Adding upstream version 4.2.upstream/4.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 5229 insertions, 0 deletions

diff --git a/Grow.c b/Grow.c
new file mode 100644
index 0000000..9c6fc95
--- /dev/null
+++ b/Grow.c
@@ -0,0 +1,5229 @@
+/*
+ * mdadm - manage Linux "md" devices aka RAID arrays.
+ *
+ * Copyright (C) 2001-2013 Neil Brown <neilb@suse.de>
+ *
+ *
+ *    This program is free software; you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation; either version 2 of the License, or
+ *    (at your option) any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program; if not, write to the Free Software
+ *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *    Author: Neil Brown
+ *    Email: <neilb@suse.de>
+ */
+#include	"mdadm.h"
+#include	"dlink.h"
+#include	<sys/mman.h>
+#include	<stddef.h>
+#include	<stdint.h>
+#include	<signal.h>
+#include	<sys/wait.h>
+
+#if ! defined(__BIG_ENDIAN) && ! defined(__LITTLE_ENDIAN)
+#error no endian defined
+#endif
+#include	"md_u.h"
+#include	"md_p.h"
+
+int restore_backup(struct supertype *st,
+		   struct mdinfo *content,
+		   int working_disks,
+		   int next_spare,
+		   char **backup_filep,
+		   int verbose)
+{
+	int i;
+	int *fdlist;
+	struct mdinfo *dev;
+	int err;
+	int disk_count = next_spare + working_disks;
+	char *backup_file = *backup_filep;
+
+	dprintf("Called restore_backup()\n");
+	fdlist = xmalloc(sizeof(int) * disk_count);
+
+	enable_fds(next_spare);
+	for (i = 0; i < next_spare; i++)
+		fdlist[i] = -1;
+	for (dev = content->devs; dev; dev = dev->next) {
+		char buf[22];
+		int fd;
+
+		sprintf(buf, "%d:%d", dev->disk.major, dev->disk.minor);
+		fd = dev_open(buf, O_RDWR);
+
+		if (dev->disk.raid_disk >= 0)
+			fdlist[dev->disk.raid_disk] = fd;
+		else
+			fdlist[next_spare++] = fd;
+	}
+
+	if (!backup_file) {
+		backup_file = locate_backup(content->sys_name);
+		*backup_filep = backup_file;
+	}
+
+	if (st->ss->external && st->ss->recover_backup)
+		err = st->ss->recover_backup(st, content);
+	else
+		err = Grow_restart(st, content, fdlist, next_spare,
+				   backup_file, verbose > 0);
+
+	while (next_spare > 0) {
+		next_spare--;
+		if (fdlist[next_spare] >= 0)
+			close(fdlist[next_spare]);
+	}
+	free(fdlist);
+	if (err) {
+		pr_err("Failed to restore critical section for reshape - sorry.\n");
+		if (!backup_file)
+			pr_err("Possibly you need to specify a --backup-file\n");
+		return 1;
+	}
+
+	dprintf("restore_backup() returns status OK.\n");
+	return 0;
+}
+
+int Grow_Add_device(char *devname, int fd, char *newdev)
+{
+	/* Add a device to an active array.
+	 * Currently, just extend a linear array.
+	 * This requires writing a new superblock on the
+	 * new device, calling the kernel to add the device,
+	 * and if that succeeds, update the superblock on
+	 * all other devices.
+	 * This means that we need to *find* all other devices.
+	 */
+	struct mdinfo info;
+
+	dev_t rdev;
+	int nfd, fd2;
+	int d, nd;
+	struct supertype *st = NULL;
+	char *subarray = NULL;
+
+	if (md_get_array_info(fd, &info.array) < 0) {
+		pr_err("cannot get array info for %s\n", devname);
+		return 1;
+	}
+
+	if (info.array.level != -1) {
+		pr_err("can only add devices to linear arrays\n");
+		return 1;
+	}
+
+	st = super_by_fd(fd, &subarray);
+	if (!st) {
+		pr_err("cannot handle arrays with superblock version %d\n",
+		       info.array.major_version);
+		return 1;
+	}
+
+	if (subarray) {
+		pr_err("Cannot grow linear sub-arrays yet\n");
+		free(subarray);
+		free(st);
+		return 1;
+	}
+
+	nfd = open(newdev, O_RDWR|O_EXCL|O_DIRECT);
+	if (nfd < 0) {
+		pr_err("cannot open %s\n", newdev);
+		free(st);
+		return 1;
+	}
+	if (!fstat_is_blkdev(nfd, newdev, &rdev)) {
+		close(nfd);
+		free(st);
+		return 1;
+	}
+	/* now check out all the devices and make sure we can read the
+	 * superblock */
+	for (d=0 ; d < info.array.raid_disks ; d++) {
+		mdu_disk_info_t disk;
+		char *dv;
+
+		st->ss->free_super(st);
+
+		disk.number = d;
+		if (md_get_disk_info(fd, &disk) < 0) {
+			pr_err("cannot get device detail for device %d\n", d);
+			close(nfd);
+			free(st);
+			return 1;
+		}
+		dv = map_dev(disk.major, disk.minor, 1);
+		if (!dv) {
+			pr_err("cannot find device file for device %d\n", d);
+			close(nfd);
+			free(st);
+			return 1;
+		}
+		fd2 = dev_open(dv, O_RDWR);
+		if (fd2 < 0) {
+			pr_err("cannot open device file %s\n", dv);
+			close(nfd);
+			free(st);
+			return 1;
+		}
+
+		if (st->ss->load_super(st, fd2, NULL)) {
+			pr_err("cannot find super block on %s\n", dv);
+			close(nfd);
+			close(fd2);
+			free(st);
+			return 1;
+		}
+		close(fd2);
+	}
+	/* Ok, looks good. Lets update the superblock and write it out to
+	 * newdev.
+	 */
+
+	info.disk.number = d;
+	info.disk.major = major(rdev);
+	info.disk.minor = minor(rdev);
+	info.disk.raid_disk = d;
+	info.disk.state = (1 << MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE);
+	if (st->ss->update_super(st, &info, "linear-grow-new", newdev,
+				 0, 0, NULL) != 0) {
+		pr_err("Preparing new metadata failed on %s\n", newdev);
+		close(nfd);
+		return 1;
+	}
+
+	if (st->ss->store_super(st, nfd)) {
+		pr_err("Cannot store new superblock on %s\n", newdev);
+		close(nfd);
+		return 1;
+	}
+	close(nfd);
+
+	if (ioctl(fd, ADD_NEW_DISK, &info.disk) != 0) {
+		pr_err("Cannot add new disk to this array\n");
+		return 1;
+	}
+	/* Well, that seems to have worked.
+	 * Now go through and update all superblocks
+	 */
+
+	if (md_get_array_info(fd, &info.array) < 0) {
+		pr_err("cannot get array info for %s\n", devname);
+		return 1;
+	}
+
+	nd = d;
+	for (d=0 ; d < info.array.raid_disks ; d++) {
+		mdu_disk_info_t disk;
+		char *dv;
+
+		disk.number = d;
+		if (md_get_disk_info(fd, &disk) < 0) {
+			pr_err("cannot get device detail for device %d\n", d);
+			return 1;
+		}
+		dv = map_dev(disk.major, disk.minor, 1);
+		if (!dv) {
+			pr_err("cannot find device file for device %d\n", d);
+			return 1;
+		}
+		fd2 = dev_open(dv, O_RDWR);
+		if (fd2 < 0) {
+			pr_err("cannot open device file %s\n", dv);
+			return 1;
+		}
+		if (st->ss->load_super(st, fd2, NULL)) {
+			pr_err("cannot find super block on %s\n", dv);
+			close(fd);
+			close(fd2);
+			return 1;
+		}
+		info.array.raid_disks = nd+1;
+		info.array.nr_disks = nd+1;
+		info.array.active_disks = nd+1;
+		info.array.working_disks = nd+1;
+
+		if (st->ss->update_super(st, &info, "linear-grow-update", dv,
+				     0, 0, NULL) != 0) {
+			pr_err("Updating metadata failed on %s\n", dv);
+			close(fd2);
+			return 1;
+		}
+
+		if (st->ss->store_super(st, fd2)) {
+			pr_err("Cannot store new superblock on %s\n", dv);
+			close(fd2);
+			return 1;
+		}
+		close(fd2);
+	}
+
+	return 0;
+}
+
+int Grow_addbitmap(char *devname, int fd, struct context *c, struct shape *s)
+{
+	/*
+	 * First check that array doesn't have a bitmap
+	 * Then create the bitmap
+	 * Then add it
+	 *
+	 * For internal bitmaps, we need to check the version,
+	 * find all the active devices, and write the bitmap block
+	 * to all devices
+	 */
+	mdu_bitmap_file_t bmf;
+	mdu_array_info_t array;
+	struct supertype *st;
+	char *subarray = NULL;
+	int major = BITMAP_MAJOR_HI;
+	unsigned long long bitmapsize, array_size;
+	struct mdinfo *mdi;
+
+	/*
+	 * We only ever get called if s->bitmap_file is != NULL, so this check
+	 * is just here to quiet down static code checkers.
+	 */
+	if (!s->bitmap_file)
+		return 1;
+
+	if (strcmp(s->bitmap_file, "clustered") == 0)
+		major = BITMAP_MAJOR_CLUSTERED;
+
+	if (ioctl(fd, GET_BITMAP_FILE, &bmf) != 0) {
+		if (errno == ENOMEM)
+			pr_err("Memory allocation failure.\n");
+		else
+			pr_err("bitmaps not supported by this kernel.\n");
+		return 1;
+	}
+	if (bmf.pathname[0]) {
+		if (strcmp(s->bitmap_file,"none") == 0) {
+			if (ioctl(fd, SET_BITMAP_FILE, -1) != 0) {
+				pr_err("failed to remove bitmap %s\n",
+					bmf.pathname);
+				return 1;
+			}
+			return 0;
+		}
+		pr_err("%s already has a bitmap (%s)\n", devname, bmf.pathname);
+		return 1;
+	}
+	if (md_get_array_info(fd, &array) != 0) {
+		pr_err("cannot get array status for %s\n", devname);
+		return 1;
+	}
+	if (array.state & (1 << MD_SB_BITMAP_PRESENT)) {
+		if (strcmp(s->bitmap_file, "none")==0) {
+			array.state &= ~(1 << MD_SB_BITMAP_PRESENT);
+			if (md_set_array_info(fd, &array) != 0) {
+				if (array.state & (1 << MD_SB_CLUSTERED))
+					pr_err("failed to remove clustered bitmap.\n");
+				else
+					pr_err("failed to remove internal bitmap.\n");
+				return 1;
+			}
+			return 0;
+		}
+		pr_err("bitmap already present on %s\n", devname);
+		return 1;
+	}
+
+	if (strcmp(s->bitmap_file, "none") == 0) {
+		pr_err("no bitmap found on %s\n", devname);
+		return 1;
+	}
+	if (array.level <= 0) {
+		pr_err("Bitmaps not meaningful with level %s\n",
+			map_num(pers, array.level)?:"of this array");
+		return 1;
+	}
+	bitmapsize = array.size;
+	bitmapsize <<= 1;
+	if (get_dev_size(fd, NULL, &array_size) &&
+	    array_size > (0x7fffffffULL << 9)) {
+		/* Array is big enough that we cannot trust array.size
+		 * try other approaches
+		 */
+		bitmapsize = get_component_size(fd);
+	}
+	if (bitmapsize == 0) {
+		pr_err("Cannot reliably determine size of array to create bitmap - sorry.\n");
+		return 1;
+	}
+
+	if (array.level == 10) {
+		int ncopies;
+
+		ncopies = (array.layout & 255) * ((array.layout >> 8) & 255);
+		bitmapsize = bitmapsize * array.raid_disks / ncopies;
+
+		if (strcmp(s->bitmap_file, "clustered") == 0 &&
+		    !is_near_layout_10(array.layout)) {
+			pr_err("only near layout is supported with clustered raid10\n");
+			return 1;
+		}
+	}
+
+	st = super_by_fd(fd, &subarray);
+	if (!st) {
+		pr_err("Cannot understand version %d.%d\n",
+			array.major_version, array.minor_version);
+		return 1;
+	}
+	if (subarray) {
+		pr_err("Cannot add bitmaps to sub-arrays yet\n");
+		free(subarray);
+		free(st);
+		return 1;
+	}
+
+	mdi = sysfs_read(fd, NULL, GET_CONSISTENCY_POLICY);
+	if (mdi) {
+		if (mdi->consistency_policy == CONSISTENCY_POLICY_PPL) {
+			pr_err("Cannot add bitmap to array with PPL\n");
+			free(mdi);
+			free(st);
+			return 1;
+		}
+		free(mdi);
+	}
+
+	if (strcmp(s->bitmap_file, "internal") == 0 ||
+	    strcmp(s->bitmap_file, "clustered") == 0) {
+		int rv;
+		int d;
+		int offset_setable = 0;
