,
 	OVL_E_CONNECTED,
 };

 enum {
 	OVL_XINO_OFF,
 	OVL_XINO_AUTO,
 	OVL_XINO_ON,
 };

 /*
  * The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
  * where:
  * origin.fh	- exported file handle of the lower file
  * origin.uuid	- uuid of the lower filesystem
  */
 #define OVL_FH_VERSION	0
 #define OVL_FH_MAGIC	0xfb

 /* CPU byte order required for fid decoding:  */
 #define OVL_FH_FLAG_BIG_ENDIAN	(1 << 0)
 #define OVL_FH_FLAG_ANY_ENDIAN	(1 << 1)
 /* Is the real inode encoded in fid an upper inode? */
 #define OVL_FH_FLAG_PATH_UPPER	(1 << 2)

 #define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN | OVL_FH_FLAG_ANY_ENDIAN | \
 			 OVL_FH_FLAG_PATH_UPPER)

 #if defined(__LITTLE_ENDIAN)
 #define OVL_FH_FLAG_CPU_ENDIAN 0
 #elif defined(__BIG_ENDIAN)
 #define OVL_FH_FLAG_CPU_ENDIAN OVL_FH_FLAG_BIG_ENDIAN
 #else
 #error Endianness not defined
 #endif

 /* The type used to be returned by overlay exportfs for misaligned fid */
 #define OVL_FILEID_V0	0xfb
 /* The type returned by overlay exportfs for 32bit aligned fid */
 #define OVL_FILEID_V1	0xf8

 /* On-disk format for "origin" file handle */
 struct ovl_fb {
 	u8 version;	/* 0 */
 	u8 magic;	/* 0xfb */
 	u8 len;		/* size of this header + size of fid */
 	u8 flags;	/* OVL_FH_FLAG_* */
 	u8 type;	/* fid_type of fid */
 	uuid_t uuid;	/* uuid of filesystem */
 	u32 fid[];	/* file identifier should be 32bit aligned in-memory */
 } __packed;

 /* In-memory and on-wire format for overlay file handle */
 struct ovl_fh {
 	u8 padding[3];	/* make sure fb.fid is 32bit aligned */
 	union {
 		struct ovl_fb fb;
 		u8 buf[0];
 	};
 } __packed;

 #define OVL_FH_WIRE_OFFSET	offsetof(struct ovl_fh, fb)
 #define OVL_FH_LEN(fh)		(OVL_FH_WIRE_OFFSET + (fh)->fb.len)
 #define OVL_FH_FID_OFFSET	(OVL_FH_WIRE_OFFSET + \
 				 offsetof(struct ovl_fb, fid))

 extern const char *const ovl_xattr_table[][2];
 static inline const char *ovl_xattr(struct ovl_fs *ofs, enum ovl_xattr ox)
 {
 	return ovl_xattr_table[ox][ofs->config.userxattr];
 }

 static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
 {
 	int err = vfs_rmdir(&init_user_ns, dir, dentry);

 	pr_debug("rmdir(%pd2) = %i\n", dentry, err);
 	return err;
 }

 static inline int ovl_do_unlink(struct inode *dir, struct dentry *dentry)
 {
 	int err = vfs_unlink(&init_user_ns, dir, dentry, NULL);

 	pr_debug("unlink(%pd2) = %i\n", dentry, err);
 	return err;
 }

 static inline int ovl_do_link(struct dentry *old_dentry, struct inode *dir,
 			      struct dentry *new_dentry)
 {
 	int err = vfs_link(old_dentry, &init_user_ns, dir, new_dentry, NULL);

 	pr_debug("link(%pd2, %pd2) = %i\n", old_dentry, new_dentry, err);
 	return err;
 }

 static inline int ovl_do_create(struct inode *dir, struct dentry *dentry,
 				umode_t mode)
 {
 	int err = vfs_create(&init_user_ns, dir, dentry, mode, true);

 	pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
 	return err;
 }

 static inline int ovl_do_mkdir(struct inode *dir, struct dentry *dentry,
 			       umode_t mode)
 {
 	int err = vfs_mkdir(&init_user_ns, dir, dentry, mode);
 	pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
 	return err;
 }

 static inline int ovl_do_mknod(struct inode *dir, struct dentry *dentry,
 			       umode_t mode, dev_t dev)
 {
 	int err = vfs_mknod(&init_user_ns, dir, dentry, mode, dev);

 	pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
 	return err;
 }

 static inline int ovl_do_symlink(struct inode *dir, struct dentry *dentry,
 				 const char *oldname)
 {
 	int err = vfs_symlink(&init_user_ns, dir, dentry, oldname);

 	pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
 	return err;
 }

 static inline ssize_t ovl_do_getxattr(struct ovl_fs *ofs, struct dentry *dentry,
 				      enum ovl_xattr ox, void *value,
 				      size_t size)
 {
 	const char *name = ovl_xattr(ofs, ox);
 	return vfs_getxattr(&init_user_ns, dentry, name, value, size);
 }

