ufs: ufs_sb_private_info: remove unused s_{2,3}apb fields

These two fields are populated and stored as a "frequently used value"
in ufs_fill_super, but are not used afterwards in the driver.

Moreover, one of the shifts triggers UBSAN: shift-out-of-bounds when
apbshift is 12 because 12 * 3 = 36 and 1 << 36 does not fit in the 32
bit integer used to store the value.

Closes: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2087853
Signed-off-by: Agathe Porte <[e-mail]>
Signed-off-by: Al Viro <[e-mail]>

fs/ufs/super.c

···
 	else
 		uspi->s_apbshift = uspi->s_bshift - 2;
 
-	uspi->s_2apbshift = uspi->s_apbshift * 2;
-	uspi->s_3apbshift = uspi->s_apbshift * 3;
 	uspi->s_apb = 1 << uspi->s_apbshift;
-	uspi->s_2apb = 1 << uspi->s_2apbshift;
-	uspi->s_3apb = 1 << uspi->s_3apbshift;
 	uspi->s_apbmask = uspi->s_apb - 1;
 	uspi->s_nspfshift = uspi->s_fshift - UFS_SECTOR_BITS;
 	uspi->s_nspb = uspi->s_nspf << uspi->s_fpbshift;

fs/ufs/ufs_fs.h

···
 
 	__u32	s_fpbmask;	/* fragments per block mask */
 	__u32	s_apb;		/* address per block */
-	__u32	s_2apb;		/* address per block^2 */
-	__u32	s_3apb;		/* address per block^3 */
 	__u32	s_apbmask;	/* address per block mask */
 	__u32	s_apbshift;	/* address per block shift */
-	__u32	s_2apbshift;	/* address per block shift * 2 */
-	__u32	s_3apbshift;	/* address per block shift * 3 */
 	__u32	s_nspfshift;	/* number of sector per fragment shift */
 	__u32	s_nspb;		/* number of sector per block */
 	__u32	s_inopf;	/* inodes per fragment */