Commit ae3aad77 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi Committed by Miklos Szeredi
Browse files

fuse: add fuse_iqueue_ops callbacks 



The /dev/fuse device uses fiq->waitq and fasync to signal that requests are
available.  These mechanisms do not apply to virtio-fs.  This patch
introduces callbacks so alternative behavior can be used.

Note that queue_interrupt() changes along these lines:

  spin_lock(&fiq->waitq.lock);
  wake_up_locked(&fiq->waitq);
+ kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
  spin_unlock(&fiq->waitq.lock);
- kill_fasync(&fiq->fasync, SIGIO, POLL_IN);

Since queue_request() and queue_forget() also call kill_fasync() inside
the spinlock this should be safe.

Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 0cc2656c

fs/fuse/cuse.c

+1 −1
Original line number Diff line number Diff line
@@ -506,7 +506,7 @@ static int cuse_channel_open(struct inode *inode, struct file *file) 
	 * Limit the cuse channel to requests that can

	 * be represented in file->f_cred->user_ns.

	 */

	fuse_conn_init(&cc->fc, file->f_cred->user_ns);

	fuse_conn_init(&cc->fc, file->f_cred->user_ns, &fuse_dev_fiq_ops, NULL);



	fud = fuse_dev_alloc(&cc->fc);

	if (!fud) {

fs/fuse/dev.c

+30 −16
Original line number Diff line number Diff line
@@ -201,14 +201,33 @@ static unsigned int fuse_req_hash(u64 unique) 
	return hash_long(unique & ~FUSE_INT_REQ_BIT, FUSE_PQ_HASH_BITS);

}



static void queue_request(struct fuse_iqueue *fiq, struct fuse_req *req)

/**

 * A new request is available, wake fiq->waitq

 */

static void fuse_dev_wake_and_unlock(struct fuse_iqueue *fiq)

__releases(fiq->lock)

{

	wake_up(&fiq->waitq);

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

	spin_unlock(&fiq->lock);

}



const struct fuse_iqueue_ops fuse_dev_fiq_ops = {

	.wake_forget_and_unlock		= fuse_dev_wake_and_unlock,

	.wake_interrupt_and_unlock	= fuse_dev_wake_and_unlock,

	.wake_pending_and_unlock	= fuse_dev_wake_and_unlock,

};

EXPORT_SYMBOL_GPL(fuse_dev_fiq_ops);



static void queue_request_and_unlock(struct fuse_iqueue *fiq,

				     struct fuse_req *req)

__releases(fiq->lock)

{

	req->in.h.len = sizeof(struct fuse_in_header) +

		fuse_len_args(req->args->in_numargs,

			      (struct fuse_arg *) req->args->in_args);

	list_add_tail(&req->list, &fiq->pending);

	wake_up(&fiq->waitq);

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

	fiq->ops->wake_pending_and_unlock(fiq);

}



void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
@@ -223,13 +242,12 @@ void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget, 
	if (fiq->connected) {

		fiq->forget_list_tail->next = forget;

		fiq->forget_list_tail = forget;

		wake_up(&fiq->waitq);

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

		fiq->ops->wake_forget_and_unlock(fiq);

	} else {

		kfree(forget);

	}

		spin_unlock(&fiq->lock);

	}

}



static void flush_bg_queue(struct fuse_conn *fc)

{
@@ -244,8 +262,7 @@ static void flush_bg_queue(struct fuse_conn *fc) 
		fc->active_background++;

		spin_lock(&fiq->lock);

		req->in.h.unique = fuse_get_unique(fiq);

		queue_request(fiq, req);

		spin_unlock(&fiq->lock);

		queue_request_and_unlock(fiq, req);

	}

}
@@ -334,10 +351,10 @@ static int queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req) 
			spin_unlock(&fiq->lock);

			return 0;

		}

		wake_up(&fiq->waitq);

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

	}

		fiq->ops->wake_interrupt_and_unlock(fiq);

	} else {

		spin_unlock(&fiq->lock);

	}

	return 0;

}
@@ -397,11 +414,10 @@ static void __fuse_request_send(struct fuse_conn *fc, struct fuse_req *req) 
		req->out.h.error = -ENOTCONN;

	} else {

		req->in.h.unique = fuse_get_unique(fiq);

		queue_request(fiq, req);

		/* acquire extra reference, since request is still needed

		   after fuse_request_end() */

		__fuse_get_request(req);

		spin_unlock(&fiq->lock);

		queue_request_and_unlock(fiq, req);



		request_wait_answer(fc, req);