+		if (st->ss->add_internal_bitmap == NULL) {
+			pr_err("Internal bitmaps not supported with %s metadata\n", st->ss->name);
+			return 1;
+		}
+		st->nodes = c->nodes;
+		st->cluster_name = c->homecluster;
+		mdi = sysfs_read(fd, NULL, GET_BITMAP_LOCATION);
+		if (mdi)
+			offset_setable = 1;
+		for (d = 0; d < st->max_devs; d++) {
+			mdu_disk_info_t disk;
+			char *dv;
+			int fd2;
+
+			disk.number = d;
+			if (md_get_disk_info(fd, &disk) < 0)
+				continue;
+			if (disk.major == 0 && disk.minor == 0)
+				continue;
+			if ((disk.state & (1 << MD_DISK_SYNC)) == 0)
+				continue;
+			dv = map_dev(disk.major, disk.minor, 1);
+			if (!dv)
+				continue;
+			if (((disk.state & (1 << MD_DISK_WRITEMOSTLY)) == 0) &&
+			   (strcmp(s->bitmap_file, "clustered") == 0)) {
+				pr_err("%s disks marked write-mostly are not supported with clustered bitmap\n",devname);
+				return 1;
+			}
+			fd2 = dev_open(dv, O_RDWR);
+			if (fd2 < 0)
+				continue;
+			rv = st->ss->load_super(st, fd2, NULL);
+			if (!rv) {
+				rv = st->ss->add_internal_bitmap(
+					st, &s->bitmap_chunk, c->delay,
+					s->write_behind, bitmapsize,
+					offset_setable, major);
+				if (!rv) {
+					st->ss->write_bitmap(st, fd2,
+							     NodeNumUpdate);
+				} else {
+					pr_err("failed to create internal bitmap - chunksize problem.\n");
+				}
+			} else {
+				pr_err("failed to load super-block.\n");
+			}
+			close(fd2);
+			if (rv)
+				return 1;
+		}
+		if (offset_setable) {
+			st->ss->getinfo_super(st, mdi, NULL);
+			if (sysfs_init(mdi, fd, NULL)) {
+				pr_err("failed to initialize sysfs.\n");
+				free(mdi);
+			}
+			rv = sysfs_set_num_signed(mdi, NULL, "bitmap/location",
+						  mdi->bitmap_offset);
+			free(mdi);
+		} else {
+			if (strcmp(s->bitmap_file, "clustered") == 0)
+				array.state |= (1 << MD_SB_CLUSTERED);
+			array.state |= (1 << MD_SB_BITMAP_PRESENT);
+			rv = md_set_array_info(fd, &array);
+		}
+		if (rv < 0) {
+			if (errno == EBUSY)
+				pr_err("Cannot add bitmap while array is resyncing or reshaping etc.\n");
+			pr_err("failed to set internal bitmap.\n");
+			return 1;
+		}
+	} else {
+		int uuid[4];
+		int bitmap_fd;
+		int d;
+		int max_devs = st->max_devs;
+
+		/* try to load a superblock */
+		for (d = 0; d < max_devs; d++) {
+			mdu_disk_info_t disk;
+			char *dv;
+			int fd2;
+			disk.number = d;
+			if (md_get_disk_info(fd, &disk) < 0)
+				continue;
+			if ((disk.major==0 && disk.minor == 0) ||
+			    (disk.state & (1 << MD_DISK_REMOVED)))
+				continue;
+			dv = map_dev(disk.major, disk.minor, 1);
+			if (!dv)
+				continue;
+			fd2 = dev_open(dv, O_RDONLY);
+			if (fd2 >= 0) {
+				if (st->ss->load_super(st, fd2, NULL) == 0) {
+					close(fd2);
+					st->ss->uuid_from_super(st, uuid);
+					break;
+				}
+				close(fd2);
+			}
+		}
+		if (d == max_devs) {
+			pr_err("cannot find UUID for array!\n");
+			return 1;
+		}
+		if (CreateBitmap(s->bitmap_file, c->force, (char*)uuid,
+				 s->bitmap_chunk, c->delay, s->write_behind,
+				 bitmapsize, major)) {
+			return 1;
+		}
+		bitmap_fd = open(s->bitmap_file, O_RDWR);
+		if (bitmap_fd < 0) {
+			pr_err("weird: %s cannot be opened\n", s->bitmap_file);
+			return 1;
+		}
+		if (ioctl(fd, SET_BITMAP_FILE, bitmap_fd) < 0) {
+			int err = errno;
+			if (errno == EBUSY)
+				pr_err("Cannot add bitmap while array is resyncing or reshaping etc.\n");
+			pr_err("Cannot set bitmap file for %s: %s\n",
+				devname, strerror(err));
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+int Grow_consistency_policy(char *devname, int fd, struct context *c, struct shape *s)
+{
+	struct supertype *st;
+	struct mdinfo *sra;
+	struct mdinfo *sd;
+	char *subarray = NULL;
+	int ret = 0;
+	char container_dev[PATH_MAX];
+	char buf[20];
+
+	if (s->consistency_policy != CONSISTENCY_POLICY_RESYNC &&
+	    s->consistency_policy != CONSISTENCY_POLICY_PPL) {
+		pr_err("Operation not supported for consistency policy %s\n",
+		       map_num(consistency_policies, s->consistency_policy));
+		return 1;
+	}
+
+	st = super_by_fd(fd, &subarray);
+	if (!st)
+		return 1;
+
+	sra = sysfs_read(fd, NULL, GET_CONSISTENCY_POLICY|GET_LEVEL|
+				   GET_DEVS|GET_STATE);
+	if (!sra) {
+		ret = 1;
+		goto free_st;
+	}
+
+	if (s->consistency_policy == CONSISTENCY_POLICY_PPL &&
+	    !st->ss->write_init_ppl) {
+		pr_err("%s metadata does not support PPL\n", st->ss->name);
+		ret = 1;
+		goto free_info;
+	}
+
+	if (sra->array.level != 5) {
+		pr_err("Operation not supported for array level %d\n",
+				sra->array.level);
+		ret = 1;
+		goto free_info;
+	}
+
+	if (sra->consistency_policy == (unsigned)s->consistency_policy) {
+		pr_err("Consistency policy is already %s\n",
+		       map_num(consistency_policies, s->consistency_policy));
+		ret = 1;
+		goto free_info;
+	} else if (sra->consistency_policy != CONSISTENCY_POLICY_RESYNC &&
+		   sra->consistency_policy != CONSISTENCY_POLICY_PPL) {
+		pr_err("Current consistency policy is %s, cannot change to %s\n",
+		       map_num(consistency_policies, sra->consistency_policy),
+		       map_num(consistency_policies, s->consistency_policy));
+		ret = 1;
+		goto free_info;
+	}
+
+	if (s->consistency_policy == CONSISTENCY_POLICY_PPL) {
+		if (sysfs_get_str(sra, NULL, "sync_action", buf, 20) <= 0) {
+			ret = 1;
+			goto free_info;
+		} else if (strcmp(buf, "reshape\n") == 0) {
+			pr_err("PPL cannot be enabled when reshape is in progress\n");
+			ret = 1;
+			goto free_info;
+		}
+	}
+
+	if (subarray) {
+		char *update;
+
+		if (s->consistency_policy == CONSISTENCY_POLICY_PPL)
+			update = "ppl";
+		else
+			update = "no-ppl";
+
+		sprintf(container_dev, "/dev/%s", st->container_devnm);
+
+		ret = Update_subarray(container_dev, subarray, update, NULL,
+				      c->verbose);
+		if (ret)
+			goto free_info;
+	}
+
+	if (s->consistency_policy == CONSISTENCY_POLICY_PPL) {
+		struct mdinfo info;
+
+		if (subarray) {
+			struct mdinfo *mdi;
+			int cfd;
+
+			cfd = open(container_dev, O_RDWR|O_EXCL);
+			if (cfd < 0) {
+				pr_err("Failed to open %s\n", container_dev);
+				ret = 1;
+				goto free_info;
+			}
+
+			ret = st->ss->load_container(st, cfd, st->container_devnm);
+			close(cfd);
+
+			if (ret) {
+				pr_err("Cannot read superblock for %s\n",
+				       container_dev);
+				goto free_info;
+			}
+
+			mdi = st->ss->container_content(st, subarray);
+			info = *mdi;
+			free(mdi);
+		}
+
+		for (sd = sra->devs; sd; sd = sd->next) {
+			int dfd;
+			char *devpath;
+
+			devpath = map_dev(sd->disk.major, sd->disk.minor, 0);
+			dfd = dev_open(devpath, O_RDWR);
+			if (dfd < 0) {
+				pr_err("Failed to open %s\n", devpath);
+				ret = 1;
+				goto free_info;
+			}
+
+			if (!subarray) {
+				ret = st->ss->load_super(st, dfd, NULL);
+				if (ret) {
+					pr_err("Failed to load super-block.\n");
+					close(dfd);
+					goto free_info;
+				}
+
+				ret = st->ss->update_super(st, sra, "ppl",
+							   devname,
+							   c->verbose, 0, NULL);
+				if (ret) {
+					close(dfd);
+					st->ss->free_super(st);
+					goto free_info;
+				}
+				st->ss->getinfo_super(st, &info, NULL);
+			}
+
+			ret |= sysfs_set_num(sra, sd, "ppl_sector",
+					     info.ppl_sector);
+			ret |= sysfs_set_num(sra, sd, "ppl_size",
+					     info.ppl_size);
+
+			if (ret) {
+				pr_err("Failed to set PPL attributes for %s\n",
+				       sd->sys_name);
+				close(dfd);
+				st->ss->free_super(st);
+				goto free_info;
+			}
+
+			ret = st->ss->write_init_ppl(st, &info, dfd);
+			if (ret)
+				pr_err("Failed to write PPL\n");
+
+			close(dfd);
+
+			if (!subarray)
+				st->ss->free_super(st);
+
+			if (ret)
+				goto free_info;
+		}
+	}
+
+	ret = sysfs_set_str(sra, NULL, "consistency_policy",
+			    map_num(consistency_policies,
+				    s->consistency_policy));
+	if (ret)
+		pr_err("Failed to change array consistency policy\n");
+
+free_info:
+	sysfs_free(sra);
+free_st:
+	free(st);
+	free(subarray);
+
+	return ret;
+}
+
+/*
+ * When reshaping an array we might need to backup some data.
+ * This is written to all spares with a 'super_block' describing it.
+ * The superblock goes 4K from the end of the used space on the
+ * device.
+ * It if written after the backup is complete.
+ * It has the following structure.
+ */
+
+static struct mdp_backup_super {
+	char	magic[16];  /* md_backup_data-1 or -2 */
+	__u8	set_uuid[16];
+	__u64	mtime;
+	/* start/sizes in 512byte sectors */
+	__u64	devstart;	/* address on backup device/file of data */
+	__u64	arraystart;
+	__u64	length;
+	__u32	sb_csum;	/* csum of preceeding bytes. */
+	__u32   pad1;
+	__u64	devstart2;	/* offset in to data of second section */
+	__u64	arraystart2;
+	__u64	length2;
+	__u32	sb_csum2;	/* csum of preceeding bytes. */
+	__u8 pad[512-68-32];
+} __attribute__((aligned(512))) bsb, bsb2;
+
+static __u32 bsb_csum(char *buf, int len)
+{
+	int i;
+	int csum = 0;
+	for (i = 0; i < len; i++)
+		csum = (csum<<3) + buf[0];
+	return __cpu_to_le32(csum);
+}
+
+static int check_idle(struct supertype *st)
+{
+	/* Check that all member arrays for this container, or the
+	 * container of this array, are idle
+	 */
+	char *container = (st->container_devnm[0]
+			   ? st->container_devnm : st->devnm);
+	struct mdstat_ent *ent, *e;
+	int is_idle = 1;
+
+	ent = mdstat_read(0, 0);
+	for (e = ent ; e; e = e->next) {
+		if (!is_container_member(e, container))
+			continue;
+		/* frozen array is not idle*/
+		if (e->percent >= 0 || e->metadata_version[9] == '-') {
+			is_idle = 0;
+			break;
+		}
+	}
+	free_mdstat(ent);
+	return is_idle;
+}
+
+static int freeze_container(struct supertype *st)
+{
+	char *container = (st->container_devnm[0]
+			   ? st->container_devnm : st->devnm);
+
+	if (!check_idle(st))
+		return -1;
+
+	if (block_monitor(container, 1)) {
+		pr_err("failed to freeze container\n");
+		return -2;
+	}
+
+	return 1;
+}
+
+static void unfreeze_container(struct supertype *st)
+{
+	char *container = (st->container_devnm[0]
+			   ? st->container_devnm : st->devnm);
+
+	unblock_monitor(container, 1);
+}
+
+static int freeze(struct supertype *st)
+{
+	/* Try to freeze resync/rebuild on this array/container.
+	 * Return -1 if the array is busy,
+	 * return -2 container cannot be frozen,
+	 * return 0 if this kernel doesn't support 'frozen'
+	 * return 1 if it worked.
