Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull VFS fixes from Al Viro: "A bunch of assorted fixes, most of them followups to overlayfs merge" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: ovl: initialize ->is_cursor Return short read or 0 at end of a raw device, not EIO isofs: don't bother with ->d_op for normal case isofs_cmp(): we'll never see a dentry for . or .. overlayfs: fix lockdep misannotation ovl: fix check for cursor overlayfs: barriers for opening upper-layer directory rcu: Provide counterpart to rcu_dereference() for non-RCU situations staging: android: logger: Fix log corruption regression

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull VFS fixes from Al Viro: "A bunch of assorted fixes, most of them followups to overlayfs merge" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: ovl: initialize ->is_cursor Return short read or 0 at end of a raw device, not EIO isofs: don't bother with ->d_op for normal case isofs_cmp(): we'll never see a dentry for . or .. overlayfs: fix lockdep misannotation ovl: fix check for cursor overlayfs: barriers for opening upper-layer directory rcu: Provide counterpart to rcu_dereference() for non-RCU situations staging: android: logger: Fix log corruption regression
Linus Torvalds
2 parents 4cb8c3593b 9f2f7d4c8d
Showing 9 changed files Side-by-side Diff
drivers/char/raw.c
drivers/staging/android/logger.c
fs/block_dev.c
fs/isofs/inode.c
fs/isofs/namei.c
fs/namei.c
fs/overlayfs/readdir.c
include/linux/fs.h
include/linux/rcupdate.h
@@ -285,7 +285,7 @@
  
 static const struct file_operations raw_fops = {
 	.read		= new_sync_read,
-	.read_iter	= generic_file_read_iter,
+	.read_iter	= blkdev_read_iter,
 	.write		= new_sync_write,
 	.write_iter	= blkdev_write_iter,
 	.fsync		= blkdev_fsync,
@@ -420,7 +420,7 @@
 	struct logger_log *log = file_get_log(iocb->ki_filp);
 	struct logger_entry header;
 	struct timespec now;
-	size_t len, count;
+	size_t len, count, w_off;
  
 	count = min_t(size_t, iocb->ki_nbytes, LOGGER_ENTRY_MAX_PAYLOAD);
  
  
  
@@ -452,11 +452,14 @@
 	memcpy(log->buffer + log->w_off, &header, len);
 	memcpy(log->buffer, (char *)&header + len, sizeof(header) - len);
  
-	len = min(count, log->size - log->w_off);
+	/* Work with a copy until we are ready to commit the whole entry */
+	w_off =  logger_offset(log, log->w_off + sizeof(struct logger_entry));
  
-	if (copy_from_iter(log->buffer + log->w_off, len, from) != len) {
+	len = min(count, log->size - w_off);
+
+	if (copy_from_iter(log->buffer + w_off, len, from) != len) {
 		/*
-		 * Note that by not updating w_off, this abandons the
+		 * Note that by not updating log->w_off, this abandons the
 		 * portion of the new entry that *was* successfully
 		 * copied, just above.  This is intentional to avoid
 		 * message corruption from missing fragments.
@@ -470,7 +473,7 @@
 		return -EFAULT;
 	}
  
-	log->w_off = logger_offset(log, log->w_off + count);
+	log->w_off = logger_offset(log, w_off + count);
 	mutex_unlock(&log->mutex);
  
 	/* wake up any blocked readers */
@@ -1585,7 +1585,7 @@
 }
 EXPORT_SYMBOL_GPL(blkdev_write_iter);
  
-static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
+ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *bd_inode = file->f_mapping->host;
@@ -1599,6 +1599,7 @@
 	iov_iter_truncate(to, size);
 	return generic_file_read_iter(iocb, to);
 }
+EXPORT_SYMBOL_GPL(blkdev_read_iter);
  
 /*
  * Try to release a page associated with block device when the system
@@ -29,13 +29,9 @@
 #define BEQUIET
  
 static int isofs_hashi(const struct dentry *parent, struct qstr *qstr);
-static int isofs_hash(const struct dentry *parent, struct qstr *qstr);
 static int isofs_dentry_cmpi(const struct dentry *parent,
 		const struct dentry *dentry,
 		unsigned int len, const char *str, const struct qstr *name);
-static int isofs_dentry_cmp(const struct dentry *parent,
-		const struct dentry *dentry,
-		unsigned int len, const char *str, const struct qstr *name);
  
