| Message ID | 1415807679-3824-1-git-send-email-danieru.dressler@gmail.com (mailing list archive) |
|---|---|
| State | Under Review |
| Headers | show |
On Thu, Nov 13, 2014 at 12:54:39AM +0900, Daniel Dressler wrote: > Our ulist data structure stores at max 64bit > values. qgroup has used this structure to store > pointers. In the future when we upgrade to 128bit > this casting of pointers to uint64_t will break. What are we going to upgrade to 128 bits? > This patch adds a BUILD_BUG ensuring that this > code will not be left untouched in the upgrade. > > It also marks this issue on the TODO list so it > may be addressed before such an upgrade. > > + (BUILD_BUG_ON_ZERO(sizeof(uintptr_t) > sizeof(u64)) + \ So it's pointers, this is similar to the 32bit -> 64bit transition, a change that will affect everything, one BUILD_BUG on does not make any difference. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 48b60db..a9a4cab 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -44,6 +44,7 @@ * - caches fuer ulists * - performance benchmarks * - check all ioctl parameters + * - do not cast uintptr_t to uint64_t in ulist usage */ /* @@ -99,8 +100,12 @@ struct btrfs_qgroup_list { struct btrfs_qgroup *member; }; -#define ptr_to_u64(x) ((u64)(uintptr_t)x) -#define u64_to_ptr(x) ((struct btrfs_qgroup *)(uintptr_t)x) +#define ptr_to_u64(x) \ + (BUILD_BUG_ON_ZERO(sizeof(uintptr_t) > sizeof(u64)) + \ + ((u64)(uintptr_t)x)) +#define u64_to_ptr(x) \ + (BUILD_BUG_ON_ZERO(sizeof(uintptr_t) > sizeof(u64)) + \ + ((struct btrfs_qgroup *)(uintptr_t)x)) static int qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,
Our ulist data structure stores at max 64bit values. qgroup has used this structure to store pointers. In the future when we upgrade to 128bit this casting of pointers to uint64_t will break. This patch adds a BUILD_BUG ensuring that this code will not be left untouched in the upgrade. It also marks this issue on the TODO list so it may be addressed before such an upgrade. Signed-off-by: Daniel Dressler <danieru.dressler@gmail.com> --- fs/btrfs/qgroup.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)