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flexnbd: Disconnect clients at the start of a mirror last pass

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Currently, we prevent clients from processing requests by taking
the server I/O lock. This leads to requests hanging for a long
time before being terminated when the migration completes, which
is not ideal. With this change, at the start of the final pass,
existing clients are closed and any new connections will be closed
immediately (so no NBD server handshake will be seen).

This is part of the work required to remove remove the server I/O
lock completely.
This commit is contained in:
nick
2013-09-10 16:03:26 +01:00
parent 0494295705
commit 487bef1f40
3 changed files with 92 additions and 30 deletions
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64
src/serve.c
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@@ -40,6 +40,7 @@ struct server * server_create (
out->success = success;
out->max_nbd_clients = max_nbd_clients;
out->use_killswitch = use_killswitch;
out->allow_new_clients = 1;
out->nbd_client = xmalloc( max_nbd_clients * sizeof( struct client_tbl_entry ) );
out->tcp_backlog = 10; /* does this need to be settable? */
@@ -499,7 +500,7 @@ void server_audit_clients( struct server * serve)
* won't have been audited against the later acl. This isn't a
* problem though, because in order to update the acl
* server_replace_acl must have been called, so the
* server_accept ioop will see a second acl_updated signal as
* server_accept loop will see a second acl_updated signal as
* soon as it hits select, and a second audit will be run.
*/
for( i = 0; i < serve->max_nbd_clients; i++ ) {
@@ -664,8 +665,14 @@ int server_accept( struct server * params )
if ( FD_ISSET( params->server_fd, &fds ) ){
client_fd = accept( params->server_fd, &client_address.generic, &socklen );
debug("Accepted nbd client socket fd %d", client_fd);
accept_nbd_client(params, client_fd, &client_address);
if ( params->allow_new_clients ) {
debug("Accepted nbd client socket fd %d", client_fd);
accept_nbd_client(params, client_fd, &client_address);
} else {
debug( "New NBD client socket %d not allowed", client_fd );
sock_try_close( client_fd );
}
}
return should_continue;
@@ -735,6 +742,44 @@ void serve_init_allocation_map(struct server* params)
}
void server_forbid_new_clients( struct server * serve )
{
serve->allow_new_clients = 1;
return;
}
void server_close_and_join_clients( struct server * serve )
{
server_close_clients( serve );
}
void server_allow_new_clients( struct server * serve )
{
serve->allow_new_clients = 0;
return;
}
void server_join_clients( struct server * serve ) {
int i;
void* status;
for (i=0; i < serve->max_nbd_clients; i++) {
pthread_t thread_id = serve->nbd_client[i].thread;
int err = 0;
if (thread_id != 0) {
debug( "joining thread %p", thread_id );
if ( 0 == (err = pthread_join( thread_id, &status ) ) ) {
serve->nbd_client[i].thread = 0;
} else {
warn( "Error %s (%i) joining thread %p", strerror( err ), err, thread_id );
}
}
}
return;
}
/* Tell the server to close all the things. */
void serve_signal_close( struct server * serve )
{
@@ -775,12 +820,10 @@ void serve_cleanup(struct server* params,
int fatal __attribute__ ((unused)) )
{
NULLCHECK( params );
void* status;
info("cleaning up");
int i;
void* status;
if (params->server_fd){ close(params->server_fd); }
/* need to stop background build if we're killed very early on */
@@ -802,14 +845,7 @@ void serve_cleanup(struct server* params,
}
if ( need_mirror_lock ) { server_unlock_start_mirror( params ); }
for (i=0; i < params->max_nbd_clients; i++) {
pthread_t thread_id = params->nbd_client[i].thread;
if (thread_id != 0) {
debug("joining thread %p", thread_id);
pthread_join(thread_id, &status);
}
}
server_join_clients( params );
if ( server_start_mirror_locked( params ) ) {
server_unlock_start_mirror( params );