[PATCH 1/2] NBD: set uninitialized devices to size 0

From: Paul Clements
Date: Fri Aug 24 2007 - 13:07:02 EST


This fixes errors with utilities (such as LVM's vgscan) that try to scan all devices. Previously this would generate read errors when uninitialized nbd devices were scanned:

# vgscan
Reading all physical volumes. This may take a while...
/dev/nbd0: read failed after 0 of 1024 at 0: Input/output error
/dev/nbd0: read failed after 0 of 1024 at 509804544: Input/output error
/dev/nbd0: read failed after 0 of 2048 at 0: Input/output error
/dev/nbd1: read failed after 0 of 1024 at 509804544: Input/output error
/dev/nbd1: read failed after 0 of 2048 at 0: Input/output error


From now on, uninitialized nbd devices will have size zero, which prevents these errors.

Patch applies and was tested against 2.6.23-rc2-mm2.

Thanks,
Paul

Signed-Off-By: Paul Clements <paul.clements@xxxxxxxxxxxx>

--- ./drivers/block/nbd.c.ERROR_RETURNS 2007-08-15 15:41:19.000000000 -0400
+++ ./drivers/block/nbd.c 2007-08-16 13:08:06.000000000 -0400
@@ -589,6 +589,9 @@ static int nbd_ioctl(struct inode *inode
printk(KERN_WARNING "%s: queue cleared\n", lo->disk->disk_name);
if (file)
fput(file);
+ lo->bytesize = 0;
+ inode->i_bdev->bd_inode->i_size = 0;
+ set_capacity(lo->disk, 0);
return lo->harderror;
case NBD_CLEAR_QUE:
/*
@@ -666,14 +669,14 @@ static int __init nbd_init(void)
mutex_init(&nbd_dev[i].tx_lock);
init_waitqueue_head(&nbd_dev[i].active_wq);
nbd_dev[i].blksize = 1024;
- nbd_dev[i].bytesize = 0x7ffffc00ULL << 10; /* 2TB */
+ nbd_dev[i].bytesize = 0;
disk->major = NBD_MAJOR;
disk->first_minor = i;
disk->fops = &nbd_fops;
disk->private_data = &nbd_dev[i];
disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
sprintf(disk->disk_name, "nbd%d", i);
- set_capacity(disk, 0x7ffffc00ULL << 1); /* 2 TB */
+ set_capacity(disk, 0);
add_disk(disk);
}