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2023-12-08 01573e231f18eb2d99162747186f59511f56b64d 
 kernel/include/linux/kernfs.h
....@@ -1,7 +1,6 @@
1
+/* SPDX-License-Identifier: GPL-2.0-only */
12 /*
23  * kernfs.h - pseudo filesystem decoupled from vfs locking
3
- *
4
- * This file is released under the GPLv2.
54  */
65 
76 #ifndef __LINUX_KERNFS_H
....@@ -27,7 +26,9 @@
2726 struct super_block;
2827 struct file_system_type;
2928 struct poll_table_struct;
29
+struct fs_context;
3030 
31
+struct kernfs_fs_context;
3132 struct kernfs_open_node;
3233 struct kernfs_iattrs;
3334 
....@@ -37,8 +38,10 @@
3738 	KERNFS_LINK		= 0x0004,
3839 };
3940 
40
-#define KERNFS_TYPE_MASK	0x000f
41
-#define KERNFS_FLAG_MASK	~KERNFS_TYPE_MASK
41
+#define KERNFS_TYPE_MASK		0x000f
42
+#define KERNFS_FLAG_MASK		~KERNFS_TYPE_MASK
43
+#define KERNFS_MAX_USER_XATTRS		128
44
+#define KERNFS_USER_XATTR_SIZE_LIMIT	(128 << 10)
4245 
4346 enum kernfs_node_flag {
4447 	KERNFS_ACTIVATED	= 0x0010,
....@@ -63,7 +66,7 @@
6366 	KERNFS_ROOT_CREATE_DEACTIVATED		= 0x0001,
6467 
6568 	/*
66
-	 * For regular flies, if the opener has CAP_DAC_OVERRIDE, open(2)
69
+	 * For regular files, if the opener has CAP_DAC_OVERRIDE, open(2)
6770 	 * succeeds regardless of the RW permissions.  sysfs had an extra
6871 	 * layer of enforcement where open(2) fails with -EACCES regardless
6972 	 * of CAP_DAC_OVERRIDE if the permission doesn't have the
....@@ -78,6 +81,11 @@
7881 	 * fhandle to access nodes of the fs.
7982 	 */
8083 	KERNFS_ROOT_SUPPORT_EXPORTOP		= 0x0004,
84
+
85
+	/*
86
+	 * Support user xattrs to be written to nodes rooted at this root.
87
+	 */
88
+	KERNFS_ROOT_SUPPORT_USER_XATTR		= 0x0008,
8189 };
8290 
8391 /* type-specific structures for kernfs_node union members */
....@@ -102,21 +110,6 @@
102110 	struct kernfs_open_node	*open;
103111 	loff_t			size;
104112 	struct kernfs_node	*notify_next;	/* for kernfs_notify() */
105
-};
106
-
107
-/* represent a kernfs node */
108
-union kernfs_node_id {
109
-	struct {
110
-		/*
111
-		 * blktrace will export this struct as a simplified 'struct
112
-		 * fid' (which is a big data struction), so userspace can use
113
-		 * it to find kernfs node. The layout must match the first two
114
-		 * fields of 'struct fid' exactly.
115
-		 */
116
-		u32		ino;
117
-		u32		generation;
118
-	};
119
-	u64			id;
120113 };
121114 
122115 /*
....@@ -155,10 +148,17 @@
155148 
156149 	void			*priv;
157150 
158
-	union kernfs_node_id	id;
151
+	/*
152
+	 * 64bit unique ID.  On 64bit ino setups, id is the ino.  On 32bit,
153
+	 * the low 32bits are ino and upper generation.
154
+	 */
155
+	u64			id;
156
+
159157 	unsigned short		flags;
160158 	umode_t			mode;
161159 	struct kernfs_iattrs	*iattr;
160
+
161
+	ANDROID_KABI_RESERVE(1);
162162 };
163163 
164164 /*
....@@ -169,7 +169,6 @@
169169  * kernfs_node parameter.
170170  */
171171 struct kernfs_syscall_ops {
172
-	int (*remount_fs)(struct kernfs_root *root, int *flags, char *data);
173172 	int (*show_options)(struct seq_file *sf, struct kernfs_root *root);
174173 
175174 	int (*mkdir)(struct kernfs_node *parent, const char *name,
....@@ -193,14 +192,16 @@
193192 
194193 	/* private fields, do not use outside kernfs proper */
195194 	struct idr		ino_idr;
196
-	u32			last_ino;
197
-	u32			next_generation;
195
+	u32			last_id_lowbits;
196
+	u32			id_highbits;
198197 	struct kernfs_syscall_ops *syscall_ops;
199198 
200199 	/* list of kernfs_super_info of this root, protected by kernfs_mutex */
201200 	struct list_head	supers;
202201 
203202 	wait_queue_head_t	deactivate_waitq;
203
+
204
+	ANDROID_KABI_RESERVE(1);
204205 };
205206 
206207 struct kernfs_open_file {
....@@ -221,6 +222,8 @@
221222 	bool			mmapped:1;
222223 	bool			released:1;
223224 	const struct vm_operations_struct *vm_ops;
225
+
226
+	ANDROID_KABI_RESERVE(1);
224227 };
225228 
226229 struct kernfs_ops {
....@@ -282,11 +285,51 @@
282285 	ANDROID_KABI_RESERVE(2);
283286 };
284287 
288
+/*
289
+ * The kernfs superblock creation/mount parameter context.
