libzfs: sendrecv: always start the progress thread, but not the timer

Current semantics are preserved, /except/ no-flag "zfs send" can now
receive SIGUSR1/SIGINFO will write the progress.

Closes: https://101010.pl/@[email protected]/110731819189629373
Signed-off-by: Ahelenia Ziemiańska <[email protected]>

Author: nabijaczleweli

lib/libzfs/libzfs_sendrecv.c

@@ -928,16 +928,24 @@ zfs_send_progress(zfs_handle_t *zhp, int fd, uint64_t *bytes_written,
 	return (0);
 }
 
+static volatile boolean_t send_progress_thread_signal_duetotimer;
 static void
-signal_nop(int sig)
+send_progress_thread_act(int sig, siginfo_t *info, void *ucontext)
 {
-	(void) sig;
+	(void) sig, (void) ucontext;
+	send_progress_thread_signal_duetotimer = info->si_code == SI_TIMER;
 }
 
+struct timer_desirability {
+	timer_t timer;
+	boolean_t desired;
+};
 static void
 timer_delete_cleanup(void *timer)
 {
-	timer_delete(timer);
+	struct timer_desirability *td = timer;
+	if (td->desired)
+		timer_delete(td->timer);
 }
 
 #ifdef SIGINFO
@@ -967,22 +975,24 @@ send_progress_thread(void *arg)
 	int err;
 
 	const struct sigaction signal_action =
-	    {.sa_handler = signal_nop};
+	    {.sa_sigaction = send_progress_thread_act, .sa_flags = SA_SIGINFO};
 	struct sigevent timer_cfg =
 	    {.sigev_notify = SIGEV_SIGNAL, .sigev_signo = SIGUSR1};
 	const struct itimerspec timer_time =
 	    {.it_value = {.tv_sec = 1}, .it_interval = {.tv_sec = 1}};
-	timer_t timer;
+	struct timer_desirability timer = {};
 
 	sigaction(SIGUSR1, &signal_action, NULL);
 #ifdef SIGINFO
 	sigaction(SIGINFO, &signal_action, NULL);
 #endif
 
-	if (timer_create(CLOCK_MONOTONIC, &timer_cfg, &timer))
-		return ((void *)(uintptr_t)errno);
-	pthread_cleanup_push(timer_delete_cleanup, timer);
-	(void) timer_settime(timer, 0, &timer_time, NULL);
+	if ((timer.desired = pa->pa_progress || pa->pa_astitle)) {
+		if (timer_create(CLOCK_MONOTONIC, &timer_cfg, &timer.timer))
+			return ((void *)(uintptr_t)errno);
+		(void) timer_settime(timer.timer, 0, &timer_time, NULL);
+	}
+	pthread_cleanup_push(timer_delete_cleanup, &timer);
 
 	if (!pa->pa_parsable && pa->pa_progress) {
 		(void) fprintf(stderr,
@@ -1033,7 +1043,8 @@ send_progress_thread(void *arg)
 			(void) fprintf(stderr, "%02d:%02d:%02d\t%llu\t%s\n",
 			    tm.tm_hour, tm.tm_min, tm.tm_sec,
 			    (u_longlong_t)bytes, zhp->zfs_name);
-		} else if (pa->pa_progress) {
+		} else if (pa->pa_progress ||
+		    !send_progress_thread_signal_duetotimer) {
 			zfs_nicebytes(bytes, buf, sizeof (buf));
 			(void) fprintf(stderr, "%02d:%02d:%02d   %5s   %s\n",
 			    tm.tm_hour, tm.tm_min, tm.tm_sec,
@@ -1246,7 +1257,7 @@ dump_snapshot(zfs_handle_t *zhp, void *arg)
 		 * poll ZFS_IOC_SEND_PROGRESS at a regular interval.
 		 */
 		sigset_t oldmask;
-		if (sdd->progress || sdd->progressastitle) {
+		{
 			pa.pa_zhp = zhp;
 			pa.pa_fd = sdd->outfd;
 			pa.pa_parsable = sdd->parsable;
@@ -1267,8 +1278,7 @@ dump_snapshot(zfs_handle_t *zhp, void *arg)
 		err = dump_ioctl(zhp, sdd->prevsnap, sdd->prevsnap_obj,
 		    fromorigin, sdd->outfd, flags, sdd->debugnv);
 
-		if ((sdd->progress || sdd->progressastitle) &&
-		    send_progress_thread_exit(zhp->zfs_hdl, tid, &oldmask))
+		if (send_progress_thread_exit(zhp->zfs_hdl, tid, &oldmask))
 			return (-1);
 	}
 
