similar to: [libnbd PATCH] info: Keep request within 4G bound

This is a rough-and-ready implementation of nbdinfo --map option, to display the allocation and other metadata of NBD exports. I only tested it lightly against nbdkit. It needs at least some tests. Command like these should work: nbdinfo --map nbd://localhost nbdinfo --map=qemu:dirty-bitmap nbd://localhost Rich.

--- info/Makefile.am | 4 + info/info-map-base-allocation-json.sh | 52 ++++++++++ info/info-map-base-allocation.sh | 49 ++++++++++ info/nbdinfo.c | 134 ++++++++++++++++++++++++-- info/nbdinfo.pod | 39 +++++++- 5 files changed, 271 insertions(+), 7 deletions(-) diff --git a/info/Makefile.am b/info/Makefile.am index

Fixes bugs with JSON output in the previous patch, and adds some tests. Rich.

This adds coalescing of adjacent extents of the same type, as mentioned by Eric Blake in the commit message here: https://github.com/libguestfs/libnbd/commit/46072f6611f80245846a445766da071e457b00cd The patch series is rather long because it detours through adding the <vector.h> library from nbdkit into libnbd and replacing ad hoc uses of realloc, char ** etc in various places. Rich.

If the server fails, nbdinfo can write partial output before the error message (albeit on different channels). Here is an example: $ nbdkit eval open='echo EIO fail >&2; exit 1' --run 'nbdinfo --json "$uri"' { "protocol": "newstyle-fixed", "TLS": false, nbdkit: eval[1]: error: /tmp/nbdkitii3pZW/open: fail nbdkit: eval[1]:

A rather trivial decoding; we may enhance it further if qemu extends things to give an integer depth alongside its tri-state encoding. --- I'll wait to push this to libnbd until the counterpart qemu patches land upstream, although it looks like I've got positive review. info/nbdinfo.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/info/nbdinfo.c b/info/nbdinfo.c index

Use the just-added nbd_opt_list_meta_context() API to give more details about each export (matching what 'qemu-nbd --list' already does). Note that this requires some shuffling: listing meta exports requires being in opt mode, but is easiest to do in list_one_export(), which requires setting opt_mode in more code paths, and deferring ready mode until the last possible minute during

Necessary when writing a client that wants to avoid unnecessary EINVAL errors from sending unaligned requests. At some point, we may want to add synchronous convenience API wrappers that do request splitting or read-modify-write to obey server constraints while still appearing to the library client as accepting any possible request. But such a wrapper should only be synchronous and not copied to

This rounds up the remaining bugs that I originally identified in: https://www.redhat.com/archives/libguestfs/2020-July/msg00153.html Eric Blake (4): api: Permit export list APIs when Connected info: Support --list with serializing servers info: Fix --json output when list size != 1 info: Permit --size --json generator/API.ml | 6 +++--- info/info-list-json.sh | 9 +++++++++

Now that we have an API, it's time to put it to use. --- info/nbdinfo.pod | 6 ++++++ info/nbdinfo.c | 18 ++++++++++++++++++ 2 files changed, 24 insertions(+) diff --git a/info/nbdinfo.pod b/info/nbdinfo.pod index 9761551..d0d20a9 100644 --- a/info/nbdinfo.pod +++ b/info/nbdinfo.pod @@ -45,6 +45,9 @@ L<https://github.com/NetworkBlockDevice/nbd/blob/master/doc/uri.md>):

Instead of having to munge a URI to supply a different export name, we can exploit the fact that nbd_opt_mode lets us change the preferred export name after nbd_connect_uri has established its socket. In fact, by doing this, nbdinfo no longer needs to directly link against libxml2, so it can now be built regardless of whether the underlying libnbd.so supports URIs (although use of the program

A single integer IS a valid JSON document, after all, at least according to RFC8259. --- info/nbdinfo.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/info/nbdinfo.c b/info/nbdinfo.c index f37ffea..2e0bf27 100644 --- a/info/nbdinfo.c +++ b/info/nbdinfo.c @@ -158,11 +158,6 @@ main (int argc, char *argv[]) usage (stderr, EXIT_FAILURE); /* You can combine certain options. */ - if

Exposing a description in single mode is harder: we'd have to request NBD_INFO_DESCRIPTION during NBD_OPT_GO. For now, the API only supports descriptions in list mode. --- info/info-list-json.sh | 3 ++- info/info-list.sh | 3 ++- info/nbdinfo.c | 21 ++++++++++++++++----- 3 files changed, 20 insertions(+), 7 deletions(-) diff --git a/info/info-list-json.sh

On 10/16/20 10:23 AM, Eric Blake wrote: > A rather trivial decoding; we may enhance it further if qemu extends > things to give an integer depth alongside its tri-state encoding. > --- > > I'll wait to push this to libnbd until the counterpart qemu patches > land upstream, although it looks like I've got positive review. Whoops, I accidentally pushed this before qemu

In v2: ack'ed preliminary patches have been pushed, and I've added a lot of testsuite coverage as well as putting the new API to use in nbdinfo. Eric Blake (2): api: Add nbd_opt_list_meta_context info: List available meta-contexts lib/internal.h | 1 + generator/API.ml | 84 ++++++++-

An incremental improvement on top of listing exports. I still think it's worth experimenting with revisiting how our API for list mode should actually work [1] (so that we can reuse a single connection for both grabbing the list and finally using NBD_OPT_GO), but this change was easier to whip together while still thinking about that. [1]

Well, I'm not quite done (I still want to get nbdinfo to work on a single nbd connection for all cases when reading the heads of the file is not required), but I'm happy with patches 1-11, and 12-13 show where I'm headed for getting NBD_OPT_INFO to work. Posting now to see if some of the earlier patches are ready to commit while I continue working on the latter half. Eric Blake (13):

On 9/26/20 11:36 AM, Richard W.M. Jones wrote: > --- > info/Makefile.am | 4 + > info/info-map-base-allocation-json.sh | 52 ++++++++++ > info/info-map-base-allocation.sh | 49 ++++++++++ > info/nbdinfo.c | 134 ++++++++++++++++++++++++-- > info/nbdinfo.pod | 39 +++++++- > 5 files changed, 271

When “nbdkit ... --run 'nbdinfo ...' > out” is expected to fail, we cannot be sure of the content of the "out" file. In particular nbdinfo produces its output incrementally, so in JSON mode there's usually a stray "{" in the output, and in non-JSON mode it usually prints the "protocol: " line. Thus it's not correct to test for the output file

On 9/29/20 6:23 AM, Richard W.M. Jones wrote: > This is not related to the current patch, but generally for libnbd: > > (1) Should we be testing interop separately for qemu-storage-daemon > (qsd), or is qsd basically qemu-nbd in a new wrapper so it's not worth > doing it? > > (2) I found a bug in the new nbdinfo behaviour: > > $ nbdkit -fv file dir=/scratch >