+	 */
+	if (st->ss->external)
+		return freeze_container(st);
+	else {
+		struct mdinfo *sra = sysfs_read(-1, st->devnm, GET_VERSION);
+		int err;
+		char buf[20];
+
+		if (!sra)
+			return -1;
+		/* Need to clear any 'read-auto' status */
+		if (sysfs_get_str(sra, NULL, "array_state", buf, 20) > 0 &&
+		    strncmp(buf, "read-auto", 9) == 0)
+			sysfs_set_str(sra, NULL, "array_state", "clean");
+
+		err = sysfs_freeze_array(sra);
+		sysfs_free(sra);
+		return err;
+	}
+}
+
+static void unfreeze(struct supertype *st)
+{
+	if (st->ss->external)
+		return unfreeze_container(st);
+	else {
+		struct mdinfo *sra = sysfs_read(-1, st->devnm, GET_VERSION);
+		char buf[20];
+
+		if (sra &&
+		    sysfs_get_str(sra, NULL, "sync_action", buf, 20) > 0 &&
+		    strcmp(buf, "frozen\n") == 0)
+			sysfs_set_str(sra, NULL, "sync_action", "idle");
+		sysfs_free(sra);
+	}
+}
+
+static void wait_reshape(struct mdinfo *sra)
+{
+	int fd = sysfs_get_fd(sra, NULL, "sync_action");
+	char action[20];
+
+	if (fd < 0)
+		return;
+
+	while (sysfs_fd_get_str(fd, action, 20) > 0 &&
+	       strncmp(action, "reshape", 7) == 0)
+		sysfs_wait(fd, NULL);
+	close(fd);
+}
+
+static int reshape_super(struct supertype *st, unsigned long long size,
+			 int level, int layout, int chunksize, int raid_disks,
+			 int delta_disks, char *backup_file, char *dev,
+			 int direction, int verbose)
+{
+	/* nothing extra to check in the native case */
+	if (!st->ss->external)
+		return 0;
+	if (!st->ss->reshape_super || !st->ss->manage_reshape) {
+		pr_err("%s metadata does not support reshape\n",
+			st->ss->name);
+		return 1;
+	}
+
+	return st->ss->reshape_super(st, size, level, layout, chunksize,
+				     raid_disks, delta_disks, backup_file, dev,
+				     direction, verbose);
+}
+
+static void sync_metadata(struct supertype *st)
+{
+	if (st->ss->external) {
+		if (st->update_tail) {
+			flush_metadata_updates(st);
+			st->update_tail = &st->updates;
+		} else
+			st->ss->sync_metadata(st);
+	}
+}
+
+static int subarray_set_num(char *container, struct mdinfo *sra, char *name, int n)
+{
+	/* when dealing with external metadata subarrays we need to be
+	 * prepared to handle EAGAIN.  The kernel may need to wait for
+	 * mdmon to mark the array active so the kernel can handle
+	 * allocations/writeback when preparing the reshape action
+	 * (md_allow_write()).  We temporarily disable safe_mode_delay
+	 * to close a race with the array_state going clean before the
+	 * next write to raid_disks / stripe_cache_size
+	 */
+	char safe[50];
+	int rc;
+
+	/* only 'raid_disks' and 'stripe_cache_size' trigger md_allow_write */
+	if (!container ||
+	    (strcmp(name, "raid_disks") != 0 &&
+	     strcmp(name, "stripe_cache_size") != 0))
+		return sysfs_set_num(sra, NULL, name, n);
+
+	rc = sysfs_get_str(sra, NULL, "safe_mode_delay", safe, sizeof(safe));
+	if (rc <= 0)
+		return -1;
+	sysfs_set_num(sra, NULL, "safe_mode_delay", 0);
+	rc = sysfs_set_num(sra, NULL, name, n);
+	if (rc < 0 && errno == EAGAIN) {
+		ping_monitor(container);
+		/* if we get EAGAIN here then the monitor is not active
+		 * so stop trying
+		 */
+		rc = sysfs_set_num(sra, NULL, name, n);
+	}
+	sysfs_set_str(sra, NULL, "safe_mode_delay", safe);
+	return rc;
+}
+
+int start_reshape(struct mdinfo *sra, int already_running,
+		  int before_data_disks, int data_disks, struct supertype *st)
+{
+	int err;
+	unsigned long long sync_max_to_set;
+
+	sysfs_set_num(sra, NULL, "suspend_lo", 0x7FFFFFFFFFFFFFFFULL);
+	err = sysfs_set_num(sra, NULL, "suspend_hi", sra->reshape_progress);
+	err = err ?: sysfs_set_num(sra, NULL, "suspend_lo",
+				   sra->reshape_progress);
+	if (before_data_disks <= data_disks)
+		sync_max_to_set = sra->reshape_progress / data_disks;
+	else
+		sync_max_to_set = (sra->component_size * data_disks
+				   - sra->reshape_progress) / data_disks;
+
+	if (!already_running)
+		sysfs_set_num(sra, NULL, "sync_min", sync_max_to_set);
+
+        if (st->ss->external)
+		err = err ?: sysfs_set_num(sra, NULL, "sync_max", sync_max_to_set);
+	else
+		err = err ?: sysfs_set_str(sra, NULL, "sync_max", "max");
+
+	if (!already_running && err == 0) {
+		int cnt = 5;
+		do {
+			err = sysfs_set_str(sra, NULL, "sync_action",
+					    "reshape");
+			if (err)
+				sleep(1);
+		} while (err && errno == EBUSY && cnt-- > 0);
+	}
+	return err;
+}
+
+void abort_reshape(struct mdinfo *sra)
+{
+	sysfs_set_str(sra, NULL, "sync_action", "idle");
+	/*
+	 * Prior to kernel commit: 23ddff3792f6 ("md: allow suspend_lo and
+	 * suspend_hi to decrease as well as increase.")
+	 * you could only increase suspend_{lo,hi} unless the region they
+	 * covered was empty.  So to reset to 0, you need to push suspend_lo
+	 * up past suspend_hi first.  So to maximize the chance of mdadm
+	 * working on all kernels, we want to keep doing that.
+	 */
+	sysfs_set_num(sra, NULL, "suspend_lo", 0x7FFFFFFFFFFFFFFFULL);
+	sysfs_set_num(sra, NULL, "suspend_hi", 0);
+	sysfs_set_num(sra, NULL, "suspend_lo", 0);
+	sysfs_set_num(sra, NULL, "sync_min", 0);
+	// It isn't safe to reset sync_max as we aren't monitoring.
+	// Array really should be stopped at this point.
+}
+
+int remove_disks_for_takeover(struct supertype *st,
+			      struct mdinfo *sra,
+			      int layout)
+{
+	int nr_of_copies;
+	struct mdinfo *remaining;
+	int slot;
+
+	if (st->ss->external) {
+		int rv = 0;
+		struct mdinfo *arrays = st->ss->container_content(st, NULL);
+		/*
+		 * containter_content returns list of arrays in container
+		 * If arrays->next is not NULL it means that there are
+		 * 2 arrays in container and operation should be blocked
+		 */
+		if (arrays) {
+			if (arrays->next)
+				rv = 1;
+			sysfs_free(arrays);
+			if (rv) {
+				pr_err("Error. Cannot perform operation on /dev/%s\n", st->devnm);
+				pr_err("For this operation it MUST be single array in container\n");
+				return rv;
+			}
+		}
+	}
+
+	if (sra->array.level == 10)
+		nr_of_copies = layout & 0xff;
+	else if (sra->array.level == 1)
+		nr_of_copies = sra->array.raid_disks;
+	else
+		return 1;
+
+	remaining = sra->devs;
+	sra->devs = NULL;
+	/* for each 'copy', select one device and remove from the list. */
+	for (slot = 0; slot < sra->array.raid_disks; slot += nr_of_copies) {
+		struct mdinfo **diskp;
+		int found = 0;
+
+		/* Find a working device to keep */
+		for (diskp =  &remaining; *diskp ; diskp = &(*diskp)->next) {
+			struct mdinfo *disk = *diskp;
+
+			if (disk->disk.raid_disk < slot)
+				continue;
+			if (disk->disk.raid_disk >= slot + nr_of_copies)
+				continue;
+			if (disk->disk.state & (1<<MD_DISK_REMOVED))
+				continue;
+			if (disk->disk.state & (1<<MD_DISK_FAULTY))
+				continue;
+			if (!(disk->disk.state & (1<<MD_DISK_SYNC)))
+				continue;
+
+			/* We have found a good disk to use! */
+			*diskp = disk->next;
+			disk->next = sra->devs;
+			sra->devs = disk;
+			found = 1;
+			break;
+		}
+		if (!found)
+			break;
+	}
+
+	if (slot < sra->array.raid_disks) {
+		/* didn't find all slots */
+		struct mdinfo **e;
+		e = &remaining;
+		while (*e)
+			e = &(*e)->next;
+		*e = sra->devs;
+		sra->devs = remaining;
+		return 1;
+	}
+
+	/* Remove all 'remaining' devices from the array */
+	while (remaining) {
+		struct mdinfo *sd = remaining;
+		remaining = sd->next;
+
+		sysfs_set_str(sra, sd, "state", "faulty");
+		sysfs_set_str(sra, sd, "slot", "none");
+		/* for external metadata disks should be removed in mdmon */
+		if (!st->ss->external)
+			sysfs_set_str(sra, sd, "state", "remove");
+		sd->disk.state |= (1<<MD_DISK_REMOVED);
+		sd->disk.state &= ~(1<<MD_DISK_SYNC);
+		sd->next = sra->devs;
+		sra->devs = sd;
+	}
+	return 0;
+}
+
+void reshape_free_fdlist(int *fdlist,
+			 unsigned long long *offsets,
+			 int size)
+{
+	int i;
+
+	for (i = 0; i < size; i++)
+		if (fdlist[i] >= 0)
+			close(fdlist[i]);
+
+	free(fdlist);
+	free(offsets);
+}
+
+int reshape_prepare_fdlist(char *devname,
+			   struct mdinfo *sra,
+			   int raid_disks,
+			   int nrdisks,
+			   unsigned long blocks,
+			   char *backup_file,
+			   int *fdlist,
+			   unsigned long long *offsets)
+{
+	int d = 0;
+	struct mdinfo *sd;
+
+	enable_fds(nrdisks);
+	for (d = 0; d <= nrdisks; d++)
+		fdlist[d] = -1;
+	d = raid_disks;
+	for (sd = sra->devs; sd; sd = sd->next) {
+		if (sd->disk.state & (1<<MD_DISK_FAULTY))
+			continue;
+		if (sd->disk.state & (1<<MD_DISK_SYNC) &&
+		    sd->disk.raid_disk < raid_disks) {
+			char *dn = map_dev(sd->disk.major, sd->disk.minor, 1);
+			fdlist[sd->disk.raid_disk] = dev_open(dn, O_RDONLY);
+			offsets[sd->disk.raid_disk] = sd->data_offset*512;
+			if (fdlist[sd->disk.raid_disk] < 0) {
+				pr_err("%s: cannot open component %s\n",
+				       devname, dn ? dn : "-unknown-");
+				d = -1;
+				goto release;
+			}
+		} else if (backup_file == NULL) {
+			/* spare */
+			char *dn = map_dev(sd->disk.major, sd->disk.minor, 1);
+				fdlist[d] = dev_open(dn, O_RDWR);
+				offsets[d] = (sd->data_offset + sra->component_size - blocks - 8)*512;
+				if (fdlist[d] < 0) {
+					pr_err("%s: cannot open component %s\n",
+						devname, dn ? dn : "-unknown-");
+					d = -1;
+					goto release;
+				}
+				d++;
+			}
+		}
+release:
+	return d;
+}
+
+int reshape_open_backup_file(char *backup_file,
+			     int fd,
+			     char *devname,
+			     long blocks,
+			     int *fdlist,
+			     unsigned long long *offsets,
+			     char *sys_name,
+			     int restart)
+{
+	/* Return 1 on success, 0 on any form of failure */
+	/* need to check backup file is large enough */
+	char buf[512];
+	struct stat stb;
+	unsigned int dev;
+	int i;
+
+	*fdlist = open(backup_file, O_RDWR|O_CREAT|(restart ? O_TRUNC : O_EXCL),
+		       S_IRUSR | S_IWUSR);
+	*offsets = 8 * 512;
+	if (*fdlist < 0) {
+		pr_err("%s: cannot create backup file %s: %s\n",
+			devname, backup_file, strerror(errno));
+		return 0;
+	}
+	/* Guard against backup file being on array device.
+	 * If array is partitioned or if LVM etc is in the
+	 * way this will not notice, but it is better than
+	 * nothing.
+	 */
+	fstat(*fdlist, &stb);
+	dev = stb.st_dev;
+	fstat(fd, &stb);
+	if (stb.st_rdev == dev) {
+		pr_err("backup file must NOT be on the array being reshaped.\n");
+		close(*fdlist);
+		return 0;
+	}
+
+	memset(buf, 0, 512);
+	for (i=0; i < blocks + 8 ; i++) {
+		if (write(*fdlist, buf, 512) != 512) {
+			pr_err("%s: cannot create backup file %s: %s\n",
+				devname, backup_file, strerror(errno));
+			return 0;
+		}
+	}
+	if (fsync(*fdlist) != 0) {
+		pr_err("%s: cannot create backup file %s: %s\n",
+			devname, backup_file, strerror(errno));
+		return 0;
+	}
+
+	if (!restart && strncmp(backup_file, MAP_DIR, strlen(MAP_DIR)) != 0) {
+		char *bu = make_backup(sys_name);
+		if (symlink(backup_file, bu))
+			pr_err("Recording backup file in " MAP_DIR " failed: %s\n",
+			       strerror(errno));
+		free(bu);
+	}
+
+	return 1;
+}
+
+unsigned long compute_backup_blocks(int nchunk, int ochunk,
+				    unsigned int ndata, unsigned int odata)
+{
+	unsigned long a, b, blocks;
+	/* So how much do we need to backup.
+	 * We need an amount of data which is both a whole number of
+	 * old stripes and a whole number of new stripes.
+	 * So LCM for (chunksize*datadisks).
+	 */
+	a = (ochunk/512) * odata;
+	b = (nchunk/512) * ndata;
+	/* Find GCD */
+	a = GCD(a, b);
+	/* LCM == product / GCD */
+	blocks = (unsigned long)(ochunk/512) * (unsigned long)(nchunk/512) *
+		odata * ndata / a;
+
+	return blocks;
+}
+
+char *analyse_change(char *devname, struct mdinfo *info, struct reshape *re)
+{
+	/* Based on the current array state in info->array and
+	 * the changes in info->new_* etc, determine:
+	 *  - whether the change is possible
+	 *  - Intermediate level/raid_disks/layout
+	 *  - whether a restriping reshape is needed
+	 *  - number of sectors in minimum change unit.  This
+	 *    will cover a whole number of stripes in 'before' and
+	 *    'after'.
+	 *
+	 * Return message if the change should be rejected
+	 *        NULL if the change can be achieved
+	 *
+	 * This can be called as part of starting a reshape, or
+	 * when assembling an array that is undergoing reshape.
