Allow the server to expose an additional metacontext to be requested
by savvy clients. qemu-nbd adds a new option -A to expose the
qemu:allocation-depth metacontext through NBD_CMD_BLOCK_STATUS; this
can also be set via QMP when using block-export-add.
qemu as client can be hacked into viewing this new context by using
the now-misnamed x-dirty-bitmap option when creating an NBD blockdev
(even though our x- naming means we could rename it, I did not think
it worth breaking back-compat of tools that have been using it while
waiting for a better solution). It is worth noting the decoding of
how such context information will appear in 'qemu-img map
--output=json':
NBD_STATE_DEPTH_UNALLOC => "zero":false, "data":true
NBD_STATE_DEPTH_LOCAL => "zero":false, "data":false
NBD_STATE_DEPTH_BACKING => "zero":true, "data":true
libnbd as client is probably a nicer way to get at the information
without having to decipher such hacks in qemu as client. ;)
Signed-off-by: Eric Blake <ebl...@redhat.com>
Message-Id: <20200930121105.667049-6-ebl...@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
[eblake: comment tweak suggested by Vladimir]
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
docs/tools/qemu-nbd.rst | 8 ++++-
qapi/block-core.json | 7 ++--
qapi/block-export.json | 12 +++++--
nbd/server.c | 2 ++
qemu-nbd.c | 26 +++++++++-----
tests/qemu-iotests/309 | 73 ++++++++++++++++++++++++++++++++++++++
tests/qemu-iotests/309.out | 22 ++++++++++++
tests/qemu-iotests/group | 1 +
8 files changed, 136 insertions(+), 15 deletions(-)
create mode 100755 tests/qemu-iotests/309
create mode 100644 tests/qemu-iotests/309.out
diff --git a/docs/tools/qemu-nbd.rst b/docs/tools/qemu-nbd.rst
index 667861cb22e9..fe41336dc550 100644
--- a/docs/tools/qemu-nbd.rst
+++ b/docs/tools/qemu-nbd.rst
@@ -72,10 +72,16 @@ driver options if ``--image-opts`` is specified.
Export the disk as read-only.
+.. option:: -A, --allocation-depth
+
+ Expose allocation depth information via the
+ ``qemu:allocation-depth`` metadata context accessible through
+ NBD_OPT_SET_META_CONTEXT.
+
.. option:: -B, --bitmap=NAME
If *filename* has a qcow2 persistent bitmap *NAME*, expose
- that bitmap via the ``qemu:dirty-bitmap:NAME`` context
+ that bitmap via the ``qemu:dirty-bitmap:NAME`` metadata context
accessible through NBD_OPT_SET_META_CONTEXT.
.. option:: -s, --snapshot
diff --git a/qapi/block-core.json b/qapi/block-core.json
index ee5ebef7f2ce..b6368f5fd9a1 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -3883,9 +3883,12 @@
#
# @tls-creds: TLS credentials ID
#
-# @x-dirty-bitmap: A "qemu:dirty-bitmap:NAME" string to query in place of
+# @x-dirty-bitmap: A metadata context name such as "qemu:dirty-bitmap:NAME"
+# or "qemu:allocation-depth" to query in place of the
# traditional "base:allocation" block status (see
-# NBD_OPT_LIST_META_CONTEXT in the NBD protocol) (since 3.0)
+# NBD_OPT_LIST_META_CONTEXT in the NBD protocol; and
+# yes, naming this option x-context would have made
+# more sense) (since 3.0)
#
# @reconnect-delay: On an unexpected disconnect, the nbd client tries to
# connect again until succeeding or encountering a serious
diff --git a/qapi/block-export.json b/qapi/block-export.json
index 65804834d905..893d5cde5dfe 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -75,14 +75,20 @@
# (Since 5.0)
#
# @bitmap: Also export the dirty bitmap reachable from @device, so the
-# NBD client can use NBD_OPT_SET_META_CONTEXT with
-# "qemu:dirty-bitmap:NAME" to inspect the bitmap. (since 4.0)
+# NBD client can use NBD_OPT_SET_META_CONTEXT with the
+# metadata context name "qemu:dirty-bitmap:NAME" to inspect the
+# bitmap. (since 4.0)
+#
+# @allocation-depth: Also export the allocation depth map for @device, so
+# the NBD client can use NBD_OPT_SET_META_CONTEXT with