 #ifdef CONFIG_JOLIET
 static int isofs_hashi_ms(const struct dentry *parent, struct qstr *qstr);
@@ -135,10 +131,6 @@
  
 static const struct dentry_operations isofs_dentry_ops[] = {
 	{
-		.d_hash		= isofs_hash,
-		.d_compare	= isofs_dentry_cmp,
-	},
-	{
 		.d_hash		= isofs_hashi,
 		.d_compare	= isofs_dentry_cmpi,
 	},
  
@@ -258,25 +250,12 @@
 }
  
 static int
-isofs_hash(const struct dentry *dentry, struct qstr *qstr)
-{
-	return isofs_hash_common(qstr, 0);
-}
-
-static int
 isofs_hashi(const struct dentry *dentry, struct qstr *qstr)
 {
 	return isofs_hashi_common(qstr, 0);
 }
  
 static int
-isofs_dentry_cmp(const struct dentry *parent, const struct dentry *dentry,
-		unsigned int len, const char *str, const struct qstr *name)
-{
-	return isofs_dentry_cmp_common(len, str, name, 0, 0);
-}
-
-static int
 isofs_dentry_cmpi(const struct dentry *parent, const struct dentry *dentry,
 		unsigned int len, const char *str, const struct qstr *name)
 {
@@ -930,7 +909,8 @@
 	if (opt.check == 'r')
 		table++;
  
-	s->s_d_op = &isofs_dentry_ops[table];
+	if (table)
+		s->s_d_op = &isofs_dentry_ops[table - 1];
  
 	/* get the root dentry */
 	s->s_root = d_make_root(inode);
@@ -18,25 +18,10 @@
 isofs_cmp(struct dentry *dentry, const char *compare, int dlen)
 {
 	struct qstr qstr;
-
-	if (!compare)
-		return 1;
-
-	/* check special "." and ".." files */
-	if (dlen == 1) {
-		/* "." */
-		if (compare[0] == 0) {
-			if (!dentry->d_name.len)
-				return 0;
-			compare = ".";
-		} else if (compare[0] == 1) {
-			compare = "..";
-			dlen = 2;
-		}
-	}
-
 	qstr.name = compare;
 	qstr.len = dlen;
+	if (likely(!dentry->d_op))
+		return dentry->d_name.len != dlen || memcmp(dentry->d_name.name, compare, dlen);
 	return dentry->d_op->d_compare(NULL, NULL, dentry->d_name.len, dentry->d_name.name, &qstr);
 }
  
@@ -146,7 +131,8 @@
 				(!(de->flags[-sbi->s_high_sierra] & 1))) &&
 			(sbi->s_showassoc ||
 				(!(de->flags[-sbi->s_high_sierra] & 4)))) {
-			match = (isofs_cmp(dentry, dpnt, dlen) == 0);
+			if (dpnt && (dlen > 1 || dpnt[0] > 1))
+				match = (isofs_cmp(dentry, dpnt, dlen) == 0);
 		}
 		if (match) {
 			isofs_normalize_block_and_offset(de,
@@ -2497,7 +2497,7 @@
 	}
  
 	mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
-	mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
+	mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2);
 	return NULL;
 }
 EXPORT_SYMBOL(lock_rename);
@@ -21,9 +21,10 @@
 	unsigned int len;
 	unsigned int type;
 	u64 ino;
-	bool is_whiteout;
 	struct list_head l_node;
 	struct rb_node node;
+	bool is_whiteout;
+	bool is_cursor;
 	char name[];
 };
  