+	 */
+	int near, far, offset, copies;
+	int new_disks;
+	int old_chunk, new_chunk;
+	/* delta_parity records change in number of devices
+	 * caused by level change
+	 */
+	int delta_parity = 0;
+
+	memset(re, 0, sizeof(*re));
+
+	/* If a new level not explicitly given, we assume no-change */
+	if (info->new_level == UnSet)
+		info->new_level = info->array.level;
+
+	if (info->new_chunk)
+		switch (info->new_level) {
+		case 0:
+		case 4:
+		case 5:
+		case 6:
+		case 10:
+			/* chunk size is meaningful, must divide component_size
+			 * evenly
+			 */
+			if (info->component_size % (info->new_chunk/512)) {
+				unsigned long long shrink = info->component_size;
+				shrink &= ~(unsigned long long)(info->new_chunk/512-1);
+				pr_err("New chunk size (%dK) does not evenly divide device size (%lluk)\n",
+				       info->new_chunk/1024, info->component_size/2);
+				pr_err("After shrinking any filesystem, \"mdadm --grow %s --size %llu\"\n",
+				       devname, shrink/2);
+				pr_err("will shrink the array so the given chunk size would work.\n");
+				return "";
+			}
+			break;
+		default:
+			return "chunk size not meaningful for this level";
+		}
+	else
+		info->new_chunk = info->array.chunk_size;
+
+	switch (info->array.level) {
+	default:
+		return "No reshape is possibly for this RAID level";
+	case LEVEL_LINEAR:
+		if (info->delta_disks != UnSet)
+			return "Only --add is supported for LINEAR, setting --raid-disks is not needed";
+		else
+			return "Only --add is supported for LINEAR, other --grow options are not meaningful";
+	case 1:
+		/* RAID1 can convert to RAID1 with different disks, or
+		 * raid5 with 2 disks, or
+		 * raid0 with 1 disk
+		 */
+		if (info->new_level > 1 && (info->component_size & 7))
+			return "Cannot convert RAID1 of this size - reduce size to multiple of 4K first.";
+		if (info->new_level == 0) {
+			if (info->delta_disks != UnSet &&
+			    info->delta_disks != 0)
+				return "Cannot change number of disks with RAID1->RAID0 conversion";
+			re->level = 0;
+			re->before.data_disks = 1;
+			re->after.data_disks = 1;
+			return NULL;
+		}
+		if (info->new_level == 1) {
+			if (info->delta_disks == UnSet)
+				/* Don't know what to do */
+				return "no change requested for Growing RAID1";
+			re->level = 1;
+			return NULL;
+		}
+		if (info->array.raid_disks != 2 && info->new_level == 5)
+			return "Can only convert a 2-device array to RAID5";
+		if (info->array.raid_disks == 2 && info->new_level == 5) {
+			re->level = 5;
+			re->before.data_disks = 1;
+			if (info->delta_disks != UnSet &&
+			    info->delta_disks != 0)
+				re->after.data_disks = 1 + info->delta_disks;
+			else
+				re->after.data_disks = 1;
+			if (re->after.data_disks < 1)
+				return "Number of disks too small for RAID5";
+
+			re->before.layout = ALGORITHM_LEFT_SYMMETRIC;
+			info->array.chunk_size = 65536;
+			break;
+		}
+		/* Could do some multi-stage conversions, but leave that to
+		 * later.
+		 */
+		return "Impossibly level change request for RAID1";
+
+	case 10:
+		/* RAID10 can be converted from near mode to
+		 * RAID0 by removing some devices.
+		 * It can also be reshaped if the kernel supports
+		 * new_data_offset.
+		 */
+		switch (info->new_level) {
+		case 0:
+			if ((info->array.layout & ~0xff) != 0x100)
+				return "Cannot Grow RAID10 with far/offset layout";
+			/*
+			 * number of devices must be multiple of
+			 * number of copies
+			 */
+			if (info->array.raid_disks %
+			    (info->array.layout & 0xff))
+				return "RAID10 layout too complex for Grow operation";
+
+			new_disks = (info->array.raid_disks /
+				     (info->array.layout & 0xff));
+			if (info->delta_disks == UnSet)
+				info->delta_disks = (new_disks
+						     - info->array.raid_disks);
+
+			if (info->delta_disks !=
+			    new_disks - info->array.raid_disks)
+				return "New number of raid-devices impossible for RAID10";
+			if (info->new_chunk &&
+			    info->new_chunk != info->array.chunk_size)
+				return "Cannot change chunk-size with RAID10 Grow";
+
+			/* looks good */
+			re->level = 0;
+			re->before.data_disks = new_disks;
+			re->after.data_disks = re->before.data_disks;
+			return NULL;
+
+		case 10:
+			near = info->array.layout & 0xff;
+			far = (info->array.layout >> 8) & 0xff;
+			offset = info->array.layout & 0x10000;
+			if (far > 1 && !offset)
+				return "Cannot reshape RAID10 in far-mode";
+			copies = near * far;
+
+			old_chunk = info->array.chunk_size * far;
+
+			if (info->new_layout == UnSet)
+				info->new_layout = info->array.layout;
+			else {
+				near = info->new_layout & 0xff;
+				far = (info->new_layout >> 8) & 0xff;
+				offset = info->new_layout & 0x10000;
+				if (far > 1 && !offset)
+					return "Cannot reshape RAID10 to far-mode";
+				if (near * far != copies)
+					return "Cannot change number of copies when reshaping RAID10";
+			}
+			if (info->delta_disks == UnSet)
+				info->delta_disks = 0;
+			new_disks = (info->array.raid_disks +
+				     info->delta_disks);
+
+			new_chunk = info->new_chunk * far;
+
+			re->level = 10;
+			re->before.layout = info->array.layout;
+			re->before.data_disks = info->array.raid_disks;
+			re->after.layout = info->new_layout;
+			re->after.data_disks = new_disks;
+			/* For RAID10 we don't do backup but do allow reshape,
+			 * so set backup_blocks to INVALID_SECTORS rather than
+			 * zero.
+			 * And there is no need to synchronise stripes on both
+			 * 'old' and  'new'.  So the important
+			 * number is the minimum data_offset difference
+			 * which is the larger of (offset copies * chunk).
+			 */
+			re->backup_blocks = INVALID_SECTORS;
+			re->min_offset_change = max(old_chunk, new_chunk) / 512;
+			if (new_disks < re->before.data_disks &&
+			    info->space_after < re->min_offset_change)
+				/* Reduce component size by one chunk */
+				re->new_size = (info->component_size -
+						re->min_offset_change);
+			else
+				re->new_size = info->component_size;
+			re->new_size = re->new_size * new_disks / copies;
+			return NULL;
+
+		default:
+			return "RAID10 can only be changed to RAID0";
+		}
+	case 0:
+		/* RAID0 can be converted to RAID10, or to RAID456 */
+		if (info->new_level == 10) {
+			if (info->new_layout == UnSet &&
+			    info->delta_disks == UnSet) {
+				/* Assume near=2 layout */
+				info->new_layout = 0x102;
+				info->delta_disks = info->array.raid_disks;
+			}
+			if (info->new_layout == UnSet) {
+				int copies = 1 + (info->delta_disks
+						  / info->array.raid_disks);
+				if (info->array.raid_disks * (copies-1) !=
+				    info->delta_disks)
+					return "Impossible number of devices for RAID0->RAID10";
+				info->new_layout = 0x100 + copies;
+			}
+			if (info->delta_disks == UnSet) {
+				int copies = info->new_layout & 0xff;
+				if (info->new_layout != 0x100 + copies)
+					return "New layout impossible for RAID0->RAID10";;
+				info->delta_disks = (copies - 1) *
+					info->array.raid_disks;
+			}
+			if (info->new_chunk &&
+			    info->new_chunk != info->array.chunk_size)
+				return "Cannot change chunk-size with RAID0->RAID10";
+			/* looks good */
+			re->level = 10;
+			re->before.data_disks = (info->array.raid_disks +
+						 info->delta_disks);
+			re->after.data_disks = re->before.data_disks;
+			re->before.layout = info->new_layout;
+			return NULL;
+		}
+
+		/* RAID0 can also covert to RAID0/4/5/6 by first converting to
+		 * a raid4 style layout of the final level.
+		 */
+		switch (info->new_level) {
+		case 4:
+			delta_parity = 1;
+		case 0:
+			re->level = 4;
+			re->before.layout = 0;
+			break;
+		case 5:
+			delta_parity = 1;
+			re->level = 5;
+			re->before.layout = ALGORITHM_PARITY_N;
+			if (info->new_layout == UnSet)
+				info->new_layout = map_name(r5layout, "default");
+			break;
+		case 6:
+			delta_parity = 2;
+			re->level = 6;
+			re->before.layout = ALGORITHM_PARITY_N;
+			if (info->new_layout == UnSet)
+				info->new_layout = map_name(r6layout, "default");
+			break;
+		default:
+			return "Impossible level change requested";
+		}
+		re->before.data_disks = info->array.raid_disks;
+		/* determining 'after' layout happens outside this 'switch' */
+		break;
+
+	case 4:
+		info->array.layout = ALGORITHM_PARITY_N;
+	case 5:
+		switch (info->new_level) {
+		case 0:
+			delta_parity = -1;
+		case 4:
+			re->level = info->array.level;
+			re->before.data_disks = info->array.raid_disks - 1;
+			re->before.layout = info->array.layout;
+			break;
+		case 5:
+			re->level = 5;
+			re->before.data_disks = info->array.raid_disks - 1;
+			re->before.layout = info->array.layout;
+			break;
+		case 6:
+			delta_parity = 1;
+			re->level = 6;
+			re->before.data_disks = info->array.raid_disks - 1;
+			switch (info->array.layout) {
+			case ALGORITHM_LEFT_ASYMMETRIC:
+				re->before.layout = ALGORITHM_LEFT_ASYMMETRIC_6;
+				break;
+			case ALGORITHM_RIGHT_ASYMMETRIC:
+				re->before.layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
+				break;
+			case ALGORITHM_LEFT_SYMMETRIC:
+				re->before.layout = ALGORITHM_LEFT_SYMMETRIC_6;
+				break;
+			case ALGORITHM_RIGHT_SYMMETRIC:
+				re->before.layout = ALGORITHM_RIGHT_SYMMETRIC_6;
+				break;
+			case ALGORITHM_PARITY_0:
+				re->before.layout = ALGORITHM_PARITY_0_6;
+				break;
+			case ALGORITHM_PARITY_N:
+				re->before.layout = ALGORITHM_PARITY_N_6;
+				break;
+			default:
+				return "Cannot convert an array with this layout";
+			}
+			break;
+		case 1:
+			if (info->array.raid_disks != 2)
+				return "Can only convert a 2-device array to RAID1";
+			if (info->delta_disks != UnSet &&
+			    info->delta_disks != 0)
+				return "Cannot set raid_disk when converting RAID5->RAID1";
+			re->level = 1;
+			info->new_chunk = 0;
+			return NULL;
+		default:
+			return "Impossible level change requested";
+		}
+		break;
+	case 6:
+		switch (info->new_level) {
+		case 4:
+		case 5:
+			delta_parity = -1;
+		case 6:
+			re->level = 6;
+			re->before.data_disks = info->array.raid_disks - 2;
+			re->before.layout = info->array.layout;
+			break;
+		default:
+			return "Impossible level change requested";
+		}
+		break;
+	}
+
+	/* If we reached here then it looks like a re-stripe is
+	 * happening.  We have determined the intermediate level
+	 * and initial raid_disks/layout and stored these in 're'.
+	 *
+	 * We need to deduce the final layout that can be atomically
+	 * converted to the end state.
+	 */
+	switch (info->new_level) {
+	case 0:
+		/* We can only get to RAID0 from RAID4 or RAID5
+		 * with appropriate layout and one extra device
+		 */
+		if (re->level != 4 && re->level != 5)
+			return "Cannot covert to RAID0 from this level";
+
+		switch (re->level) {
+		case 4:
+			re->before.layout = 0;
+			re->after.layout = 0;
+			break;
+		case 5:
+			re->after.layout = ALGORITHM_PARITY_N;
+			break;
+		}
+		break;
+
+	case 4:
+		/* We can only get to RAID4 from RAID5 */
+		if (re->level != 4 && re->level != 5)
+			return "Cannot convert to RAID4 from this level";
+
+		switch (re->level) {
+		case 4:
+			re->after.layout = 0;
+			break;
+		case 5:
+			re->after.layout = ALGORITHM_PARITY_N;
+			break;
+		}
+		break;
+
+	case 5:
+		/* We get to RAID5 from RAID5 or RAID6 */
+		if (re->level != 5 && re->level != 6)
+			return "Cannot convert to RAID5 from this level";
+
+		switch (re->level) {
+		case 5:
+			if (info->new_layout == UnSet)
+				re->after.layout = re->before.layout;
+			else
+				re->after.layout = info->new_layout;
+			break;
+		case 6:
+			if (info->new_layout == UnSet)
+				info->new_layout = re->before.layout;
+
+			/* after.layout needs to be raid6 version of new_layout */
+			if (info->new_layout == ALGORITHM_PARITY_N)
+				re->after.layout = ALGORITHM_PARITY_N;
+			else {
+				char layout[40];
+				char *ls = map_num(r5layout, info->new_layout);
+				int l;
+				if (ls) {
+					/* Current RAID6 layout has a RAID5
+					 * equivalent - good
+					 */
+					strcat(strcpy(layout, ls), "-6");
+					l = map_name(r6layout, layout);
+					if (l == UnSet)
+						return "Cannot find RAID6 layout to convert to";
+				} else {
+					/* Current RAID6 has no equivalent.