 static inline int ovl_do_setxattr(struct ovl_fs *ofs, struct dentry *dentry,
 				  enum ovl_xattr ox, const void *value,
 				  size_t size)
 {
 	const char *name = ovl_xattr(ofs, ox);
 	int err = vfs_setxattr(&init_user_ns, dentry, name, value, size, 0);
 	pr_debug("setxattr(%pd2, \"%s\", \"%*pE\", %zu, 0) = %i\n",
 		 dentry, name, min((int)size, 48), value, size, err);
 	return err;
 }

 static inline int ovl_do_removexattr(struct ovl_fs *ofs, struct dentry *dentry,
 				     enum ovl_xattr ox)
 {
 	const char *name = ovl_xattr(ofs, ox);
 	int err = vfs_removexattr(&init_user_ns, dentry, name);
 	pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
 	return err;
 }

 static inline int ovl_do_rename(struct inode *olddir, struct dentry *olddentry,
 				struct inode *newdir, struct dentry *newdentry,
 				unsigned int flags)
 {
 	int err;
 	struct renamedata rd = {
 		.old_mnt_userns	= &init_user_ns,
 		.old_dir 	= olddir,
 		.old_dentry 	= olddentry,
 		.new_mnt_userns	= &init_user_ns,
 		.new_dir 	= newdir,
 		.new_dentry 	= newdentry,
 		.flags 		= flags,
 	};

 	pr_debug("rename(%pd2, %pd2, 0x%x)\n", olddentry, newdentry, flags);
 	err = vfs_rename(&rd);
 	if (err) {
 		pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
 			 olddentry, newdentry, err);
 	}
 	return err;
 }

 static inline int ovl_do_whiteout(struct inode *dir, struct dentry *dentry)
 {
 	int err = vfs_whiteout(&init_user_ns, dir, dentry);
 	pr_debug("whiteout(%pd2) = %i\n", dentry, err);
 	return err;
 }

 static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
 {
 	struct dentry *ret = vfs_tmpfile(&init_user_ns, dentry, mode, 0);
 	int err = PTR_ERR_OR_ZERO(ret);

 	pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
 	return ret;
 }

 static inline bool ovl_open_flags_need_copy_up(int flags)
 {
 	if (!flags)
 		return false;

 	return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
 }

 /* util.c */
 int ovl_want_write(struct dentry *dentry);
 void ovl_drop_write(struct dentry *dentry);
 struct dentry *ovl_workdir(struct dentry *dentry);
 const struct cred *ovl_override_creds(struct super_block *sb);
 int ovl_can_decode_fh(struct super_block *sb);
 struct dentry *ovl_indexdir(struct super_block *sb);
 bool ovl_index_all(struct super_block *sb);
 bool ovl_verify_lower(struct super_block *sb);
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
 bool ovl_dentry_remote(struct dentry *dentry);
 void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
 			     unsigned int mask);
 bool ovl_dentry_weird(struct dentry *dentry);
 enum ovl_path_type ovl_path_type(struct dentry *dentry);
 void ovl_path_upper(struct dentry *dentry, struct path *path);
 void ovl_path_lower(struct dentry *dentry, struct path *path);
 void ovl_path_lowerdata(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_lowerdata(struct dentry *dentry);
 const struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
 struct dentry *ovl_dentry_real(struct dentry *dentry);
 struct dentry *ovl_i_dentry_upper(struct inode *inode);
 struct inode *ovl_inode_upper(struct inode *inode);
 struct inode *ovl_inode_lower(struct inode *inode);
 struct inode *ovl_inode_lowerdata(struct inode *inode);
 struct inode *ovl_inode_real(struct inode *inode);
 struct inode *ovl_inode_realdata(struct inode *inode);
 struct ovl_dir_cache *ovl_dir_cache(struct inode *inode);
 void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache);
 void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry);
 void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry);
 bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry);
 bool ovl_dentry_is_opaque(struct dentry *dentry);
 bool ovl_dentry_is_whiteout(struct dentry *dentry);
 void ovl_dentry_set_opaque(struct dentry *dentry);
 bool ovl_dentry_has_upper_alias(struct dentry *dentry);
 void ovl_dentry_set_upper_alias(struct dentry *dentry);
 bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags);
 bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags);
 bool ovl_has_upperdata(struct inode *inode);
 void ovl_set_upperdata(struct inode *inode);
 bool ovl_redirect_dir(struct super_block *sb);
 const char *ovl_dentry_get_redirect(struct dentry *dentry);
 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
 void ovl_inode_update(struct inode *inode, struct dentry *upperdentry);
 void ovl_dir_modified(struct dentry *dentry, bool impurity);
 u64 ovl_dentry_version_get(struct dentry *dentry);
 bool ovl_is_whiteout(struct dentry *dentry);
 struct file *ovl_path_open(struct path *path, int flags);
 int ovl_copy_up_start(struct dentry *dentry, int flags);
 void ovl_copy_up_end(struct dentry *dentry);
 bool ovl_already_copied_up(struct dentry *dentry, int flags);
 bool ovl_check_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry);
 bool ovl_check_dir_xattr(struct super_block *sb, struct dentry *dentry,
 			 enum ovl_xattr ox);
 int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
 		       enum ovl_xattr ox, const void *value, size_t size,
 		       int xerr);
 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry);
 void ovl_set_flag(unsigned long flag, struct inode *inode);
 void ovl_clear_flag(unsigned long flag, struct inode *inode);
 bool ovl_test_flag(unsigned long flag, struct inode *inode);
 bool ovl_inuse_trylock(struct dentry *dentry);
 void ovl_inuse_unlock(struct dentry *dentry);
 bool ovl_is_inuse(struct dentry *dentry);
 bool ovl_need_index(struct dentry *dentry);
 int ovl_nlink_start(struct dentry *dentry);
 void ovl_nlink_end(struct dentry *dentry);
 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
 int ovl_check_metacopy_xattr(struct ovl_fs *ofs, struct dentry *dentry);
 bool ovl_is_metacopy_dentry(struct dentry *dentry);
 char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct dentry *dentry,
 			     int padding);
 int ovl_sync_status(struct ovl_fs *ofs);

