Commit 65a9bb25 authored by Markus Armbruster's avatar Markus Armbruster Committed by Kevin Wolf
Browse files

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: default avatarMarkus Armbruster <armbru@redhat.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarBenoit Canet <benoit@irqsave.net>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 69f87f71

block.c

+19 −10
Original line number Diff line number Diff line
@@ -701,6 +701,7 @@ static int find_image_format(BlockDriverState *bs, const char *filename, 


/**

 * 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 @@ int64_t bdrv_get_allocated_file_size(BlockDriverState *bs) 
}



/**

 * 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 @@ int64_t bdrv_getlength(BlockDriverState *bs) 
            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,

include/block/block.h

+1 −0
Original line number Diff line number Diff line
@@ -275,6 +275,7 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, 
    const char *backing_file);

int bdrv_get_backing_file_depth(BlockDriverState *bs);

int bdrv_truncate(BlockDriverState *bs, int64_t offset);

int64_t bdrv_nb_sectors(BlockDriverState *bs);

int64_t bdrv_getlength(BlockDriverState *bs);

int64_t bdrv_get_allocated_file_size(BlockDriverState *bs);

void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr);