1 files changed, 160 insertions, 0 deletions
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
new file mode 100644
index 000000000..a479680a5
--- /dev/null
+++ b/fs/overlayfs/ovl_entry.h
@@ -0,0 +1,160 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ * Copyright (C) 2016 Red Hat, Inc.
+ */
+
+struct ovl_config {
+	char *lowerdir;
+	char *upperdir;
+	char *workdir;
+	bool default_permissions;
+	bool redirect_dir;
+	bool redirect_follow;
+	const char *redirect_mode;
+	bool index;
+	bool uuid;
+	bool nfs_export;
+	int xino;
+	bool metacopy;
+	bool userxattr;
+	bool ovl_volatile;
+};
+
+struct ovl_sb {
+	struct super_block *sb;
+	dev_t pseudo_dev;
+	/* Unusable (conflicting) uuid */
+	bool bad_uuid;
+	/* Used as a lower layer (but maybe also as upper) */
+	bool is_lower;
+};
+
+struct ovl_layer {
+	/* ovl_free_fs() relies on @mnt being the first member! */
+	struct vfsmount *mnt;
+	/* Trap in ovl inode cache */
+	struct inode *trap;
+	struct ovl_sb *fs;
+	/* Index of this layer in fs root (upper idx == 0) */
+	int idx;
+	/* One fsid per unique underlying sb (upper fsid == 0) */
+	int fsid;
+};
+
+/*
+ * ovl_free_fs() relies on @mnt being the first member when unmounting
+ * the private mounts created for each layer. Let's check both the
+ * offset and type.
+ */
+static_assert(offsetof(struct ovl_layer, mnt) == 0);
+static_assert(__same_type(typeof_member(struct ovl_layer, mnt), struct vfsmount *));
+
+struct ovl_path {
+	const struct ovl_layer *layer;
+	struct dentry *dentry;
+};
+
+/* private information held for overlayfs's superblock */
+struct ovl_fs {
+	unsigned int numlayer;
+	/* Number of unique fs among layers including upper fs */
+	unsigned int numfs;
+	const struct ovl_layer *layers;
+	struct ovl_sb *fs;
+	/* workbasedir is the path at workdir= mount option */
+	struct dentry *workbasedir;
+	/* workdir is the 'work' directory under workbasedir */
+	struct dentry *workdir;
+	/* index directory listing overlay inodes by origin file handle */
+	struct dentry *indexdir;
+	long namelen;
+	/* pathnames of lower and upper dirs, for show_options */
+	struct ovl_config config;
+	/* creds of process who forced instantiation of super block */
+	const struct cred *creator_cred;
+	bool tmpfile;
+	bool noxattr;
+	/* Did we take the inuse lock? */
+	bool upperdir_locked;
+	bool workdir_locked;
+	bool share_whiteout;
+	/* Traps in ovl inode cache */
+	struct inode *workbasedir_trap;
+	struct inode *workdir_trap;
+	struct inode *indexdir_trap;
+	/* -1: disabled, 0: same fs, 1..32: number of unused ino bits */
+	int xino_mode;
+	/* For allocation of non-persistent inode numbers */
+	atomic_long_t last_ino;
+	/* Whiteout dentry cache */
+	struct dentry *whiteout;
+	/* r/o snapshot of upperdir sb's only taken on volatile mounts */
+	errseq_t errseq;
+};
+
+static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
+{
+	return ofs->layers[0].mnt;
+}
+
+static inline struct user_namespace *ovl_upper_mnt_userns(struct ovl_fs *ofs)
+{
+	return mnt_user_ns(ovl_upper_mnt(ofs));
+}
+
+static inline struct ovl_fs *OVL_FS(struct super_block *sb)
+{
+	return (struct ovl_fs *)sb->s_fs_info;
+}
+
+static inline bool ovl_should_sync(struct ovl_fs *ofs)
+{
+	return !ofs->config.ovl_volatile;
+}
+
+/* private information held for every overlayfs dentry */
+struct ovl_entry {
+	union {
+		struct {
+			unsigned long flags;
+		};
+		struct rcu_head rcu;
+	};
+	unsigned numlower;
+	struct ovl_path lowerstack[];
+};
+
+struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
+
+static inline struct ovl_entry *OVL_E(struct dentry *dentry)
+{
+	return (struct ovl_entry *) dentry->d_fsdata;
+}
+
+struct ovl_inode {
+	union {
+		struct ovl_dir_cache *cache;	/* directory */
+		struct inode *lowerdata;	/* regular file */
+	};
+	const char *redirect;
+	u64 version;
+	unsigned long flags;
+	struct inode vfs_inode;
+	struct dentry *__upperdentry;
+	struct ovl_path lowerpath;
+
+	/* synchronize copy up and more */
+	struct mutex lock;
+};
+
+static inline struct ovl_inode *OVL_I(struct inode *inode)
+{
+	return container_of(inode, struct ovl_inode, vfs_inode);
+}
+
+static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
+{
+	return READ_ONCE(oi->__upperdentry);
+}