@@ -92,6 +93,7 @@
 		p->type = d_type;
 		p->ino = ino;
 		p->is_whiteout = false;
+		p->is_cursor = false;
 	}
  
 	return p;
@@ -251,7 +253,7 @@
  
 	mutex_lock(&dir->d_inode->i_mutex);
 	list_for_each_entry(p, rdd->list, l_node) {
-		if (!p->name)
+		if (p->is_cursor)
 			continue;
  
 		if (p->type != DT_CHR)
@@ -307,7 +309,6 @@
 	}
 out:
 	return err;
-
 }
  
 static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
@@ -316,7 +317,7 @@
 	loff_t off = 0;
  
 	list_for_each_entry(p, &od->cache->entries, l_node) {
-		if (!p->name)
+		if (p->is_cursor)
 			continue;
 		if (off >= pos)
 			break;
@@ -389,7 +390,7 @@
  
 		p = list_entry(od->cursor.l_node.next, struct ovl_cache_entry, l_node);
 		/* Skip cursors */
-		if (p->name) {
+		if (!p->is_cursor) {
 			if (!p->is_whiteout) {
 				if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
 					break;
  
@@ -454,12 +455,13 @@
 	if (!od->is_upper && ovl_path_type(dentry) == OVL_PATH_MERGE) {
 		struct inode *inode = file_inode(file);
  
-		realfile = od->upperfile;
+		realfile =lockless_dereference(od->upperfile);
 		if (!realfile) {
 			struct path upperpath;
  
 			ovl_path_upper(dentry, &upperpath);
 			realfile = ovl_path_open(&upperpath, O_RDONLY);
+			smp_mb__before_spinlock();
 			mutex_lock(&inode->i_mutex);
 			if (!od->upperfile) {
 				if (IS_ERR(realfile)) {
@@ -518,6 +520,7 @@
 	od->realfile = realfile;
 	od->is_real = (type != OVL_PATH_MERGE);
 	od->is_upper = (type != OVL_PATH_LOWER);
+	od->cursor.is_cursor = true;
 	file->private_data = od;
  
 	return 0;
@@ -569,7 +572,7 @@
 {
 	struct ovl_cache_entry *p;
  
-	mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_PARENT);
+	mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_CHILD);
 	list_for_each_entry(p, list, l_node) {
 		struct dentry *dentry;
  
@@ -639,11 +639,13 @@
  * 2: child/target
  * 3: xattr
  * 4: second non-directory
- * The last is for certain operations (such as rename) which lock two
+ * 5: second parent (when locking independent directories in rename)
+ *
+ * I_MUTEX_NONDIR2 is for certain operations (such as rename) which lock two
  * non-directories at once.
  *
  * The locking order between these classes is
- * parent -> child -> normal -> xattr -> second non-directory
+ * parent[2] -> child -> grandchild -> normal -> xattr -> second non-directory
  */
 enum inode_i_mutex_lock_class
 {
@@ -651,7 +653,8 @@
 	I_MUTEX_PARENT,
 	I_MUTEX_CHILD,
 	I_MUTEX_XATTR,
-	I_MUTEX_NONDIR2
+	I_MUTEX_NONDIR2,
+	I_MUTEX_PARENT2,
 };
  
 void lock_two_nondirectories(struct inode *, struct inode*);
@@ -2466,6 +2469,7 @@
 extern ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos);
  
 /* fs/block_dev.c */
+extern ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to);
 extern ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from);
 extern int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
 			int datasync);
@@ -617,6 +617,21 @@
 #define RCU_INITIALIZER(v) (typeof(*(v)) __force __rcu *)(v)
  
