From 385a17bfc3cb035333c8a91eddc78a6e04c4625e Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Mon, 10 Apr 2006 22:54:52 -0700 Subject: [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: Jeff Dike Signed-off-by: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fuse/dev.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) (limited to 'fs/fuse/dev.c') diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index b2e8613..438770f 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -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 = { -- cgit v1.1