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viro@parcelfarce.linux.theplanet.co.uk wrote:
>On Sun, Jun 22, 2003 at 01:28:12PM -0600, Lou Langholtz wrote:
>
>
>
>>4. that the allocation of request_queue is dynamic and seperate from
>>other allocated objects [Al]
>>
>>
>
>*Ugh*. Not on ->open(), please... _If_ you really want that sort of
>on-demand allocation - make it happen via blk_register_region() and
>allocate both gendisk and queue at once.
>
>However, I would suggest to make that a separate patch and for now allocate
>queues at the same place where you allocate gendisks, without any on-demand
>stuff.
>
>
Okay, here's the patch now updated to be without the on-demand stuff and
with queues allocated all where alloc_disk is used. How is this patch now?
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filename="nbd-patch1.3"
diff -urN linux-2.5.72/drivers/block/nbd.c linux-2.5.72-p1.5/drivers/block/nbd.c
--- linux-2.5.72/drivers/block/nbd.c 2003-06-16 22:19:44.000000000 -0600
+++ linux-2.5.72-p1.5/drivers/block/nbd.c 2003-06-22 19:13:08.199124846 -0600
@@ -28,6 +28,9 @@
* the transmit lock. <steve@chygwyn.com>
* 02-10-11 Allow hung xmit to be aborted via SIGKILL & various fixes.
* <Paul.Clements@SteelEye.com> <James.Bottomley@SteelEye.com>
+ * 03-06-22 Make nbd work with new linux 2.5 block layer design. This fixes
+ * memory corruption from module removal and possible memory corruption
+ * from sending/receiving disk data. <ldl@aros.net>
*
* possible FIXME: make set_sock / set_blksize / set_size / do_it one syscall
* why not: would need verify_area and friends, would share yet another
@@ -63,6 +66,16 @@
static struct nbd_device nbd_dev[MAX_NBD];
+/*
+ * Use just one lock (or at most 1 per NIC). Two arguments for this:
+ * 1. Each NIC is essentially a synchronization point for all servers
+ * accessed through that NIC so there's no need to have more locks
+ * than NICs anyway.
+ * 2. More locks lead to more "Dirty cache line bouncing" which will slow
+ * down each lock to the point where they're actually slower than just
+ * a single lock.
+ * Thanks go to Jens Axboe and Al Viro for their LKML emails explaining this!
+ */
static spinlock_t nbd_lock = SPIN_LOCK_UNLOCKED;
#define DEBUG( s )
@@ -168,6 +181,17 @@
return result;
}
+static inline int sock_send_bvec(struct socket *sock, struct bio_vec *bvec,
+ int flags)
+{
+ int result;
+ void *kaddr = kmap(bvec->bv_page);
+ result = nbd_xmit(1, sock, kaddr + bvec->bv_offset, bvec->bv_len,
+ flags);
+ kunmap(bvec->bv_page);
+ return result;
+}
+
#define FAIL( s ) { printk( KERN_ERR "NBD: " s "(result %d)\n", result ); goto error_out; }
void nbd_send_req(struct nbd_device *lo, struct request *req)
@@ -209,7 +233,7 @@
if ((i < (bio->bi_vcnt - 1)) || bio->bi_next)
flags = MSG_MORE;
DEBUG("data, ");
- result = nbd_xmit(1, sock, page_address(bvec->bv_page) + bvec->bv_offset, bvec->bv_len, flags);
+ result = sock_send_bvec(sock, bvec, flags);
if (result <= 0)
FAIL("Send data failed.");
}
@@ -244,6 +268,16 @@
return NULL;
}
+static inline int sock_recv_bvec(struct socket *sock, struct bio_vec *bvec)
+{
+ int result;
+ void *kaddr = kmap(bvec->bv_page);