+# the metadata context name "qemu:allocation-depth" to
+# inspect allocation details. (since 5.2)
#
# Since: 5.0
##
{ 'struct': 'BlockExportOptionsNbd',
'data': { '*name': 'str', '*description': 'str',
- '*bitmap': 'str' } }
+ '*bitmap': 'str', '*allocation-depth': 'bool' } }
##
# @NbdServerAddOptions:
diff --git a/nbd/server.c b/nbd/server.c
index ae6f8a8e5429..30cfe0eee467 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1597,6 +1597,8 @@ static int nbd_export_create(BlockExport *blk_exp,
BlockExportOptions *exp_args,
assert(strlen(exp->export_bitmap_context) < NBD_MAX_STRING_SIZE);
}
+ exp->allocation_depth = arg->allocation_depth;
+
blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
QTAILQ_INSERT_TAIL(&exports, exp, next);
diff --git a/qemu-nbd.c b/qemu-nbd.c
index bc644a0670b6..847fde435a7f 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -99,6 +99,7 @@ static void usage(const char *name)
"\n"
"Exposing part of the image:\n"
" -o, --offset=OFFSET offset into the image\n"
+" -A, --allocation-depth expose the allocation depth\n"
" -B, --bitmap=NAME expose a persistent dirty bitmap\n"
"\n"
"General purpose options:\n"
@@ -519,7 +520,7 @@ int main(int argc, char **argv)
char *device = NULL;
QemuOpts *sn_opts = NULL;
const char *sn_id_or_name = NULL;
- const char *sopt = "hVb:o:p:rsnc:dvk:e:f:tl:x:T:D:B:L";
+ const char *sopt = "hVb:o:p:rsnc:dvk:e:f:tl:x:T:D:AB:L";
struct option lopt[] = {
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, 'V' },
@@ -528,6 +529,7 @@ int main(int argc, char **argv)
{ "socket", required_argument, NULL, 'k' },
{ "offset", required_argument, NULL, 'o' },
{ "read-only", no_argument, NULL, 'r' },
+ { "allocation-depth", no_argument, NULL, 'A' },
{ "bitmap", required_argument, NULL, 'B' },
{ "connect", required_argument, NULL, 'c' },
{ "disconnect", no_argument, NULL, 'd' },
@@ -569,6 +571,7 @@ int main(int argc, char **argv)
QDict *options = NULL;
const char *export_name = NULL; /* defaults to "" later for server mode */
const char *export_description = NULL;
+ bool alloc_depth = false;
const char *bitmap = NULL;
const char *tlscredsid = NULL;
bool imageOpts = false;
@@ -694,6 +697,9 @@ int main(int argc, char **argv)
readonly = true;
flags &= ~BDRV_O_RDWR;
break;
+ case 'A':
+ alloc_depth = true;
+ break;
case 'B':
bitmap = optarg;
break;
@@ -791,8 +797,8 @@ int main(int argc, char **argv)
exit(EXIT_FAILURE);
}
if (export_name || export_description || dev_offset ||
- device || disconnect || fmt || sn_id_or_name || bitmap ||
- seen_aio || seen_discard || seen_cache) {
+ device || disconnect || fmt || sn_id_or_name || alloc_depth ||
+ bitmap || seen_aio || seen_discard || seen_cache) {
error_report("List mode is incompatible with per-device settings");
exit(EXIT_FAILURE);
}
@@ -1072,12 +1078,14 @@ int main(int argc, char **argv)
.has_writable = true,
.writable = !readonly,
.u.nbd = {
- .has_name = true,
- .name = g_strdup(export_name),
- .has_description = !!export_description,
- .description = g_strdup(export_description),
- .has_bitmap = !!bitmap,
- .bitmap = g_strdup(bitmap),
+ .has_name = true,
+ .name = g_strdup(export_name),
+ .has_description = !!export_description,
+ .description = g_strdup(export_description),
+ .has_bitmap = !!bitmap,
+ .bitmap = g_strdup(bitmap),
+ .has_allocation_depth = alloc_depth,
+ .allocation_depth = alloc_depth,
},
};
blk_exp_add(export_opts, &error_fatal);
diff --git a/tests/qemu-iotests/309 b/tests/qemu-iotests/309
new file mode 100755
index 000000000000..b6734794bb68
--- /dev/null
+++ b/tests/qemu-iotests/309
@@ -0,0 +1,73 @@
+#!/usr/bin/env bash
+#
+# Test qemu-nbd -A
+#
+# Copyright (C) 2018-2020 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+
+seq="$(basename $0)"
+echo "QA output created by $seq"
+
+status=1 # failure is the default!
