Re: [PATCH] Allow NBD to be used locally

> Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net> > --- > drivers/block/nbd.c | 146 ++++++++++++++++++++++++++++++++++----------------- > include/linux/nbd.h | 4 +- > 2 files changed, 100 insertions(+), 50 deletions(-) > > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c > index b4c0888..de6685e 100644 > --- a/drivers/block/nbd.c > +++ b/drivers/block/nbd.c > @@ -29,6 +29,7 @@ > #include <linux/kernel.h> > #include <net/sock.h> > #include <linux/net.h> > +#include <linux/kthread.h> > > #include <asm/uaccess.h> > #include <asm/system.h> > @@ -434,6 +435,87 @@ static void nbd_clear_que(struct nbd_device *lo) > } > > > +static void nbd_handle_req(struct nbd_device *lo, struct request *req) > +{ > + if (!blk_fs_request(req)) > + goto error_out; > + > + nbd_cmd(req) = NBD_CMD_READ; > + if (rq_data_dir(req) == WRITE) { > + nbd_cmd(req) = NBD_CMD_WRITE; > + if (lo->flags & NBD_READ_ONLY) { > + printk(KERN_ERR "%s: Write on read-only\n", > + lo->disk->disk_name); > + goto error_out; > + } > + } > + > + req->errors = 0; > + > + mutex_lock(&lo->tx_lock); > + if (unlikely(!lo->sock)) { > + mutex_unlock(&lo->tx_lock); > + printk(KERN_ERR "%s: Attempted send on closed socket\n", > + lo->disk->disk_name); > + req->errors++; > + nbd_end_request(req); > + return; > + } > + > + lo->active_req = req; > + > + if (nbd_send_req(lo, req) != 0) { > + printk(KERN_ERR "%s: Request send failed\n", > + lo->disk->disk_name); > + req->errors++; > + nbd_end_request(req); > + } else { > + spin_lock(&lo->queue_lock); > + list_add(&req->queuelist, &lo->queue_head); > + spin_unlock(&lo->queue_lock); > + } > + > + lo->active_req = NULL; > + mutex_unlock(&lo->tx_lock); > + wake_up_all(&lo->active_wq); > + > + return; > + > +error_out: > + req->errors++; > + nbd_end_request(req); > +} > + > +static int nbd_thread(void *data) > +{ > + struct nbd_device *lo = data; > + struct request *req; > + > + set_user_nice(current, -20); > + while (!kthread_should_stop() || !list_empty(&lo->waiting_queue)) { > + /* wait something to do */ > + wait_event_interruptible(lo->waiting_wq, > + kthread_should_stop() || > + !list_empty(&lo->waiting_queue)); > + > + /* extract request */ > + > + if (list_empty(&lo->waiting_queue)) > + continue; > + > + spin_lock_irq(&lo->queue_lock); > + req = list_entry(lo->waiting_queue.next, struct request, > + queuelist); > + list_del_init(&req->queuelist); > + spin_unlock_irq(&lo->queue_lock); > + > + /* handle request */ > + > + nbd_handle_req(lo, req); > + } > + return 0; > +} > + > /* > * We always wait for result of write, for now. It would be nice to make it optional > * in future > @@ -449,65 +531,23 @@ static void do_nbd_request(struct request_queue * q) > struct nbd_device *lo; > > blkdev_dequeue_request(req); > + > + spin_unlock_irq(q->queue_lock); > + > dprintk(DBG_BLKDEV, "%s: request %p: dequeued (flags=%x)\n", > req->rq_disk->disk_name, req, req->cmd_type); > > - if (!blk_fs_request(req)) > - goto error_out; > - > lo = req->rq_disk->private_data; > > BUG_ON(lo->magic != LO_MAGIC); > > - nbd_cmd(req) = NBD_CMD_READ; > - if (rq_data_dir(req) == WRITE) { > - nbd_cmd(req) = NBD_CMD_WRITE; > - if (lo->flags & NBD_READ_ONLY) { > - printk(KERN_ERR "%s: Write on read-only\n", > - lo->disk->disk_name); > - goto error_out; > - } > - } > + spin_lock_irq(&lo->queue_lock); > + list_add_tail(&req->queuelist, &lo->waiting_queue); > + spin_unlock_irq(&lo->queue_lock); > > - req->errors = 0; > - spin_unlock_irq(q->queue_lock); > - > - mutex_lock(&lo->tx_lock); > - if (unlikely(!lo->sock)) { > - mutex_unlock(&lo->tx_lock); > - printk(KERN_ERR "%s: Attempted send on closed socket\n", > - lo->disk->disk_name); > - req->errors++; > - nbd_end_request(req); > - spin_lock_irq(q->queue_lock); > - continue; > - } > - > - lo->active_req = req; > - > - if (nbd_send_req(lo, req) != 0) { > - printk(KERN_ERR "%s: Request send failed\n", > - lo->disk->disk_name); > - req->errors++; > - nbd_end_request(req); > - } else { > - spin_lock(&lo->queue_lock); > - list_add(&req->queuelist, &lo->queue_head); > - spin_unlock(&lo->queue_lock); > - } > - > - lo->active_req = NULL; > - mutex_unlock(&lo->tx_lock); > - wake_up_all(&lo->active_wq); > + wake_up(&lo->waiting_wq); > > spin_lock_irq(q->queue_lock); > - continue; > - > -error_out: > - req->errors++; > - spin_unlock(q->queue_lock); > - nbd_end_request(req); > - spin_lock(q->queue_lock); > } > } > > @@ -517,6 +557,7 @@ static int nbd_ioctl(struct inode *inode, struct file *file, > struct nbd_device *lo = inode->i_bdev->bd_disk->private_data; > int error; > struct request sreq ; > + struct task_struct *thread; > > if (!capable(CAP_SYS_ADMIN)) > return -EPERM; > @@ -599,7 +640,12 @@ static int nbd_ioctl(struct inode *inode, struct file *file, > case NBD_DO_IT: > if (!lo->file) > return -EINVAL; > + thread = kthread_create(nbd_thread, lo, lo->disk->disk_name); > + if (IS_ERR(thread)) > + return PTR_ERR(thread); > + wake_up_process(thread); > error = nbd_do_it(lo); > + kthread_stop(thread); > if (error) > return error; > sock_shutdown(lo, 1); > @@ -684,10 +730,12 @@ static int __init nbd_init(void) > nbd_dev[i].file = NULL; > nbd_dev[i].magic = LO_MAGIC; > nbd_dev[i].flags = 0; > + INIT_LIST_HEAD(&nbd_dev[i].waiting_queue); > spin_lock_init(&nbd_dev[i].queue_lock); > INIT_LIST_HEAD(&nbd_dev[i].queue_head); > mutex_init(&nbd_dev[i].tx_lock); > init_waitqueue_head(&nbd_dev[i].active_wq); > + init_waitqueue_head(&nbd_dev[i].waiting_wq); > nbd_dev[i].blksize = 1024; > nbd_dev[i].bytesize = 0; > disk->major = NBD_MAJOR; > diff --git a/include/linux/nbd.h b/include/linux/nbd.h > index cc2b472..94f40c9 100644 > --- a/include/linux/nbd.h > +++ b/include/linux/nbd.h > @@ -57,9 +57,11 @@ struct nbd_device { > int magic; > > spinlock_t queue_lock; > - struct list_head queue_head;/* Requests are added here... */ > + struct list_head queue_head; /* Requests waiting result */ > struct request *active_req; > wait_queue_head_t active_wq; > + struct list_head waiting_queue; /* Requests to be sent */ > + wait_queue_head_t waiting_wq; > > struct mutex tx_lock; > struct gendisk *disk;


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