From ce52f92f047a1d95246b20c091e2cc342af919bf Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.de>
Date: Mon, 16 May 2011 17:28:27 +1000
Subject: [PATCH] Grow: accept --assume-clean with --grow --size

When an array is resized to have larger members, --assume-clean will
disable any resync if the kernel supports it (2.6.40 and later).

Signed-off-by: NeilBrown <neilb@suse.de>
---
 Grow.c     | 10 +++++++++-
 mdadm.8.in |  7 +++++++
 mdadm.c    |  3 ++-
 mdadm.h    |  2 +-
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/Grow.c b/Grow.c
index 1e1e9f8..62622bd 100644
--- a/Grow.c
+++ b/Grow.c
@@ -1293,7 +1293,7 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
 		 long long size,
 		 int level, char *layout_str, int chunksize, int raid_disks,
 		 struct mddev_dev *devlist,
-		 int force)
+		 int assume_clean, int force)
 {
 	/* Make some changes in the shape of an array.
 	 * The kernel must support the change.
@@ -1491,6 +1491,14 @@ int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
 			rv = 1;
 			goto release;
 		}
+		if (assume_clean) {
+			/* This will fail on kernels newer than 2.6.40 unless
+			 * a backport has been arranged.
+			 */
+			if (sra == NULL ||
+			    sysfs_set_str(sra, NULL, "resync_start", "none") < 0)
+				fprintf(stderr, Name ": --assume-clean not support with --grow on this kernel\n");
+		}
 		ioctl(fd, GET_ARRAY_INFO, &array);
 		size = get_component_size(fd)/2;
 		if (size == 0)
diff --git a/mdadm.8.in b/mdadm.8.in
index 3fbfcce..e1d5651 100644
--- a/mdadm.8.in
+++ b/mdadm.8.in
@@ -702,6 +702,13 @@ with zeros before creation the operator knows the array is
 actually clean. If that is the case, such as after running
 badblocks, this argument can be used to tell mdadm the
 facts the operator knows.
+.IP
+When an array is resized to a larger size with
+.B "\-\-grow \-\-size="
+the new space is normally resynced in that same way that the whole
+array is resynced at creation.  From Linux version 2.6.40,
+.B \-\-assume\-clean
+can be used with that command to avoid the automatic resync.
 
 .TP
 .BR \-\-backup\-file=
diff --git a/mdadm.c b/mdadm.c
index d55e9cf..fb51051 100644
--- a/mdadm.c
+++ b/mdadm.c
@@ -542,6 +542,7 @@ int main(int argc, char *argv[])
 
 		case O(CREATE,AssumeClean):
 		case O(BUILD,AssumeClean): /* assume clean */
+		case O(GROW,AssumeClean):
 			assume_clean = 1;
 			continue;
 
@@ -1637,7 +1638,7 @@ int main(int argc, char *argv[])
 			rv = Grow_reshape(devlist->devname, mdfd, quiet, backup_file,
 					  size, level, layout_str, chunk, raiddisks,
 					  devlist->next,
-					  force);
+					  assume_clean, force);
 		} else if (array_size < 0)
 			fprintf(stderr, Name ": no changes to --grow\n");
 		break;
diff --git a/mdadm.h b/mdadm.h
index 8277594..9437d04 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -1013,7 +1013,7 @@ extern int Grow_reshape(char *devname, int fd, int quiet, char *backup_file,
 			long long size,
 			int level, char *layout_str, int chunksize, int raid_disks,
 			struct mddev_dev *devlist,
-			int force);
+			int assume_clean, int force);
 extern int Grow_restart(struct supertype *st, struct mdinfo *info,
 			int *fdlist, int cnt, char *backup_file, int verbose);
 extern int Grow_continue(int mdfd, struct supertype *st,