From 3b1f244c59b7045680e615d50dc444a316abd891 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Tue, 27 Oct 2020 00:05:52 -0500 Subject: nbd: Allow export of multiple bitmaps for one device With this, 'qemu-nbd -B b0 -B b1 -f qcow2 img.qcow2' can let you sniff out multiple bitmaps from one server. qemu-img as client can still only read one bitmap per client connection, but other NBD clients (hello libnbd) can now read multiple bitmaps in a single pass. Signed-off-by: Eric Blake Reviewed-by: Vladimir Sementsov-Ogievskiy Message-Id: <20201027050556.269064-8-eblake@redhat.com> --- nbd/server.c | 100 +++++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 70 insertions(+), 30 deletions(-) (limited to 'nbd') diff --git a/nbd/server.c b/nbd/server.c index 42d494bc96..b6841e4554 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -27,6 +27,7 @@ #include "qemu/units.h" #define NBD_META_ID_BASE_ALLOCATION 0 +/* Dirty bitmaps use 'NBD_META_ID_DIRTY_BITMAP + i', so keep this id last. */ #define NBD_META_ID_DIRTY_BITMAP 1 /* @@ -94,7 +95,8 @@ struct NBDExport { BlockBackend *eject_notifier_blk; Notifier eject_notifier; - BdrvDirtyBitmap *export_bitmap; + BdrvDirtyBitmap **export_bitmaps; + size_t nr_export_bitmaps; }; static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports); @@ -106,7 +108,10 @@ typedef struct NBDExportMetaContexts { NBDExport *exp; size_t count; /* number of negotiated contexts */ bool base_allocation; /* export base:allocation context (block status) */ - bool bitmap; /* export qemu:dirty-bitmap: */ + bool *bitmaps; /* + * export qemu:dirty-bitmap:, + * sized by exp->nr_export_bitmaps + */ } NBDExportMetaContexts; struct NBDClient { @@ -857,6 +862,8 @@ static bool nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta, static bool nbd_meta_qemu_query(NBDClient *client, NBDExportMetaContexts *meta, const char *query) { + size_t i; + if (!nbd_strshift(&query, "qemu:")) { return false; } @@ -864,24 +871,33 @@ static bool nbd_meta_qemu_query(NBDClient *client, NBDExportMetaContexts *meta, if (!*query) { if (client->opt == NBD_OPT_LIST_META_CONTEXT) { - meta->bitmap = !!meta->exp->export_bitmap; + memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps); } trace_nbd_negotiate_meta_query_parse("empty"); return true; } if (nbd_strshift(&query, "dirty-bitmap:")) { - const char *bm_name; - trace_nbd_negotiate_meta_query_parse("dirty-bitmap:"); - if (!meta->exp->export_bitmap) { - trace_nbd_negotiate_meta_query_skip("no dirty-bitmap exported"); + if (!*query) { + if (client->opt == NBD_OPT_LIST_META_CONTEXT) { + memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps); + } + trace_nbd_negotiate_meta_query_parse("empty"); return true; } - bm_name = bdrv_dirty_bitmap_name(meta->exp->export_bitmap); - if (nbd_meta_empty_or_pattern(client, bm_name, query)) { - meta->bitmap = true; + + for (i = 0; i < meta->exp->nr_export_bitmaps; i++) { + const char *bm_name; + + bm_name = bdrv_dirty_bitmap_name(meta->exp->export_bitmaps[i]); + if (strcmp(bm_name, query) == 0) { + meta->bitmaps[i] = true; + trace_nbd_negotiate_meta_query_parse(query); + return true; + } } + trace_nbd_negotiate_meta_query_skip("no dirty-bitmap match"); return true; } @@ -943,9 +959,10 @@ static int nbd_negotiate_meta_queries(NBDClient *client, { int ret; g_autofree char *export_name = NULL; - NBDExportMetaContexts local_meta; + g_autofree bool *bitmaps = NULL; + NBDExportMetaContexts local_meta = {0}; uint32_t nb_queries; - int i; + size_t i; size_t count = 0; if (!client->structured_reply) { @@ -960,6 +977,7 @@ static int nbd_negotiate_meta_queries(NBDClient *client, meta = &local_meta; } + g_free(meta->bitmaps); memset(meta, 0, sizeof(*meta)); ret = nbd_opt_read_name(client, &export_name, NULL, errp); @@ -974,6 +992,10 @@ static int nbd_negotiate_meta_queries(NBDClient *client, return nbd_opt_drop(client, NBD_REP_ERR_UNKNOWN, errp, "export '%s' not present", sane_name); } + meta->bitmaps = g_new0(bool, meta->exp->nr_export_bitmaps); + if (client->opt == NBD_OPT_LIST_META_CONTEXT) { + bitmaps = meta->bitmaps; + } ret = nbd_opt_read(client, &nb_queries, sizeof(nb_queries), false, errp); if (ret <= 0) { @@ -986,7 +1008,7 @@ static int nbd_negotiate_meta_queries(NBDClient *client, if (client->opt == NBD_OPT_LIST_META_CONTEXT && !nb_queries) { /* enable all known contexts */ meta->base_allocation = true; - meta->bitmap = !!meta->exp->export_bitmap; + memset(meta->bitmaps, 1, meta->exp->nr_export_bitmaps); } else { for (i = 0; i < nb_queries; ++i) { ret = nbd_negotiate_meta_query(client, meta, errp); @@ -1006,13 +1028,19 @@ static int nbd_negotiate_meta_queries(NBDClient *client, count++; } - if (meta->bitmap) { - const char *bm_name = bdrv_dirty_bitmap_name(meta->exp->export_bitmap); - g_autofree char *context = g_strdup_printf("qemu:dirty-bitmap:%s", - bm_name); + for (i = 0; i < meta->exp->nr_export_bitmaps; i++) { + const char *bm_name; + g_autofree char *context = NULL; + + if (!meta->bitmaps[i]) { + continue; + } + + bm_name = bdrv_dirty_bitmap_name(meta->exp->export_bitmaps[i]); + context = g_strdup_printf("qemu:dirty-bitmap:%s", bm_name); ret = nbd_negotiate_send_meta_context(client, context, - NBD_META_ID_DIRTY_BITMAP, + NBD_META_ID_DIRTY_BITMAP + i, errp); if (ret < 0) { return ret; @@ -1366,6 +1394,7 @@ void nbd_client_put(NBDClient *client) QTAILQ_REMOVE(&client->exp->clients, client, next); blk_exp_unref(&client->exp->common); } + g_free(client->export_meta.bitmaps); g_free(client); } } @@ -1482,6 +1511,7 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args, bool readonly = !exp_args->writable; bool shared = !exp_args->writable; strList *bitmaps; + size_t i; int ret; assert(exp_args->type == BLOCK_EXPORT_TYPE_NBD); @@ -1541,12 +1571,12 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args, } exp->size = QEMU_ALIGN_DOWN(size, BDRV_SECTOR_SIZE); - /* XXX Allow more than one bitmap */ - if (arg->bitmaps && arg->bitmaps->next) { - error_setg(errp, "multiple bitmaps per export not supported yet"); - return -EOPNOTSUPP; - } for (bitmaps = arg->bitmaps; bitmaps; bitmaps = bitmaps->next) { + exp->nr_export_bitmaps++; + } + exp->export_bitmaps = g_new0(BdrvDirtyBitmap *, exp->nr_export_bitmaps); + for (i = 0, bitmaps = arg->bitmaps; bitmaps; + i++, bitmaps = bitmaps->next) { const char *bitmap = bitmaps->value; BlockDriverState *bs = blk_bs(blk); BdrvDirtyBitmap *bm = NULL; @@ -1580,11 +1610,15 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args, goto fail; } - bdrv_dirty_bitmap_set_busy(bm, true); - exp->export_bitmap = bm; + exp->export_bitmaps[i] = bm; assert(strlen(bitmap) <= BDRV_BITMAP_MAX_NAME_SIZE); } + /* Mark bitmaps busy in a separate loop, to simplify roll-back concerns. */ + for (i = 0; i < exp->nr_export_bitmaps; i++) { + bdrv_dirty_bitmap_set_busy(exp->export_bitmaps[i], true); + } + blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp); QTAILQ_INSERT_TAIL(&exports, exp, next); @@ -1592,6 +1626,7 @@ static int nbd_export_create(BlockExport *blk_exp, BlockExportOptions *exp_args, return 0; fail: + g_free(exp->export_bitmaps); g_free(exp->name); g_free(exp->description); return ret; @@ -1641,6 +1676,7 @@ static void nbd_export_request_shutdown(BlockExport *blk_exp) static void nbd_export_delete(BlockExport *blk_exp) { + size_t i; NBDExport *exp = container_of(blk_exp, NBDExport, common); assert(exp->name == NULL); @@ -1658,8 +1694,8 @@ static void nbd_export_delete(BlockExport *blk_exp) blk_aio_detach, exp); } - if (exp->export_bitmap) { - bdrv_dirty_bitmap_set_busy(exp->export_bitmap, false); + for (i = 0; i < exp->nr_export_bitmaps; i++) { + bdrv_dirty_bitmap_set_busy(exp->export_bitmaps[i], false); } } @@ -2268,6 +2304,7 @@ static coroutine_fn int nbd_handle_request(NBDClient *client, int flags; NBDExport *exp = client->exp; char *msg; + size_t i; switch (request->type) { case NBD_CMD_CACHE: @@ -2358,12 +2395,15 @@ static coroutine_fn int nbd_handle_request(NBDClient *client, } } - if (client->export_meta.bitmap) { + for (i = 0; i < client->exp->nr_export_bitmaps; i++) { + if (!client->export_meta.bitmaps[i]) { + continue; + } ret = nbd_co_send_bitmap(client, request->handle, - client->exp->export_bitmap, + client->exp->export_bitmaps[i], request->from, request->len, dont_fragment, !--contexts_remaining, - NBD_META_ID_DIRTY_BITMAP, errp); + NBD_META_ID_DIRTY_BITMAP + i, errp); if (ret < 0) { return ret; } -- cgit v1.2.1