From: Johannes Sixt <j6t@kdbg.org>
Date: Tue, 10 Mar 2026 20:56:14 GMT
Subject: Re: [PATCH v3 00/10] upload-pack: reduce lock contention when writing packfile data
Message-ID: <2116166d-1aa2-46e5-b912-6268ebbcad4f@kdbg.org>
In-Reply-To: <20260310-pks-upload-pack-write-contention-v3-0-8bc97aa3e267@pks.im>

Am 10.03.26 um 14:24 schrieb Patrick Steinhardt:
>       compat/posix: introduce writev(3p) wrapper
>       wrapper: introduce writev(3p) wrappers

I looked at these two patches.

At first, I was thrown off by the early exits when bytes_written == 0.
But I convinced myself that it makes sense:

- In the emulation, if the underlying write(2) does return 0, it makes
sense to signal a partial successful write to the caller of writev. It's
the best we can do when earlier blocks have already been written. A
return value of 0 is strange and may be an indication of future
problems, so let's just stop the work we are doing and let the upper
layers deal with the problem.

- In writev_in_full we need to treat the case specially in order to
guarantee forward progress.  Treating it as ENOSPC is plucked out of
thin air, I guess, but not unreasonable.

In conclusion, these patches look good.

-- Hannes