+					 * If it is already a '-6' layout we
+					 * can leave it unchanged, else we must
+					 * fail
+					 */
+					ls = map_num(r6layout,
+						     info->new_layout);
+					if (!ls ||
+					    strcmp(ls+strlen(ls)-2, "-6") != 0)
+						return "Please specify new layout";
+					l = info->new_layout;
+				}
+				re->after.layout = l;
+			}
+		}
+		break;
+
+	case 6:
+		/* We must already be at level 6 */
+		if (re->level != 6)
+			return "Impossible level change";
+		if (info->new_layout == UnSet)
+			re->after.layout = info->array.layout;
+		else
+			re->after.layout = info->new_layout;
+		break;
+	default:
+		return "Impossible level change requested";
+	}
+	if (info->delta_disks == UnSet)
+		info->delta_disks = delta_parity;
+
+	re->after.data_disks =
+		(re->before.data_disks + info->delta_disks - delta_parity);
+
+	switch (re->level) {
+	case 6:
+		re->parity = 2;
+		break;
+	case 4:
+	case 5:
+		re->parity = 1;
+		break;
+	default:
+		re->parity = 0;
+		break;
+	}
+	/* So we have a restripe operation, we need to calculate the number
+	 * of blocks per reshape operation.
+	 */
+	re->new_size = info->component_size * re->before.data_disks;
+	if (info->new_chunk == 0)
+		info->new_chunk = info->array.chunk_size;
+	if (re->after.data_disks == re->before.data_disks &&
+	    re->after.layout == re->before.layout &&
+	    info->new_chunk == info->array.chunk_size) {
+		/* Nothing to change, can change level immediately. */
+		re->level = info->new_level;
+		re->backup_blocks = 0;
+		return NULL;
+	}
+	if (re->after.data_disks == 1 && re->before.data_disks == 1) {
+		/* chunk and layout changes make no difference */
+		re->level = info->new_level;
+		re->backup_blocks = 0;
+		return NULL;
+	}
+
+	if (re->after.data_disks == re->before.data_disks &&
+	    get_linux_version() < 2006032)
+		return "in-place reshape is not safe before 2.6.32 - sorry.";
+
+	if (re->after.data_disks < re->before.data_disks &&
+	    get_linux_version() < 2006030)
+		return "reshape to fewer devices is not supported before 2.6.30 - sorry.";
+
+	re->backup_blocks = compute_backup_blocks(
+		info->new_chunk, info->array.chunk_size,
+		re->after.data_disks, re->before.data_disks);
+	re->min_offset_change = re->backup_blocks / re->before.data_disks;
+
+	re->new_size = info->component_size * re->after.data_disks;
+	return NULL;
+}
+
+static int set_array_size(struct supertype *st, struct mdinfo *sra,
+			  char *text_version)
+{
+	struct mdinfo *info;
+	char *subarray;
+	int ret_val = -1;
+
+	if ((st == NULL) || (sra == NULL))
+		return ret_val;
+
+	if (text_version == NULL)
+		text_version = sra->text_version;
+	subarray = strchr(text_version + 1, '/')+1;
+	info = st->ss->container_content(st, subarray);
+	if (info) {
+		unsigned long long current_size = 0;
+		unsigned long long new_size = info->custom_array_size/2;
+
+		if (sysfs_get_ll(sra, NULL, "array_size", &current_size) == 0 &&
+		    new_size > current_size) {
+			if (sysfs_set_num(sra, NULL, "array_size", new_size)
+					< 0)
+				dprintf("Error: Cannot set array size");
+			else {
+				ret_val = 0;
+				dprintf("Array size changed");
+			}
+			dprintf_cont(" from %llu to %llu.\n",
+				     current_size, new_size);
+		}
+		sysfs_free(info);
+	} else
+		dprintf("Error: set_array_size(): info pointer in NULL\n");
+
+	return ret_val;
+}
+
+static int reshape_array(char *container, int fd, char *devname,
+			 struct supertype *st, struct mdinfo *info,
+			 int force, struct mddev_dev *devlist,
+			 unsigned long long data_offset,
+			 char *backup_file, int verbose, int forked,
+			 int restart, int freeze_reshape);
+static int reshape_container(char *container, char *devname,
+			     int mdfd,
+			     struct supertype *st,
+			     struct mdinfo *info,
+			     int force,
+			     char *backup_file, int verbose,
+			     int forked, int restart, int freeze_reshape);
+
+int Grow_reshape(char *devname, int fd,
+		 struct mddev_dev *devlist,
+		 unsigned long long data_offset,
+		 struct context *c, struct shape *s)
+{
+	/* Make some changes in the shape of an array.
+	 * The kernel must support the change.
+	 *
+	 * There are three different changes.  Each can trigger
+	 * a resync or recovery so we freeze that until we have
+	 * requested everything (if kernel supports freezing - 2.6.30).
+	 * The steps are:
+	 *  - change size (i.e. component_size)
+	 *  - change level
+	 *  - change layout/chunksize/ndisks
+	 *
+	 * The last can require a reshape.  It is different on different
+	 * levels so we need to check the level before actioning it.
+	 * Some times the level change needs to be requested after the
+	 * reshape (e.g. raid6->raid5, raid5->raid0)
+	 *
+	 */
+	struct mdu_array_info_s array;
+	int rv = 0;
+	struct supertype *st;
+	char *subarray = NULL;
+
+	int frozen;
+	int changed = 0;
+	char *container = NULL;
+	int cfd = -1;
+
+	struct mddev_dev *dv;
+	int added_disks;
+
+	struct mdinfo info;
+	struct mdinfo *sra;
+
+	if (md_get_array_info(fd, &array) < 0) {
+		pr_err("%s is not an active md array - aborting\n",
+			devname);
+		return 1;
+	}
+	if (s->level != UnSet && s->chunk) {
+		pr_err("Cannot change array level in the same operation as changing chunk size.\n");
+		return 1;
+	}
+
+	if (data_offset != INVALID_SECTORS && array.level != 10 &&
+	    (array.level < 4 || array.level > 6)) {
+		pr_err("--grow --data-offset not yet supported\n");
+		return 1;
+	}
+
+	if (s->size > 0 &&
+	    (s->chunk || s->level!= UnSet || s->layout_str || s->raiddisks)) {
+		pr_err("cannot change component size at the same time as other changes.\n"
+			"   Change size first, then check data is intact before making other changes.\n");
+		return 1;
+	}
+
+	if (s->raiddisks && s->raiddisks < array.raid_disks &&
+	    array.level > 1 && get_linux_version() < 2006032 &&
+	    !check_env("MDADM_FORCE_FEWER")) {
+		pr_err("reducing the number of devices is not safe before Linux 2.6.32\n"
+			"       Please use a newer kernel\n");
+		return 1;
+	}
+
+	if (array.level > 1 && s->size > 1 &&
+	    (unsigned long long) (array.chunk_size / 1024) > s->size) {
+		pr_err("component size must be larger than chunk size.\n");
+		return 1;
+	}
+
+	st = super_by_fd(fd, &subarray);
+	if (!st) {
+		pr_err("Unable to determine metadata format for %s\n", devname);
+		return 1;
+	}
+	if (s->raiddisks > st->max_devs) {
+		pr_err("Cannot increase raid-disks on this array beyond %d\n", st->max_devs);
+		return 1;
+	}
+	if (s->level == 0 && (array.state & (1 << MD_SB_BITMAP_PRESENT)) &&
+		!(array.state & (1 << MD_SB_CLUSTERED)) && !st->ss->external) {
+		array.state &= ~(1 << MD_SB_BITMAP_PRESENT);
+		if (md_set_array_info(fd, &array) != 0) {
+			pr_err("failed to remove internal bitmap.\n");
+			return 1;
+		}
+	}
+
+	/* in the external case we need to check that the requested reshape is
+	 * supported, and perform an initial check that the container holds the
+	 * pre-requisite spare devices (mdmon owns final validation)
+	 */
+	if (st->ss->external) {
+		int retval;
+
+		if (subarray) {
+			container = st->container_devnm;
+			cfd = open_dev_excl(st->container_devnm);
+		} else {
+			container = st->devnm;
+			close(fd);
+			cfd = open_dev_excl(st->devnm);
+			fd = cfd;
+		}
+		if (cfd < 0) {
+			pr_err("Unable to open container for %s\n", devname);
+			free(subarray);
+			return 1;
+		}
+
+		retval = st->ss->load_container(st, cfd, NULL);
+
+		if (retval) {
+			pr_err("Cannot read superblock for %s\n", devname);
+			free(subarray);
+			return 1;
+		}
+
+		/* check if operation is supported for metadata handler */
+		if (st->ss->container_content) {
+			struct mdinfo *cc = NULL;
+			struct mdinfo *content = NULL;
+
+			cc = st->ss->container_content(st, subarray);
+			for (content = cc; content ; content = content->next) {
+				int allow_reshape = 1;
+
+				/* check if reshape is allowed based on metadata
+				 * indications stored in content.array.status
+				 */
+				if (content->array.state &
+				    (1 << MD_SB_BLOCK_VOLUME))
+					allow_reshape = 0;
+				if (content->array.state &
+				    (1 << MD_SB_BLOCK_CONTAINER_RESHAPE))
+					allow_reshape = 0;
+				if (!allow_reshape) {
+					pr_err("cannot reshape arrays in container with unsupported metadata: %s(%s)\n",
+					       devname, container);
+					sysfs_free(cc);
+					free(subarray);
+					return 1;
+				}
+				if (content->consistency_policy ==
+				    CONSISTENCY_POLICY_PPL) {
+					pr_err("Operation not supported when ppl consistency policy is enabled\n");
+					sysfs_free(cc);
+					free(subarray);
+					return 1;
+				}
+				if (content->consistency_policy ==
+				    CONSISTENCY_POLICY_BITMAP) {
+					pr_err("Operation not supported when write-intent bitmap is enabled\n");
+					sysfs_free(cc);
+					free(subarray);
+					return 1;
+				}
+			}
+			sysfs_free(cc);
+		}
+		if (mdmon_running(container))
+			st->update_tail = &st->updates;
+	}
+
+	added_disks = 0;
+	for (dv = devlist; dv; dv = dv->next)
+		added_disks++;
+	if (s->raiddisks > array.raid_disks &&
+	    array.spare_disks + added_disks <
+	    (s->raiddisks - array.raid_disks) &&
+	    !c->force) {
+		pr_err("Need %d spare%s to avoid degraded array, and only have %d.\n"
+		       "       Use --force to over-ride this check.\n",
+		       s->raiddisks - array.raid_disks,
+		       s->raiddisks - array.raid_disks == 1 ? "" : "s",
+		       array.spare_disks + added_disks);
+		return 1;
+	}
+
+	sra = sysfs_read(fd, NULL, GET_LEVEL | GET_DISKS | GET_DEVS |
+			 GET_STATE | GET_VERSION);
+	if (sra) {
+		if (st->ss->external && subarray == NULL) {
+			array.level = LEVEL_CONTAINER;
+			sra->array.level = LEVEL_CONTAINER;
+		}
+	} else {
+		pr_err("failed to read sysfs parameters for %s\n",
+			devname);
+		return 1;
+	}
+	frozen = freeze(st);
+	if (frozen < -1) {
+		/* freeze() already spewed the reason */
+		sysfs_free(sra);
+		return 1;
+	} else if (frozen < 0) {
+		pr_err("%s is performing resync/recovery and cannot be reshaped\n", devname);
+		sysfs_free(sra);
+		return 1;
+	}
+
+	/* ========= set size =============== */
+	if (s->size > 0 &&
+	    (s->size == MAX_SIZE || s->size != (unsigned)array.size)) {
+		unsigned long long orig_size = get_component_size(fd)/2;
+		unsigned long long min_csize;
+		struct mdinfo *mdi;
+		int raid0_takeover = 0;
+
+		if (orig_size == 0)
+			orig_size = (unsigned) array.size;
+
+		if (orig_size == 0) {
+			pr_err("Cannot set device size in this type of array.\n");
+			rv = 1;
+			goto release;
+		}
+
+		if (reshape_super(st, s->size, UnSet, UnSet, 0, 0, UnSet, NULL,
+				  devname, APPLY_METADATA_CHANGES,
+				  c->verbose > 0)) {
+			rv = 1;
+			goto release;
+		}
+		sync_metadata(st);
+		if (st->ss->external) {
+			/* metadata can have size limitation
+			 * update size value according to metadata information
+			 */
+			struct mdinfo *sizeinfo =
+				st->ss->container_content(st, subarray);
+			if (sizeinfo) {
+				unsigned long long new_size =
+					sizeinfo->custom_array_size/2;
+				int data_disks = get_data_disks(
+						sizeinfo->array.level,
+						sizeinfo->array.layout,
+						sizeinfo->array.raid_disks);
+				new_size /= data_disks;
+				dprintf("Metadata size correction from %llu to %llu (%llu)\n",
+					orig_size, new_size,
+					new_size * data_disks);
+				s->size = new_size;
+				sysfs_free(sizeinfo);
+			}
+		}
+
+		/* Update the size of each member device in case
+		 * they have been resized.  This will never reduce
+		 * below the current used-size.  The "size" attribute
+		 * understands '0' to mean 'max'.
