[PATCH] nbd: Don't create all MAX_NBD devices by default all the time
This patches adds the "nbds_max" parameter to the nbd kernel module, which
limits the number of nbds allocated. Previously, always all 128 entries
were allocated unconditionally, which used to waste resources and
needlessly flood the hotplug system with events. (Defaults to 16 now.)
Signed-off-by: Lars Marowsky-Bree <lmb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index efdf044..9e268dd 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -78,6 +78,7 @@
#define DBG_RX 0x0200
#define DBG_TX 0x0400
static unsigned int debugflags;
+static unsigned int nbds_max = 16;
#endif /* NDEBUG */
static struct nbd_device nbd_dev[MAX_NBD];
@@ -647,7 +648,13 @@
return -EIO;
}
- for (i = 0; i < MAX_NBD; i++) {
+ if (nbds_max > MAX_NBD) {
+ printk(KERN_CRIT "nbd: cannot allocate more than %u nbds; %u requested.\n", MAX_NBD,
+ nbds_max);
+ return -EINVAL;
+ }
+
+ for (i = 0; i < nbds_max; i++) {
struct gendisk *disk = alloc_disk(1);
if (!disk)
goto out;
@@ -673,7 +680,7 @@
dprintk(DBG_INIT, "nbd: debugflags=0x%x\n", debugflags);
devfs_mk_dir("nbd");
- for (i = 0; i < MAX_NBD; i++) {
+ for (i = 0; i < nbds_max; i++) {
struct gendisk *disk = nbd_dev[i].disk;
nbd_dev[i].file = NULL;
nbd_dev[i].magic = LO_MAGIC;
@@ -706,8 +713,9 @@
static void __exit nbd_cleanup(void)
{
int i;
- for (i = 0; i < MAX_NBD; i++) {
+ for (i = 0; i < nbds_max; i++) {
struct gendisk *disk = nbd_dev[i].disk;
+ nbd_dev[i].magic = 0;
if (disk) {
del_gendisk(disk);
blk_cleanup_queue(disk->queue);
@@ -725,6 +733,8 @@
MODULE_DESCRIPTION("Network Block Device");
MODULE_LICENSE("GPL");
+module_param(nbds_max, int, 0444);
+MODULE_PARM_DESC(nbds_max, "How many network block devices to initialize.");
#ifndef NDEBUG
module_param(debugflags, int, 0644);
MODULE_PARM_DESC(debugflags, "flags for controlling debug output");