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authorStefan Hajnoczi <stefanha@linux.vnet.ibm.com>2011-03-29 20:04:41 +0100
committerKevin Wolf <kwolf@redhat.com>2011-04-07 13:51:47 +0200
commit46a4e4e6085c1e5ae498e350009ff6d321d9ee67 (patch)
tree7fed98f269c27d26b150bf5576b86b513bb02af0 /block.c
parentb8c6d0958943c96ca9401961a1200568c7ec0268 (diff)
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 <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r--block.c14
1 files changed, 6 insertions, 8 deletions
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 */