Piggy-back on the guest CD-ROM polling to poll on the host. Open and
close the host CD-ROM file descriptor to ensure we read the new size and
not a stale size.
Two things are going on here:
1. If hald/udisks is not already polling CD-ROMs on the host then
re-opening the CD-ROM causes the host to read the new medium's size.
2. There is a bug in Linux which means the CD-ROM file descriptor must
be re-opened in order for lseek(2) to see the new size. The
inode size gets out of sync with the underlying device (which you can
confirm by checking that /sys/block/sr0/size and lseek(2) do not
match after media change). I have raised this with the
maintainers but we need a workaround for the foreseeable future.
Note that these changes are all in a #ifdef __linux__ section.
Signed-off-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com>
---
block/raw-posix.c | 26 ++++++++++++++++++++++----
1 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 6b72470..8b5205c 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1238,10 +1238,28 @@ static int cdrom_is_inserted(BlockDriverState *bs)
BDRVRawState *s = bs->opaque;
int ret;
- ret = ioctl(s->fd, CDROM_DRIVE_STATUS, CDSL_CURRENT);
- if (ret == CDS_DISC_OK)
- return 1;
- return 0;
+ /*
+ * Close the file descriptor if no medium is present and open it to poll
+ * again. This ensures the medium size is refreshed. If the file
+ * descriptor is kept open the size can become stale. This is essentially
+ * replicating CD-ROM polling but is driven by the guest. As the guest
+ * polls, we poll the host.
+ */
+
+ if (s->fd == -1) {
+ s->fd = qemu_open(bs->filename, s->open_flags, 0644);
+ if (s->fd < 0) {
+ return 0;
+ }
+ }
+
+ ret = (ioctl(s->fd, CDROM_DRIVE_STATUS, CDSL_CURRENT) == CDS_DISC_OK);
+
+ if (!ret) {
+ close(s->fd);
+ s->fd = -1;
+ }
+ return ret;
}
static int cdrom_eject(BlockDriverState *bs, int eject_flag)
--
1.7.4.1