 static inline bool ovl_is_impuredir(struct super_block *sb,
 				    struct dentry *dentry)
 {
 	return ovl_check_dir_xattr(sb, dentry, OVL_XATTR_IMPURE);
 }

 /*
  * With xino=auto, we do best effort to keep all inodes on same st_dev and
  * d_ino consistent with st_ino.
  * With xino=on, we do the same effort but we warn if we failed.
  */
 static inline bool ovl_xino_warn(struct super_block *sb)
 {
 	return OVL_FS(sb)->config.xino == OVL_XINO_ON;
 }

 /* All layers on same fs? */
 static inline bool ovl_same_fs(struct super_block *sb)
 {
 	return OVL_FS(sb)->xino_mode == 0;
 }

 /* All overlay inodes have same st_dev? */
 static inline bool ovl_same_dev(struct super_block *sb)
 {
 	return OVL_FS(sb)->xino_mode >= 0;
 }

 static inline unsigned int ovl_xino_bits(struct super_block *sb)
 {
 	return ovl_same_dev(sb) ? OVL_FS(sb)->xino_mode : 0;
 }

 static inline void ovl_inode_lock(struct inode *inode)
 {
 	mutex_lock(&OVL_I(inode)->lock);
 }

 static inline int ovl_inode_lock_interruptible(struct inode *inode)
 {
 	return mutex_lock_interruptible(&OVL_I(inode)->lock);
 }

 static inline void ovl_inode_unlock(struct inode *inode)
 {
 	mutex_unlock(&OVL_I(inode)->lock);
 }


 /* namei.c */
 int ovl_check_fb_len(struct ovl_fb *fb, int fb_len);

 static inline int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
 {
 	if (fh_len < sizeof(struct ovl_fh))
 		return -EINVAL;

 	return ovl_check_fb_len(&fh->fb, fh_len - OVL_FH_WIRE_OFFSET);
 }

 struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
 				  struct vfsmount *mnt, bool connected);
 int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
 			struct dentry *upperdentry, struct ovl_path **stackp);
 int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry,
 		      enum ovl_xattr ox, struct dentry *real, bool is_upper,
 		      bool set);
 struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index);
 int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);
 int ovl_get_index_name(struct ovl_fs *ofs, struct dentry *origin,
 		       struct qstr *name);
 struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);
 struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
 				struct dentry *origin, bool verify);
 int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
 struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 			  unsigned int flags);
 bool ovl_lower_positive(struct dentry *dentry);

 static inline int ovl_verify_origin(struct ovl_fs *ofs, struct dentry *upper,
 				    struct dentry *origin, bool set)
 {
 	return ovl_verify_set_fh(ofs, upper, OVL_XATTR_ORIGIN, origin,
 				 false, set);
 }

 static inline int ovl_verify_upper(struct ovl_fs *ofs, struct dentry *index,
 				   struct dentry *upper, bool set)
 {
 	return ovl_verify_set_fh(ofs, index, OVL_XATTR_UPPER, upper, true, set);
 }

 /* readdir.c */
 extern const struct file_operations ovl_dir_operations;
 struct file *ovl_dir_real_file(const struct file *file, bool want_upper);
 int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list);
 void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list);
 void ovl_cache_free(struct list_head *list);
 void ovl_dir_cache_free(struct inode *inode);
 int ovl_check_d_type_supported(struct path *realpath);
 int ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
 			struct dentry *dentry, int level);
 int ovl_indexdir_cleanup(struct ovl_fs *ofs);