 /**
+ * lockless_dereference() - safely load a pointer for later dereference
+ * @p: The pointer to load
+ *
+ * Similar to rcu_dereference(), but for situations where the pointed-to
+ * object's lifetime is managed by something other than RCU.  That
+ * "something other" might be reference counting or simple immortality.
+ */
+#define lockless_dereference(p) \
+({ \
+	typeof(p) _________p1 = ACCESS_ONCE(p); \
+	smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
+	(_________p1); \
+})
+
+/**
  * rcu_assign_pointer() - assign to RCU-protected pointer
  * @p: pointer to assign to
  * @v: value to assign (publish)
...	...	@@ -285,7 +285,7 @@
285	285
286	286	static const struct file_operations raw_fops = {
287	287	.read = new_sync_read,
288		- .read_iter = generic_file_read_iter,
	288	+ .read_iter = blkdev_read_iter,
289	289	.write = new_sync_write,
290	290	.write_iter = blkdev_write_iter,
291	291	.fsync = blkdev_fsync,
...	...	@@ -420,7 +420,7 @@
420	420	struct logger_log *log = file_get_log(iocb->ki_filp);
421	421	struct logger_entry header;
422	422	struct timespec now;
423		- size_t len, count;
	423	+ size_t len, count, w_off;
424	424
425	425	count = min_t(size_t, iocb->ki_nbytes, LOGGER_ENTRY_MAX_PAYLOAD);
426	426
427	427
428	428
...	...	@@ -452,11 +452,14 @@
452	452	memcpy(log->buffer + log->w_off, &header, len);
453	453	memcpy(log->buffer, (char *)&header + len, sizeof(header) - len);
454	454
455		- len = min(count, log->size - log->w_off);
	455	+ /* Work with a copy until we are ready to commit the whole entry */
	456	+ w_off = logger_offset(log, log->w_off + sizeof(struct logger_entry));
456	457
457		- if (copy_from_iter(log->buffer + log->w_off, len, from) != len) {
	458	+ len = min(count, log->size - w_off);
	459	+
	460	+ if (copy_from_iter(log->buffer + w_off, len, from) != len) {
458	461	/*
459		- * Note that by not updating w_off, this abandons the
	462	+ * Note that by not updating log->w_off, this abandons the
460	463	* portion of the new entry that was successfully
461	464	* copied, just above. This is intentional to avoid
462	465	* message corruption from missing fragments.
...	...	@@ -470,7 +473,7 @@
470	473	return -EFAULT;
471	474	}
472	475
473		- log->w_off = logger_offset(log, log->w_off + count);
	476	+ log->w_off = logger_offset(log, w_off + count);
474	477	mutex_unlock(&log->mutex);
475	478
476	479	/* wake up any blocked readers */
...	...	@@ -1585,7 +1585,7 @@
1585	1585	}
1586	1586	EXPORT_SYMBOL_GPL(blkdev_write_iter);
1587	1587
1588		-static ssize_t blkdev_read_iter(struct kiocb iocb, struct iov_iter to)
	1588	+ssize_t blkdev_read_iter(struct kiocb iocb, struct iov_iter to)
1589	1589	{
1590	1590	struct file *file = iocb->ki_filp;
1591	1591	struct inode *bd_inode = file->f_mapping->host;
...	...	@@ -1599,6 +1599,7 @@
1599	1599	iov_iter_truncate(to, size);
1600	1600	return generic_file_read_iter(iocb, to);
1601	1601	}
	1602	+EXPORT_SYMBOL_GPL(blkdev_read_iter);
1602	1603
1603	1604	/*
1604	1605	* Try to release a page associated with block device when the system
...	...	@@ -29,13 +29,9 @@
29	29	#define BEQUIET
30	30
31	31	static int isofs_hashi(const struct dentry parent, struct qstr qstr);
32		-static int isofs_hash(const struct dentry parent, struct qstr qstr);
33	32	static int isofs_dentry_cmpi(const struct dentry *parent,
34	33	const struct dentry *dentry,
35	34	unsigned int len, const char str, const struct qstr name);
36		-static int isofs_dentry_cmp(const struct dentry *parent,
37		- const struct dentry *dentry,
38		- unsigned int len, const char str, const struct qstr name);
39	35
40	36	#ifdef CONFIG_JOLIET
41	37	static int isofs_hashi_ms(const struct dentry parent, struct qstr qstr);
...	...	@@ -135,10 +131,6 @@
