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 <[email protected]> --- block/raw-posix.c | 25 +++++++++++++++++++++---- 1 files changed, 21 insertions(+), 4 deletions(-) diff --git a/block/raw-posix.c b/block/raw-posix.c index a95c8d4..ac95467 100644 --- a/block/raw-posix.c +++ b/block/raw-posix.c @@ -1240,10 +1240,27 @@ 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; + /* + * Opening and closing on each drive status check 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
