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authorEric Blake2020-10-27 06:05:52 +0100
committerEric Blake2020-10-30 21:10:15 +0100
commit3b1f244c59b7045680e615d50dc444a316abd891 (patch)
treeb4bddcd527010e7db1f162e842faa42e54d2f2a0 /nbd
parentnbd: Refactor counting of metadata contexts (diff)
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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 <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20201027050556.269064-8-eblake@redhat.com>
Diffstat (limited to 'nbd')
-rw-r--r--nbd/server.c100
1 files changed, 70 insertions, 30 deletions
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:<export bitmap name> */
+ bool *bitmaps; /*
+ * export qemu:dirty-bitmap:<export bitmap name>,
+ * 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;
}