From 46a4e4e6085c1e5ae498e350009ff6d321d9ee67 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 29 Mar 2011 20:04:41 +0100 Subject: block: Do not cache device size for removable media 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 Signed-off-by: Kevin Wolf --- block.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) (limited to 'block.c') diff --git a/block.c b/block.c index d8da3b09d3..f731c7afbf 100644 --- a/block.c +++ b/block.c @@ -1161,14 +1161,12 @@ 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 */ -- cgit v1.2.1