+ result = nbd_xmit(0, sock, kaddr + bvec->bv_offset, bvec->bv_len,
+ MSG_WAITALL);
+ kunmap(bvec->bv_page);
+ return result;
+}
+
#define HARDFAIL( s ) { printk( KERN_ERR "NBD: " s "(result %d)\n", result ); lo->harderror = result; return NULL; }
struct request *nbd_read_stat(struct nbd_device *lo)
/* NULL returned = something went wrong, inform userspace */
@@ -251,10 +285,11 @@
int result;
struct nbd_reply reply;
struct request *req;
+ struct socket *sock = lo->sock;
DEBUG("reading control, ");
reply.magic = 0;
- result = nbd_xmit(0, lo->sock, (char *) &reply, sizeof(reply), MSG_WAITALL);
+ result = nbd_xmit(0, sock, (char *) &reply, sizeof(reply), MSG_WAITALL);
if (result <= 0)
HARDFAIL("Recv control failed.");
req = nbd_find_request(lo, reply.handle);
@@ -268,14 +303,17 @@
FAIL("Other side returned error.");
if (nbd_cmd(req) == NBD_CMD_READ) {
- struct bio *bio = req->bio;
+ int i;
+ struct bio *bio;
DEBUG("data, ");
- do {
- result = nbd_xmit(0, lo->sock, bio_data(bio), bio->bi_size, MSG_WAITALL);
- if (result <= 0)
- HARDFAIL("Recv data failed.");
- bio = bio->bi_next;
- } while(bio);
+ rq_for_each_bio(bio, req) {
+ struct bio_vec *bvec;
+ bio_for_each_segment(bvec, bio, i) {
+ result = sock_recv_bvec(sock, bvec);
+ if (result <= 0)
+ HARDFAIL("Recv data failed.");
+ }
+ }
}
DEBUG("done.\n");
return req;
@@ -538,8 +576,6 @@
* (Just smiley confuses emacs :-)
*/
-static struct request_queue nbd_queue;
-
static int __init nbd_init(void)
{
int err = -ENOMEM;
@@ -555,6 +591,17 @@
if (!disk)
goto out;
nbd_dev[i].disk = disk;
+ /*
+ * The new linux 2.5 block layer implementation requires
+ * every gendisk to have its very own request_queue struct.
+ * These structs are big so we dynamically allocate them.
+ */
+ disk->queue = kmalloc(sizeof(struct request_queue), GFP_KERNEL);
+ if (!disk->queue) {
+ put_disk(disk);
+ goto out;
+ }
+ blk_init_queue(disk->queue, do_nbd_request, &nbd_lock);
}
if (register_blkdev(NBD_MAJOR, "nbd")) {
@@ -564,7 +611,6 @@
#ifdef MODULE
printk("nbd: registered device at major %d\n", NBD_MAJOR);
#endif
- blk_init_queue(&nbd_queue, do_nbd_request, &nbd_lock);
devfs_mk_dir("nbd");
for (i = 0; i < MAX_NBD; i++) {
struct gendisk *disk = nbd_dev[i].disk;
@@ -582,7 +628,6 @@
disk->first_minor = i;
disk->fops = &nbd_fops;
disk->private_data = &nbd_dev[i];
- disk->queue = &nbd_queue;
sprintf(disk->disk_name, "nbd%d", i);
sprintf(disk->devfs_name, "nbd/%d", i);
set_capacity(disk, 0x3ffffe);
@@ -591,8 +636,10 @@
return 0;
out:
- while (i--)
+ while (i--) {
+ kfree(nbd_dev[i].disk->queue);
put_disk(nbd_dev[i].disk);
+ }
return err;
}
@@ -600,12 +647,22 @@
{
int i;
for (i = 0; i < MAX_NBD; i++) {
- del_gendisk(nbd_dev[i].disk);
- put_disk(nbd_dev[i].disk);
+ struct gendisk *disk = nbd_dev[i].disk;
+ if (disk) {
+ if (disk->queue) {
+ blk_cleanup_queue(disk->queue);
+ kfree(disk->queue);
+ disk->queue = NULL;
+ }
+ del_gendisk(disk);
+ put_disk(disk);
+ }
}
devfs_remove("nbd");
- blk_cleanup_queue(&nbd_queue);
unregister_blkdev(NBD_MAJOR, "nbd");
+#ifdef MODULE
+ printk("nbd: unregistered device at major %d\n", NBD_MAJOR);
+#endif
}
module_init(nbd_init);
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