fd935ce4c9
The three-way hand-off has a problem: there's no way to arrange for the state of the migration to be unambiguous in case of failure. If the final "disconnect" message is lost (as in, the destination never receives it whether it is sent by the sender or not), the destination has no option but to quit with an error status and let a human sort it out. However, at that point we can either arrange to have a .INCOMPLETE file still on disc or not - and it doesn't matter which we choose, we can still end up with dataloss by picking a specific calamity to have befallen the sender. Given this, it makes sense to fall back to a simpler protocol: just send all the data, then send a "disconnect" message. This has the same downside that we need a human to sort out specific failure cases, but combined with --unlink before sending "disconnect" (see next patch) it will always be possible for a human to disambiguate, whether the destination quit with an error status or not.
118 lines
3.1 KiB
C
118 lines
3.1 KiB
C
#ifndef SERVE_H
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#define SERVE_H
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#include <sys/types.h>
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#include <unistd.h>
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#include "flexnbd.h"
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#include "parse.h"
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#include "acl.h"
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static const int block_allocation_resolution = 4096;//128<<10;
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struct client_tbl_entry {
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pthread_t thread;
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union mysockaddr address;
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struct client * client;
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};
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#define MAX_NBD_CLIENTS 16
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struct server {
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/* The flexnbd wrapper this server is attached to */
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struct flexnbd * flexnbd;
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/** address/port to bind to */
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union mysockaddr bind_to;
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/** (static) file name to serve */
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char* filename;
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/** file name of INCOMPLETE flag */
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char* filename_incomplete;
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/** TCP backlog for listen() */
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int tcp_backlog;
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/** (static) file name of UNIX control socket (or NULL if none) */
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char* control_socket_name;
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/** size of file */
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uint64_t size;
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/** Claims around any I/O to this file */
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struct flexthread_mutex * l_io;
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/** to interrupt accept loop and clients, write() to close_signal[1] */
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struct self_pipe * close_signal;
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/** access control list */
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struct acl * acl;
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/** acl_updated_signal will be signalled after the acl struct
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* has been replaced
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*/
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struct self_pipe * acl_updated_signal;
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/* Claimed around any updates to the ACL. */
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struct flexthread_mutex * l_acl;
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struct mirror* mirror;
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struct mirror_super * mirror_super;
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int server_fd;
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int control_fd;
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struct bitset_mapping* allocation_map;
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int max_nbd_clients;
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struct client_tbl_entry *nbd_client;
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/* Marker for whether this server has control over the data in
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* the file, or if we're waiting to receive it from an inbound
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* migration which hasn't yet finished.
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*/
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int has_control;
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};
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struct server * server_create(
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struct flexnbd * flexnbd,
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char* s_ip_address,
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char* s_port,
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char* s_file,
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int default_deny,
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int acl_entries,
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char** s_acl_entries,
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int max_nbd_clients,
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int has_control );
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void server_destroy( struct server * );
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int server_is_closed(struct server* serve);
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void server_dirty(struct server *serve, off64_t from, int len);
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void server_lock_io( struct server * serve);
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void server_unlock_io( struct server* serve );
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void serve_signal_close( struct server *serve );
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void serve_wait_for_close( struct server * serve );
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void server_replace_acl( struct server *serve, struct acl * acl);
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void server_control_arrived( struct server *serve );
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int server_is_in_control( struct server *serve );
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int server_default_deny( struct server * serve );
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int server_io_locked( struct server * serve );
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int server_acl_locked( struct server * serve );
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void server_lock_acl( struct server *serve );
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void server_unlock_acl( struct server *serve );
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int server_is_mirroring( struct server * serve );
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void server_abandon_mirror( struct server * serve );
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void server_unlink( struct server * serve );
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int do_serve( struct server * );
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struct mode_readwrite_params {
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union mysockaddr connect_to;
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union mysockaddr connect_from;
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off64_t from;
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off64_t len;
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int data_fd;
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int client;
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};
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#endif
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