 /* inode.c */
 int ovl_set_nlink_upper(struct dentry *dentry);
 int ovl_set_nlink_lower(struct dentry *dentry);
 unsigned int ovl_get_nlink(struct ovl_fs *ofs, struct dentry *lowerdentry,
 			   struct dentry *upperdentry,
 			   unsigned int fallback);
 int ovl_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 		struct iattr *attr);
 int ovl_getattr(struct user_namespace *mnt_userns, const struct path *path,
 		struct kstat *stat, u32 request_mask, unsigned int flags);
 int ovl_permission(struct user_namespace *mnt_userns, struct inode *inode,
 		   int mask);
 int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
 		  const void *value, size_t size, int flags);
 int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
 		  void *value, size_t size);
 ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
 struct posix_acl *ovl_get_acl(struct inode *inode, int type);
 int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags);
 bool ovl_is_private_xattr(struct super_block *sb, const char *name);

 struct ovl_inode_params {
 	struct inode *newinode;
 	struct dentry *upperdentry;
 	struct ovl_path *lowerpath;
 	bool index;
 	unsigned int numlower;
 	char *redirect;
 	struct dentry *lowerdata;
 };
 void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
 		    unsigned long ino, int fsid);
 struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
 struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
 			       bool is_upper);
 bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir);
 struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir);
 struct inode *ovl_get_inode(struct super_block *sb,
 			    struct ovl_inode_params *oip);
 static inline void ovl_copyattr(struct inode *from, struct inode *to)
 {
 	to->i_uid = from->i_uid;
 	to->i_gid = from->i_gid;
 	to->i_mode = from->i_mode;
 	to->i_atime = from->i_atime;
 	to->i_mtime = from->i_mtime;
 	to->i_ctime = from->i_ctime;
 	i_size_write(to, i_size_read(from));
 }

 static inline void ovl_copyflags(struct inode *from, struct inode *to)
 {
 	unsigned int mask = S_SYNC | S_IMMUTABLE | S_APPEND | S_NOATIME;

 	inode_set_flags(to, from->i_flags & mask, mask);
 }

 /* dir.c */
 extern const struct inode_operations ovl_dir_inode_operations;
 int ovl_cleanup_and_whiteout(struct ovl_fs *ofs, struct inode *dir,
 			     struct dentry *dentry);
 struct ovl_cattr {
 	dev_t rdev;
 	umode_t mode;
 	const char *link;
 	struct dentry *hardlink;
 };

 #define OVL_CATTR(m) (&(struct ovl_cattr) { .mode = (m) })

 struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry,
 			       struct ovl_cattr *attr);
 int ovl_cleanup(struct inode *dir, struct dentry *dentry);
 struct dentry *ovl_lookup_temp(struct dentry *workdir);
 struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr);

 /* file.c */
 extern const struct file_operations ovl_file_operations;
 int __init ovl_aio_request_cache_init(void);
 void ovl_aio_request_cache_destroy(void);
 long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 long ovl_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);

 /* copy_up.c */
 int ovl_copy_up(struct dentry *dentry);
 int ovl_copy_up_with_data(struct dentry *dentry);
 int ovl_maybe_copy_up(struct dentry *dentry, int flags);
 int ovl_copy_xattr(struct super_block *sb, struct dentry *old,
 		   struct dentry *new);
 int ovl_set_attr(struct dentry *upper, struct kstat *stat);
 struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real,
 				  bool is_upper);
 int ovl_set_origin(struct ovl_fs *ofs, struct dentry *dentry,
 		   struct dentry *lower, struct dentry *upper);

 /* export.c */
 extern const struct export_operations ovl_export_operations;
	/* SPDX-License-Identifier: GPL-2.0-only */
	/*
	*
	* Copyright (C) 2011 Novell Inc.
	*/

	#include <linux/kernel.h>
	#include <linux/uuid.h>
	#include <linux/fs.h>
	#include "ovl_entry.h"

	#undef pr_fmt
	#define pr_fmt(fmt) "overlayfs: " fmt

	enum ovl_path_type {
	__OVL_PATH_UPPER = (1 << 0),
	__OVL_PATH_MERGE = (1 << 1),
	__OVL_PATH_ORIGIN = (1 << 2),
	};

	#define OVL_TYPE_UPPER(type) ((type) & __OVL_PATH_UPPER)
	#define OVL_TYPE_MERGE(type) ((type) & __OVL_PATH_MERGE)
	#define OVL_TYPE_ORIGIN(type) ((type) & __OVL_PATH_ORIGIN)

	#define OVL_XATTR_NAMESPACE "overlay."
	#define OVL_XATTR_TRUSTED_PREFIX XATTR_TRUSTED_PREFIX OVL_XATTR_NAMESPACE
	#define OVL_XATTR_USER_PREFIX XATTR_USER_PREFIX OVL_XATTR_NAMESPACE

	enum ovl_xattr {
	OVL_XATTR_OPAQUE,
	OVL_XATTR_REDIRECT,
	OVL_XATTR_ORIGIN,
	OVL_XATTR_IMPURE,
	OVL_XATTR_NLINK,
	OVL_XATTR_UPPER,
	OVL_XATTR_METACOPY,
	};

	enum ovl_inode_flag {
	/* Pure upper dir that may contain non pure upper entries */
	OVL_IMPURE,
	/* Non-merge dir that may contain whiteout entries */
	OVL_WHITEOUTS,
	OVL_INDEX,
	OVL_UPPERDATA,
	/* Inode number will remain constant over copy up. */
	OVL_CONST_INO,
	};

	enum ovl_entry_flag {
	OVL_E_UPPER_ALIAS,
	OVL_E_OPAQUE,
	OVL_E_CONNECTED,
	};

	enum {
	OVL_XINO_OFF,
	OVL_XINO_AUTO,
	OVL_XINO_ON,
	};

