similar to: [nbdkit PATCH 0/2] Avoid oddities with files unaligned to granularity

Based on Rich's review of my v1 that touched only cache.c, I have now tried to bring all three filters with alignment rounding in line with one another. There is definitely room for future improvements once we teach nbdkit to let filters and plugins advertise block sizes, but I'm hoping to get NBD_CMD_CACHE implemented first. Eric Blake (2): blocksize: Process requests in linear order

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

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]

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

I'm not sure exactly which version we're up to, but let's say it's version 4. I'm a lot happier with this version: - all filters have been reviewed and changed where I think that's necessary - can_extents is properly defined and implemented now - NBD protocol is followed - I believe it addresses all previous review points where possible The "only" thing

This has already been pushed upstream. I am simply posting these here so we have a reference in the mailing list in case we find bugs later (as I'm sure we will - it's a complex patch series). Great thanks to Eric Blake for tireless review on this one. It also seems to have identified a few minor bugs in qemu along the way. Rich.

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

Ultimately, both the blocksize and swab filters want to return aligned extents to the client. I'm posting this as a snapshot of my work in progress on how I plan to get there (it's not quite working yet, but I'm done for today and wanted to at least document my ideas). I might also add a convenience function for nbdkit_extents_offset, since we have a number of filters that repeat the

Although the time spent in memcpy/memset probably pales in comparison to time spent in socket I/O, it's still worth worth reducing the number of times we have to utilize a bounce buffer when we already have aligned data. Signed-off-by: Eric Blake <eblake@redhat.com> --- filters/cache/cache.c | 60 ++++++++++++++++++++++++++++--------------- 1 file changed, 39 insertions(+), 21

For existing commits, this is almost identical to v1, except that I updated some commit messages and reordered the commits in a somewhat more logical sequence. The main changes are the extra commits: [06/11] plugins: Return NBD_FLAG_CAN_MULTI_CONN from some readonly plugins. - Readonly plugins that can set the flag unconditionally. [09/11] partitioning: Return NBD_FLAG_CAN_MULTI_CONN. [10/11]

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

While working on adding assertions to pthread_mutex_lock calls, I noticed that the truncate filter's use of mutex didn't really protect us, and isn't really necessary. Cleaning that up also spotted a couple of other potential cleanups. Eric Blake (4): filters: Drop useless .open callbacks truncate: Fix corruption when plugin changes per-connection size truncate: Test for safe

First thing to say is that I need to do a *lot* more testing on this, so this is just an early peek. In particular, although it passed ‘make check && make check-valgrind’ I have *not* tested it against a multi-conn-aware client such as the Linux kernel >= 4.9. This implements NBD_FLAG_CAN_MULTI_CONN, described in the protocol doc as: "NBD_FLAG_CAN_MULTI_CONN: Indicates that

v4: https://www.redhat.com/archives/libguestfs/2019-January/msg00032.html v5: - Now we set the block size at run time. I'd like to say that I was able to test this change, but unfortunately I couldn't find any easy way to create a filesystem on x86-64 with a block size > 4K. Ext4 doesn't support it at all, and XFS doesn't support block size > page size (and I

I do have a question about whether patch 2 is right, or whether I've exposed a bigger problem in the truncate (and possibly other) filter, but the rest seem fairly straightforward. Eric Blake (4): server: Check for pthread lock failures truncate: Factor out reading real_size under mutex plugins: Check for mutex failures filters: Check for mutex failures filters/cache/cache.c

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

Eric, you'll probably find the design "interesting" ... It does work, for me at least. Rich.

Patch 3 still needs tests added, but it is at least working from my simple command line tests. Eric Blake (3): server: Implement nbdkit_is_tls for use during .open server: Expose final thread_model to filter's .get_ready tlsdummy: New filter docs/nbdkit-filter.pod | 21 +- docs/nbdkit-plugin.pod | 34 ++- docs/nbdkit-tls.pod

This adds a cache filter, which works like the COW filter in reverse. For realistic use it needs a bit more work, especially to add limits on the size of the cache, a more sensible cache replacement policy, and perhaps some kind of background worker to write dirty blocks out. Rich.

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