Commit 00c570f4 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

fuse: device fd clone 



Allow an open fuse device to be "cloned".  Userspace can create a clone by:

      newfd = open("/dev/fuse", O_RDWR)
      ioctl(newfd, FUSE_DEV_IOC_CLONE, &oldfd);

At this point newfd will refer to the same fuse connection as oldfd.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Reviewed-by: default avatarAshish Samant <ashish.samant@oracle.com>
parent ee314a87

Documentation/ioctl/ioctl-number.txt

+1 −0
Original line number Diff line number Diff line
@@ -321,6 +321,7 @@ Code Seq#(hex) Include File Comments 
0xDB	00-0F	drivers/char/mwave/mwavepub.h

0xDD	00-3F	ZFCP device driver	see drivers/s390/scsi/

					<mailto:aherrman@de.ibm.com>

0xE5	00-3F	linux/fuse.h

0xEC	00-01	drivers/platform/chrome/cros_ec_dev.h	ChromeOS EC driver

0xF3	00-3F	drivers/usb/misc/sisusbvga/sisusb.h	sisfb (in development)

					<mailto:thomas@winischhofer.net>

fs/fuse/dev.c

+40 −0
Original line number Diff line number Diff line
@@ -2197,6 +2197,44 @@ static int fuse_dev_fasync(int fd, struct file *file, int on) 
	return fasync_helper(fd, file, on, &fc->iq.fasync);

}



static int fuse_device_clone(struct fuse_conn *fc, struct file *new)

{

	if (new->private_data)

		return -EINVAL;



	new->private_data = fuse_conn_get(fc);



	return 0;

}



static long fuse_dev_ioctl(struct file *file, unsigned int cmd,

			   unsigned long arg)

{

	int err = -ENOTTY;



	if (cmd == FUSE_DEV_IOC_CLONE) {

		int oldfd;



		err = -EFAULT;

		if (!get_user(oldfd, (__u32 __user *) arg)) {

			struct file *old = fget(oldfd);



			err = -EINVAL;

			if (old) {

				struct fuse_conn *fc = fuse_get_conn(old);



				if (fc) {

					mutex_lock(&fuse_mutex);

					err = fuse_device_clone(fc, file);

					mutex_unlock(&fuse_mutex);

				}

				fput(old);

			}

		}

	}

	return err;

}



const struct file_operations fuse_dev_operations = {

	.owner		= THIS_MODULE,

	.open		= fuse_dev_open,
@@ -2208,6 +2246,8 @@ const struct file_operations fuse_dev_operations = { 
	.poll		= fuse_dev_poll,

	.release	= fuse_dev_release,

	.fasync		= fuse_dev_fasync,

	.unlocked_ioctl = fuse_dev_ioctl,

	.compat_ioctl   = fuse_dev_ioctl,

};

EXPORT_SYMBOL_GPL(fuse_dev_operations);

include/uapi/linux/fuse.h

+3 −0
Original line number Diff line number Diff line
@@ -755,4 +755,7 @@ struct fuse_notify_retrieve_in { 
	uint64_t	dummy4;

};



/* Device ioctls: */

#define FUSE_DEV_IOC_CLONE	_IOR(229, 0, uint32_t)



#endif /* _LINUX_FUSE_H */

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