add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/fs/overlayfs/ovl_entry.h
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@@ -1,11 +1,8 @@
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+/* SPDX-License-Identifier: GPL-2.0-only */
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 /*
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  *
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  * Copyright (C) 2011 Novell Inc.
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  * Copyright (C) 2016 Red Hat, Inc.
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- *
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- * This program is free software; you can redistribute it and/or modify it
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- * under the terms of the GNU General Public License version 2 as published by
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- * the Free Software Foundation.
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  */
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 struct ovl_config {
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@@ -20,15 +17,21 @@
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 	bool nfs_export;
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 	int xino;
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 	bool metacopy;
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+	bool ovl_volatile;
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 	bool override_creds;
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 };
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 struct ovl_sb {
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 	struct super_block *sb;
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 	dev_t pseudo_dev;
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+	/* Unusable (conflicting) uuid */
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+	bool bad_uuid;
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+	/* Used as a lower layer (but maybe also as upper) */
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+	bool is_lower;
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 };
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 struct ovl_layer {
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+	/* ovl_free_fs() relies on @mnt being the first member! */
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 	struct vfsmount *mnt;
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 	/* Trap in ovl inode cache */
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 	struct inode *trap;
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@@ -39,19 +42,26 @@
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 	int fsid;
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 };
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+/*
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+ * ovl_free_fs() relies on @mnt being the first member when unmounting
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+ * the private mounts created for each layer. Let's check both the
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+ * offset and type.
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+ */
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+static_assert(offsetof(struct ovl_layer, mnt) == 0);
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+static_assert(__same_type(typeof_member(struct ovl_layer, mnt), struct vfsmount *));
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+
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 struct ovl_path {
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-	struct ovl_layer *layer;
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+	const struct ovl_layer *layer;
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 	struct dentry *dentry;
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 };
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 /* private information held for overlayfs's superblock */
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 struct ovl_fs {
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-	struct vfsmount *upper_mnt;
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-	unsigned int numlower;
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-	/* Number of unique lower sb that differ from upper sb */
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-	unsigned int numlowerfs;
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-	struct ovl_layer *lower_layers;
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-	struct ovl_sb *lower_fs;
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+	unsigned int numlayer;
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+	/* Number of unique fs among layers including upper fs */
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+	unsigned int numfs;
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+	const struct ovl_layer *layers;
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+	struct ovl_sb *fs;
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 	/* workbasedir is the path at workdir= mount option */
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 	struct dentry *workbasedir;
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 	/* workdir is the 'work' directory under workbasedir */
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@@ -68,15 +78,36 @@
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 	/* Did we take the inuse lock? */
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 	bool upperdir_locked;
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 	bool workdir_locked;
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+	bool share_whiteout;
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 	/* Traps in ovl inode cache */
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-	struct inode *upperdir_trap;
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 	struct inode *workbasedir_trap;
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 	struct inode *workdir_trap;
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 	struct inode *indexdir_trap;
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-	/* Inode numbers in all layers do not use the high xino_bits */
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-	unsigned int xino_bits;
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+	/* -1: disabled, 0: same fs, 1..32: number of unused ino bits */
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+	int xino_mode;
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+	/* For allocation of non-persistent inode numbers */
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+	atomic_long_t last_ino;
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+	/* Whiteout dentry cache */
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+	struct dentry *whiteout;
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+	/* r/o snapshot of upperdir sb's only taken on volatile mounts */
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+	errseq_t errseq;
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 };
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+static inline struct vfsmount *ovl_upper_mnt(struct ovl_fs *ofs)
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+{
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+	return ofs->layers[0].mnt;
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+}
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+
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+static inline struct ovl_fs *OVL_FS(struct super_block *sb)
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+{
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+	return (struct ovl_fs *)sb->s_fs_info;
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+}
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+
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+static inline bool ovl_should_sync(struct ovl_fs *ofs)
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+{
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+	return !ofs->config.ovl_volatile;
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+}
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+
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 /* private information held for every overlayfs dentry */
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 struct ovl_entry {
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 	union {