From 151060ac13144208bd7601d17e4c92c59b98072f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 14 Apr 2009 10:54:54 +0900 Subject: CUSE: implement CUSE - Character device in Userspace CUSE enables implementing character devices in userspace. With recent additions of ioctl and poll support, FUSE already has most of what's necessary to implement character devices. All CUSE has to do is bonding all those components - FUSE, chardev and the driver model - nicely. When client opens /dev/cuse, kernel starts conversation with CUSE_INIT. The client tells CUSE which device it wants to create. As the previous patch made fuse_file usable without associated fuse_inode, CUSE doesn't create super block or inodes. It attaches fuse_file to cdev file->private_data during open and set ff->fi to NULL. The rest of the operation is almost identical to FUSE direct IO case. Each CUSE device has a corresponding directory /sys/class/cuse/DEVNAME (which is symlink to /sys/devices/virtual/class/DEVNAME if SYSFS_DEPRECATED is turned off) which hosts "waiting" and "abort" among other things. Those two files have the same meaning as the FUSE control files. The only notable lacking feature compared to in-kernel implementation is mmap support. Signed-off-by: Tejun Heo Signed-off-by: Miklos Szeredi --- include/linux/fuse.h | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'include/linux/fuse.h') diff --git a/include/linux/fuse.h b/include/linux/fuse.h index 162e5defe683..d41ed593f79f 100644 --- a/include/linux/fuse.h +++ b/include/linux/fuse.h @@ -120,6 +120,13 @@ struct fuse_file_lock { #define FUSE_EXPORT_SUPPORT (1 << 4) #define FUSE_BIG_WRITES (1 << 5) +/** + * CUSE INIT request/reply flags + * + * CUSE_UNRESTRICTED_IOCTL: use unrestricted ioctl + */ +#define CUSE_UNRESTRICTED_IOCTL (1 << 0) + /** * Release flags */ @@ -210,6 +217,9 @@ enum fuse_opcode { FUSE_DESTROY = 38, FUSE_IOCTL = 39, FUSE_POLL = 40, + + /* CUSE specific operations */ + CUSE_INIT = 4096, }; enum fuse_notify_code { @@ -401,6 +411,27 @@ struct fuse_init_out { __u32 max_write; }; +#define CUSE_INIT_INFO_MAX 4096 + +struct cuse_init_in { + __u32 major; + __u32 minor; + __u32 unused; + __u32 flags; +}; + +struct cuse_init_out { + __u32 major; + __u32 minor; + __u32 unused; + __u32 flags; + __u32 max_read; + __u32 max_write; + __u32 dev_major; /* chardev major */ + __u32 dev_minor; /* chardev minor */ + __u32 spare[10]; +}; + struct fuse_interrupt_in { __u64 unique; }; -- cgit v1.2.1