+
+_cleanup()
+{
+ _cleanup_test_img
+ nbd_server_stop
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+. ./common.nbd
+
+_supported_fmt qcow2
+_supported_proto file
+_supported_os Linux
+_require_command QEMU_NBD
+
+echo
+echo "=== Initial image setup ==="
+echo
+
+TEST_IMG="$TEST_IMG.base" _make_test_img 4M
+$QEMU_IO -c 'w 0 2M' -f $IMGFMT "$TEST_IMG.base" | _filter_qemu_io
+_make_test_img -b "$TEST_IMG.base" -F $IMGFMT 4M
+$QEMU_IO -c 'w 1M 2M' -f $IMGFMT "$TEST_IMG" | _filter_qemu_io
+
+echo
+echo "=== Check allocation over NBD ==="
+echo
+
+$QEMU_IMG map --output=json -f qcow2 "$TEST_IMG"
+IMG="driver=nbd,server.type=unix,server.path=$nbd_unix_socket"
+nbd_server_start_unix_socket -r -f qcow2 -A "$TEST_IMG"
+# Normal -f raw NBD block status loses access to allocation information
+$QEMU_IMG map --output=json --image-opts \
+ "$IMG" | _filter_qemu_img_map
+# But since we used -A, and use x-dirty-bitmap as a hack for reading bitmaps,
+# we can reconstruct it, by abusing block status to report:
+# NBD_STATE_DEPTH_UNALLOC => "zero":false, "data":true
+# NBD_STATE_DEPTH_LOCAL => "zero":false, "data":false
+# NBD_STATE_DEPTH_BACKING => "zero":true, "data":true
+$QEMU_IMG map --output=json --image-opts \
+ "$IMG,x-dirty-bitmap=qemu:allocation-depth" | _filter_qemu_img_map
+
+# success, all done
+echo '*** done'
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/309.out b/tests/qemu-iotests/309.out
new file mode 100644
index 000000000000..db75bb6b0df9
--- /dev/null
+++ b/tests/qemu-iotests/309.out
@@ -0,0 +1,22 @@
+QA output created by 309
+
+=== Initial image setup ===
+
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=4194304
+wrote 2097152/2097152 bytes at offset 0
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=4194304
backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
+wrote 2097152/2097152 bytes at offset 1048576
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+=== Check allocation over NBD ===
+
+[{ "start": 0, "length": 1048576, "depth": 1, "zero": false, "data": true,
"offset": 327680},
+{ "start": 1048576, "length": 2097152, "depth": 0, "zero": false, "data":
true, "offset": 327680},
+{ "start": 3145728, "length": 1048576, "depth": 1, "zero": true, "data":
false}]
+[{ "start": 0, "length": 3145728, "depth": 0, "zero": false, "data": true,
"offset": OFFSET},
+{ "start": 3145728, "length": 1048576, "depth": 0, "zero": true, "data":
false, "offset": OFFSET}]
+[{ "start": 0, "length": 1048576, "depth": 0, "zero": true, "data": true,
"offset": OFFSET},
+{ "start": 1048576, "length": 2097152, "depth": 0, "zero": false, "data":
false},
+{ "start": 3145728, "length": 1048576, "depth": 0, "zero": false, "data":
true, "offset": OFFSET}]
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 9e4f7c01530d..a567fa97d7e5 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -315,3 +315,4 @@
304 rw quick
305 rw quick
307 rw quick export
+309 rw auto quick
--
2.28.0
