search for: fua

Two hopefully useful additions to the fua filter. The second one is kind of like cache=unsafe in qemu, in that it exchanges correctness for speed. Useful for data which is easily recreated in the event of a crash or for people who like living on the edge and have good backups. Rich.

This drops all FUA and flush requests. --- filters/fua/nbdkit-fua-filter.pod | 27 +++++++++++++++++---- filters/fua/fua.c | 39 +++++++++++++++++++++++++++---- tests/test-fua.sh | 33 ++++++++++++++++---------- 3 files changed, 79 insertions(+), 20 deletions(-) diff --git a/filters/...

...ethods are called properly in the second and subsequent filters. This causes an additional log message to be emitted (correctly) from the newly called .prepare method in the log filter: 2018-08-01 15:17:45.249533 connection=1 Connect [...] However this extra log message incidentally breaks the FUA test. Fix this by filtering out the additional log message before counting the instances of the fua=1 flag in this test. Thanks: Eric Blake. --- tests/test-fua.sh | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tests/test-fua.sh b/tests/test-fua.sh index 8a8c7fc..0329807...

On Wed, Apr 11, 2018 at 12:03:41AM -0500, Eric Blake wrote: > +=item C<can_fua> > + > +(Optional) > + > + def can_fua(h): > + # return a boolean > + > +Unlike the C counterpart, the Python callback does not need a > +tri-state return value, because Python introspection is sufficient to > +learn whether callbacks support FUA. Thus, this functio...

On 5/22/20 4:32 PM, Richard W.M. Jones wrote: > This drops all FUA and flush requests. > --- > filters/fua/nbdkit-fua-filter.pod | 27 +++++++++++++++++---- > filters/fua/fua.c | 39 +++++++++++++++++++++++++++---- > tests/test-fua.sh | 33 ++++++++++++++++---------- > 3 files changed, 79 insertions(+), 20 deleti...

...and subsequent > filters. > > This causes an additional log message to be emitted (correctly) from > the newly called .prepare method in the log filter: > > 2018-08-01 15:17:45.249533 connection=1 Connect [...] > > However this extra log message incidentally breaks the FUA test. > > Fix this by filtering out the additional log message before counting > the instances of the fua=1 flag in this test. > > Thanks: Eric Blake. > --- > tests/test-fua.sh | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) I did something similar, but wit...

Expose support for the FUA flag to pwrite, zero, and trim, as well as a can_fua callback, for use in python plugins. There are some slight semantic differences: the C plugin had to switch to a new API with a single uint32_t flags argument (so we don't have to keep adding new ABI when new flags are added), but in so doin...

...emu-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 expose the flags through the language bindings Patch 7 is RFC; Rich and I debated on IRC whether we want it (the code in plugin_register() sounds like it tries hard to support newer plugins with older nbdkit), or whether we sho...

[still a work in progress, as I finish rebasing to capture the ideas raised on the list, but posting now for initial feedback] The NBD protocol supports Forced Unit Access (FUA) as a more efficient way to wait for just one write to land in persistent storage, rather than all outstanding writes at the time of a flush; modeled after the kernel's block I/O flag of the same name. While we can emulate the proper semantics with a full-blown flush, there are some plugins th...

We document that a plugin callback should return 0 on success, but other places in the code treat all values other than -1 as success (perhaps we should treat all negative values as errors, instead of exactly -1, but that may break binary back-compatibility). However, when reworking where FUA fallback occurs, we introduced a subtle change: if a plugin returns a positive value on success, and the client requested FUA, we ended up reporting success to the client without performing FUA. Fixes: 4f37c64ffdd42fab5c5d9c6157db396b60866a7a Signed-off-by: Eric Blake <eblake@redhat.com> ---...

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....

