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authorEric Blake <eblake@redhat.com>2020-10-27 00:05:55 -0500
committerEric Blake <eblake@redhat.com>2020-10-30 15:22:00 -0500
commitdbc7b01492371e4a54b92d2b6d968f9b863cc794 (patch)
tree24812091f95b86d03192a23bec70e21d9a5b74eb
parent71719cd57fc02ddfd91a4a3ca3f469bfb4d221bc (diff)
downloadqemu-arm-dbc7b01492371e4a54b92d2b6d968f9b863cc794.tar.gz
nbd: Add 'qemu-nbd -A' to expose allocation depth
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 is hacked into viewing the key aspects of this new context by abusing the already-experimental x-dirty-bitmap option to collapse all depths greater than 2, which results in a tri-state value visible in the output of 'qemu-img map --output=json' (yes, that means x-dirty-bitmap is now a bit of a misnomer, but I didn't feel like renaming it as it would introduce a needless break of back-compat, even though we make no compat guarantees with x- members): unallocated (depth 0) => "zero":false, "data":true local (depth 1) => "zero":false, "data":false backing (depth 2+) => "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 <eblake@redhat.com> Message-Id: <20201027050556.269064-11-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
-rw-r--r--block/nbd.c26
-rw-r--r--docs/tools/qemu-nbd.rst8
-rw-r--r--nbd/server.c2
-rw-r--r--qapi/block-core.json7
-rw-r--r--qapi/block-export.json7
-rw-r--r--qemu-nbd.c12
-rwxr-xr-xtests/qemu-iotests/30977
-rw-r--r--tests/qemu-iotests/309.out22
-rw-r--r--tests/qemu-iotests/group1
9 files changed, 151 insertions, 11 deletions
diff --git a/block/nbd.c b/block/nbd.c
index 4548046cd7..42536702b6 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -135,6 +135,7 @@ typedef struct BDRVNBDState {
QCryptoTLSCreds *tlscreds;
const char *hostname;
char *x_dirty_bitmap;
+ bool alloc_depth;
bool wait_connect;
NBDConnectThread *connect_thread;
@@ -961,6 +962,16 @@ static int nbd_parse_blockstatus_payload(BDRVNBDState *s,
trace_nbd_parse_blockstatus_compliance("extent length too large");
}
+ /*
+ * HACK: if we are using x-dirty-bitmaps to access
+ * qemu:allocation-depth, treat all depths > 2 the same as 2,
+ * since nbd_client_co_block_status is only expecting the low two
+ * bits to be set.
+ */
+ if (s->alloc_depth && extent->flags > 2) {
+ extent->flags = 2;
+ }
+
return 0;
}
@@ -1795,11 +1806,16 @@ static int nbd_client_handshake(BlockDriverState *bs, QIOChannelSocket *sioc,
s->sioc = NULL;
return ret;
}
- if (s->x_dirty_bitmap && !s->info.base_allocation) {
- error_setg(errp, "requested x-dirty-bitmap %s not found",
- s->x_dirty_bitmap);
- ret = -EINVAL;
- goto fail;
+ if (s->x_dirty_bitmap) {
+ if (!s->info.base_allocation) {
+ error_setg(errp, "requested x-dirty-bitmap %s not found",
+ s->x_dirty_bitmap);
+ ret = -EINVAL;
+ goto fail;
+ }
+ if (strcmp(s->x_dirty_bitmap, "qemu:allocation-depth") == 0) {
+ s->alloc_depth = true;
+ }
}
if (s->info.flags & NBD_FLAG_READ_ONLY) {
ret = bdrv_apply_auto_read_only(bs, "NBD export is read-only", errp);
diff --git a/docs/tools/qemu-nbd.rst b/docs/tools/qemu-nbd.rst
index 667861cb22..fe41336dc5 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/nbd/server.c b/nbd/server.c
index ebbefcb6d3..d145e1a690 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1641,6 +1641,8 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args,
bdrv_dirty_bitmap_set_busy(exp->export_bitmaps[i], true);
}
+ 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/qapi/block-core.json b/qapi/block-core.json
index e00fc27b5e..1b8b4156b4 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -3905,9 +3905,12 @@
#
# @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 c4125f4d21..a9f488f99c 100644
--- a/qapi/block-export.json
+++ b/qapi/block-export.json
@@ -90,11 +90,16 @@
# the metadata context name "qemu:dirty-bitmap:BITMAP" to inspect
# each bitmap.
#
+# @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: 5.2
##
{ 'struct': 'BlockExportOptionsNbd',
'base': 'BlockExportOptionsNbdBase',
- 'data': { '*bitmaps': ['str'] } }
+ 'data': { '*bitmaps': ['str'], '*allocation-depth': 'bool' } }
##
# @BlockExportOptionsVhostUserBlk:
diff --git a/qemu-nbd.c b/qemu-nbd.c
index 74e73a7465..75ced65030 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -100,6 +100,7 @@ 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"
@@ -524,7 +525,7 @@ 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' },
@@ -533,6 +534,7 @@ 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' },
@@ -575,6 +577,7 @@ int main(int argc, char **argv)
const char *export_name = NULL; /* defaults to "" later for server mode */
const char *export_description = NULL;
strList *bitmaps = NULL;
+ bool alloc_depth = false;
const char *tlscredsid = NULL;
bool imageOpts = false;
bool writethrough = true;
@@ -689,6 +692,9 @@ int main(int argc, char **argv)
readonly = true;
flags &= ~BDRV_O_RDWR;
break;
+ case 'A':
+ alloc_depth = true;
+ break;
case 'B':
QAPI_LIST_PREPEND(bitmaps, g_strdup(optarg));
break;
@@ -787,7 +793,7 @@ int main(int argc, char **argv)
}
if (export_name || export_description || dev_offset ||
device || disconnect || fmt || sn_id_or_name || bitmaps ||
- seen_aio || seen_discard || seen_cache) {
+ alloc_depth || seen_aio || seen_discard || seen_cache) {
error_report("List mode is incompatible with per-device settings");
exit(EXIT_FAILURE);
}
@@ -1073,6 +1079,8 @@ int main(int argc, char **argv)
.description = g_strdup(export_description),
.has_bitmaps = !!bitmaps,
.bitmaps = bitmaps,
+ .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 0000000000..fb61157c2e
--- /dev/null
+++ b/tests/qemu-iotests/309
@@ -0,0 +1,77 @@
+#!/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 when we use -A, coupled with x-dirty-bitmap in the client for feeding
+# 2-bit block status from an alternative NBD metadata context (note that
+# the client code for x-dirty-bitmap intentionally collapses all depths
+# beyond 2 into a single value), we can determine:
+# unallocated (depth 0) => "zero":false, "data":true
+# local (depth 1) => "zero":false, "data":false
+# backing (depth 2+) => "zero":true, "data":true
+$QEMU_IMG map --output=json --image-opts \
+ "$IMG,x-dirty-bitmap=qemu:allocation-depth" | _filter_qemu_img_map
+# More accurate results can be obtained by other NBD clients such as
+# libnbd, but this test works without such external dependencies.
+
+# 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 0000000000..db75bb6b0d
--- /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 3432989283..2960dff728 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