From: Jeff Dike 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 --- fs/fuse/dev.c | 17 ++++++++++++++++- fs/fuse/fuse_i.h | 3 +++ fs/fuse/inode.c | 1 + 3 files changed, 20 insertions(+), 1 deletion(-) diff -puN fs/fuse/dev.c~fuse-add-o_async-support-to-fuse-device fs/fuse/dev.c --- devel/fs/fuse/dev.c~fuse-add-o_async-support-to-fuse-device 2006-04-01 16:22:38.000000000 -0800 +++ devel-akpm/fs/fuse/dev.c 2006-04-01 16:22:38.000000000 -0800 @@ -317,6 +317,7 @@ static void queue_request(struct fuse_co 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 *f 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 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_op .writev = fuse_dev_writev, .poll = fuse_dev_poll, .release = fuse_dev_release, + .fasync = fuse_dev_fasync, }; static struct miscdevice fuse_miscdevice = { diff -puN fs/fuse/fuse_i.h~fuse-add-o_async-support-to-fuse-device fs/fuse/fuse_i.h --- devel/fs/fuse/fuse_i.h~fuse-add-o_async-support-to-fuse-device 2006-04-01 16:22:38.000000000 -0800 +++ devel-akpm/fs/fuse/fuse_i.h 2006-04-01 16:22:38.000000000 -0800 @@ -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) diff -puN fs/fuse/inode.c~fuse-add-o_async-support-to-fuse-device fs/fuse/inode.c --- devel/fs/fuse/inode.c~fuse-add-o_async-support-to-fuse-device 2006-04-01 16:22:38.000000000 -0800 +++ devel-akpm/fs/fuse/inode.c 2006-04-01 16:22:38.000000000 -0800 @@ -216,6 +216,7 @@ static void fuse_put_super(struct super_ 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); _