...int (*zero) (void *handle, uint32_t count, uint64_t offset, int may_trim); int errno_is_preserved; void (*async_pread) (void *op, void *handle, void *buf, uint32_t count, uint64_t offset); void (*async_pwrite) (void *op, void *handle, const void *buf, uint32_t count, uint64_t offset, int fua); void (*async_flush) (void *op, void *handle); void (*async_trim) (void *op, void *handle, uint32_t count, uint64_t offset, int fua); void (*async_zero) (void *op, void *handle, uint32_t count, uint64_t offset, int may_trim, int fua); ... } Additionally there are a few helper functions fo...

...| 2 +- docs/nbdkit-service.pod | 2 +- docs/nbdkit-tls.pod | 2 +- filters/cow/nbdkit-cow-filter.pod | 4 ++-- filters/delay/nbdkit-delay-filter.pod | 2 +- filters/error/nbdkit-error-filter.pod | 6 +++--- filters/fua/nbdkit-fua-filter.pod | 8 ++++---- filters/log/nbdkit-log-filter.pod | 4 ++-- filters/nozero/nbdkit-nozero-filter.pod | 4 ++-- filters/offset/nbdkit-offset-filter.pod | 4 ++-- filters/partition/nbdkit-partition-filter.pod | 2 +- plugins/file/file.c...

...an 25, 2017 at 08:55:18PM -0600, Eric Blake wrote: >> On 01/20/2017 02:16 PM, Eric Blake wrote: >>> Reject rather than silently ignoring unknown client request flags. >>> >> >>> >>> + /* Validate flags */ >>> + if (flags & ~NBD_CMD_FLAG_FUA) { >>> + nbdkit_error ("invalid request: unknown flag (0x%x)", flags); >>> + *error = EINVAL; >>> + return 0; >>> + } >> >> Right now, our NBD_CMD_FLAG_FUA implementation causes a full flush >> action from the plugin, even if...

...| 2 +- docs/nbdkit-service.pod | 2 +- docs/nbdkit-tls.pod | 2 +- filters/cow/nbdkit-cow-filter.pod | 4 ++-- filters/delay/nbdkit-delay-filter.pod | 2 +- filters/error/nbdkit-error-filter.pod | 6 +++--- filters/fua/nbdkit-fua-filter.pod | 8 ++++---- filters/log/nbdkit-log-filter.pod | 4 ++-- filters/nozero/nbdkit-nozero-filter.pod | 4 ++-- filters/offset/nbdkit-offset-filter.pod | 4 ++-- filters/partition/nbdkit-partition-filter.pod | 2 +- plugins/file/file.c...

...is an RFC to see which pieces we like best out of the various proposals, rather than something that should be applied as-is. Eric Blake (5): python: Let zero's may_trim parameter be optional python: Expose can_zero callback python: Update internals to plugin API level 2 python: Expose FUA support python: Add can_fast_zero support plugins/python/nbdkit-python-plugin.pod | 122 ++++++++-- plugins/python/python.c | 286 ++++++++++++++++++++++-- plugins/python/example.py | 6 +- tests/test.py | 6 +- 4 files changed, 375 in...

...n EROFS. On the other hand (a) plugins don't usually implement can_write because the "autosensing" usually works, and (b) it doesn't crash or do anything particularly bad. can_trim/trim and can_flush/flush are similar. However unfortunately src/plugins.c now assert-fails if the FUA flag is present but plugin.flush does not exist. Is this a bug? Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many p...

The NBD protocol supports Forced Unit Access (FUA) as a more efficient way to wait for just one write to land in persistent storage, rather than all outstanding writes at the time of a flush; modeled after the kernel's block I/O flag of the same name. While we can emulate the proper semantics with a full-blown flush, there are some plugins th...

...ewer nbdkit will always support > +plugins compiled against an older API version, but plugins that opt in > +to newer versions require a new enough nbdkit. For now, the maximum > +version is 2, which enables fine-tuned response to client flags > +including efficient Forced Unit Access (FUA) on writes. > + > =head1 C<nbdkit-plugin.h> > > -All plugins should start by including this header file: > +All plugins should start by including this header file, after > +optionally choosing an API version: > > #include <nbdkit-plugin.h> I'm in favour...

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-Jan...