Commit ff0c7d15 authored by Nick Piggin's avatar Nick Piggin
Browse files

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: default avatarNick Piggin <npiggin@kernel.dk>
parent fa0d7e3d

fs/inode.c

+6 −0
Original line number Diff line number Diff line
@@ -257,6 +257,12 @@ static struct inode *alloc_inode(struct super_block *sb) 
	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));

fs/pipe.c

+5 −1
Original line number Diff line number Diff line
@@ -1253,6 +1253,10 @@ out: 
	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 @@ out: 
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 = {

include/linux/fs.h

+1 −0
Original line number Diff line number Diff line
@@ -2233,6 +2233,7 @@ extern void iget_failed(struct inode *); 
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 *);

include/linux/net.h

+1 −0
Original line number Diff line number Diff line
@@ -120,6 +120,7 @@ enum sock_shutdown_cmd { 
struct socket_wq {

	wait_queue_head_t	wait;

	struct fasync_struct	*fasync_list;

	struct rcu_head		rcu;

} ____cacheline_aligned_in_smp;



/**

net/socket.c

+9 −8
Original line number Diff line number Diff line
@@ -262,20 +262,21 @@ static struct inode *sock_alloc_inode(struct super_block *sb) 
}





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)