Support --assume-clean for --create

Signed-off-by: Neil Brown <neilb@suse.de>

ChangeLog

@@ -9,6 +9,7 @@ Changes Prior to this release
 	depending on context.
     -   Allow scanning of devices listed in /proc/partitions even
 	if they don't appear in /dev.
+    -   Support --assume-clean in --create mode as well as --build
 
 Changes Prior to 2.1 release
     -   Fix assembling of raid10 array when devices are missing.

Create.c

@@ -35,7 +35,7 @@ int Create(struct supertype *st, char *mddev, int mdfd,
 	   int chunk, int level, int layout, unsigned long size, int raiddisks, int sparedisks,
 	   char *name,
 	   int subdevs, mddev_dev_t devlist,
-	   int runstop, int verbose, int force,
+	   int runstop, int verbose, int force, int assume_clean,
 	   char *bitmap_file, int bitmap_chunk, int write_behind, int delay)
 {
 	/*
@@ -288,7 +288,7 @@ int Create(struct supertype *st, char *mddev, int mdfd,
 	 * as missing, so that a reconstruct happens (faster than re-parity)
 	 * FIX: Can we do this for raid6 as well?
 	 */
-	if (force == 0 && first_missing >= raiddisks) {
+	if (assume_clean==0 && force == 0 && first_missing >= raiddisks) {
 		switch ( level ) {
 		case 5:
 			insert_point = raiddisks-1;
@@ -318,6 +318,8 @@ int Create(struct supertype *st, char *mddev, int mdfd,
 	       (insert_point < raiddisks || first_missing < raiddisks) )
 	     ||
 	     ( level == 6 && missing_disks == 2)
+	     ||
+	     assume_clean
 		)
 		array.state = 1; /* clean, but one+ drive will be missing */
 	else

mdadm.8

@@ -476,9 +476,12 @@ which means to choose the largest size that fits on all current drives.
 .BR --assume-clean
 Tell
 .I mdadm
-that the array pre-existed and is known to be clean.  This is only
-really useful for Building RAID1 array.  Only use this if you really
-know what you are doing.  This is currently only supported for --build.
+that the array pre-existed and is known to be clean.  It can be useful
+when trying to recover from a major failure as you can be sure that no
+data will be affected unless you actually write to the array.  It can
+also be used when creating a RAID1 or RAID10 if you want to avoid the
+initial resync, however this practice - while normally safe - is not
+recommended.   Use this ony if you really know what you are doing.
 
 .TP
 .BR -N ", " --name=

mdadm.c

@@ -1002,7 +1002,7 @@ int main(int argc, char *argv[])
 
 		rv = Create(ss, devlist->devname, mdfd, chunk, level, layout, size<0 ? 0 : size,
 			    raiddisks, sparedisks, ident.name,
-			    devs_found-1, devlist->next, runstop, verbose-quiet, force,
+			    devs_found-1, devlist->next, runstop, verbose-quiet, force, assume_clean,
 			    bitmap_file, bitmap_chunk, write_behind, delay);
 		break;
 	case MISC:

mdadm.h

@@ -250,7 +250,7 @@ extern int Create(struct supertype *st, char *mddev, int mdfd,
 		  int chunk, int level, int layout, unsigned long size, int raiddisks, int sparedisks,
 		  char *name,
 		  int subdevs, mddev_dev_t devlist,
-		  int runstop, int verbose, int force,
+		  int runstop, int verbose, int force, int assume_clean,
 		  char *bitmap_file, int bitmap_chunk, int write_behind, int delay);
 
 extern int Detail(char *dev, int brief, int test);