fs: avoid inode RCU freeing for pseudo fs

Pseudo filesystems that don't put inode on RCU list or reachable by rcu-walk dentries do not need to RCU free their inodes. Signed-off-by: Nick Piggin <npiggin@kernel.dk>

fs: avoid inode RCU freeing for pseudo fs
Pseudo filesystems that don't put inode on RCU list or reachable by rcu-walk dentries do not need to RCU free their inodes. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Nick Piggin
1 parent fa0d7e3de6
Showing 5 changed files with 22 additions and 9 deletions Side-by-side Diff
fs/inode.c
fs/pipe.c
include/linux/fs.h
include/linux/net.h
net/socket.c
@@ -257,6 +257,12 @@
 	return inode;
 }
  
+void free_inode_nonrcu(struct inode *inode)
+{
+	kmem_cache_free(inode_cachep, inode);
+}
+EXPORT_SYMBOL(free_inode_nonrcu);
+
 void __destroy_inode(struct inode *inode)
 {
 	BUG_ON(inode_has_buffers(inode));
@@ -1253,6 +1253,10 @@
 	return ret;
 }
  
+static const struct super_operations pipefs_ops = {
+	.destroy_inode = free_inode_nonrcu,
+};
+
 /*
  * pipefs should _never_ be mounted by userland - too much of security hassle,
  * no real gain from having the whole whorehouse mounted. So we don't need
@@ -1262,7 +1266,7 @@
 static struct dentry *pipefs_mount(struct file_system_type *fs_type,
 			 int flags, const char *dev_name, void *data)
 {
-	return mount_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC);
+	return mount_pseudo(fs_type, "pipe:", &pipefs_ops, PIPEFS_MAGIC);
 }
  
 static struct file_system_type pipe_fs_type = {
@@ -2233,6 +2233,7 @@
 extern void end_writeback(struct inode *);
 extern void __destroy_inode(struct inode *);
 extern struct inode *new_inode(struct super_block *);
+extern void free_inode_nonrcu(struct inode *inode);
 extern int should_remove_suid(struct dentry *);
 extern int file_remove_suid(struct file *);
  
@@ -120,6 +120,7 @@
 struct socket_wq {
 	wait_queue_head_t	wait;
 	struct fasync_struct	*fasync_list;
+	struct rcu_head		rcu;
 } ____cacheline_aligned_in_smp;
  
 /**
@@ -262,20 +262,21 @@
 }
  
  
-static void sock_free_rcu(struct rcu_head *head)
+
+static void wq_free_rcu(struct rcu_head *head)
 {
-	struct inode *inode = container_of(head, struct inode, i_rcu);
-	struct socket_alloc *ei = container_of(inode, struct socket_alloc,
-								vfs_inode);
+	struct socket_wq *wq = container_of(head, struct socket_wq, rcu);
  
-	kfree(ei->socket.wq);
-	INIT_LIST_HEAD(&inode->i_dentry);
-	kmem_cache_free(sock_inode_cachep, ei);
+	kfree(wq);
 }
  
 static void sock_destroy_inode(struct inode *inode)
 {
-	call_rcu(&inode->i_rcu, sock_free_rcu);
+	struct socket_alloc *ei;
+
+	ei = container_of(inode, struct socket_alloc, vfs_inode);
+	call_rcu(&ei->socket.wq->rcu, wq_free_rcu);
+	kmem_cache_free(sock_inode_cachep, ei);
 }
  
 static void init_once(void *foo)
...	...	@@ -257,6 +257,12 @@
257	257	return inode;
258	258	}
259	259
	260	+void free_inode_nonrcu(struct inode *inode)
	261	+{
	262	+ kmem_cache_free(inode_cachep, inode);
	263	+}
	264	+EXPORT_SYMBOL(free_inode_nonrcu);
	265	+
260	266	void __destroy_inode(struct inode *inode)
261	267	{
262	268	BUG_ON(inode_has_buffers(inode));
...	...	@@ -1253,6 +1253,10 @@
1253	1253	return ret;
1254	1254	}
1255	1255
	1256	+static const struct super_operations pipefs_ops = {
	1257	+ .destroy_inode = free_inode_nonrcu,
	1258	+};
	1259	+
1256	1260	/*
1257	1261	* pipefs should _never_ be mounted by userland - too much of security hassle,
1258	1262	* no real gain from having the whole whorehouse mounted. So we don't need
...	...	@@ -1262,7 +1266,7 @@
1262	1266	static struct dentry pipefs_mount(struct file_system_type fs_type,
1263	1267	int flags, const char dev_name, void data)
1264	1268	{
1265		- return mount_pseudo(fs_type, "pipe:", NULL, PIPEFS_MAGIC);
	1269	+ return mount_pseudo(fs_type, "pipe:", &pipefs_ops, PIPEFS_MAGIC);
1266	1270	}
1267	1271
1268	1272	static struct file_system_type pipe_fs_type = {
...	...	@@ -2233,6 +2233,7 @@
2233	2233	extern void end_writeback(struct inode *);
2234	2234	extern void __destroy_inode(struct inode *);
2235	2235	extern struct inode new_inode(struct super_block );
	2236	+extern void free_inode_nonrcu(struct inode *inode);
2236	2237	extern int should_remove_suid(struct dentry *);
2237	2238	extern int file_remove_suid(struct file *);
2238	2239
...	...	@@ -120,6 +120,7 @@
120	120	struct socket_wq {
121	121	wait_queue_head_t wait;
122	122	struct fasync_struct *fasync_list;
	123	+ struct rcu_head rcu;
123	124	} ____cacheline_aligned_in_smp;
124	125
125	126	/**
...	...	@@ -262,20 +262,21 @@
262	262	}
263	263
264	264
265		-static void sock_free_rcu(struct rcu_head *head)
	265	+
	266	+static void wq_free_rcu(struct rcu_head *head)
266	267	{
267		- struct inode *inode = container_of(head, struct inode, i_rcu);
268		- struct socket_alloc *ei = container_of(inode, struct socket_alloc,
269		- vfs_inode);
	268	+ struct socket_wq *wq = container_of(head, struct socket_wq, rcu);
270	269
271		- kfree(ei->socket.wq);
272		- INIT_LIST_HEAD(&inode->i_dentry);
273		- kmem_cache_free(sock_inode_cachep, ei);
	270	+ kfree(wq);
274	271	}
275	272
276	273	static void sock_destroy_inode(struct inode *inode)
277	274	{
278		- call_rcu(&inode->i_rcu, sock_free_rcu);
	275	+ struct socket_alloc *ei;
	276	+
	277	+ ei = container_of(inode, struct socket_alloc, vfs_inode);
	278	+ call_rcu(&ei->socket.wq->rcu, wq_free_rcu);
	279	+ kmem_cache_free(sock_inode_cachep, ei);
279	280	}
280	281
281	282	static void init_once(void *foo)