	/*
	* The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
	* where:
	* origin.fh - exported file handle of the lower file
	* origin.uuid - uuid of the lower filesystem
	*/
	#define OVL_FH_VERSION 0
	#define OVL_FH_MAGIC 0xfb

	/* CPU byte order required for fid decoding: */
	#define OVL_FH_FLAG_BIG_ENDIAN (1 << 0)
	#define OVL_FH_FLAG_ANY_ENDIAN (1 << 1)
	/* Is the real inode encoded in fid an upper inode? */
	#define OVL_FH_FLAG_PATH_UPPER (1 << 2)

	#define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN \| OVL_FH_FLAG_ANY_ENDIAN \| \
	OVL_FH_FLAG_PATH_UPPER)

	#if defined(__LITTLE_ENDIAN)
	#define OVL_FH_FLAG_CPU_ENDIAN 0
	#elif defined(__BIG_ENDIAN)
	#define OVL_FH_FLAG_CPU_ENDIAN OVL_FH_FLAG_BIG_ENDIAN
	#else
	#error Endianness not defined
	#endif

	/* The type used to be returned by overlay exportfs for misaligned fid */
	#define OVL_FILEID_V0 0xfb
	/* The type returned by overlay exportfs for 32bit aligned fid */
	#define OVL_FILEID_V1 0xf8

	/* On-disk format for "origin" file handle */
	struct ovl_fb {
	u8 version; /* 0 */
	u8 magic; /* 0xfb */
	u8 len; /* size of this header + size of fid */
	u8 flags; /* OVL_FH_FLAG_* */
	u8 type; /* fid_type of fid */
	uuid_t uuid; /* uuid of filesystem */
	u32 fid[]; /* file identifier should be 32bit aligned in-memory */
	} __packed;

	/* In-memory and on-wire format for overlay file handle */
	struct ovl_fh {
	u8 padding[3]; /* make sure fb.fid is 32bit aligned */
	union {
	struct ovl_fb fb;
	u8 buf[0];
	};
	} __packed;

	#define OVL_FH_WIRE_OFFSET offsetof(struct ovl_fh, fb)
	#define OVL_FH_LEN(fh) (OVL_FH_WIRE_OFFSET + (fh)->fb.len)
	#define OVL_FH_FID_OFFSET (OVL_FH_WIRE_OFFSET + \
	offsetof(struct ovl_fb, fid))

	extern const char *const ovl_xattr_table[][2];
	static inline const char ovl_xattr(struct ovl_fs ofs, enum ovl_xattr ox)
	{
	return ovl_xattr_table[ox][ofs->config.userxattr];
	}

	static inline int ovl_do_rmdir(struct inode dir, struct dentry dentry)
	{
	int err = vfs_rmdir(&init_user_ns, dir, dentry);

	pr_debug("rmdir(%pd2) = %i\n", dentry, err);
	return err;
	}

	static inline int ovl_do_unlink(struct inode dir, struct dentry dentry)
	{
	int err = vfs_unlink(&init_user_ns, dir, dentry, NULL);

	pr_debug("unlink(%pd2) = %i\n", dentry, err);
	return err;
	}

	static inline int ovl_do_link(struct dentry old_dentry, struct inode dir,
	struct dentry *new_dentry)
	{
	int err = vfs_link(old_dentry, &init_user_ns, dir, new_dentry, NULL);

	pr_debug("link(%pd2, %pd2) = %i\n", old_dentry, new_dentry, err);
	return err;
	}

	static inline int ovl_do_create(struct inode dir, struct dentry dentry,
	umode_t mode)
	{
	int err = vfs_create(&init_user_ns, dir, dentry, mode, true);

	pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
	return err;
	}

	static inline int ovl_do_mkdir(struct inode dir, struct dentry dentry,
	umode_t mode)
	{
	int err = vfs_mkdir(&init_user_ns, dir, dentry, mode);
	pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
	return err;
	}

	static inline int ovl_do_mknod(struct inode dir, struct dentry dentry,
	umode_t mode, dev_t dev)
	{
	int err = vfs_mknod(&init_user_ns, dir, dentry, mode, dev);

	pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
	return err;
	}

	static inline int ovl_do_symlink(struct inode dir, struct dentry dentry,
	const char *oldname)
	{
	int err = vfs_symlink(&init_user_ns, dir, dentry, oldname);

	pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
	return err;
	}

	static inline ssize_t ovl_do_getxattr(struct ovl_fs ofs, struct dentry dentry,
	enum ovl_xattr ox, void *value,
	size_t size)
	{
	const char *name = ovl_xattr(ofs, ox);
	return vfs_getxattr(&init_user_ns, dentry, name, value, size);
	}

