search for: minblocks

The upstream NBD protocol recently clarified that servers can advertise block size limitations to clients that ask with NBD_OPT_GO (although we're still a ways off from implementing that in nbdkit); and that in the absence of that, then clients should agree on limits using out-of-band information or stick to sane defaults (everything 512-byte-aligned, no reads or writes larger than 32M). But

The upstream NBD protocol recently clarified that servers can advertise block size limitations to clients that ask with NBD_OPT_GO (although we're still a ways off from implementing that in nbdkit); and that in the absence of that, then clients should agree on limits using out-of-band information or stick to sane defaults (everything 512-byte-aligned, no reads or writes larger than 32M). But

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

It is easy to demonstrate that our blocksize filter has a bug: if the minblock= setting is a higher granularity than the underlying plugin actually supports, and the client is trying to collect block status for the entire disk, a mid-block transition in the plugin can result in the filter rounding a request so small that it no longer makes progress, causing the client to see: nbd.Error:

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

When using a filter that rounds up to alignment boundaries, the tail bytes of the plugin are difficult to access correctly. Rather than duplicating lots of code already in the truncate filter, it's easier to just make the other filters default to rounding down and add doc links on how to round up instead. Eric Blake (2): blocksize: Lift restriction against 0-size file cache, cow: Round

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]

--- filters/blocksize/nbdkit-blocksize-filter.pod | 4 ++-- filters/blocksize/blocksize.c | 19 +++++++++++++++++++ 2 files changed, 21 insertions(+), 2 deletions(-) diff --git a/filters/blocksize/nbdkit-blocksize-filter.pod b/filters/blocksize/nbdkit-blocksize-filter.pod index b6cf4dd..0abed2f 100644 --- a/filters/blocksize/nbdkit-blocksize-filter.pod +++

On 1/5/19 8:50 AM, Richard W.M. Jones wrote: > I examined each filter to see which ones implement a cache and do not > properly consider consistency across clients for flush requests. For > these filters we should force .can_multi_conn to return false. > > I believe only one filter (blocksize) needs to be updated and all the > other ones are safe. > --- >

I examined each filter to see which ones implement a cache and do not properly consider consistency across clients for flush requests. For these filters we should force .can_multi_conn to return false. I believe only one filter (blocksize) needs to be updated and all the other ones are safe. --- filters/blocksize/blocksize.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git

On 9/11/18 1:47 PM, Richard W.M. Jones wrote: > This assumes bashisms, but bash is required to run the tests. > > This is mostly simple refactoring. Except for the test-memory*.sh > tests where nbdkit used to run in the foreground, but that seems to be > a consequence of some left over debugging. > --- > +++ b/tests/functions.sh.in > @@ -32,6 +32,41 @@ > # OF THE

On Tue, Sep 11, 2018 at 03:02:47PM -0500, Eric Blake wrote: [Lots of issues] I'll fix all these, thanks. > > files="blocksize1.img blocksize1.log blocksize1.sock blocksize1.pid > >@@ -72,27 +73,13 @@ cleanup () > > trap cleanup INT QUIT TERM EXIT ERR > > # Run two parallel nbdkit; to compare the logs and see what changes. > >-nbdkit -P blocksize1.pid -U

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]

Similar to the previous patch in caching size, we want to avoid calling into the plugin more than once per connection on any of the flag determination callbacks. The following script demonstrates the speedup, where we avoid repeated calls into a slow can_fua. Pre-patch: $ cat script case "$1" in get_size) echo 1m;; can_fua) sleep 1; echo native;; can_write | can_zero |

Combine much common code into tests/functions.sh. Patch 1: Preparation for patch 3. Patch 2: Fix a long-standing bug in how man pages links are generated. Patch 3: Common code for iterating a test function over every plugin. Patch 4: Common code for starting nbdkit in a test and waiting for the PID file to appear. This is the largest and most complex of the patches but is

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

--- docs/nbdkit-captive.pod | 4 ++-- docs/nbdkit-plugin.pod | 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 +++---

--- docs/nbdkit-captive.pod | 4 ++-- docs/nbdkit-plugin.pod | 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 +++---

This assumes bashisms, but bash is required to run the tests. This is mostly simple refactoring. Except for the test-memory*.sh tests where nbdkit used to run in the foreground, but that seems to be a consequence of some left over debugging. --- tests/functions.sh.in | 35 ++++++++++++++++++++ tests/test-blocksize.sh | 23 +++---------- tests/test-cache.sh

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