Rework sr_raid_sync(). XXX WIP!

Author: martelletto

sys/dev/softraid.c

@@ -4088,8 +4088,9 @@ sr_raid_start_stop(struct sr_workunit *wu)
 int
 sr_raid_sync(struct sr_workunit *wu)
 {
+	struct sr_workunit	*wup;
 	struct sr_discipline	*sd = wu->swu_dis;
-	int			ios = 0, rv = 0, retries = 15;
+	int			ios = 0, rv = ETIMEDOUT, retries = 15;
 
 	if (!(wu->swu_flags & SR_WUF_FAKE)) {
 		/* When we are not a fake sync we must not acount the sync
@@ -4100,41 +4101,59 @@ sr_raid_sync(struct sr_workunit *wu)
 		ios = 1;
 	}
 
-	mtx_enter(&sd->sd_wu_mtx);
-
 	DNPRINTF(SR_D_DIS, "%s: sr_raid_sync %d fake %d\n",
 	    DEVNAME(sd->sd_sc),
 	    sd->sd_wu_pending,
 	    wu->swu_flags & SR_WUF_FAKE);
 
-	/* diagnostic */
 	if (sd->sd_sync != 0) {
-		printf("sd->sd_sync != 0, called reentrant\n");
+		/* Sync in progress. Wait and return. */
+		return tsleep(&sd->sd_sync, PRIBIO | PCATCH, "sr_sync1", 0);
+	}
+
+	/*
+         * Mark the WUs we need to dispose of.
+         */
+	mtx_enter(&sd->sd_wu_mtx);
+        TAILQ_FOREACH(wup, &sd->sd_wu_pendq, swu_link) {
+		KASSERT((wup->swu_flags & SR_WUF_SEEN) == 0);
+		wup->swu_flags |= SR_WUF_SEEN;
 	}
 
 	sd->sd_sync = 1;
-	for (;;) {
+
+	while (retries-- > 0) {
+		/* Wait a bit for I/O to drain. */
+		msleep(sd, &sd->sd_wu_mtx, PWAIT, "sr_sync2", 1 * hz);
 		if (sd->sd_wu_pending <= ios) {
+			/* We can be sure all of the marked WUs are gone. */
+			rv = 0;
 			break;
 		}
-
-		/* wait a bit for io to drain */
-		if (msleep(sd, &sd->sd_wu_mtx, PWAIT, "sr_sync", 1 * hz) ==
-		    EWOULDBLOCK) {
-			if (retries-- > 0) {
+		TAILQ_FOREACH(wup, &sd->sd_wu_pendq, swu_link) {
+			if (wup->swu_flags & SR_WUF_SEEN) {
+				/*
+				 * One of the observed WUs is still around.
+				 * Try again.
+				 */
 				continue;
 			}
+		}
+		rv = 0;
+		break;
+	}
 
-			/* print timeout for now */
-			printf("%s: sr_raid_sync timeout\n",
-			    DEVNAME(sd->sd_sc));
+	if (rv != 0) {
+		/* print timeout for now */
+		printf("%s: sr_raid_sync timeout\n",
+		    DEVNAME(sd->sd_sc));
 
-			DNPRINTF(SR_D_DIS, "%s: sr_raid_sync timeout\n",
-			    DEVNAME(sd->sd_sc));
-			rv = 1;
-			break;
-		}
+		DNPRINTF(SR_D_DIS, "%s: sr_raid_sync timeout\n",
+		    DEVNAME(sd->sd_sc));
 	}
+
+	/* XXX TODO: DIOCCACHESYNC on the real disk(s) */
+
 	sd->sd_sync = 0;
 	mtx_leave(&sd->sd_wu_mtx);
 

sys/dev/softraidvar.h

@@ -387,6 +387,7 @@ struct sr_workunit {
 #define SR_WUF_WAKEUP		(1<<4)		/* Wakeup on I/O completion. */
 #define SR_WUF_DISCIPLINE	(1<<5)		/* Discipline specific I/O. */
 #define SR_WUF_FAKE		(1<<6)		/* Faked workunit. */
+#define SR_WUF_SEEN		(1<<7)		/* Observed during a sync. */
 
 	/* workunit io range */
 	daddr_t			swu_blk_start;