Commit 135b9088 authored by Ronnie Sahlberg's avatar Ronnie Sahlberg Committed by Paolo Bonzini

iscsi: Set number of blocks to 0 for blank CDROM devices

The number of blocks of the device is used to compute the device size
in bdrv_getlength()/iscsi_getlength().
For MMC devices, the ReturnedLogicalBlockAddress in the READCAPACITY10
has a special meaning when it is 0.
In this case it does not mean that LBA 0 is the last accessible LBA,
and thus the device has 1 readable block, but instead it means that the
disc is blank and there are no readable blocks.

This change ensures that when the iSCSI LUN is loaded with a blank
DVD-R disk or similar that bdrv_getlength() will return the correct
size of the device as 0 bytes.
Signed-off-by: default avatarRonnie Sahlberg <>
parent 0f1da449
......@@ -721,7 +721,12 @@ iscsi_readcapacity10_cb(struct iscsi_context *iscsi, int status,
itask->iscsilun->block_size = rc10->block_size;
itask->iscsilun->num_blocks = rc10->lba + 1;
if (rc10->lba == 0) {
/* blank disk loaded */
itask->iscsilun->num_blocks = 0;
} else {
itask->iscsilun->num_blocks = rc10->lba + 1;
itask->bs->total_sectors = itask->iscsilun->num_blocks *
itask->iscsilun->block_size / BDRV_SECTOR_SIZE ;
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