	static inline int ovl_do_setxattr(struct ovl_fs ofs, struct dentry dentry,
	enum ovl_xattr ox, const void *value,
	size_t size)
	{
	const char *name = ovl_xattr(ofs, ox);
	int err = vfs_setxattr(&init_user_ns, dentry, name, value, size, 0);
	pr_debug("setxattr(%pd2, \"%s\", \"%*pE\", %zu, 0) = %i\n",
	dentry, name, min((int)size, 48), value, size, err);
	return err;
	}

	static inline int ovl_do_removexattr(struct ovl_fs ofs, struct dentry dentry,
	enum ovl_xattr ox)
	{
	const char *name = ovl_xattr(ofs, ox);
	int err = vfs_removexattr(&init_user_ns, dentry, name);
	pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
	return err;
	}

	static inline int ovl_do_rename(struct inode olddir, struct dentry olddentry,
	struct inode newdir, struct dentry newdentry,
	unsigned int flags)
	{
	int err;
	struct renamedata rd = {
	.old_mnt_userns = &init_user_ns,
	.old_dir = olddir,
	.old_dentry = olddentry,
	.new_mnt_userns = &init_user_ns,
	.new_dir = newdir,
	.new_dentry = newdentry,
	.flags = flags,
	};

	pr_debug("rename(%pd2, %pd2, 0x%x)\n", olddentry, newdentry, flags);
	err = vfs_rename(&rd);
	if (err) {
	pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
	olddentry, newdentry, err);
	}
	return err;
	}

	static inline int ovl_do_whiteout(struct inode dir, struct dentry dentry)
	{
	int err = vfs_whiteout(&init_user_ns, dir, dentry);
	pr_debug("whiteout(%pd2) = %i\n", dentry, err);
	return err;
	}

	static inline struct dentry ovl_do_tmpfile(struct dentry dentry, umode_t mode)
	{
	struct dentry *ret = vfs_tmpfile(&init_user_ns, dentry, mode, 0);
	int err = PTR_ERR_OR_ZERO(ret);

	pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
	return ret;
	}

	static inline bool ovl_open_flags_need_copy_up(int flags)
	{
	if (!flags)
	return false;

	return ((OPEN_FMODE(flags) & FMODE_WRITE) \|\| (flags & O_TRUNC));
	}

	/* util.c */
	int ovl_want_write(struct dentry *dentry);
	void ovl_drop_write(struct dentry *dentry);
	struct dentry ovl_workdir(struct dentry dentry);
	const struct cred ovl_override_creds(struct super_block sb);
	int ovl_can_decode_fh(struct super_block *sb);
	struct dentry ovl_indexdir(struct super_block sb);
	bool ovl_index_all(struct super_block *sb);
	bool ovl_verify_lower(struct super_block *sb);
	struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
	bool ovl_dentry_remote(struct dentry *dentry);
	void ovl_dentry_update_reval(struct dentry dentry, struct dentry upperdentry,
	unsigned int mask);
	bool ovl_dentry_weird(struct dentry *dentry);
	enum ovl_path_type ovl_path_type(struct dentry *dentry);
	void ovl_path_upper(struct dentry dentry, struct path path);
	void ovl_path_lower(struct dentry dentry, struct path path);
	void ovl_path_lowerdata(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_lowerdata(struct dentry dentry);
	const struct ovl_layer ovl_layer_lower(struct dentry dentry);
	struct dentry ovl_dentry_real(struct dentry dentry);
	struct dentry ovl_i_dentry_upper(struct inode inode);
	struct inode ovl_inode_upper(struct inode inode);
	struct inode ovl_inode_lower(struct inode inode);
	struct inode ovl_inode_lowerdata(struct inode inode);
	struct inode ovl_inode_real(struct inode inode);
	struct inode ovl_inode_realdata(struct inode inode);
	struct ovl_dir_cache ovl_dir_cache(struct inode inode);
	void ovl_set_dir_cache(struct inode inode, struct ovl_dir_cache cache);
	void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry);
	void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry);
	bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry);
	bool ovl_dentry_is_opaque(struct dentry *dentry);
	bool ovl_dentry_is_whiteout(struct dentry *dentry);
	void ovl_dentry_set_opaque(struct dentry *dentry);
	bool ovl_dentry_has_upper_alias(struct dentry *dentry);
	void ovl_dentry_set_upper_alias(struct dentry *dentry);
	bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags);
	bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags);
	bool ovl_has_upperdata(struct inode *inode);
	void ovl_set_upperdata(struct inode *inode);
	bool ovl_redirect_dir(struct super_block *sb);
	const char ovl_dentry_get_redirect(struct dentry dentry);
	void ovl_dentry_set_redirect(struct dentry dentry, const char redirect);
	void ovl_inode_update(struct inode inode, struct dentry upperdentry);
	void ovl_dir_modified(struct dentry *dentry, bool impurity);
	u64 ovl_dentry_version_get(struct dentry *dentry);
	bool ovl_is_whiteout(struct dentry *dentry);
	struct file ovl_path_open(struct path path, int flags);
	int ovl_copy_up_start(struct dentry *dentry, int flags);
	void ovl_copy_up_end(struct dentry *dentry);
	bool ovl_already_copied_up(struct dentry *dentry, int flags);
	bool ovl_check_origin_xattr(struct ovl_fs ofs, struct dentry dentry);
	bool ovl_check_dir_xattr(struct super_block sb, struct dentry dentry,
	enum ovl_xattr ox);
	int ovl_check_setxattr(struct dentry dentry, struct dentry upperdentry,
	enum ovl_xattr ox, const void *value, size_t size,
	int xerr);
	int ovl_set_impure(struct dentry dentry, struct dentry upperdentry);
	void ovl_set_flag(unsigned long flag, struct inode *inode);
	void ovl_clear_flag(unsigned long flag, struct inode *inode);
	bool ovl_test_flag(unsigned long flag, struct inode *inode);
	bool ovl_inuse_trylock(struct dentry *dentry);
	void ovl_inuse_unlock(struct dentry *dentry);
	bool ovl_is_inuse(struct dentry *dentry);
	bool ovl_need_index(struct dentry *dentry);
	int ovl_nlink_start(struct dentry *dentry);
	void ovl_nlink_end(struct dentry *dentry);
	int ovl_lock_rename_workdir(struct dentry workdir, struct dentry upperdir);
	int ovl_check_metacopy_xattr(struct ovl_fs ofs, struct dentry dentry);
	bool ovl_is_metacopy_dentry(struct dentry *dentry);
	char ovl_get_redirect_xattr(struct ovl_fs ofs, struct dentry *dentry,
	int padding);
	int ovl_sync_status(struct ovl_fs *ofs);

