Commit 385a17bf authored by Jeff Dike's avatar Jeff Dike Committed by Linus Torvalds
Browse files

[PATCH] fuse: add O_ASYNC support to FUSE device 



This adds asynchronous notification to FUSE - a FUSE server can request
O_ASYNC on a /dev/fuse file descriptor and receive SIGIO when there is input
available.

One subtlety - fuse_dev_fasync, which is called when O_ASYNC is requested,
does no locking, unlink the other methods.  I think it's unnecessary, as the
fuse_conn.fasync list is manipulated only by fasync_helper and kill_fasync,
which provide their own locking.  It would also be wrong to use the fuse_lock,
as it's a spin lock and fasync_helper can sleep.  My one concern with this is
the fuse_conn going away underneath fuse_dev_fasync - sys_fcntl takes a
reference on the file struct, so this seems not to be a problem.

Signed-off-by: default avatarJeff Dike <jdike@addtoit.com>
Signed-off-by: default avatarMiklos Szeredi <miklos@szeredi.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 7025d9ad

fs/fuse/dev.c

+16 −1
Original line number Diff line number Diff line
@@ -317,6 +317,7 @@ static void queue_request(struct fuse_conn *fc, struct fuse_req *req) 
	list_add_tail(&req->list, &fc->pending);

	req->state = FUSE_REQ_PENDING;

	wake_up(&fc->waitq);

	kill_fasync(&fc->fasync, SIGIO, POLL_IN);

}



/*
@@ -901,6 +902,7 @@ void fuse_abort_conn(struct fuse_conn *fc) 
		end_requests(fc, &fc->pending);

		end_requests(fc, &fc->processing);

		wake_up_all(&fc->waitq);

		kill_fasync(&fc->fasync, SIGIO, POLL_IN);

	}

	spin_unlock(&fuse_lock);

}
@@ -917,12 +919,24 @@ static int fuse_dev_release(struct inode *inode, struct file *file) 
		end_requests(fc, &fc->processing);

	}

	spin_unlock(&fuse_lock);

	if (fc)

	if (fc) {

		fasync_helper(-1, file, 0, &fc->fasync);

		kobject_put(&fc->kobj);

	}



	return 0;

}



static int fuse_dev_fasync(int fd, struct file *file, int on)

{

	struct fuse_conn *fc = fuse_get_conn(file);

	if (!fc)

		return -ENODEV;



	/* No locking - fasync_helper does its own locking */

	return fasync_helper(fd, file, on, &fc->fasync);

}



const struct file_operations fuse_dev_operations = {

	.owner		= THIS_MODULE,

	.llseek		= no_llseek,
@@ -932,6 +946,7 @@ const struct file_operations fuse_dev_operations = { 
	.writev		= fuse_dev_writev,

	.poll		= fuse_dev_poll,

	.release	= fuse_dev_release,

	.fasync		= fuse_dev_fasync,

};



static struct miscdevice fuse_miscdevice = {

fs/fuse/fuse_i.h

+3 −0
Original line number Diff line number Diff line
@@ -318,6 +318,9 @@ struct fuse_conn { 


	/** kobject */

	struct kobject kobj;



	/** O_ASYNC requests */

	struct fasync_struct *fasync;

};



static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)

fs/fuse/inode.c

+1 −0
Original line number Diff line number Diff line
@@ -216,6 +216,7 @@ static void fuse_put_super(struct super_block *sb) 
	spin_unlock(&fuse_lock);

	up_write(&fc->sbput_sem);

	/* Flush all readers on this fs */

	kill_fasync(&fc->fasync, SIGIO, POLL_IN);

	wake_up_all(&fc->waitq);

	kobject_del(&fc->kobj);

	kobject_put(&fc->kobj);

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