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Subjectnbd fixes
Hi!

Nbd was broken by block device changes [it currently does not work at
all]. Now it is fixed (with andrea's cooperation). Please apply.

Pavel
PS: James, please test this.

--- clean/drivers/block/nbd.c Mon Feb 21 10:32:22 2000
+++ linux/drivers/block/nbd.c Thu Mar 9 23:55:45 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)
*
@@ -24,6 +24,7 @@
* structure with userland
*/

+#undef NBD_PLUGGABLE
#define PARANOIA
#include <linux/major.h>

@@ -62,10 +63,11 @@
static int requests_out;
#endif

+static void nbd_plug_device(request_queue_t *q, kdev_t dev) { }
+
static int nbd_open(struct inode *inode, struct file *file)
{
int dev;
- struct nbd_device *nbdev;

if (!inode)
return -EINVAL;
@@ -73,12 +75,7 @@
if (dev >= MAX_NBD)
return -ENODEV;

- nbdev = &nbd_dev[dev];
nbd_dev[dev].refcnt++;
- if (!(nbdev->flags & NBD_INITIALISED)) {
- init_MUTEX(&nbdev->queue_lock);
- nbdev->flags |= NBD_INITIALISED;
- }
MOD_INC_USE_COUNT;
return 0;
}
@@ -215,12 +212,18 @@
void nbd_do_it(struct nbd_device *lo)
{
struct request *req;
+ int dequeued;

down (&lo->queue_lock);
- while (!list_empty(&lo->queue_head)) {
+ while (1) {
+ up (&lo->queue_lock);
req = nbd_read_stat(lo);
- if (!req)
+ down (&lo->queue_lock);
+
+ if (!req) {
+ printk(KERN_ALERT "req should never be null\n" );
goto out;
+ }
#ifdef PARANOIA
if (req != blkdev_entry_prev_request(&lo->queue_head)) {
printk(KERN_ALERT "NBD: I have problem...\n");
@@ -237,9 +240,11 @@
list_del(&req->queue);
up (&lo->queue_lock);

- nbd_end_request(req);
+ dequeued = nbd_end_request(req);

down (&lo->queue_lock);
+ if (!dequeued)
+ list_add(&req->queue, &lo->queue_head);
}
out:
up (&lo->queue_lock);
@@ -248,26 +253,36 @@
void nbd_clear_que(struct nbd_device *lo)
{
struct request *req;
+ int dequeued;
+
+#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);
#ifdef PARANOIA
+ if (!req) {
+ printk( KERN_ALERT "NBD: panic, panic, panic\n" );
+ break;
+ }
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);
up(&lo->queue_lock);

- nbd_end_request(req);
+ dequeued = nbd_end_request(req);

down(&lo->queue_lock);
+ if (!dequeued)
+ list_add(&req->queue, &lo->queue_head);
}
}

@@ -289,6 +304,10 @@

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)
@@ -469,12 +488,17 @@
blksize_size[MAJOR_NR] = nbd_blksizes;
blk_size[MAJOR_NR] = nbd_sizes;
blk_init_queue(BLK_DEFAULT_QUEUE(MAJOR_NR), do_nbd_request);
+#ifndef NBD_PLUGGABLE
+ blk_queue_pluggable(BLK_DEFAULT_QUEUE(MAJOR_NR), nbd_plug_device);
+#endif
blk_queue_headactive(BLK_DEFAULT_QUEUE(MAJOR_NR), 0);
for (i = 0; i < MAX_NBD; i++) {
nbd_dev[i].refcnt = 0;
nbd_dev[i].file = NULL;
nbd_dev[i].magic = LO_MAGIC;
nbd_dev[i].flags = 0;
+ INIT_LIST_HEAD(&nbd_dev[i].queue_head);
+ init_MUTEX(&nbd_dev[i].queue_lock);
nbd_blksizes[i] = 1024;
nbd_blksize_bits[i] = 10;
nbd_bytesizes[i] = 0x7ffffc00; /* 2GB */
--- clean/include/linux/nbd.h Sat Feb 19 19:52:22 2000
+++ linux/include/linux/nbd.h Thu Mar 9 23:15:04 2000
@@ -30,22 +30,35 @@
extern int requests_out;
#endif

-static void
+static int
nbd_end_request(struct request *req)
{
unsigned long flags;
+ int ret = 0;

#ifdef PARANOIA
requests_out++;
#endif
+ /*
+ * This is a very dirty hack that we have to do to handle
+ * merged requests because end_request stuff is a bit
+ * broken. The fact we have to do this only if there
+ * aren't errors looks even more silly.
+ */
+ if (!req->errors) {
+ req->sector += req->current_nr_sectors;
+ req->nr_sectors -= req->current_nr_sectors;
+ }
+
spin_lock_irqsave(&io_request_lock, flags);
if (end_that_request_first( req, !req->errors, "nbd" ))
goto out;
+ ret = 1;
end_that_request_last( req );

out:
spin_unlock_irqrestore(&io_request_lock, flags);
- return;
+ return ret;
}

#define MAX_NBD 128
@@ -56,7 +69,6 @@
int harderror; /* Code of hard error */
#define NBD_READ_ONLY 0x0001
#define NBD_WRITE_NOCHK 0x0002
-#define NBD_INITIALISED 0x0004
struct socket * sock;
struct file * file; /* If == NULL, device is not ready, yet */
int magic; /* FIXME: not if debugging is off */
--
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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