+		 */
+		min_csize = 0;
+		for (mdi = sra->devs; mdi; mdi = mdi->next) {
+			sysfs_set_num(sra, mdi, "size",
+				      s->size == MAX_SIZE ? 0 : s->size);
+			if (array.not_persistent == 0 &&
+			    array.major_version == 0 &&
+			    get_linux_version() < 3001000) {
+				/* Dangerous to allow size to exceed 2TB */
+				unsigned long long csize;
+				if (sysfs_get_ll(sra, mdi, "size",
+						 &csize) == 0) {
+					if (csize >= 2ULL*1024*1024*1024)
+						csize = 2ULL*1024*1024*1024;
+					if ((min_csize == 0 ||
+					     (min_csize > csize)))
+						min_csize = csize;
+				}
+			}
+		}
+		if (min_csize && s->size > min_csize) {
+			pr_err("Cannot safely make this array use more than 2TB per device on this kernel.\n");
+			rv = 1;
+			goto size_change_error;
+		}
+		if (min_csize && s->size == MAX_SIZE) {
+			/* Don't let the kernel choose a size - it will get
+			 * it wrong
+			 */
+			pr_err("Limited v0.90 array to 2TB per device\n");
+			s->size = min_csize;
+		}
+		if (st->ss->external) {
+			if (sra->array.level == 0) {
+				rv = sysfs_set_str(sra, NULL, "level", "raid5");
+				if (!rv) {
+					raid0_takeover = 1;
+					/* get array parameters after takeover
+					 * to change one parameter at time only
+					 */
+					rv = md_get_array_info(fd, &array);
+				}
+			}
+			/* make sure mdmon is
+			 * aware of the new level */
+			if (!mdmon_running(st->container_devnm))
+				start_mdmon(st->container_devnm);
+			ping_monitor(container);
+			if (mdmon_running(st->container_devnm) &&
+					st->update_tail == NULL)
+				st->update_tail = &st->updates;
+		}
+
+		if (s->size == MAX_SIZE)
+			s->size = 0;
+		array.size = s->size;
+		if (s->size & ~INT32_MAX) {
+			/* got truncated to 32bit, write to
+			 * component_size instead
+			 */
+			if (sra)
+				rv = sysfs_set_num(sra, NULL,
+						   "component_size", s->size);
+			else
+				rv = -1;
+		} else {
+			rv = md_set_array_info(fd, &array);
+
+			/* manage array size when it is managed externally
+			 */
+			if ((rv == 0) && st->ss->external)
+				rv = set_array_size(st, sra, sra->text_version);
+		}
+
+		if (raid0_takeover) {
+			/* do not recync non-existing parity,
+			 * we will drop it anyway
+			 */
+			sysfs_set_str(sra, NULL, "sync_action", "frozen");
+			/* go back to raid0, drop parity disk
+			 */
+			sysfs_set_str(sra, NULL, "level", "raid0");
+			md_get_array_info(fd, &array);
+		}
+
+size_change_error:
+		if (rv != 0) {
+			int err = errno;
+
+			/* restore metadata */
+			if (reshape_super(st, orig_size, UnSet, UnSet, 0, 0,
+					  UnSet, NULL, devname,
+					  ROLLBACK_METADATA_CHANGES,
+					  c->verbose) == 0)
+				sync_metadata(st);
+			pr_err("Cannot set device size for %s: %s\n",
+				devname, strerror(err));
+			if (err == EBUSY &&
+			    (array.state & (1<<MD_SB_BITMAP_PRESENT)))
+				cont_err("Bitmap must be removed before size can be changed\n");
+			rv = 1;
+			goto release;
+		}
+		if (s->assume_clean) {
+			/* This will fail on kernels older than 3.0 unless
+			 * a backport has been arranged.
+			 */
+			if (sra == NULL ||
+			    sysfs_set_str(sra, NULL, "resync_start",
+					  "none") < 0)
+				pr_err("--assume-clean not supported with --grow on this kernel\n");
+		}
+		md_get_array_info(fd, &array);
+		s->size = get_component_size(fd)/2;
+		if (s->size == 0)
+			s->size = array.size;
+		if (c->verbose >= 0) {
+			if (s->size == orig_size)
+				pr_err("component size of %s unchanged at %lluK\n",
+					devname, s->size);
+			else
+				pr_err("component size of %s has been set to %lluK\n",
+					devname, s->size);
+		}
+		changed = 1;
+	} else if (array.level != LEVEL_CONTAINER) {
+		s->size = get_component_size(fd)/2;
+		if (s->size == 0)
+			s->size = array.size;
+	}
+
+	/* See if there is anything else to do */
+	if ((s->level == UnSet || s->level == array.level) &&
+	    (s->layout_str == NULL) &&
+	    (s->chunk == 0 || s->chunk == array.chunk_size) &&
+	    data_offset == INVALID_SECTORS &&
+	    (s->raiddisks == 0 || s->raiddisks == array.raid_disks)) {
+		/* Nothing more to do */
+		if (!changed && c->verbose >= 0)
+			pr_err("%s: no change requested\n", devname);
+		goto release;
+	}
+
+	/* ========= check for Raid10/Raid1 -> Raid0 conversion ===============
+	 * current implementation assumes that following conditions must be met:
+	 * - RAID10:
+	 *	- far_copies == 1
+	 *	- near_copies == 2
+	 */
+	if ((s->level == 0 && array.level == 10 && sra &&
+	     array.layout == ((1 << 8) + 2) && !(array.raid_disks & 1)) ||
+	    (s->level == 0 && array.level == 1 && sra)) {
+		int err;
+
+		err = remove_disks_for_takeover(st, sra, array.layout);
+		if (err) {
+			dprintf("Array cannot be reshaped\n");
+			if (cfd > -1)
+				close(cfd);
+			rv = 1;
+			goto release;
+		}
+		/* Make sure mdmon has seen the device removal
+		 * and updated metadata before we continue with
+		 * level change
+		 */
+		if (container)
+			ping_monitor(container);
+	}
+
+	memset(&info, 0, sizeof(info));
+	info.array = array;
+	if (sysfs_init(&info, fd, NULL)) {
+		pr_err("failed to initialize sysfs.\n");
+		rv = 1;
+		goto release;
+	}
+	strcpy(info.text_version, sra->text_version);
+	info.component_size = s->size*2;
+	info.new_level = s->level;
+	info.new_chunk = s->chunk * 1024;
+	if (info.array.level == LEVEL_CONTAINER) {
+		info.delta_disks = UnSet;
+		info.array.raid_disks = s->raiddisks;
+	} else if (s->raiddisks)
+		info.delta_disks = s->raiddisks - info.array.raid_disks;
+	else
+		info.delta_disks = UnSet;
+	if (s->layout_str == NULL) {
+		info.new_layout = UnSet;
+		if (info.array.level == 6 &&
+		    (info.new_level == 6 || info.new_level == UnSet) &&
+		    info.array.layout >= 16) {
+			pr_err("%s has a non-standard layout.  If you wish to preserve this\n", devname);
+			cont_err("during the reshape, please specify --layout=preserve\n");
+			cont_err("If you want to change it, specify a layout or use --layout=normalise\n");
+			rv = 1;
+			goto release;
+		}
+	} else if (strcmp(s->layout_str, "normalise") == 0 ||
+		   strcmp(s->layout_str, "normalize") == 0) {
+		/* If we have a -6 RAID6 layout, remove the '-6'. */
+		info.new_layout = UnSet;
+		if (info.array.level == 6 && info.new_level == UnSet) {
+			char l[40], *h;
+			strcpy(l, map_num(r6layout, info.array.layout));
+			h = strrchr(l, '-');
+			if (h && strcmp(h, "-6") == 0) {
+				*h = 0;
+				info.new_layout = map_name(r6layout, l);
+			}
+		} else {
+			pr_err("%s is only meaningful when reshaping a RAID6 array.\n", s->layout_str);
+			rv = 1;
+			goto release;
+		}
+	} else if (strcmp(s->layout_str, "preserve") == 0) {
+		/* This means that a non-standard RAID6 layout
+		 * is OK.
+		 * In particular:
+		 * - When reshape a RAID6 (e.g. adding a device)
+		 *   which is in a non-standard layout, it is OK
+		 *   to preserve that layout.
+		 * - When converting a RAID5 to RAID6, leave it in
+		 *   the XXX-6 layout, don't re-layout.
+		 */
+		if (info.array.level == 6 && info.new_level == UnSet)
+			info.new_layout = info.array.layout;
+		else if (info.array.level == 5 && info.new_level == 6) {
+			char l[40];
+			strcpy(l, map_num(r5layout, info.array.layout));
+			strcat(l, "-6");
+			info.new_layout = map_name(r6layout, l);
+		} else {
+			pr_err("%s in only meaningful when reshaping to RAID6\n", s->layout_str);
+			rv = 1;
+			goto release;
+		}
+	} else {
+		int l = info.new_level;
+		if (l == UnSet)
+			l = info.array.level;
+		switch (l) {
+		case 5:
+			info.new_layout = map_name(r5layout, s->layout_str);
+			break;
+		case 6:
+			info.new_layout = map_name(r6layout, s->layout_str);
+			break;
+		case 10:
+			info.new_layout = parse_layout_10(s->layout_str);
+			break;
+		case LEVEL_FAULTY:
+			info.new_layout = parse_layout_faulty(s->layout_str);
+			break;
+		default:
+			pr_err("layout not meaningful with this level\n");
+			rv = 1;
+			goto release;
+		}
+		if (info.new_layout == UnSet) {
+			pr_err("layout %s not understood for this level\n",
+				s->layout_str);
+			rv = 1;
+			goto release;
+		}
+	}
+
+	if (array.level == LEVEL_FAULTY) {
+		if (s->level != UnSet && s->level != array.level) {
+			pr_err("cannot change level of Faulty device\n");
+			rv =1 ;
+		}
+		if (s->chunk) {
+			pr_err("cannot set chunksize of Faulty device\n");
+			rv =1 ;
+		}
+		if (s->raiddisks && s->raiddisks != 1) {
+			pr_err("cannot set raid_disks of Faulty device\n");
+			rv =1 ;
+		}
+		if (s->layout_str) {
+			if (md_get_array_info(fd, &array) != 0) {
+				dprintf("Cannot get array information.\n");
+				goto release;
+			}
+			array.layout = info.new_layout;
+			if (md_set_array_info(fd, &array) != 0) {
+				pr_err("failed to set new layout\n");
+				rv = 1;
+			} else if (c->verbose >= 0)
+				printf("layout for %s set to %d\n",
+				       devname, array.layout);
+		}
+	} else if (array.level == LEVEL_CONTAINER) {
+		/* This change is to be applied to every array in the
+		 * container.  This is only needed when the metadata imposes
+		 * restraints of the various arrays in the container.
+		 * Currently we only know that IMSM requires all arrays
+		 * to have the same number of devices so changing the
+		 * number of devices (On-Line Capacity Expansion) must be
+		 * performed at the level of the container
+		 */
+		close_fd(&fd);
+		rv = reshape_container(container, devname, -1, st, &info,
+				       c->force, c->backup_file, c->verbose,
+				       0, 0, 0);
+		frozen = 0;
+	} else {
+		/* get spare devices from external metadata
+		 */
+		if (st->ss->external) {
+			struct mdinfo *info2;
+
+			info2 = st->ss->container_content(st, subarray);
+			if (info2) {
+				info.array.spare_disks =
+					info2->array.spare_disks;
+				sysfs_free(info2);
+			}
+		}
+
+		/* Impose these changes on a single array.  First
+		 * check that the metadata is OK with the change. */
+
+		if (reshape_super(st, 0, info.new_level,
+				  info.new_layout, info.new_chunk,
+				  info.array.raid_disks, info.delta_disks,
+				  c->backup_file, devname,
+				  APPLY_METADATA_CHANGES, c->verbose)) {
+			rv = 1;
+			goto release;
+		}
+		sync_metadata(st);
+		rv = reshape_array(container, fd, devname, st, &info, c->force,
+				   devlist, data_offset, c->backup_file,
+				   c->verbose, 0, 0, 0);
+		frozen = 0;
+	}
+release:
+	sysfs_free(sra);
+	if (frozen > 0)
+		unfreeze(st);
+	return rv;
+}
+
+/* verify_reshape_position()
+ *	Function checks if reshape position in metadata is not farther
+ *	than position in md.
+ * Return value:
+ *	 0 : not valid sysfs entry
+ *		it can be caused by not started reshape, it should be started
+ *		by reshape array or raid0 array is before takeover
+ *	-1 :	error, reshape position is obviously wrong
+ *	 1 :	success, reshape progress correct or updated
+*/
+static int verify_reshape_position(struct mdinfo *info, int level)
+{
+	int ret_val = 0;
+	char buf[40];
+	int rv;
+
+	/* read sync_max, failure can mean raid0 array */
+	rv = sysfs_get_str(info, NULL, "sync_max", buf, 40);
+
+	if (rv > 0) {
+		char *ep;
+		unsigned long long position = strtoull(buf, &ep, 0);
+
+		dprintf("Read sync_max sysfs entry is: %s\n", buf);
+		if (!(ep == buf || (*ep != 0 && *ep != '\n' && *ep != ' '))) {
+			position *= get_data_disks(level,
+						   info->new_layout,
+						   info->array.raid_disks);
+			if (info->reshape_progress < position) {
+				dprintf("Corrected reshape progress (%llu) to md position (%llu)\n",
+					info->reshape_progress, position);
+				info->reshape_progress = position;
+				ret_val = 1;
+			} else if (info->reshape_progress > position) {
+				pr_err("Fatal error: array reshape was not properly frozen (expected reshape position is %llu, but reshape progress is %llu.\n",
+				       position, info->reshape_progress);
+				ret_val = -1;
+			} else {
+				dprintf("Reshape position in md and metadata are the same;");
+				ret_val = 1;
+			}
+		}
+	} else if (rv == 0) {
+		/* for valid sysfs entry, 0-length content
+		 * should be indicated as error
+		 */
+		ret_val = -1;
+	}
+
+	return ret_val;
+}
+
+static unsigned long long choose_offset(unsigned long long lo,
+					unsigned long long hi,
+					unsigned long long min,
+					unsigned long long max)
+{
+	/* Choose a new offset between hi and lo.
+	 * It must be between min and max, but
+	 * we would prefer something near the middle of hi/lo, and also
+	 * prefer to be aligned to a big power of 2.
+	 *
+	 * So we start with the middle, then for each bit,
+	 * starting at '1' and increasing, if it is set, we either
+	 * add it or subtract it if possible, preferring the option
+	 * which is furthest from the boundary.
+	 *
+	 * We stop once we get a 1MB alignment. As units are in sectors,
+	 * 1MB = 2*1024 sectors.
