similar to: [nbdkit PATCH 0/2] errno cleanup patches

POSIX allows but does not require ENOTSUP and EOPNOTSUPP to map to the same errno value. This patch has no impact on Linux, but does affect other systems: we want to be permissive in what we accept (either spelling, since the two are commonly confused), while strict in what we generate (we documented EOPNOTSUPP as the trigger to fall back to .write, so stick to that internally where it makes

This cleans up the existing code base with regards to implicit use of errno from language bindings, then rebases the previous work in python on top of that. I'm still playing with the perl bindings, but got further after reading 'perldoc perlembed'. Eric Blake (4): plugins: Don't use bogus errno from non-C plugins plugins: Add new nbdkit_set_error() utility function python:

I still don't have .prepare/.finalize working cleanly across reopen, but did find a nasty bug where a botched assertion means we failed to notice reads beyond EOF in both the xz and retry filter. Refactoring backend.c will make .finalize work easier. Eric Blake (5): xz: Avoid reading beyond EOF retry: Check size before transactions tests: Test retry when get_size values change

Similar to python and perl. But MUCH easier (especially considering that this is the first time I've every tried to run Ruby). I even had fun making set_error() polymorphic. Eric Blake (2): ruby: Expose nbdkit_set_error to ruby script ruby: Support zero callback plugins/ruby/example.rb | 11 ++++++++ plugins/ruby/nbdkit-ruby-plugin.pod | 54

Fix some things I noticed while reviewing v1, and follow Rich's idea to add a new nbdkit_set_error() utility function with a binding for Python users to request a particular error (rather than being forced to live with whatever stale value is in errno after all the intermediate binding glue code). I could not easily find out how to register a C function callable from perl bindings, and have

Tested via: term1$ qemu-nbd -k $PWD/sock -t -f raw -x foo junk --trace=nbd_\* term2$ ./nbdkit -f -v -e bar nbd socket=$PWD/sock export=foo term3$ qemu-io -t none -f raw nbd://localhost:10809/bar --trace=nbd_\* and checking the traces to see that 'w 0 1' vs. 'w -f 0 1' was able to influence whether the FUA flag showed up at the server in term1. Still to go: figure out how to

Here's what I'm currently playing with; I'm not ready to commit anything until I rebase my FUA work on top of this, as I only want to break filter ABI once between releases. Eric Blake (2): backend: Rework internal/filter error return semantics filters: Add log filter TODO | 2 - docs/nbdkit-filter.pod | 84 +++++++-- docs/nbdkit.pod

And fill out most of the missing bits of the API. Rich.

As mentioned in my reviews, I wonder if we should make our python callbacks look a bit more Pythonic by having kwargs added for each new flag that we want to expose. The idea was first floated here: https://www.redhat.com/archives/libguestfs/2018-April/msg00108.html Note that with my proposal, there is no need for a python script to expose a global API_VERSION variable; new flags are added

v1: https://www.redhat.com/archives/libguestfs/2019-November/msg00153.html v2: - Fix implementation of can_cache. - Add implementation of can_fua. - Add a very thorough test suite which tests every command + flag combination.

After more than a month since v2 [1], I've finally got my FUA support series polished. This is all of my outstanding patches, even though some of them were originally posted in separate threads from the original FUA post [2], [3] [1] https://www.redhat.com/archives/libguestfs/2018-January/msg00113.html [2] https://www.redhat.com/archives/libguestfs/2018-January/msg00219.html [3]

Another couple things I noticed that are worth improving, but aren't strictly related to implementing fast zero support. Eric Blake (2): server: Assert sane error responses nozero: More efficient FUA handling filters/nozero/nozero.c | 17 +++++++++++-- server/filters.c | 56 +++++++++++++++++++++++++++++++++-------- server/protocol.c | 32 +++++++++++++++++------ 3 files

v1 -> v2: - Fixed everything mentioned in the review. Rich.

Somewhat invasive but mostly mechanical change to how plugins are called. This patch is in preparation for adding a second backend subtype for filters. Rich.

Requires patch 1 and 2 of the python series: https://www.redhat.com/archives/libguestfs/2017-January/msg00126.html This is the perl implementation along the same lines. We still haven't decided if patch 1 of the python series should change OCaml to report errno as reliable or not, but perhaps we can commit that patch as-is now and then touch things up further when we actually get set_error

This is a cover letter to a series of patches being proposed in tandem to four different projects: - nbd: Document a new NBD_CMD_FLAG_FAST_ZERO command flag - qemu: Implement the flag for both clients and server - libnbd: Implement the flag for clients - nbdkit: Implement the flag for servers, including the nbd passthrough client If you want to test the patches together, I've pushed a

Since v1: add the blocksize filter, add testsuite coverage of the log filter, several fixes to the log filter based on what adding tests revealed I'm still working on FUA flag support patches on top of this; the patches should all be committed in the same release, as we want to minimize the number of releases that cause a filter ABI/API bump Eric Blake (3): backend: Rework internal/filter

The concern is a client is blocked while processing a request. The nbdkit server design requires a thread per request being processed regardless of the number of connections or clients. We want to run 1000's of requests in parallel without needing a thread at nbdkit layer per request in flight. Our plugin layer is built around boost asio and a few threads in a worker pool running an io

A combination of the work that both Rich and I have been doing lately, where filters use only the new API with flags on every command that the client can send over the wire (we can then add support for more flags in nbdkit without having to add new callbacks, as NBD adds more flags upstream). Eric Blake (4): protocol: Split flags from cmd field in requests backend: Pass flags argument through

Mapping of EOVERFLOW was missed in commit 6f8c8084. Mapping of EOPNOTSUPP is essential for .zero to trigger a fallback to .pwrite, missed in commit 6c0e00e9 (not to mention that it becomes a valid protocol failure once fast zero support is added). There is no Unix.ENOTSUP, or that would get the same treatment per commit abb2b47c. Preserving EROFS and EFBIG is useful because protocol.c