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nbd: Refactor counting of metadata contexts 

Rather than open-code the count of negotiated contexts at several
sites, embed it directly into the struct.  This will make it easier
for upcoming commits to support even more simultaneous contexts.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20201027050556.269064-7-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
This commit is contained in:
Eric Blake 2020-10-27 00:05:51 -05:00
parent 02e87e3b1c
commit 47ec485e8d
1 changed files with 15 additions and 11 deletions
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26
nbd/server.c
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@ -104,8 +104,7 @@ static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
* NBD_OPT_LIST_META_CONTEXT. */
typedef struct NBDExportMetaContexts {
NBDExport *exp;
bool valid; /* means that negotiation of the option finished without
errors */
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> */
} NBDExportMetaContexts;
@ -445,7 +444,9 @@ static int nbd_negotiate_handle_list(NBDClient *client, Error **errp)
static void nbd_check_meta_export(NBDClient *client)
{
client->export_meta.valid &= client->exp == client->export_meta.exp;
if (client->exp != client->export_meta.exp) {
client->export_meta.count = 0;
}
}
/* Send a reply to NBD_OPT_EXPORT_NAME.
@ -945,6 +946,7 @@ static int nbd_negotiate_meta_queries(NBDClient *client,
NBDExportMetaContexts local_meta;
uint32_t nb_queries;
int i;
size_t count = 0;
if (!client->structured_reply) {
return nbd_opt_invalid(client, errp,
@ -1001,6 +1003,7 @@ static int nbd_negotiate_meta_queries(NBDClient *client,
if (ret < 0) {
return ret;
}
count++;
}
if (meta->bitmap) {
@ -1014,11 +1017,12 @@ static int nbd_negotiate_meta_queries(NBDClient *client,
if (ret < 0) {
return ret;
}
count++;
}
ret = nbd_negotiate_send_rep(client, NBD_REP_ACK, errp);
if (ret == 0) {
meta->valid = true;
meta->count = count;
}
return ret;
@ -2337,18 +2341,16 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
return nbd_send_generic_reply(client, request->handle, -EINVAL,
"need non-zero length", errp);
}
if (client->export_meta.valid &&
(client->export_meta.base_allocation ||
client->export_meta.bitmap))
{
if (client->export_meta.count) {
bool dont_fragment = request->flags & NBD_CMD_FLAG_REQ_ONE;
int contexts_remaining = client->export_meta.count;
if (client->export_meta.base_allocation) {
ret = nbd_co_send_block_status(client, request->handle,
blk_bs(exp->common.blk),
request->from,
request->len, dont_fragment,
!client->export_meta.bitmap,
!--contexts_remaining,
NBD_META_ID_BASE_ALLOCATION,
errp);
if (ret < 0) {
@ -2360,13 +2362,15 @@ static coroutine_fn int nbd_handle_request(NBDClient *client,
ret = nbd_co_send_bitmap(client, request->handle,
client->exp->export_bitmap,
request->from, request->len,
dont_fragment,
true, NBD_META_ID_DIRTY_BITMAP, errp);
dont_fragment, !--contexts_remaining,
NBD_META_ID_DIRTY_BITMAP, errp);
if (ret < 0) {
return ret;
}
}
assert(!contexts_remaining);
return 0;
} else {
return nbd_send_generic_reply(client, request->handle, -EINVAL,