Shriram Rajagopalan
2012-Feb-29 17:42 UTC
[PATCH 3 of 3 RESEND V5] libxl: refactor migrate_domain and generalize migrate_receive
# HG changeset patch
# User Shriram Rajagopalan <rshriram@cs.ubc.ca>
# Date 1330534783 28800
# Node ID b3faa2880bd3d05d0d515287f21597ac830bd13e
# Parent d2c0bd5c1b414465b1a370f89caceaa7ee6a8ba2
libxl: refactor migrate_domain and generalize migrate_receive
Refactor some tasks like establishing the migration channel,
initial migration protocol exchange into separate functions,
to facilitate re-use, when remus support is introduced. Also,
make migrate_receive generic (instead of resorting to stdin and
stdout as the file descriptors for communication).
Signed-off-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
diff -r d2c0bd5c1b41 -r b3faa2880bd3 tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c Wed Feb 29 08:59:36 2012 -0800
+++ b/tools/libxl/xl_cmdimpl.c Wed Feb 29 08:59:43 2012 -0800
@@ -2600,6 +2600,43 @@ static int save_domain(const char *p, co
exit(0);
}
+static pid_t create_migration_child(const char *rune, int *send_fd,
+ int *recv_fd)
+{
+ int sendpipe[2], recvpipe[2];
+ pid_t child = -1;
+
+ if (!rune || !send_fd || !recv_fd)
+ return -1;
+
+ MUST( libxl_pipe(ctx, sendpipe) );
+ MUST( libxl_pipe(ctx, recvpipe) );
+
+ child = libxl_fork(ctx);
+ if (child==-1) exit(1);
+
+ if (!child) {
+ dup2(sendpipe[0], 0);
+ dup2(recvpipe[1], 1);
+ close(sendpipe[0]); close(sendpipe[1]);
+ close(recvpipe[0]); close(recvpipe[1]);
+ execlp("sh","sh","-c",rune,(char*)0);
+ perror("failed to exec sh");
+ exit(-1);
+ }
+
+ close(sendpipe[0]);
+ close(recvpipe[1]);
+ *send_fd = sendpipe[1];
+ *recv_fd = recvpipe[0];
+
+ /* if receiver dies, we get an error and can clean up
+ rather than just dying */
+ signal(SIGPIPE, SIG_IGN);
+
+ return child;
+}
+
static int migrate_read_fixedmessage(int fd, const void *msg, int msgsz,
const char *what, const char *rune) {
char buf[msgsz];
@@ -2685,53 +2722,17 @@ static void migration_child_report(pid_t
migration_child = 0;
}
-static void migrate_domain(const char *domain_spec, const char *rune,
- const char *override_config_file)
+static void migrate_do_preamble(int send_fd, int recv_fd, pid_t child,
+ uint8_t *config_data, int config_len,
+ const char *rune)
{
- pid_t child = -1;
- int rc;
- int sendpipe[2], recvpipe[2];
- int send_fd, recv_fd;
- libxl_domain_suspend_info suspinfo;
- char *away_domname;
- char rc_buf;
- uint8_t *config_data;
- int config_len;
-
- save_domain_core_begin(domain_spec, override_config_file,
- &config_data, &config_len);
-
- if (!config_len) {
- fprintf(stderr, "No config file stored for running domain and
"
- "none supplied - cannot migrate.\n");
+ int rc = 0;
+
+ if (send_fd < 0 || recv_fd < 0) {
+ fprintf(stderr, "migrate_do_preamble: invalid file
descriptors\n");
exit(1);
}
- MUST( libxl_pipe(ctx, sendpipe) );
- MUST( libxl_pipe(ctx, recvpipe) );
-
- child = libxl_fork(ctx);
- if (child==-1) exit(1);
-
- if (!child) {
- dup2(sendpipe[0], 0);
- dup2(recvpipe[1], 1);
- close(sendpipe[0]); close(sendpipe[1]);
- close(recvpipe[0]); close(recvpipe[1]);
- execlp("sh","sh","-c",rune,(char*)0);
- perror("failed to exec sh");
- exit(-1);
- }
-
- close(sendpipe[0]);
- close(recvpipe[1]);
- send_fd = sendpipe[1];
- recv_fd = recvpipe[0];
-
- signal(SIGPIPE, SIG_IGN);
- /* if receiver dies, we get an error and can clean up
- rather than just dying */
-
rc = migrate_read_fixedmessage(recv_fd, migrate_receiver_banner,
sizeof(migrate_receiver_banner)-1,
"banner", rune);
