Nbd is broken

From: Pavel Machek (pavel@suse.cz)
Date: Fri Mar 03 2000 - 18:04:02 EST

  • Next message: Pavel Machek: "Hercules framebuffer support"

    Hi!

    While updating nbd, fatal errors sneaked in. Here is patch that makes
    it better, but not ok. I was not able to repair within hour :-(.

                                                                    Pavel

    --- clean/drivers/block/nbd.c Mon Feb 21 10:32:22 2000
    +++ linux/drivers/block/nbd.c Fri Mar 3 23:55:19 2000
    @@ -4,7 +4,7 @@
      * Note that you can not swap over this thing, yet. Seems to work but
      * deadlocks sometimes - you can not swap over TCP in general.
      *
    - * Copyright 1997 Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
    + * Copyright 1997-2000 Pavel Machek <pavel@ucw.cz>
      *
      * (part of code stolen from loop.c)
      *
    @@ -77,6 +77,7 @@
             nbd_dev[dev].refcnt++;
             if (!(nbdev->flags & NBD_INITIALISED)) {
                     init_MUTEX(&nbdev->queue_lock);
    + INIT_LIST_HEAD(&nbdev->queue_head);
                     nbdev->flags |= NBD_INITIALISED;
             }
             MOD_INC_USE_COUNT;
    @@ -218,7 +219,10 @@
     
             down (&lo->queue_lock);
             while (!list_empty(&lo->queue_head)) {
    + up (&lo->queue_lock);
                     req = nbd_read_stat(lo);
    + down (&lo->queue_lock);
    +
                     if (!req)
                             goto out;
     #ifdef PARANOIA
    @@ -249,17 +253,22 @@
     {
             struct request *req;
     
    +#ifdef PARANOIA
    + if (lo->magic != LO_MAGIC) {
    + printk(KERN_ERR "NBD: nbd_dev[] corrupted: Not enough magic when clearing!\n");
    + return;
    + }
    +#endif
    +
             while (!list_empty(&lo->queue_head)) {
                     req = blkdev_entry_prev_request(&lo->queue_head);
    + if (!req)
    + break;
     #ifdef PARANOIA
                     if (lo != &nbd_dev[MINOR(req->rq_dev)]) {
                             printk(KERN_ALERT "NBD: request corrupted when clearing!\n");
                             continue;
                     }
    - if (lo->magic != LO_MAGIC) {
    - printk(KERN_ERR "NBD: nbd_dev[] corrupted: Not enough magic when clearing!\n");
    - return;
    - }
     #endif
                     req->errors++;
                     list_del(&req->queue);
    @@ -289,6 +298,10 @@
     
             while (!QUEUE_EMPTY) {
                     req = CURRENT;
    +#ifdef PARANOIA
    + if (!req)
    + FAIL("que not empty but no request?");
    +#endif
                     dev = MINOR(req->rq_dev);
     #ifdef PARANOIA
                     if (dev >= MAX_NBD)
    @@ -309,7 +322,9 @@
                     spin_unlock_irq(&io_request_lock);
     
                     down (&lo->queue_lock);
    +printk("8\n");
                     list_add(&req->queue, &lo->queue_head);
    +printk("9\n");
                     nbd_send_req(lo->sock, req); /* Why does this block? */
                     up (&lo->queue_lock);
      

    -- 
I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents me at discuss@linmodems.org

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