135	131
136	132	static const struct dentry_operations isofs_dentry_ops[] = {
137	133	{
138		- .d_hash = isofs_hash,
139		- .d_compare = isofs_dentry_cmp,
140		- },
141		- {
142	134	.d_hash = isofs_hashi,
143	135	.d_compare = isofs_dentry_cmpi,
144	136	},
145	137
...	...	@@ -258,25 +250,12 @@
258	250	}
259	251
260	252	static int
261		-isofs_hash(const struct dentry dentry, struct qstr qstr)
262		-{
263		- return isofs_hash_common(qstr, 0);
264		-}
265		-
266		-static int
267	253	isofs_hashi(const struct dentry dentry, struct qstr qstr)
268	254	{
269	255	return isofs_hashi_common(qstr, 0);
270	256	}
271	257
272	258	static int
273		-isofs_dentry_cmp(const struct dentry parent, const struct dentry dentry,
274		- unsigned int len, const char str, const struct qstr name)
275		-{
276		- return isofs_dentry_cmp_common(len, str, name, 0, 0);
277		-}
278		-
279		-static int
280	259	isofs_dentry_cmpi(const struct dentry parent, const struct dentry dentry,
281	260	unsigned int len, const char str, const struct qstr name)
282	261	{
...	...	@@ -930,7 +909,8 @@
930	909	if (opt.check == 'r')
931	910	table++;
932	911
933		- s->s_d_op = &isofs_dentry_ops[table];
	912	+ if (table)
	913	+ s->s_d_op = &isofs_dentry_ops[table - 1];
934	914
935	915	/* get the root dentry */
936	916	s->s_root = d_make_root(inode);
...	...	@@ -18,25 +18,10 @@
18	18	isofs_cmp(struct dentry dentry, const char compare, int dlen)
19	19	{
20	20	struct qstr qstr;
21		-
22		- if (!compare)
23		- return 1;
24		-
25		- /* check special "." and ".." files */
26		- if (dlen == 1) {
27		- /* "." */
28		- if (compare[0] == 0) {
29		- if (!dentry->d_name.len)
30		- return 0;
31		- compare = ".";
32		- } else if (compare[0] == 1) {
33		- compare = "..";
34		- dlen = 2;
35		- }
36		- }
37		-
38	21	qstr.name = compare;
39	22	qstr.len = dlen;
	23	+ if (likely(!dentry->d_op))
	24	+ return dentry->d_name.len != dlen \|\| memcmp(dentry->d_name.name, compare, dlen);
40	25	return dentry->d_op->d_compare(NULL, NULL, dentry->d_name.len, dentry->d_name.name, &qstr);
41	26	}
42	27
...	...	@@ -146,7 +131,8 @@
146	131	(!(de->flags[-sbi->s_high_sierra] & 1))) &&
147	132	(sbi->s_showassoc \|\|
148	133	(!(de->flags[-sbi->s_high_sierra] & 4)))) {
149		- match = (isofs_cmp(dentry, dpnt, dlen) == 0);
	134	+ if (dpnt && (dlen > 1 \|\| dpnt[0] > 1))
	135	+ match = (isofs_cmp(dentry, dpnt, dlen) == 0);
150	136	}
151	137	if (match) {
152	138	isofs_normalize_block_and_offset(de,
...	...	@@ -2497,7 +2497,7 @@
2497	2497	}
2498	2498
2499	2499	mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
2500		- mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
	2500	+ mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2);
2501	2501	return NULL;
2502	2502	}
2503	2503	EXPORT_SYMBOL(lock_rename);
...	...	@@ -21,9 +21,10 @@
21	21	unsigned int len;
22	22	unsigned int type;
23	23	u64 ino;
24		- bool is_whiteout;
25	24	struct list_head l_node;
26	25	struct rb_node node;
	26	+ bool is_whiteout;
	27	+ bool is_cursor;
27	28	char name[];
28	29	};
29	30
...	...	@@ -92,6 +93,7 @@
92	93	p->type = d_type;
93	94	p->ino = ino;
94	95	p->is_whiteout = false;
	96	+ p->is_cursor = false;
95	97	}
96	98
97	99	return p;
...	...	@@ -251,7 +253,7 @@
251	253
252	254	mutex_lock(&dir->d_inode->i_mutex);
253	255	list_for_each_entry(p, rdd->list, l_node) {
254		- if (!p->name)
	256	+ if (p->is_cursor)
255	257	continue;
256	258
257	259	if (p->type != DT_CHR)
...	...	@@ -307,7 +309,6 @@
307	309	}
308	310	out:
309	311	return err;
310		-
311	312	}
312	313
313	314	static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
...	...	@@ -316,7 +317,7 @@
316	317	loff_t off = 0;
317	318
318	319	list_for_each_entry(p, &od->cache->entries, l_node) {
