Looks good to me (there are a few minor nits or optional alternative proposals)

Remove unused sha256.c and use sed instead of awk.

In D24596#548787, @rgrimes wrote:

In D24596#548776, @emaste wrote:

POSIX allows implementations to do what they want with read() on a directory and grep's behaviour follows from that, so I think it's within the spirit for us to show errors or not, as we see fit.

Please do not change the default, that would just make our greps defaults different than linux and everyone else. Just "recommend" the use of grep -d skip in the UPDATE entry, the RELEASE NOTES, and perhaps by adding t as an example, aka commented out, in /root/csh.cshrc and /root/.profile, and perhaps in the usr/share/skel files.

I've requested a new exp-run with this one.

IMHO I think it's not worth the effort to make this knob-controllable and the old behavior should be gone: directories are not stored in an uniform format, it varies from file system to file system and I'd be really surprised if anything would depend on the old behavior: for starters, these application would have already been broken many years ago when we move to a different file system. Neither fsck_ffs nor fsck_msdosfs rely on being able to read() directories directly, and I don't see any legitimate reason that an application should do it either.

Could you please incorporate the manual page change from D24814 into this one?

https://reviews.freebsd.org/D24596 is a superset of this changeset (except manual page change).

LGTM (please be sure to bump .Dd dates for manual pages.

Makes sense, I've updated the patch, could you please take another look?

Address reviewer comment (unconditionally calculate badbytes).

Please take another look, thanks!

Address reviewer comments.

Round down chunksize if it's not fully aligned.

Address reviewer comment.

Tested on a hard drive; this reduced the time for format by 2/3:

x before
+ after
+------------------------------------------------------------+
|+++                                                       xx|
||A|                                                       AM|
+------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x   3          7.24          7.33          7.29     7.2866667   0.045092498
+   3          2.36          2.49           2.4     2.4166667   0.066583281
Difference at 95.0% confidence
	-4.87 +/- 0.128884
	-66.8344% +/- 1.50101%
	(Student's t, pooled s = 0.0568624)

In D24500#538939, @wulf wrote:

In D24500#538927, @delphij wrote:

When INVARIANT is enabled, the prev and next pointers would be TRASHIT'ed (set to -1 or 0xffffffffffffffff).

Thanks for explanation. This means 'TRASHIT' calls in LIST_FOREACH macro in queue.h are bogus. They assumes that free() must be called within FOREACH loop. But that is It is not evdev case. free() is called asynchronously here.

In D24500#538844, @wulf wrote:

Do you have some local modifications of cdev.c? Especially with relaxed locking in evdev_dtor()?

Looks good to me overall, but I think we don't really need to scan the first 36 characters because validate_uuid would have checked it.