290
+ */
291
+struct kernfs_fs_context {
292
+	struct kernfs_root	*root;		/* Root of the hierarchy being mounted */
293
+	void			*ns_tag;	/* Namespace tag of the mount (or NULL) */
294
+	unsigned long		magic;		/* File system specific magic number */
295
+
296
+	/* The following are set/used by kernfs_mount() */
297
+	bool			new_sb_created;	/* Set to T if we allocated a new sb */
298
+};
299
+
285300 #ifdef CONFIG_KERNFS
286301 
287302 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
288303 {
289304 	return kn->flags & KERNFS_TYPE_MASK;
305
+}
306
+
307
+static inline ino_t kernfs_id_ino(u64 id)
308
+{
309
+	/* id is ino if ino_t is 64bit; otherwise, low 32bits */
310
+	if (sizeof(ino_t) >= sizeof(u64))
311
+		return id;
312
+	else
313
+		return (u32)id;
314
+}
315
+
316
+static inline u32 kernfs_id_gen(u64 id)
317
+{
318
+	/* gen is fixed at 1 if ino_t is 64bit; otherwise, high 32bits */
319
+	if (sizeof(ino_t) >= sizeof(u64))
320
+		return 1;
321
+	else
322
+		return id >> 32;
323
+}
324
+
325
+static inline ino_t kernfs_ino(struct kernfs_node *kn)
326
+{
327
+	return kernfs_id_ino(kn->id);
328
+}
329
+
330
+static inline ino_t kernfs_gen(struct kernfs_node *kn)
331
+{
332
+	return kernfs_id_gen(kn->id);
290333 }
291334 
292335 /**
....@@ -368,17 +411,20 @@
368411 			     struct poll_table_struct *pt);
369412 void kernfs_notify(struct kernfs_node *kn);
370413 
414
+int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
415
+		     void *value, size_t size);
416
+int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
417
+		     const void *value, size_t size, int flags);
418
+
371419 const void *kernfs_super_ns(struct super_block *sb);
372
-struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
373
-			       struct kernfs_root *root, unsigned long magic,
374
-			       bool *new_sb_created, const void *ns);
420
+int kernfs_get_tree(struct fs_context *fc);
421
+void kernfs_free_fs_context(struct fs_context *fc);
375422 void kernfs_kill_sb(struct super_block *sb);
376
-struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns);
377423 
378424 void kernfs_init(void);
379425 
380
-struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
381
-	const union kernfs_node_id *id);
426
+struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root,
427
+						   u64 id);
382428 #else	/* CONFIG_KERNFS */
383429 
384430 static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
....@@ -472,14 +518,21 @@
472518 
473519 static inline void kernfs_notify(struct kernfs_node *kn) { }
474520 
521
+static inline int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
522
+				   void *value, size_t size)
523
+{ return -ENOSYS; }
524
+
525
+static inline int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
526
+				   const void *value, size_t size, int flags)
527
+{ return -ENOSYS; }
528
+
475529 static inline const void *kernfs_super_ns(struct super_block *sb)
476530 { return NULL; }
477531 
478
-static inline struct dentry *
479
-kernfs_mount_ns(struct file_system_type *fs_type, int flags,
480
-		struct kernfs_root *root, unsigned long magic,
481
-		bool *new_sb_created, const void *ns)
482
-{ return ERR_PTR(-ENOSYS); }
532
+static inline int kernfs_get_tree(struct fs_context *fc)
533
+{ return -ENOSYS; }
534
+
535
+static inline void kernfs_free_fs_context(struct fs_context *fc) { }
483536 
484537 static inline void kernfs_kill_sb(struct super_block *sb) { }
485538 
....@@ -493,10 +546,11 @@
493546  * @buf: buffer to copy @kn's name into
494547  * @buflen: size of @buf
495548  *
496
- * Builds and returns the full path of @kn in @buf of @buflen bytes.  The
497
- * path is built from the end of @buf so the returned pointer usually
498
- * doesn't match @buf.  If @buf isn't long enough, @buf is nul terminated
499
- * and %NULL is returned.
549
+ * If @kn is NULL result will be "(null)".
550
+ *
551
+ * Returns the length of the full path.  If the full length is equal to or
552
+ * greater than @buflen, @buf contains the truncated path with the trailing
553
+ * '\0'.  On error, -errno is returned.
500554  */
501555 static inline int kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen)
502556 {
....@@ -559,15 +613,6 @@
559613 				const char *new_name)
560614 {
561615 	return kernfs_rename_ns(kn, new_parent, new_name, NULL);
562
-}
563
-
564
-static inline struct dentry *
565
-kernfs_mount(struct file_system_type *fs_type, int flags,
566
-		struct kernfs_root *root, unsigned long magic,
567
-		bool *new_sb_created)
568
-{
569
-	return kernfs_mount_ns(fs_type, flags, root,
570
-				magic, new_sb_created, NULL);
571616 }
572617 
573618 #endif	/* __LINUX_KERNFS_H */