From dbc7b01492371e4a54b92d2b6d968f9b863cc794 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Tue, 27 Oct 2020 00:05:55 -0500 Subject: [PATCH] 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 Message-Id: <20201027050556.269064-11-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy --- block/nbd.c | 26 ++++++++++--- docs/tools/qemu-nbd.rst | 8 +++- nbd/server.c | 2 + qapi/block-core.json | 7 +++- qapi/block-export.json | 7 +++- qemu-nbd.c | 12 +++++- tests/qemu-iotests/309 | 77 ++++++++++++++++++++++++++++++++++++++ tests/qemu-iotests/309.out | 22 +++++++++++ tests/qemu-iotests/group | 1 + 9 files changed, 151 insertions(+), 11 deletions(-) create mode 100755 tests/qemu-iotests/309 create mode 100644 tests/qemu-iotests/309.out 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 . +# + +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