The Friday 30 May 2014 à 20:13:43 (+0200), Markus Armbruster wrote : > 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 <[email protected]> > Reviewed-by: Eric Blake <[email protected]> > --- > block.c | 29 +++++++++++++++++++---------- > include/block/block.h | 1 + > 2 files changed, 20 insertions(+), 10 deletions(-) > > diff --git a/block.c b/block.c > index a517d72..14dc5fe 100644 > --- a/block.c > +++ b/block.c > @@ -693,6 +693,7 @@ 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) > { > @@ -3551,11 +3552,12 @@ 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; > > @@ -3565,19 +3567,26 @@ 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, > diff --git a/include/block/block.h b/include/block/block.h > index faee3aa..4a1e875 100644 > --- a/include/block/block.h > +++ b/include/block/block.h > @@ -279,6 +279,7 @@ 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); > -- > 1.9.3 > > Reviewed-by: Benoit Canet <[email protected]>
