From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: [PATCH] md: avoid warning for 32-bit sector_t Date: Wed, 16 Dec 2015 15:02:19 +1100 Message-ID: <87si339h2s.fsf@notabene.neil.brown.name> References: <65226011.NWtA6TWNA3@wuerfel> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Return-path: In-Reply-To: <65226011.NWtA6TWNA3@wuerfel> Sender: linux-kernel-owner@vger.kernel.org To: Arnd Bergmann , linux-raid@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: linux-raid.ids --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue, Nov 24 2015, Arnd Bergmann wrote: > When CONFIG_LBDAF is not set, sector_t is only 32-bits wide, which > means we cannot have devices with more than 2TB, and the code that > is trying to handle compatibility support for large devices in > md version 0.90 is meaningless but also causes a compile-time warning: > > drivers/md/md.c: In function 'super_90_load': > drivers/md/md.c:1029:19: warning: large integer implicitly truncated to u= nsigned type [-Woverflow] > drivers/md/md.c: In function 'super_90_rdev_size_change': > drivers/md/md.c:1323:17: warning: large integer implicitly truncated to u= nsigned type [-Woverflow] > > This adds a check for CONFIG_LBDAF to avoid even getting into this > code path, and also adds an explicit cast to let the compiler know > it doesn't have to warn about the truncation. > > Signed-off-by: Arnd Bergmann > --- > Noticed on ARM randconfig builds with recent gcc versions. > > diff --git a/drivers/md/md.c b/drivers/md/md.c > index 0b48c5d7c489..ee9a7ab44f32 100644 > --- a/drivers/md/md.c > +++ b/drivers/md/md.c > @@ -1025,8 +1025,9 @@ static int super_90_load(struct md_rdev *rdev, stru= ct md_rdev *refdev, int minor > * (not needed for Linear and RAID0 as metadata doesn't > * record this size) > */ > - if (rdev->sectors >=3D (2ULL << 32) && sb->level >=3D 1) > - rdev->sectors =3D (2ULL << 32) - 2; > + if (IS_ENABLED(CONFIG_LBDAF) && (u64)rdev->sectors >=3D (2ULL << 32) && > + sb->level >=3D 1) > + rdev->sectors =3D (sector_t)(2ULL << 32) - 2; >=20=20 > if (rdev->sectors < ((sector_t)sb->size) * 2 && sb->level >=3D 1) > /* "this cannot possibly happen" ... */ > @@ -1319,8 +1320,9 @@ super_90_rdev_size_change(struct md_rdev *rdev, sec= tor_t num_sectors) > /* Limit to 4TB as metadata cannot record more than that. > * 4TB =3D=3D 2^32 KB, or 2*2^32 sectors. > */ > - if (num_sectors >=3D (2ULL << 32) && rdev->mddev->level >=3D 1) > - num_sectors =3D (2ULL << 32) - 2; > + if (IS_ENABLED(CONFIG_LBDAF) && (u64)num_sectors >=3D (2ULL << 32) && > + rdev->mddev->level >=3D 1) > + num_sectors =3D (sector_t)(2ULL << 32) - 2; > md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size, > rdev->sb_page); > md_super_wait(rdev->mddev); applied, thanks. NeilBrown --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJWcOJLAAoJEDnsnt1WYoG5vDkP/3RdLR0rx9/R/nyrMlOhIQfS Ilry8JcJ72hRLKcUCN5onBhLqXqrl9bDlkZEyVbZ0VfJEqwm0nY/E83pPlSk1PN3 cxokPCA5LuBjY5pTYn1BtdG2bQreLcCdJPCoSvvMxoPzuogNCAfG5LLmoLdYIXP/ j3pDu6h1XJGH9fUJl+X+er2txUk+dL+WfkwVC8H/x7ibV8uOUqlY5NkTPyCQwDsJ uK1R8p79SL1RhlUJqRgozWE1K5EUbvEFyFKqJWtoGRgXALcwf8b3FeQPxhC1lBt8 tx+36HLqIX7Obfq4zS3OCHrr8+kfJuS48/daKVfgVPdLat8yPDepPVugEqnmJGR1 PDn49SDChZZatYKqQCBVgrTrnWSleQ8V775nA0zMikyrqWJ8PIyPhjJYNjv9/yHy gOQZkXVsLRfQ10au2QdoZlUsFJ4rfF4XYO1NGYNgN+KQLgxMh9hdMyrS4vkmgqUh 8yvPZ8eqWpReuuy1YlLtNVF/zUIpFo5/2QuueaJ5M1Kf+LzIGC+TX5g9gxcR6li+ 2GszE+9ak5Lk17/T2Ue2dqgVsyUYtE/2LJceQP6sOghx8xVR1XFPuEQANkOAUyhc kXd//lIb2Y2uBYaeJs6oWEpuNHnZjdK0x1flf6TrugGHJX9bDy68kzRfIyZSFAny kZyobpT2wcOD3CeiNk0m =SNM4 -----END PGP SIGNATURE----- --=-=-=--