similar to: [PATCH nbdkit 0/3] tests: Test export flags (eflags).

v1 was here: https://www.redhat.com/archives/libguestfs/2018-December/thread.html#00123 v2: - Document "-" instead of "script=-" and use it in the test; and verify this also works on FreeBSD; and verify that it doesn't depend on the particular behaviour of our wrapper script and should work with installed nbdkit too. - Fix handling of zero flags parameter. -

I'm still working my way through the filters before this series will be complete, but this is enough of a start to at least get some feedback on the idea of implementing another NBD protocol extension. Eric Blake (9): server: Internal hooks for implementing NBD_CMD_CACHE plugins: Add .cache callback file, split: Implement .cache with posix_fadvise nbd: Implement NBD_CMD_CACHE

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

When I added .can_FOO caching in 1.16, I missed the case that the sh plugin itself was calling .can_flush twice in some situations (in order to default .can_fua). Then right after, I regressed it to call .can_zero twice (in order to default .can_fast_zero). I also missed that .thread_model could use better caching, because at the time, I did not add testsuite coverage. Fix that now. Eric Blake

--- tests/Makefile.am | 3 + tests/test-eflags.sh | 222 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 225 insertions(+) diff --git a/tests/Makefile.am b/tests/Makefile.am index a01c47c..173d622 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -282,6 +282,9 @@ test_oldstyle_LDADD = libtest.la $(LIBGUESTFS_LIBS) endif HAVE_LIBGUESTFS +# Test export flags. +TESTS

Allow plugins to affect the handling of the new NBD_CMD_FLAG_FAST_ZERO flag, then update affected plugins. In particular, in-memory plugins are always fast; the full plugin is better served by omitting .zero and relying on .pwrite fallback; nbd takes advantage of libnbd extensions proposed in parallel to pass through support; and v2 language bindings expose the choice to their scripts. The

Since v1: - rework .can_cache to be tri-state, with default of no advertisement (ripple effect through other patches) - add a lot more patches in order to round out filter support And in the meantime, Rich pushed NBD_CMD_CACHE support into libnbd, so in theory we now have a way to test cache commands through the entire stack. Eric Blake (24): server: Internal hooks for implementing

Until the next few patches expose and implement new callbacks for filters and plugins, our initial implementation for NBD_CMD_CACHE is to just blindly advertise the feature, and call into .pread with an ignored buffer. Note that for bisection reasons, this patch treats any use of a filter as a forced .can_cache of false to bypass the filter's caching; once all affected filters are patched to

Rich pointed out that making thread_model dynamic even for plugins makes some sense, so here is the code for doing it for 'sh'. I'm less confident on how to do it for OCaml and Rust (not to mention that those allow the plugin to already compile in their model, rather than the language binding glue forcing a model). The other languages (lua, perl, python, ruby) still need to be

In commit c306fa93ab and neighbors (v1.15.1), a concerted effort went into caching the results of .can_FOO callbacks, with commit messages demonstrating that a plugin with a slow callback should not have that delay magnified multiple times. But nothing was added to the testsuite at the time, and with the sh and eval plugins, we still have two scenarios where we did not take advantage of the

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.

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

v3 was here: https://www.redhat.com/archives/libguestfs/2019-November/msg00209.html In v4: - Rebase on top of current master. Includes various fixes and updates required because of Nir's patches that went into master. - Fix api_version() -> API_VERSION in patch 2 noted previously on the mailing list. Rich.

v2 was here: https://www.redhat.com/archives/libguestfs/2019-November/msg00163.html I pushed patch 1 (with spelling fix), patch 4 and patch 5 since those were previously ACKed on the list. Differences in v3: - Add error checking to PyModule_AddIntConstant. - Use API_VERSION constant instead of function. - Add max API version supported to --dump-plugin output. - Print API_VERSION selected by

This is a subset of the last half of the larger 9-patch series. The uncontroversial first half of that series is pushed, but here, I tried to reduce the size of the patches by splitting out some of the more complex changes, so that the rest of the changes remaining in the series are more mechanical. In turn, it forced me to write timing tests, which let me spot another spot where we are wasting

First out of our four language bindings to add FUA support (for reference, I added 'zero' support for python, perl, and ruby back in 1.1.13, then Rich had to add it for ocaml in 1.1.20). I tested this heavily under python 2, but for now only compile tested under python 3; I plan to do further testing there and make any tweaks if necessary. I wrote patch 5 early on, but then realized I

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

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

It's easy to use the sh script to demonstrate that nbdkit is inefficiently calling into .get_size, .can_fua, and friends more than necessary. We've also commented on the list in the past that it would be nice to ensure that when filters call into next_ops, they are not violating constraints (as we've have to fix several bugs in the past where we did not have such checking to protect

This allows us to add the following callbacks: - can_zero returns boolean - can_fua should print "none", "emulate" or "native" Furthermore the following callbacks are modified in a backwards compatible manner: - pwrite adding flags parameter - trim adding flags parameter This change is not backwards compatible: - zero may_trim