On 3/30/12 2:38 PM, Eric Sandeen wrote: > On 3/30/12 8:19 AM, Richard W.M. Jones wrote: >> On Fri, Mar 30, 2012 at 01:57:26PM +0100, Richard W.M. Jones wrote: >>> [I'm tracking this issue here: >>> https://bugzilla.redhat.com/show_bug.cgi?id=808421] >> >> A bit of further investigation: >> >> I'm currently not passing EXT2_FLAG_64BITS when opening the >> filesystem. Passing this flag fixes the issue, so I'm going to do >> that (are there any downsides?) >> >> It seems like a non-64-bit-compatible bitmap was being created, and >> that doesn't have the bitmap->bitmap_ops field initialized because >> gen_bitmap.c doesn't use this field. Somehow, though, we end up >> calling a function in gen_bitmap64.c which requires that this field be >> defined. >> >> Rich. >> > > Well here's what's busted: > > if (bitmap->bitmap_ops->find_first_zero) > return bitmap->bitmap_ops->find_first_zero(bitmap, start, end, out); > > if (!bitmap || !EXT2FS_IS_64_BITMAP(bitmap) || bitmap->cluster_bits) > return EINVAL; > > bitmap->bitmap_ops->find_first_zero only exists for a 64-bit bitmap, which > gets tested after we try to deref it :( > > I wonder if this fixes it: I guess it doesn't. Seems ext2fs_find_first_zero_generic_bmap needs a 32-bit-bitmap fallback. -Eric > diff --git a/lib/ext2fs/gen_bitmap64.c b/lib/ext2fs/gen_bitmap64.c > index b57df54..ce6c23d 100644 > --- a/lib/ext2fs/gen_bitmap64.c > +++ b/lib/ext2fs/gen_bitmap64.c > @@ -768,7 +768,7 @@ errcode_t ext2fs_find_first_zero_generic_bmap(ext2fs_generic_bitmap bitmap, > { > int b; > > - if (bitmap->bitmap_ops->find_first_zero) > + if (EXT2FS_IS_64_BITMAP(bitmap) && bitmap->bitmap_ops->find_first_zero) > return bitmap->bitmap_ops->find_first_zero(bitmap, start, end, out); > > if (!bitmap || !EXT2FS_IS_64_BITMAP(bitmap) || bitmap->cluster_bits) > > > But then the next conditional would give us EINVAL since !EXT2FS_IS_64_BITMAP, > and I don't think things would go well after that either. > > I am a little confused by the existence of two different > struct ext2fs_struct_generic_bitmap's in the code. But treating one as the > other looks doomed to failure ;) > > I haven't wrapped my head around this yet. > > -Eric > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
