@@ -1153,14 +1153,12 @@ int64_t bdrv_getlength(BlockDriverState *bs)
if (!drv)
return -ENOMEDIUM;
- /* Fixed size devices use the total_sectors value for speed instead of
- issuing a length query (like lseek) on each call. Also, legacy block
- drivers don't provide a bdrv_getlength function and must use
- total_sectors. */
- if (!bs->growable || !drv->bdrv_getlength) {
- return bs->total_sectors * BDRV_SECTOR_SIZE;
- }
- return drv->bdrv_getlength(bs);
+ if (bs->growable || bs->removable) {
+ if (drv->bdrv_getlength) {
+ return drv->bdrv_getlength(bs);
+ }
+ }
+ return bs->total_sectors * BDRV_SECTOR_SIZE;
}
/* return 0 as number of sectors if no device present or error */
The block layer caches the device size to avoid doing lseek(fd, 0, SEEK_END) every time this value is needed. For removable media the device size becomes stale if a new medium is inserted. This patch simply prevents device size caching for removable media. A smarter solution is to update the cached device size when a new medium is inserted. Given that there are currently bugs with CD-ROM media change I do not want to implement that approach until we've gotten things correct first. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> --- block.c | 12 +++++------- 1 files changed, 5 insertions(+), 7 deletions(-)