	static inline bool ovl_is_impuredir(struct super_block *sb,
	struct dentry *dentry)
	{
	return ovl_check_dir_xattr(sb, dentry, OVL_XATTR_IMPURE);
	}

	/*
	* With xino=auto, we do best effort to keep all inodes on same st_dev and
	* d_ino consistent with st_ino.
	* With xino=on, we do the same effort but we warn if we failed.
	*/
	static inline bool ovl_xino_warn(struct super_block *sb)
	{
	return OVL_FS(sb)->config.xino == OVL_XINO_ON;
	}

	/* All layers on same fs? */
	static inline bool ovl_same_fs(struct super_block *sb)
	{
	return OVL_FS(sb)->xino_mode == 0;
	}

	/* All overlay inodes have same st_dev? */
	static inline bool ovl_same_dev(struct super_block *sb)
	{
	return OVL_FS(sb)->xino_mode >= 0;
	}

	static inline unsigned int ovl_xino_bits(struct super_block *sb)
	{
	return ovl_same_dev(sb) ? OVL_FS(sb)->xino_mode : 0;
	}

	static inline void ovl_inode_lock(struct inode *inode)
	{
	mutex_lock(&OVL_I(inode)->lock);
	}

	static inline int ovl_inode_lock_interruptible(struct inode *inode)
	{
	return mutex_lock_interruptible(&OVL_I(inode)->lock);
	}

	static inline void ovl_inode_unlock(struct inode *inode)
	{
	mutex_unlock(&OVL_I(inode)->lock);
	}


	/* namei.c */
	int ovl_check_fb_len(struct ovl_fb *fb, int fb_len);

	static inline int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
	{
	if (fh_len < sizeof(struct ovl_fh))
	return -EINVAL;

	return ovl_check_fb_len(&fh->fb, fh_len - OVL_FH_WIRE_OFFSET);
	}

	struct dentry ovl_decode_real_fh(struct ovl_fs ofs, struct ovl_fh *fh,
	struct vfsmount *mnt, bool connected);
	int ovl_check_origin_fh(struct ovl_fs ofs, struct ovl_fh fh, bool connected,
	struct dentry upperdentry, struct ovl_path *stackp);
	int ovl_verify_set_fh(struct ovl_fs ofs, struct dentry dentry,
	enum ovl_xattr ox, struct dentry *real, bool is_upper,
	bool set);
	struct dentry ovl_index_upper(struct ovl_fs ofs, struct dentry *index);
	int ovl_verify_index(struct ovl_fs ofs, struct dentry index);
	int ovl_get_index_name(struct ovl_fs ofs, struct dentry origin,
	struct qstr *name);
	struct dentry ovl_get_index_fh(struct ovl_fs ofs, struct ovl_fh *fh);
	struct dentry ovl_lookup_index(struct ovl_fs ofs, struct dentry *upper,
	struct dentry *origin, bool verify);
	int ovl_path_next(int idx, struct dentry dentry, struct path path);
	struct dentry ovl_lookup(struct inode dir, struct dentry *dentry,
	unsigned int flags);
	bool ovl_lower_positive(struct dentry *dentry);

	static inline int ovl_verify_origin(struct ovl_fs ofs, struct dentry upper,
	struct dentry *origin, bool set)
	{
	return ovl_verify_set_fh(ofs, upper, OVL_XATTR_ORIGIN, origin,
	false, set);
	}

	static inline int ovl_verify_upper(struct ovl_fs ofs, struct dentry index,
	struct dentry *upper, bool set)
	{
	return ovl_verify_set_fh(ofs, index, OVL_XATTR_UPPER, upper, true, set);
	}

