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 unsigned 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 unsigned 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 <arnd@xxxxxxxx> > --- > 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, struct md_rdev *refdev, int minor > * (not needed for Linear and RAID0 as metadata doesn't > * record this size) > */ > - if (rdev->sectors >= (2ULL << 32) && sb->level >= 1) > - rdev->sectors = (2ULL << 32) - 2; > + if (IS_ENABLED(CONFIG_LBDAF) && (u64)rdev->sectors >= (2ULL << 32) && > + sb->level >= 1) > + rdev->sectors = (sector_t)(2ULL << 32) - 2; > > if (rdev->sectors < ((sector_t)sb->size) * 2 && sb->level >= 1) > /* "this cannot possibly happen" ... */ > @@ -1319,8 +1320,9 @@ super_90_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors) > /* Limit to 4TB as metadata cannot record more than that. > * 4TB == 2^32 KB, or 2*2^32 sectors. > */ > - if (num_sectors >= (2ULL << 32) && rdev->mddev->level >= 1) > - num_sectors = (2ULL << 32) - 2; > + if (IS_ENABLED(CONFIG_LBDAF) && (u64)num_sectors >= (2ULL << 32) && > + rdev->mddev->level >= 1) > + num_sectors = (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
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