@@ -1612,7 +1622,7 @@ estimate_size(zfs_handle_t *zhp, const char *from, int fd, sendflags_t *flags,
 	pthread_t ptid;
 	sigset_t oldmask;
 
-	if (flags->progress || flags->progressastitle) {
+	{
 		pa.pa_zhp = zhp;
 		pa.pa_fd = fd;
 		pa.pa_parsable = flags->parsable;
@@ -1634,8 +1644,7 @@ estimate_size(zfs_handle_t *zhp, const char *from, int fd, sendflags_t *flags,
 	    redactbook, fd, &size);
 	*sizep = size;
 
-	if ((flags->progress || flags->progressastitle) &&
-	    send_progress_thread_exit(zhp->zfs_hdl, ptid, &oldmask))
+	if (send_progress_thread_exit(zhp->zfs_hdl, ptid, &oldmask))
 		return (-1);
 
 	if (!flags->progress && !flags->parsable)
@@ -1931,7 +1940,7 @@ zfs_send_resume_impl_cb_impl(libzfs_handle_t *hdl, sendflags_t *flags,
 		 * If progress reporting is requested, spawn a new thread to
 		 * poll ZFS_IOC_SEND_PROGRESS at a regular interval.
 		 */
-		if (flags->progress || flags->progressastitle) {
+		{
 			pa.pa_zhp = zhp;
 			pa.pa_fd = outfd;
 			pa.pa_parsable = flags->parsable;
@@ -1957,8 +1966,7 @@ zfs_send_resume_impl_cb_impl(libzfs_handle_t *hdl, sendflags_t *flags,
 		if (redact_book != NULL)
 			free(redact_book);
 
-		if ((flags->progressastitle || flags->progress) &&
-		    send_progress_thread_exit(hdl, tid, &oldmask)) {
+		if (send_progress_thread_exit(hdl, tid, &oldmask)) {
 			zfs_close(zhp);
 			return (-1);
 		}
@@ -2744,7 +2752,7 @@ zfs_send_one_cb_impl(zfs_handle_t *zhp, const char *from, int fd,
 	 * ZFS_IOC_SEND_PROGRESS at a regular interval.
 	 */
 	sigset_t oldmask;
-	if (flags->progress || flags->progressastitle) {
+	{
 		pa.pa_zhp = zhp;
 		pa.pa_fd = fd;
 		pa.pa_parsable = flags->parsable;
@@ -2767,8 +2775,7 @@ zfs_send_one_cb_impl(zfs_handle_t *zhp, const char *from, int fd,
 	err = lzc_send_redacted(name, from, fd,
 	    lzc_flags_from_sendflags(flags), redactbook);
 
-	if ((flags->progress || flags->progressastitle) &&
-	    send_progress_thread_exit(hdl, ptid, &oldmask))
+	if (send_progress_thread_exit(hdl, ptid, &oldmask))
 			return (-1);
 
 	if (err == 0 && (flags->props || flags->holds || flags->backup)) {

man/man8/zfs-send.8

@@ -29,7 +29,7 @@
 .\" Copyright 2018 Nexenta Systems, Inc.
 .\" Copyright 2019 Joyent, Inc.
 .\"
-.Dd January 12, 2023
+.Dd July 27, 2023
 .Dt ZFS-SEND 8
 .Os
 .
@@ -297,6 +297,12 @@ This flag can only be used in conjunction with
 .It Fl v , -verbose
 Print verbose information about the stream package generated.
 This information includes a per-second report of how much data has been sent.
+The same report can be requested by sending
+.Dv SIGINFO
+or
+.Dv SIGUSR1 ,
+regardless of
+.Fl v .
 .Pp
 The format of the stream is committed.
 You will be able to receive your streams on future versions of ZFS.
@@ -433,6 +439,12 @@ and the verbose output goes to standard error
 .It Fl v , -verbose
 Print verbose information about the stream package generated.
 This information includes a per-second report of how much data has been sent.
+The same report can be requested by sending
+.Dv SIGINFO
+or
+.Dv SIGUSR1 ,
+regardless of
+.Fl v .
 .El
 .It Xo
 .Nm zfs
@@ -669,6 +681,10 @@ ones on the source, and are ready to be used, while the parent snapshot on the
 target contains none of the username and password data present on the source,
 because it was removed by the redacted send operation.
 .
+.Sh SIGNALS
+See
+.Fl v .
+.
 .Sh EXAMPLES
 .\" These are, respectively, examples 12, 13 from zfs.8
 .\" Make sure to update them bidirectionally