8:02 a.m.
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 insertions(+), 7 deletions(-)
An interesting followup might be adding options for --start and --length
to map out only a subset of the file. That was recently added to
qemu-img map, because there are cases where a file is fragmented enough
that getting the entire map can be time-consuming, in relation to
mapping out just a subset of the image.
+++ b/info/info-map-base-allocation-json.sh
@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+# nbd client library in userspace
+# Copyright (C) 2020 Red Hat Inc.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+. ../tests/functions.sh
+
+set -e
+set -x
+
+requires nbdkit --version
+requires nbdsh --version
Why are we requiring nbdsh in the libnbd testsuite? :) Is there a
configure option where you can have nbdinfo but not nbdsh?
On the other hand, we _do_ require URI support (libxml2); maybe it's
worth porting 'requires_nbdsh_uri' from nbdkit back to libnbd's
functions.sh, and using that...
+requires jq --version
+
+out=info-base-allocation-json.out
+cleanup_fn rm -f $out
+rm -f $out
+
+# Note the memory plugin uses a 32K page size, and extents
+# are always aligned with this.
+nbdkit -U - memory 1M --run '
+ nbdsh -u "$uri" \
...since you are depending on it.
+/* Callback handling --map. */
+static const char *
+extent_description (const char *metacontext, uint32_t type)
+{
+ if (strcmp (metacontext, "base:allocation") == 0) {
Should we favor the use of LIBNBD_CONTEXT_BASE_ALLOCATION instead of
open-coding this?
+ switch (type) {
+ case 0: return "allocated";
+ case 1: return "zero";
+ case 2: return "hole";
+ case 3: return "hole,zero";
+ }
+ }
+ else if (strcmp (metacontext, "qemu:dirty-bitmap") == 0) {
I see you've figured out since that this is not the context name
actually returned by qemu.
+ switch (type) {
+ case 0: return "clean";
+ case 1: return "dirty";
+ }
+ }
+
+ return "unknown";
+}
+
+++ b/info/nbdinfo.pod
@@ -4,7 +4,7 @@ nbdinfo - display information and metadata about NBD servers and exports
=head1 SYNOPSIS
- nbdinfo [--json] [--size] NBD-URI
+ nbdinfo [--json] [--map] [--size] NBD-URI
nbdinfo -L|--list NBD-URI
@@ -20,6 +20,8 @@ nbdinfo - display information and metadata about NBD servers and
exports
nbdinfo --size nbd://example.com
+ nbdinfo --map nbd://example.com
+
nbdinfo --json nbd://example.com
nbdinfo --list nbd://example.com
@@ -84,6 +86,32 @@ the I<--json> parameter:
]
}
+=head3 Map
+
+To show a map which areas of the disk are allocated and sparse, use
+the I<--map> option:
+
+ $ nbdinfo --map nbd://localhost/
+ 0 1048576 0 allocated
+ 1048576 1048576 3 hole,zero
+
+The fields are: start size type description.
+
+The type field is an integer showing the raw value from the NBD
+protocol. For some maps nbdinfo knows how to translate the type into
+a printable description.
+
+By default this shows the C<"base:allocation"> map, but you can show
+other maps too:
+
+ $ nbdinfo --map=qemu:dirty-bitmap nbd://localhost/
+ 0 1048576 1 dirty
+
+For more information on NBD maps, see I<Metadata querying> in the NBD
+protocol. I<--json> can also be used here for parsable JSON output.
+
+=head3 List of exports
+
To list all the exports available on an NBD server use the I<--list>
(I<-L>) option.
Looks like I have more to add here once nbd_opt_info_meta_context lands
for displaying available contexts during --list, and auto-selecting
contexts with --map.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org