block: New bdrv_nb_sectors()
A call to retrieve the image size converts between bytes and sectors
several times:
* BlockDriver method bdrv_getlength() returns bytes.
* refresh_total_sectors() converts to sectors, rounding up, and stores
in total_sectors.
* bdrv_getlength() converts total_sectors back to bytes (now rounded
up to a multiple of the sector size).
* Callers wanting sectors rather bytes convert it right back.
Example: bdrv_get_geometry().
bdrv_nb_sectors() provides a way to omit the last two conversions.
It's exactly bdrv_getlength() with the conversion to bytes omitted.
It's functionally like bdrv_get_geometry() without its odd error
handling.
Reimplement bdrv_getlength() and bdrv_get_geometry() on top of
bdrv_nb_sectors().
The next patches will convert some users of bdrv_getlength() to
bdrv_nb_sectors().
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/block.c b/block.c
index 8cf519b..1239bb3 100644
--- a/block.c
+++ b/block.c
@@ -701,6 +701,7 @@
/**
* Set the current 'total_sectors' value
+ * Return 0 on success, -errno on error.
*/
static int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
{
@@ -3536,11 +3537,12 @@
}
/**
- * Length of a file in bytes. Return < 0 if error or unknown.
+ * Return number of sectors on success, -errno on error.
*/
-int64_t bdrv_getlength(BlockDriverState *bs)
+int64_t bdrv_nb_sectors(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
+
if (!drv)
return -ENOMEDIUM;
@@ -3550,19 +3552,26 @@
return ret;
}
}
- return bs->total_sectors * BDRV_SECTOR_SIZE;
+ return bs->total_sectors;
+}
+
+/**
+ * Return length in bytes on success, -errno on error.
+ * The length is always a multiple of BDRV_SECTOR_SIZE.
+ */
+int64_t bdrv_getlength(BlockDriverState *bs)
+{
+ int64_t ret = bdrv_nb_sectors(bs);
+
+ return ret < 0 ? ret : ret * BDRV_SECTOR_SIZE;
}
/* return 0 as number of sectors if no device present or error */
void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr)
{
- int64_t length;
- length = bdrv_getlength(bs);
- if (length < 0)
- length = 0;
- else
- length = length >> BDRV_SECTOR_BITS;
- *nb_sectors_ptr = length;
+ int64_t nb_sectors = bdrv_nb_sectors(bs);
+
+ *nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors;
}
void bdrv_set_on_error(BlockDriverState *bs, BlockdevOnError on_read_error,
