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[PATCH] fuse: add O_ASYNC support to FUSE device

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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 <jdike@addtoit.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jeff Dike 2006-04-10 22:54:52 -07:00 committed by Linus Torvalds
parent 7025d9ad10
commit 385a17bfc3
3 changed files with 20 additions and 1 deletions
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17
fs/fuse/dev.c
View file

@ -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 = {

3
fs/fuse/fuse_i.h
View file

@ -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)

1
fs/fuse/inode.c
View file

@ -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);