From 621ea11b58562fff53d75fc343727c8007edba77 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Tue, 10 May 2011 12:53:51 +1000
Subject: [PATCH] Grow: handle abort/restart of grow while being monitored.

If a device fails while the grow is being monitored but the array is
still functional, the Grow will appear to abort and then almost
instantly restart from where it was up to.

So if it appears to abort, wait up to 10 seconds for a restart (it
should be much much less than this.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 Grow.c | 39 ++++++++++++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 9 deletions(-)

diff --git a/Grow.c b/Grow.c
index 0a08448..5840a2c 100644
--- a/Grow.c
+++ b/Grow.c
@@ -2625,10 +2625,9 @@ int progress_reshape(struct mdinfo *info, struct reshape *reshape,
 	if (fd < 0)
 		goto check_progress;
 
-	if (sysfs_fd_get_ll(fd, &completed) < 0) {
-		close(fd);
+	if (sysfs_fd_get_ll(fd, &completed) < 0)
 		goto check_progress;
-	}
+
 	while (completed < max_progress && completed < wait_point) {
 		/* Check that sync_action is still 'reshape' to avoid
 		 * waiting forever on a dead array
@@ -2653,10 +2652,8 @@ int progress_reshape(struct mdinfo *info, struct reshape *reshape,
 		FD_ZERO(&rfds);
 		FD_SET(fd, &rfds);
 		select(fd+1, NULL, NULL, &rfds, NULL);
-		if (sysfs_fd_get_ll(fd, &completed) < 0) {
-			close(fd);
+		if (sysfs_fd_get_ll(fd, &completed) < 0)
 			goto check_progress;
-		}
 	}
 	/* Some kernels reset 'sync_completed' to zero,
 	 * we need to have real point we are in md
@@ -2689,13 +2686,37 @@ check_progress:
 	/* if we couldn't read a number from sync_completed, then
 	 * either the reshape did complete, or it aborted.
 	 * We can tell which by checking for 'none' in reshape_position.
+	 * If it did abort, then it might immediately restart if it
+	 * it was just a device failure that leaves us degraded but
+	 * functioning.
 	 */
 	strcpy(buf, "hi");
 	if (sysfs_get_str(info, NULL, "reshape_position", buf, sizeof(buf)) < 0
-	    || strncmp(buf, "none", 4) != 0)
-		return -2; /* abort */
-	else {
+	    || strncmp(buf, "none", 4) != 0) {
+		/* The abort might only be temporary.  Wait up to 10
+		 * seconds for fd to contain a valid number again.
+		 */
+		struct timeval tv;
+		int rv = -2;
+		tv.tv_sec = 10;
+		tv.tv_usec = 0;
+		while (fd >= 0 && rv < 0) {
+			fd_set rfds;
+			FD_ZERO(&rfds);
+			FD_SET(fd, &rfds);
+			if (select(fd+1, NULL, NULL, &rfds, &tv) != 1)
+				break;
+			if (sysfs_fd_get_ll(fd, &completed) >= 0)
+				/* all good again */
+				rv = 1;
+		}
+		if (fd >= 0)
+			close(fd);
+		return rv; /* abort */
+	} else {
 		/* Maybe racing with array shutdown - check state */
+		if (fd >= 0)
+			close(fd);
 		if (sysfs_get_str(info, NULL, "array_state", buf, sizeof(buf)) < 0
 		    || strncmp(buf, "inactive", 8) == 0
 		    || strncmp(buf, "clear",5) == 0)