+	 */
+	unsigned long long choice = (lo + hi) / 2;
+	unsigned long long bit = 1;
+
+	for (bit = 1; bit < 2*1024; bit = bit << 1) {
+		unsigned long long bigger, smaller;
+		if (! (bit & choice))
+			continue;
+		bigger = choice + bit;
+		smaller = choice - bit;
+		if (bigger > max && smaller < min)
+			break;
+		if (bigger > max)
+			choice = smaller;
+		else if (smaller < min)
+			choice = bigger;
+		else if (hi - bigger > smaller - lo)
+			choice = bigger;
+		else
+			choice = smaller;
+	}
+	return choice;
+}
+
+static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
+			       char *devname, int delta_disks,
+			       unsigned long long data_offset,
+			       unsigned long long min,
+			       int can_fallback)
+{
+	struct mdinfo *sd;
+	int dir = 0;
+	int err = 0;
+	unsigned long long before, after;
+
+	/* Need to find min space before and after so same is used
+	 * on all devices
+	 */
+	before = UINT64_MAX;
+	after = UINT64_MAX;
+	for (sd = sra->devs; sd; sd = sd->next) {
+		char *dn;
+		int dfd;
+		int rv;
+		struct supertype *st2;
+		struct mdinfo info2;
+
+		if (sd->disk.state & (1<<MD_DISK_FAULTY))
+			continue;
+		dn = map_dev(sd->disk.major, sd->disk.minor, 0);
+		dfd = dev_open(dn, O_RDONLY);
+		if (dfd < 0) {
+			pr_err("%s: cannot open component %s\n",
+				devname, dn ? dn : "-unknown-");
+			goto release;
+		}
+		st2 = dup_super(st);
+		rv = st2->ss->load_super(st2,dfd, NULL);
+		close(dfd);
+		if (rv) {
+			free(st2);
+			pr_err("%s: cannot get superblock from %s\n",
+				devname, dn);
+			goto release;
+		}
+		st2->ss->getinfo_super(st2, &info2, NULL);
+		st2->ss->free_super(st2);
+		free(st2);
+		if (info2.space_before == 0 &&
+		    info2.space_after == 0) {
+			/* Metadata doesn't support data_offset changes */
+			if (!can_fallback)
+				pr_err("%s: Metadata version doesn't support data_offset changes\n",
+				       devname);
+			goto fallback;
+		}
+		if (before > info2.space_before)
+			before = info2.space_before;
+		if (after > info2.space_after)
+			after = info2.space_after;
+
+		if (data_offset != INVALID_SECTORS) {
+			if (dir == 0) {
+				if (info2.data_offset == data_offset) {
+					pr_err("%s: already has that data_offset\n",
+					       dn);
+					goto release;
+				}
+				if (data_offset < info2.data_offset)
+					dir = -1;
+				else
+					dir = 1;
+			} else if ((data_offset <= info2.data_offset &&
+				    dir == 1) ||
+				   (data_offset >= info2.data_offset &&
+				    dir == -1)) {
+				pr_err("%s: differing data offsets on devices make this --data-offset setting impossible\n",
+					dn);
+				goto release;
+			}
+		}
+	}
+	if (before == UINT64_MAX)
+		/* impossible really, there must be no devices */
+		return 1;
+
+	for (sd = sra->devs; sd; sd = sd->next) {
+		char *dn = map_dev(sd->disk.major, sd->disk.minor, 0);
+		unsigned long long new_data_offset;
+
+		if (sd->disk.state & (1<<MD_DISK_FAULTY))
+			continue;
+		if (delta_disks < 0) {
+			/* Don't need any space as array is shrinking
+			 * just move data_offset up by min
+			 */
+			if (data_offset == INVALID_SECTORS)
+				new_data_offset = sd->data_offset + min;
+			else {
+				if (data_offset < sd->data_offset + min) {
+					pr_err("--data-offset too small for %s\n",
+						dn);
+					goto release;
+				}
+				new_data_offset = data_offset;
+			}
+		} else if (delta_disks > 0) {
+			/* need space before */
+			if (before < min) {
+				if (can_fallback)
+					goto fallback;
+				pr_err("Insufficient head-space for reshape on %s\n",
+					dn);
+				goto release;
+			}
+			if (data_offset == INVALID_SECTORS)
+				new_data_offset = sd->data_offset - min;
+			else {
+				if (data_offset > sd->data_offset - min) {
+					pr_err("--data-offset too large for %s\n",
+						dn);
+					goto release;
+				}
+				new_data_offset = data_offset;
+			}
+		} else {
+			if (dir == 0) {
+				/* can move up or down.  If 'data_offset'
+				 * was set we would have already decided,
+				 * so just choose direction with most space.
+				 */
+				if (before > after)
+					dir = -1;
+				else
+					dir = 1;
+			}
+			sysfs_set_str(sra, NULL, "reshape_direction",
+				      dir == 1 ? "backwards" : "forwards");
+			if (dir > 0) {
+				/* Increase data offset */
+				if (after < min) {
+					if (can_fallback)
+						goto fallback;
+					pr_err("Insufficient tail-space for reshape on %s\n",
+						dn);
+					goto release;
+				}
+				if (data_offset != INVALID_SECTORS &&
+				    data_offset < sd->data_offset + min) {
+					pr_err("--data-offset too small on %s\n",
+						dn);
+					goto release;
+				}
+				if (data_offset != INVALID_SECTORS)
+					new_data_offset = data_offset;
+				else
+					new_data_offset = choose_offset(sd->data_offset,
+									sd->data_offset + after,
+									sd->data_offset + min,
+									sd->data_offset + after);
+			} else {
+				/* Decrease data offset */
+				if (before < min) {
+					if (can_fallback)
+						goto fallback;
+					pr_err("insufficient head-room on %s\n",
+						dn);
+					goto release;
+				}
+				if (data_offset != INVALID_SECTORS &&
+				    data_offset > sd->data_offset - min) {
+					pr_err("--data-offset too large on %s\n",
+						dn);
+					goto release;
+				}
+				if (data_offset != INVALID_SECTORS)
+					new_data_offset = data_offset;
+				else
+					new_data_offset = choose_offset(sd->data_offset - before,
+									sd->data_offset,
+									sd->data_offset - before,
+									sd->data_offset - min);
+			}
+		}
+		err = sysfs_set_num(sra, sd, "new_offset", new_data_offset);
+		if (err < 0 && errno == E2BIG) {
+			/* try again after increasing data size to max */
+			err = sysfs_set_num(sra, sd, "size", 0);
+			if (err < 0 && errno == EINVAL &&
+			    !(sd->disk.state & (1<<MD_DISK_SYNC))) {
+				/* some kernels have a bug where you cannot
+				 * use '0' on spare devices. */
+				sysfs_set_num(sra, sd, "size",
+					      (sra->component_size + after)/2);
+			}
+			err = sysfs_set_num(sra, sd, "new_offset",
+					    new_data_offset);
+		}
+		if (err < 0) {
+			if (errno == E2BIG && data_offset != INVALID_SECTORS) {
+				pr_err("data-offset is too big for %s\n", dn);
+				goto release;
+			}
+			if (sd == sra->devs &&
+			    (errno == ENOENT || errno == E2BIG))
+				/* Early kernel, no 'new_offset' file,
+				 * or kernel doesn't like us.
+				 * For RAID5/6 this is not fatal
+				 */
+				return 1;
+			pr_err("Cannot set new_offset for %s\n", dn);
+			break;
+		}
+	}
+	return err;
+release:
+	return -1;
+fallback:
+	/* Just use a backup file */
+	return 1;
+}
+
+static int raid10_reshape(char *container, int fd, char *devname,
+			  struct supertype *st, struct mdinfo *info,
+			  struct reshape *reshape,
+			  unsigned long long data_offset,
+			  int force, int verbose)
+{
+	/* Changing raid_disks, layout, chunksize or possibly
+	 * just data_offset for a RAID10.
+	 * We must always change data_offset.  We change by at least
+	 * ->min_offset_change which is the largest of the old and new
+	 * chunk sizes.
+	 * If raid_disks is increasing, then data_offset must decrease
+	 * by at least this copy size.
+	 * If raid_disks is unchanged, data_offset must increase or
+	 * decrease by at least min_offset_change but preferably by much more.
+	 * We choose half of the available space.
+	 * If raid_disks is decreasing, data_offset must increase by
+	 * at least min_offset_change.  To allow of this, component_size
+	 * must be decreased by the same amount.
+	 *
+	 * So we calculate the required minimum and direction, possibly
+	 * reduce the component_size, then iterate through the devices
+	 * and set the new_data_offset.
+	 * If that all works, we set chunk_size, layout, raid_disks, and start
+	 * 'reshape'
+	 */
+	struct mdinfo *sra;
+	unsigned long long min;
+	int err = 0;
+
+	sra = sysfs_read(fd, NULL,
+			 GET_COMPONENT|GET_DEVS|GET_OFFSET|GET_STATE|GET_CHUNK
+		);
+	if (!sra) {
+		pr_err("%s: Cannot get array details from sysfs\n", devname);
+		goto release;
+	}
+	min = reshape->min_offset_change;
+
+	if (info->delta_disks)
+		sysfs_set_str(sra, NULL, "reshape_direction",
+			      info->delta_disks < 0 ? "backwards" : "forwards");
+	if (info->delta_disks < 0 && info->space_after < min) {
+		int rv = sysfs_set_num(sra, NULL, "component_size",
+				       (sra->component_size - min)/2);
+		if (rv) {
+			pr_err("cannot reduce component size\n");
+			goto release;
+		}
+	}
+	err = set_new_data_offset(sra, st, devname, info->delta_disks,
+				  data_offset, min, 0);
+	if (err == 1) {
+		pr_err("Cannot set new_data_offset: RAID10 reshape not\n");
+		cont_err("supported on this kernel\n");
+		err = -1;
+	}
+	if (err < 0)
+		goto release;
+
+	if (!err && sysfs_set_num(sra, NULL, "chunk_size", info->new_chunk) < 0)
+		err = errno;
+	if (!err && sysfs_set_num(sra, NULL, "layout",
+				  reshape->after.layout) < 0)
+		err = errno;
+	if (!err &&
+	    sysfs_set_num(sra, NULL, "raid_disks",
+			  info->array.raid_disks + info->delta_disks) < 0)
+		err = errno;
+	if (!err && sysfs_set_str(sra, NULL, "sync_action", "reshape") < 0)
+		err = errno;
+	if (err) {
+		pr_err("Cannot set array shape for %s\n",
+		       devname);
+		if (err == EBUSY &&
+		    (info->array.state & (1<<MD_SB_BITMAP_PRESENT)))
+			cont_err("       Bitmap must be removed before shape can be changed\n");
+		goto release;
+	}
+	sysfs_free(sra);
+	return 0;
+release:
+	sysfs_free(sra);
+	return 1;
+}
+
+static void get_space_after(int fd, struct supertype *st, struct mdinfo *info)
+{
+	struct mdinfo *sra, *sd;
+	/* Initialisation to silence compiler warning */
+	unsigned long long min_space_before = 0, min_space_after = 0;
+	int first = 1;
+
+	sra = sysfs_read(fd, NULL, GET_DEVS);
+	if (!sra)
+		return;
+	for (sd = sra->devs; sd; sd = sd->next) {
+		char *dn;
+		int dfd;
+		struct supertype *st2;
+		struct mdinfo info2;
+
+		if (sd->disk.state & (1<<MD_DISK_FAULTY))
+			continue;
+		dn = map_dev(sd->disk.major, sd->disk.minor, 0);
+		dfd = dev_open(dn, O_RDONLY);
+		if (dfd < 0)
+			break;
+		st2 = dup_super(st);
+		if (st2->ss->load_super(st2,dfd, NULL)) {
+			close(dfd);
+			free(st2);
+			break;
+		}
+		close(dfd);
+		st2->ss->getinfo_super(st2, &info2, NULL);
+		st2->ss->free_super(st2);
+		free(st2);
+		if (first ||
+		    min_space_before > info2.space_before)
+			min_space_before = info2.space_before;
+		if (first ||
+		    min_space_after > info2.space_after)
+			min_space_after = info2.space_after;
+		first = 0;
+	}
+	if (sd == NULL && !first) {
+		info->space_after = min_space_after;
+		info->space_before = min_space_before;
+	}
+	sysfs_free(sra);
+}
+
+static void update_cache_size(char *container, struct mdinfo *sra,
+			      struct mdinfo *info,
+			      int disks, unsigned long long blocks)
+{
+	/* Check that the internal stripe cache is
+	 * large enough, or it won't work.
+	 * It must hold at least 4 stripes of the larger
+	 * chunk size
+	 */
+	unsigned long cache;
+	cache = max(info->array.chunk_size, info->new_chunk);
+	cache *= 4; /* 4 stripes minimum */
+	cache /= 512; /* convert to sectors */
+	/* make sure there is room for 'blocks' with a bit to spare */
+	if (cache < 16 + blocks / disks)
+		cache = 16 + blocks / disks;
+	cache /= (4096/512); /* Convert from sectors to pages */
+
+	if (sra->cache_size < cache)
+		subarray_set_num(container, sra, "stripe_cache_size",
+				 cache+1);
+}
+
+static int impose_reshape(struct mdinfo *sra,
+			  struct mdinfo *info,
+			  struct supertype *st,
+			  int fd,
+			  int restart,
+			  char *devname, char *container,
+			  struct reshape *reshape)
+{
+	struct mdu_array_info_s array;
+
+	sra->new_chunk = info->new_chunk;
+
+	if (restart) {
+		/* for external metadata checkpoint saved by mdmon can be lost
+		 * or missed /due to e.g. crash/. Check if md is not during
+		 * restart farther than metadata points to.
+		 * If so, this means metadata information is obsolete.