		/* Pairs with smp_wmb() in fuse_request_end() */
@@ -570,14 +586,12 @@ static int fuse_simple_notify_reply(struct fuse_conn *fc, 


	spin_lock(&fiq->lock);

	if (fiq->connected) {

		queue_request(fiq, req);

		spin_unlock(&fiq->lock);

		queue_request_and_unlock(fiq, req);

	} else {

		err = -ENODEV;

		spin_unlock(&fiq->lock);

		fuse_put_request(fc, req);

	}

	spin_unlock(&fiq->lock);



	return err;

}

fs/fuse/fuse_i.h

+41 −1
Original line number Diff line number Diff line
@@ -355,6 +355,39 @@ struct fuse_req { 


};



struct fuse_iqueue;



/**

 * Input queue callbacks

 *

 * Input queue signalling is device-specific.  For example, the /dev/fuse file

 * uses fiq->waitq and fasync to wake processes that are waiting on queue

 * readiness.  These callbacks allow other device types to respond to input

 * queue activity.

 */

struct fuse_iqueue_ops {

	/**

	 * Signal that a forget has been queued

	 */

	void (*wake_forget_and_unlock)(struct fuse_iqueue *fiq)

		__releases(fiq->lock);



	/**

	 * Signal that an INTERRUPT request has been queued

	 */

	void (*wake_interrupt_and_unlock)(struct fuse_iqueue *fiq)

		__releases(fiq->lock);



	/**

	 * Signal that a request has been queued

	 */

	void (*wake_pending_and_unlock)(struct fuse_iqueue *fiq)

		__releases(fiq->lock);

};



/** /dev/fuse input queue operations */

extern const struct fuse_iqueue_ops fuse_dev_fiq_ops;



struct fuse_iqueue {

	/** Connection established */

	unsigned connected;
@@ -383,6 +416,12 @@ struct fuse_iqueue { 


	/** O_ASYNC requests */

	struct fasync_struct *fasync;



	/** Device-specific callbacks */

	const struct fuse_iqueue_ops *ops;



	/** Device-specific state */

	void *priv;

};



#define FUSE_PQ_HASH_BITS 8
@@ -882,7 +921,8 @@ struct fuse_conn *fuse_conn_get(struct fuse_conn *fc); 
/**

 * Initialize fuse_conn

 */

void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns);

void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns,

		    const struct fuse_iqueue_ops *fiq_ops, void *fiq_priv);



/**

 * Release reference to fuse_conn

fs/fuse/inode.c

+9 −4
Original line number Diff line number Diff line
@@ -568,7 +568,9 @@ static int fuse_show_options(struct seq_file *m, struct dentry *root) 
	return 0;

}



static void fuse_iqueue_init(struct fuse_iqueue *fiq)

static void fuse_iqueue_init(struct fuse_iqueue *fiq,

			     const struct fuse_iqueue_ops *ops,

			     void *priv)

{

	memset(fiq, 0, sizeof(struct fuse_iqueue));

	spin_lock_init(&fiq->lock);
@@ -577,6 +579,8 @@ static void fuse_iqueue_init(struct fuse_iqueue *fiq) 
	INIT_LIST_HEAD(&fiq->interrupts);

	fiq->forget_list_tail = &fiq->forget_list_head;

	fiq->connected = 1;

	fiq->ops = ops;

	fiq->priv = priv;

}



static void fuse_pqueue_init(struct fuse_pqueue *fpq)
@@ -590,7 +594,8 @@ static void fuse_pqueue_init(struct fuse_pqueue *fpq) 
	fpq->connected = 1;

}



void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns)

void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns,

		    const struct fuse_iqueue_ops *fiq_ops, void *fiq_priv)

{

	memset(fc, 0, sizeof(*fc));

	spin_lock_init(&fc->lock);
@@ -599,7 +604,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns) 
	refcount_set(&fc->count, 1);

	atomic_set(&fc->dev_count, 1);

	init_waitqueue_head(&fc->blocked_waitq);

	fuse_iqueue_init(&fc->iq);

	fuse_iqueue_init(&fc->iq, fiq_ops, fiq_priv);

	INIT_LIST_HEAD(&fc->bg_queue);

	INIT_LIST_HEAD(&fc->entry);

	INIT_LIST_HEAD(&fc->devices);
@@ -1209,7 +1214,7 @@ static int fuse_fill_super(struct super_block *sb, struct fs_context *fsc) 
	if (!fc)

		goto err_fput;



	fuse_conn_init(fc, sb->s_user_ns);

	fuse_conn_init(fc, sb->s_user_ns, &fuse_dev_fiq_ops, NULL);

	fc->release = fuse_free_conn;

	sb->s_fs_info = fc;

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