@@ -2744,6 +2745,34 @@ static void migrate_domain(const char *d
save_domain_core_writeconfig(send_fd, "migration stream",
config_data, config_len);
+}
+
+static void migrate_domain(const char *domain_spec, const char *rune,
+ const char *override_config_file)
+{
+ pid_t child = -1;
+ int rc;
+ int send_fd = -1, recv_fd = -1;
+ libxl_domain_suspend_info suspinfo;
+ char *away_domname;
+ char rc_buf;
+ uint8_t *config_data;
+ int config_len;
+
+ save_domain_core_begin(domain_spec, override_config_file,
+ &config_data, &config_len);
+
+ if (!config_len) {
+ fprintf(stderr, "No config file stored for running domain and
"
+ "none supplied - cannot migrate.\n");
+ exit(1);
+ }
+
+ child = create_migration_child(rune, &send_fd, &recv_fd);
+
+ migrate_do_preamble(send_fd, recv_fd, child, config_data, config_len,
+ rune);
+
xtl_stdiostream_adjust_flags(logger, XTL_STDIOSTREAM_HIDE_PROGRESS, 0);
memset(&suspinfo, 0, sizeof(suspinfo));
@@ -2867,7 +2896,8 @@ static void core_dump_domain(const char
if (rc) { fprintf(stderr,"core dump failed
(rc=%d)\n",rc);exit(-1); }
}
-static void migrate_receive(int debug, int daemonize, int monitor)
+static void migrate_receive(int debug, int daemonize, int monitor,
+ int send_fd, int recv_fd)
{
int rc, rc2;
char rc_buf;
@@ -2879,7 +2909,7 @@ static void migrate_receive(int debug, i
fprintf(stderr, "migration target: Ready to receive domain.\n");
- CHK_ERRNO( libxl_write_exactly(ctx, 1,
+ CHK_ERRNO( libxl_write_exactly(ctx, send_fd,
migrate_receiver_banner,
sizeof(migrate_receiver_banner)-1,
"migration ack stream",
@@ -2891,7 +2921,7 @@ static void migrate_receive(int debug, i
dom_info.monitor = monitor;
dom_info.paused = 1;
dom_info.restore_file = "incoming migration stream";
- dom_info.migrate_fd = 0; /* stdin */
+ dom_info.migrate_fd = recv_fd;
dom_info.migration_domname_r = &migration_domname;
dom_info.no_incr_generationid = 1;
@@ -2905,13 +2935,13 @@ static void migrate_receive(int debug, i
fprintf(stderr, "migration target: Transfer complete,"
" requesting permission to start domain.\n");
- rc = libxl_write_exactly(ctx, 1,
+ rc = libxl_write_exactly(ctx, send_fd,
migrate_receiver_ready,
sizeof(migrate_receiver_ready),
"migration ack stream", "ready
message");
if (rc) exit(-rc);
- rc = migrate_read_fixedmessage(0, migrate_permission_to_go,
+ rc = migrate_read_fixedmessage(recv_fd, migrate_permission_to_go,
sizeof(migrate_permission_to_go),
"GO message", 0);
if (rc) goto perhaps_destroy_notify_rc;
@@ -2930,7 +2960,7 @@ static void migrate_receive(int debug, i
rc = 0;
perhaps_destroy_notify_rc:
- rc2 = libxl_write_exactly(ctx, 1,
+ rc2 = libxl_write_exactly(ctx, send_fd,
migrate_report, sizeof(migrate_report),
"migration ack stream",
"success/failure report");
@@ -2938,7 +2968,7 @@ static void migrate_receive(int debug, i
rc_buf = -rc;
assert(!!rc_buf == !!rc);
- rc2 = libxl_write_exactly(ctx, 1, &rc_buf, 1,
+ rc2 = libxl_write_exactly(ctx, send_fd, &rc_buf, 1,
"migration ack stream",
"success/failure code");
if (rc2) exit(-ERROR_BADFAIL);
@@ -2956,7 +2986,7 @@ static void migrate_receive(int debug, i
fprintf(stderr, "migration target: Cleanup OK, granting
sender"
" permission to resume.\n");
- rc2 = libxl_write_exactly(ctx, 1,
+ rc2 = libxl_write_exactly(ctx, send_fd,
migrate_permission_to_go,
sizeof(migrate_permission_to_go),
"migration ack stream",
@@ -3052,7 +3082,9 @@ int main_migrate_receive(int argc, char
help("migrate-receive");
return 2;
}
- migrate_receive(debug, daemonize, monitor);
+ migrate_receive(debug, daemonize, monitor,
+ STDOUT_FILENO, STDIN_FILENO);
+
return 0;
}