	/* readdir.c */
	extern const struct file_operations ovl_dir_operations;
	struct file ovl_dir_real_file(const struct file file, bool want_upper);
	int ovl_check_empty_dir(struct dentry dentry, struct list_head list);
	void ovl_cleanup_whiteouts(struct dentry upper, struct list_head list);
	void ovl_cache_free(struct list_head *list);
	void ovl_dir_cache_free(struct inode *inode);
	int ovl_check_d_type_supported(struct path *realpath);
	int ovl_workdir_cleanup(struct inode dir, struct vfsmount mnt,
	struct dentry *dentry, int level);
	int ovl_indexdir_cleanup(struct ovl_fs *ofs);

	/* inode.c */
	int ovl_set_nlink_upper(struct dentry *dentry);
	int ovl_set_nlink_lower(struct dentry *dentry);
	unsigned int ovl_get_nlink(struct ovl_fs ofs, struct dentry lowerdentry,
	struct dentry *upperdentry,
	unsigned int fallback);
	int ovl_setattr(struct user_namespace mnt_userns, struct dentry dentry,
	struct iattr *attr);
	int ovl_getattr(struct user_namespace mnt_userns, const struct path path,
	struct kstat *stat, u32 request_mask, unsigned int flags);
	int ovl_permission(struct user_namespace mnt_userns, struct inode inode,
	int mask);
	int ovl_xattr_set(struct dentry dentry, struct inode inode, const char *name,
	const void *value, size_t size, int flags);
	int ovl_xattr_get(struct dentry dentry, struct inode inode, const char *name,
	void *value, size_t size);
	ssize_t ovl_listxattr(struct dentry dentry, char list, size_t size);
	struct posix_acl ovl_get_acl(struct inode inode, int type);
	int ovl_update_time(struct inode inode, struct timespec64 ts, int flags);
	bool ovl_is_private_xattr(struct super_block sb, const char name);

	struct ovl_inode_params {
	struct inode *newinode;
	struct dentry *upperdentry;
	struct ovl_path *lowerpath;
	bool index;
	unsigned int numlower;
	char *redirect;
	struct dentry *lowerdata;
	};
	void ovl_inode_init(struct inode inode, struct ovl_inode_params oip,
	unsigned long ino, int fsid);
	struct inode ovl_new_inode(struct super_block sb, umode_t mode, dev_t rdev);
	struct inode ovl_lookup_inode(struct super_block sb, struct dentry *real,
	bool is_upper);
	bool ovl_lookup_trap_inode(struct super_block sb, struct dentry dir);
	struct inode ovl_get_trap_inode(struct super_block sb, struct dentry *dir);
	struct inode ovl_get_inode(struct super_block sb,
	struct ovl_inode_params *oip);
	static inline void ovl_copyattr(struct inode from, struct inode to)
	{
	to->i_uid = from->i_uid;
	to->i_gid = from->i_gid;
	to->i_mode = from->i_mode;
	to->i_atime = from->i_atime;
	to->i_mtime = from->i_mtime;
	to->i_ctime = from->i_ctime;
	i_size_write(to, i_size_read(from));
	}

	static inline void ovl_copyflags(struct inode from, struct inode to)
	{
	unsigned int mask = S_SYNC \| S_IMMUTABLE \| S_APPEND \| S_NOATIME;

	inode_set_flags(to, from->i_flags & mask, mask);
	}

	/* dir.c */
	extern const struct inode_operations ovl_dir_inode_operations;
	int ovl_cleanup_and_whiteout(struct ovl_fs ofs, struct inode dir,
	struct dentry *dentry);
	struct ovl_cattr {
	dev_t rdev;
	umode_t mode;
	const char *link;
	struct dentry *hardlink;
	};

	#define OVL_CATTR(m) (&(struct ovl_cattr) { .mode = (m) })

	struct dentry ovl_create_real(struct inode dir, struct dentry *newdentry,
	struct ovl_cattr *attr);
	int ovl_cleanup(struct inode dir, struct dentry dentry);
	struct dentry ovl_lookup_temp(struct dentry workdir);
	struct dentry ovl_create_temp(struct dentry workdir, struct ovl_cattr *attr);

	/* file.c */
	extern const struct file_operations ovl_file_operations;
	int __init ovl_aio_request_cache_init(void);
	void ovl_aio_request_cache_destroy(void);
	long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
	long ovl_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);

	/* copy_up.c */
	int ovl_copy_up(struct dentry *dentry);
	int ovl_copy_up_with_data(struct dentry *dentry);
	int ovl_maybe_copy_up(struct dentry *dentry, int flags);
	int ovl_copy_xattr(struct super_block sb, struct dentry old,
	struct dentry *new);
	int ovl_set_attr(struct dentry upper, struct kstat stat);
	struct ovl_fh ovl_encode_real_fh(struct ovl_fs ofs, struct dentry *real,
	bool is_upper);
	int ovl_set_origin(struct ovl_fs ofs, struct dentry dentry,
	struct dentry lower, struct dentry upper);

	/* export.c */
	extern const struct export_operations ovl_export_operations;