319		- if (!p->name)
	320	+ if (p->is_cursor)
320	321	continue;
321	322	if (off >= pos)
322	323	break;
...	...	@@ -389,7 +390,7 @@
389	390
390	391	p = list_entry(od->cursor.l_node.next, struct ovl_cache_entry, l_node);
391	392	/* Skip cursors */
392		- if (p->name) {
	393	+ if (!p->is_cursor) {
393	394	if (!p->is_whiteout) {
394	395	if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
395	396	break;
396	397
...	...	@@ -454,12 +455,13 @@
454	455	if (!od->is_upper && ovl_path_type(dentry) == OVL_PATH_MERGE) {
455	456	struct inode *inode = file_inode(file);
456	457
457		- realfile = od->upperfile;
	458	+ realfile =lockless_dereference(od->upperfile);
458	459	if (!realfile) {
459	460	struct path upperpath;
460	461
461	462	ovl_path_upper(dentry, &upperpath);
462	463	realfile = ovl_path_open(&upperpath, O_RDONLY);
	464	+ smp_mb__before_spinlock();
463	465	mutex_lock(&inode->i_mutex);
464	466	if (!od->upperfile) {
465	467	if (IS_ERR(realfile)) {
...	...	@@ -518,6 +520,7 @@
518	520	od->realfile = realfile;
519	521	od->is_real = (type != OVL_PATH_MERGE);
520	522	od->is_upper = (type != OVL_PATH_LOWER);
	523	+ od->cursor.is_cursor = true;
521	524	file->private_data = od;
522	525
523	526	return 0;
...	...	@@ -569,7 +572,7 @@
569	572	{
570	573	struct ovl_cache_entry *p;
571	574
572		- mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_PARENT);
	575	+ mutex_lock_nested(&upper->d_inode->i_mutex, I_MUTEX_CHILD);
573	576	list_for_each_entry(p, list, l_node) {
574	577	struct dentry *dentry;
575	578
...	...	@@ -639,11 +639,13 @@
639	639	* 2: child/target
640	640	* 3: xattr
641	641	* 4: second non-directory
642		- * The last is for certain operations (such as rename) which lock two
	642	+ * 5: second parent (when locking independent directories in rename)
	643	+ *
	644	+ * I_MUTEX_NONDIR2 is for certain operations (such as rename) which lock two
643	645	* non-directories at once.
644	646	*
645	647	* The locking order between these classes is
646		- * parent -> child -> normal -> xattr -> second non-directory
	648	+ * parent[2] -> child -> grandchild -> normal -> xattr -> second non-directory
647	649	*/
648	650	enum inode_i_mutex_lock_class
649	651	{
...	...	@@ -651,7 +653,8 @@
651	653	I_MUTEX_PARENT,
652	654	I_MUTEX_CHILD,
653	655	I_MUTEX_XATTR,
654		- I_MUTEX_NONDIR2
	656	+ I_MUTEX_NONDIR2,
	657	+ I_MUTEX_PARENT2,
655	658	};
656	659
657	660	void lock_two_nondirectories(struct inode , struct inode);
...	...	@@ -2466,6 +2469,7 @@
2466	2469	extern ssize_t new_sync_write(struct file filp, const char __user buf, size_t len, loff_t *ppos);
2467	2470
2468	2471	/* fs/block_dev.c */
	2472	+extern ssize_t blkdev_read_iter(struct kiocb iocb, struct iov_iter to);
2469	2473	extern ssize_t blkdev_write_iter(struct kiocb iocb, struct iov_iter from);
2470	2474	extern int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
2471	2475	int datasync);
...	...	@@ -617,6 +617,21 @@
617	617	#define RCU_INITIALIZER(v) (typeof((v)) __force __rcu )(v)
618	618
619	619	/**
	620	+ * lockless_dereference() - safely load a pointer for later dereference
	621	+ * @p: The pointer to load
	622	+ *
	623	+ * Similar to rcu_dereference(), but for situations where the pointed-to
	624	+ * object's lifetime is managed by something other than RCU. That
	625	+ * "something other" might be reference counting or simple immortality.
	626	+ */
	627	+#define lockless_dereference(p) \
	628	+({ \
	629	+ typeof(p) _________p1 = ACCESS_ONCE(p); \
	630	+ smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
	631	+ (_________p1); \
	632	+})
	633	+
	634	+/**
620	635	* rcu_assign_pointer() - assign to RCU-protected pointer
621	636	* @p: pointer to assign to
622	637	* @v: value to assign (publish)