similar to: [nbdkit PATCH 0/2] Use new libnbd _notify functions

libnbd 0.1.7 was released today, which breaks compilation of nbdkit-nbd-plugin. We could work around it by using #ifdef LIBNBD_HAVE_XXX to learn about the renamed functions, but supporting older versions is not all that important when we don't yet have API stability. So patch 1 copes by just bumping the minimum version instead, except that we have yet another pending libnbd patch with an API

We no longer have to track a linked list of in-flight transactions that are pending resolution, but rely instead on libnbd 0.1.6+ doing it on our behalf. Normally, we will get to call nbdplug_register() prior to the notify callback being reached, but under a heavily-loaded system, it is conceivable that the libnbd state machine can manage to fire off our request and receive a server reply all

--- configure.ac | 4 ++-- plugins/nbd/nbd.c | 12 +++++++++--- README | 2 +- 3 files changed, 12 insertions(+), 6 deletions(-) diff --git a/configure.ac b/configure.ac index 8c7ee8b..0ce78c7 100644 --- a/configure.ac +++ b/configure.ac @@ -718,12 +718,12 @@ AC_ARG_WITH([libnbd], [], [with_libnbd=check]) AS_IF([test "$with_libnbd" != "no"],[ -

Patch 1 played with an early draft of Rich's Fedora 30 libnbd package: https://bugzilla.redhat.com/show_bug.cgi?id=1713767#c17 Note that comment 21 provides a newer package 0.1.1-1 with a different API; and that libnbd has more unreleased API changes in the pipeline (whether that will be called 0.2 or 0.1.2); so we'll have to tweak things based on what is actually available in distros.

libnbd-0.1.2-1 is now available in Fedora 29/30 updates-testing, although it was not compiled against libxml2 so it lacks uri support (I ended up testing patch 4 with a self-built libnbd). Diffs since v1 - rebase to master, bump from libnbd 0.1 to 0.1.2, add URI support, better timing results Still not done - patch 5 needs associated tests Eric Blake (5): nbd: Check for libnbd nbd:

libnbd-0.1.4-1 is now available in Fedora 29/30 updates testing. Diffs since v2 - rebase to master, bump from libnbd 0.1.2 to 0.1.3+, add tests to TLS usage which flushed out the need to turn relative pathnames into absolute, doc tweaks Now that the testsuite covers TLS and libnbd has been fixed to provide the things I found lacking when developing v2, I'm leaning towards pushing this on

The 0.9.8 release breaks API, requiring a number of changes: - Use symbolic constants instead of magic numbers/open-coded strings (well, the string for "base:allocation" was present before this libnbd bump) - Change callbacks to drop the valid_flag parameter - Add _is to nbd_read_only call - Drop the _callback suffix on nbd_aio_FOO calls - Add a struct for managing callback/user_data

libnbd 0.1.8 is due out soon, which reorders several function arguments. Signed-off-by: Eric Blake <eblake@redhat.com> --- configure.ac | 4 ++-- plugins/nbd/nbd.c | 17 +++++++++-------- 2 files changed, 11 insertions(+), 10 deletions(-) diff --git a/configure.ac b/configure.ac index 3b355667..77f08f46 100644 --- a/configure.ac +++ b/configure.ac @@ -718,12 +718,12 @@

When using the nbd_aio_FOO_callback commands, there is nothing further to be learned about the command by calling nbd_aio_command_completed() compared to what the callback already had access to. There are still scenarios where manually retiring the command after the fact is useful (whether the return was 0 to keep the status unchanged, or -1 to alter the retirement status to *error), but by

This conversion should be feature compatible with the standalone nbd code. Note that the use of libnbd makes the binary for this particular plugin fall under an LGPLv2+ license rather than BSD; but the source code in nbd.c remains BSD. A lot of code simply disappears, now that I'm no longer directly utilizing the NBD protocol files but relying on libnbd. Coordination between threads from

This conversion should be feature compatible with the standalone nbd code. Note that the use of libnbd makes the binary for this particular plugin fall under an LGPLv2+ license rather than BSD; but the source code in nbd.c remains BSD. A lot of code simply disappears, now that I'm no longer directly utilizing the NBD protocol files but relying on libnbd. Coordination between threads from

I ran some local testing on my Fedora 29 system via: $ ./nbdkit memory 1m $ for i in `seq 10`; do ./nbdkit -U - --filter=stats nbd \ statsappend=true statsfile=$file hostname=localhost port=10809 \ --run '~/libnbd/examples/threaded-reads-and-writes $unixsocket' done Pre-patch, the runs averaged 1.266s, 1.30E+08 bits/s Post-patch, the runs averaged 1.154s, 1.42E+08

libnbd 0.1.5 was released today, but is not yet packaged for Fedora. I'd prefer to bump the minimum version in the pkg-config check in configure.ac, as such, I won't be pushing this patch as-is, but waiting until Fedora does have the newer build. But anyone playing with a self-built libnbd library in the meantime needs this patch to deal with the ABI change. --- plugins/nbd/nbd.c | 11

With this, I am finally able to get the nbd plugin to do out-of-order responses to the client. Once this series goes in, we should be ready for Rich to cut a release. Eric Blake (4): nbd: Split reading into separate thread nbd: Protect writes with mutex nbd: Enable parallel handling tests: Test parallel nbd behavior plugins/nbd/nbd.c | 217

It is necessary to kick the state machine any time another thread blocks due to write() encountering a full buffer, to get the reader thread to learn that it must now poll on POLLOUT rather than just POLLIN. POSIX only provides two ways to do this: either poll() on a second fd (our pipe-to-self trick), or interrupt the polling with EINTR due to delivery of a signal. So, I played with the latter

Updated based on other changes that have happened in the meantime: - rely more on cleanup.h (throughout) - split structured read for easier review (patch 2 and 3 were combined in v1) - rely on nbdkit not leaking a server's partial answer (patch 3) - add tests (patch 5) - other bug fixes I found while testing it - drop EOVERFLOW patch for now; it will be separate once upstream NBD protocol

The reason the deadlock is that: Task Btrfs-cleaner umount() down_write(&s->s_umount) sync_filesystem() do auto-defragment and produce lots of dirty pages close_ctree() wait for the end of btrfs-cleaner start_transaction reserve space shrink_delalloc() writeback_inodes_sb_nr_if_idle()

I still need more soak time on testing, to see whether I can: a) reproduce the hang with patch 2 not applied b) feel confident that patch 2 is sufficient to fix the race, or else determine that I also need to augment the loop condition in the reader thread to additionally break out of the loop when the pipe-to-self sees EOF even when nbd_aio_is_dead() has not yet been satisfied I'm also

Hi Eric, There's a memory leak in the nbd client. The message (below) is not very useful because somehow debuginfo is missing in the plugin. However it's easily reproducible by doing: make check-valgrind TESTS=test-nbd I tried the attached patch to fix what I thought was the bug, but sadly the fix doesn't work for me :-( So I guess something else is going on, but it does look as

I fixed the deadlock - turned out to be an actual bug in the nbd plugin (see patch 8). I changed the command syntax so it's now: nbdkit nbd command=qemu arg=-f arg=qcow2 arg=/path/to/disk.qcow2 Nir wrote: 18:08 < nsoffer> rwmjones: regarding the nbd proxy patches, did you have specific flow that help us? 18:08 < nsoffer> rwmjones: or this is just a way to support qcow2 in the