+		 */
+		if (st->ss->external)
+			verify_reshape_position(info, reshape->level);
+		sra->reshape_progress = info->reshape_progress;
+	} else {
+		sra->reshape_progress = 0;
+		if (reshape->after.data_disks < reshape->before.data_disks)
+			/* start from the end of the new array */
+			sra->reshape_progress = (sra->component_size
+						 * reshape->after.data_disks);
+	}
+
+	md_get_array_info(fd, &array);
+	if (info->array.chunk_size == info->new_chunk &&
+	    reshape->before.layout == reshape->after.layout &&
+	    st->ss->external == 0) {
+		/* use SET_ARRAY_INFO but only if reshape hasn't started */
+		array.raid_disks = reshape->after.data_disks + reshape->parity;
+		if (!restart && md_set_array_info(fd, &array) != 0) {
+			int err = errno;
+
+			pr_err("Cannot set device shape for %s: %s\n",
+			       devname, strerror(errno));
+
+			if (err == EBUSY &&
+			    (array.state & (1<<MD_SB_BITMAP_PRESENT)))
+				cont_err("Bitmap must be removed before shape can be changed\n");
+
+			goto release;
+		}
+	} else if (!restart) {
+		/* set them all just in case some old 'new_*' value
+		 * persists from some earlier problem.
+		 */
+		int err = 0;
+		if (sysfs_set_num(sra, NULL, "chunk_size", info->new_chunk) < 0)
+			err = errno;
+		if (!err && sysfs_set_num(sra, NULL, "layout",
+					  reshape->after.layout) < 0)
+			err = errno;
+		if (!err && subarray_set_num(container, sra, "raid_disks",
+					     reshape->after.data_disks +
+					     reshape->parity) < 0)
+			err = errno;
+		if (err) {
+			pr_err("Cannot set device shape for %s\n", devname);
+
+			if (err == EBUSY &&
+			    (array.state & (1<<MD_SB_BITMAP_PRESENT)))
+				cont_err("Bitmap must be removed before shape can be changed\n");
+			goto release;
+		}
+	}
+	return 0;
+release:
+	return -1;
+}
+
+static int impose_level(int fd, int level, char *devname, int verbose)
+{
+	char *c;
+	struct mdu_array_info_s array;
+	struct mdinfo info;
+
+	if (sysfs_init(&info, fd, NULL)) {
+		pr_err("failed to initialize sysfs.\n");
+		return  1;
+	}
+
+	md_get_array_info(fd, &array);
+	if (level == 0 && (array.level >= 4 && array.level <= 6)) {
+		/* To convert to RAID0 we need to fail and
+		 * remove any non-data devices. */
+		int found = 0;
+		int d;
+		int data_disks = array.raid_disks - 1;
+		if (array.level == 6)
+			data_disks -= 1;
+		if (array.level == 5 && array.layout != ALGORITHM_PARITY_N)
+			return -1;
+		if (array.level == 6 && array.layout != ALGORITHM_PARITY_N_6)
+			return -1;
+		sysfs_set_str(&info, NULL,"sync_action", "idle");
+		/* First remove any spares so no recovery starts */
+		for (d = 0, found = 0;
+		     d < MAX_DISKS && found < array.nr_disks; d++) {
+			mdu_disk_info_t disk;
+			disk.number = d;
+			if (md_get_disk_info(fd, &disk) < 0)
+				continue;
+			if (disk.major == 0 && disk.minor == 0)
+				continue;
+			found++;
+			if ((disk.state & (1 << MD_DISK_ACTIVE)) &&
+			    disk.raid_disk < data_disks)
+				/* keep this */
+				continue;
+			ioctl(fd, HOT_REMOVE_DISK,
+			      makedev(disk.major, disk.minor));
+		}
+		/* Now fail anything left */
+		md_get_array_info(fd, &array);
+		for (d = 0, found = 0;
+		     d < MAX_DISKS && found < array.nr_disks; d++) {
+			mdu_disk_info_t disk;
+			disk.number = d;
+			if (md_get_disk_info(fd, &disk) < 0)
+				continue;
+			if (disk.major == 0 && disk.minor == 0)
+				continue;
+			found++;
+			if ((disk.state & (1 << MD_DISK_ACTIVE)) &&
+			    disk.raid_disk < data_disks)
+				/* keep this */
+				continue;
+			ioctl(fd, SET_DISK_FAULTY,
+			      makedev(disk.major, disk.minor));
+			hot_remove_disk(fd, makedev(disk.major, disk.minor), 1);
+		}
+	}
+	c = map_num(pers, level);
+	if (c) {
+		int err = sysfs_set_str(&info, NULL, "level", c);
+		if (err) {
+			err = errno;
+			pr_err("%s: could not set level to %s\n",
+				devname, c);
+			if (err == EBUSY &&
+			    (array.state & (1<<MD_SB_BITMAP_PRESENT)))
+				cont_err("Bitmap must be removed before level can be changed\n");
+			return err;
+		}
+		if (verbose >= 0)
+			pr_err("level of %s changed to %s\n", devname, c);
+	}
+	return 0;
+}
+
+int sigterm = 0;
+static void catch_term(int sig)
+{
+	sigterm = 1;
+}
+
+static int reshape_array(char *container, int fd, char *devname,
+			 struct supertype *st, struct mdinfo *info,
+			 int force, struct mddev_dev *devlist,
+			 unsigned long long data_offset,
+			 char *backup_file, int verbose, int forked,
+			 int restart, int freeze_reshape)
+{
+	struct reshape reshape;
+	int spares_needed;
+	char *msg;
+	int orig_level = UnSet;
+	int odisks;
+	int delayed;
+
+	struct mdu_array_info_s array;
+	char *c;
+
+	struct mddev_dev *dv;
+	int added_disks;
+
+	int *fdlist = NULL;
+	unsigned long long *offsets = NULL;
+	int d;
+	int nrdisks;
+	int err;
+	unsigned long blocks;
+	unsigned long long array_size;
+	int done;
+	struct mdinfo *sra = NULL;
+	char buf[20];
+
+	/* when reshaping a RAID0, the component_size might be zero.
+	 * So try to fix that up.
+	 */
+	if (md_get_array_info(fd, &array) != 0) {
+		dprintf("Cannot get array information.\n");
+		goto release;
+	}
+	if (array.level == 0 && info->component_size == 0) {
+		get_dev_size(fd, NULL, &array_size);
+		info->component_size = array_size / array.raid_disks;
+	}
+
+	if (array.level == 10)
+		/* Need space_after info */
+		get_space_after(fd, st, info);
+
+	if (info->reshape_active) {
+		int new_level = info->new_level;
+		info->new_level = UnSet;
+		if (info->delta_disks > 0)
+			info->array.raid_disks -= info->delta_disks;
+		msg = analyse_change(devname, info, &reshape);
+		info->new_level = new_level;
+		if (info->delta_disks > 0)
+			info->array.raid_disks += info->delta_disks;
+		if (!restart)
+			/* Make sure the array isn't read-only */
+			ioctl(fd, RESTART_ARRAY_RW, 0);
+	} else
+		msg = analyse_change(devname, info, &reshape);
+	if (msg) {
+		/* if msg == "", error has already been printed */
+		if (msg[0])
+			pr_err("%s\n", msg);
+		goto release;
+	}
+	if (restart && (reshape.level != info->array.level ||
+			reshape.before.layout != info->array.layout ||
+			reshape.before.data_disks + reshape.parity !=
+			info->array.raid_disks - max(0, info->delta_disks))) {
+		pr_err("reshape info is not in native format - cannot continue.\n");
+		goto release;
+	}
+
+	if (st->ss->external && restart && (info->reshape_progress == 0) &&
+	    !((sysfs_get_str(info, NULL, "sync_action",
+			     buf, sizeof(buf)) > 0) &&
+	      (strncmp(buf, "reshape", 7) == 0))) {
+		/* When reshape is restarted from '0', very begin of array
+		 * it is possible that for external metadata reshape and array
+		 * configuration doesn't happen.
+		 * Check if md has the same opinion, and reshape is restarted
+		 * from 0. If so, this is regular reshape start after reshape
+		 * switch in metadata to next array only.
+		 */
+		if ((verify_reshape_position(info, reshape.level) >= 0) &&
+		    (info->reshape_progress == 0))
+			restart = 0;
+	}
+	if (restart) {
+		/*
+		 * reshape already started. just skip to monitoring
+		 * the reshape
+		 */
+		if (reshape.backup_blocks == 0)
+			return 0;
+		if (restart & RESHAPE_NO_BACKUP)
+			return 0;
+
+		/* Need 'sra' down at 'started:' */
+		sra = sysfs_read(fd, NULL,
+				 GET_COMPONENT|GET_DEVS|GET_OFFSET|GET_STATE|
+				 GET_CHUNK|GET_CACHE);
+		if (!sra) {
+			pr_err("%s: Cannot get array details from sysfs\n",
+			       devname);
+			goto release;
+		}
+
+		if (!backup_file)
+			backup_file = locate_backup(sra->sys_name);
+
+		goto started;
+	}
+	/* The container is frozen but the array may not be.
+	 * So freeze the array so spares don't get put to the wrong use
+	 * FIXME there should probably be a cleaner separation between
+	 * freeze_array and freeze_container.
+	 */
+	sysfs_freeze_array(info);
+	/* Check we have enough spares to not be degraded */
+	added_disks = 0;
+	for (dv = devlist; dv ; dv=dv->next)
+		added_disks++;
+	spares_needed = max(reshape.before.data_disks,
+			    reshape.after.data_disks) +
+		reshape.parity - array.raid_disks;
+
+	if (!force && info->new_level > 1 && info->array.level > 1 &&
+	    spares_needed > info->array.spare_disks + added_disks) {
+		pr_err("Need %d spare%s to avoid degraded array, and only have %d.\n"
+		       "       Use --force to over-ride this check.\n",
+		       spares_needed,
+		       spares_needed == 1 ? "" : "s",
+		       info->array.spare_disks + added_disks);
+		goto release;
+	}
+	/* Check we have enough spares to not fail */
+	spares_needed = max(reshape.before.data_disks,
+			    reshape.after.data_disks)
+		- array.raid_disks;
+	if ((info->new_level > 1 || info->new_level == 0) &&
+	    spares_needed > info->array.spare_disks +added_disks) {
+		pr_err("Need %d spare%s to create working array, and only have %d.\n",
+		       spares_needed, spares_needed == 1 ? "" : "s",
+		       info->array.spare_disks + added_disks);
+		goto release;
+	}
+
+	if (reshape.level != array.level) {
+		int err = impose_level(fd, reshape.level, devname, verbose);
+		if (err)
+			goto release;
+		info->new_layout = UnSet; /* after level change,
+					   * layout is meaningless */
+		orig_level = array.level;
+		sysfs_freeze_array(info);
+
+		if (reshape.level > 0 && st->ss->external) {
+			/* make sure mdmon is aware of the new level */
+			if (mdmon_running(container))
+				flush_mdmon(container);
+
+			if (!mdmon_running(container))
+				start_mdmon(container);
+			ping_monitor(container);
+			if (mdmon_running(container) && st->update_tail == NULL)
+				st->update_tail = &st->updates;
+		}
+	}
+	/* ->reshape_super might have chosen some spares from the
+	 * container that it wants to be part of the new array.
+	 * We can collect them with ->container_content and give
+	 * them to the kernel.
+	 */
+	if (st->ss->reshape_super && st->ss->container_content) {
+		char *subarray = strchr(info->text_version+1, '/')+1;
+		struct mdinfo *info2 =
+			st->ss->container_content(st, subarray);
+		struct mdinfo *d;
+
+		if (info2) {
+			if (sysfs_init(info2, fd, st->devnm)) {
+				pr_err("unable to initialize sysfs for %s\n",
+				       st->devnm);
+				free(info2);
+				goto release;
+			}
+			/* When increasing number of devices, we need to set
+			 * new raid_disks before adding these, or they might
+			 * be rejected.
+			 */
+			if (reshape.backup_blocks &&
+			    reshape.after.data_disks >
+			    reshape.before.data_disks)
+				subarray_set_num(container, info2, "raid_disks",
+						 reshape.after.data_disks +
+						 reshape.parity);
+			for (d = info2->devs; d; d = d->next) {
+				if (d->disk.state == 0 &&
+				    d->disk.raid_disk >= 0) {
+					/* This is a spare that wants to
+					 * be part of the array.
+					 */
+					add_disk(fd, st, info2, d);
+				}
+			}
+			sysfs_free(info2);
+		}
+	}
+	/* We might have been given some devices to add to the
+	 * array.  Now that the array has been changed to the right
+	 * level and frozen, we can safely add them.
+	 */
+	if (devlist) {
+		if (Manage_subdevs(devname, fd, devlist, verbose, 0, NULL, 0))
+			goto release;
+	}
+
+	if (reshape.backup_blocks == 0 && data_offset != INVALID_SECTORS)
+		reshape.backup_blocks = reshape.before.data_disks * info->array.chunk_size/512;
+	if (reshape.backup_blocks == 0) {
+		/* No restriping needed, but we might need to impose
+		 * some more changes: layout, raid_disks, chunk_size
+		 */
+		/* read current array info */
+		if (md_get_array_info(fd, &array) != 0) {
+			dprintf("Cannot get array information.\n");
+			goto release;
+		}
+		/* compare current array info with new values and if
+		 * it is different update them to new */
+		if (info->new_layout != UnSet &&
+		    info->new_layout != array.layout) {
+			array.layout = info->new_layout;
+			if (md_set_array_info(fd, &array) != 0) {
+				pr_err("failed to set new layout\n");
+				goto release;
+			} else if (verbose >= 0)
+				printf("layout for %s set to %d\n",
+				       devname, array.layout);
+		}
+		if (info->delta_disks != UnSet && info->delta_disks != 0 &&
+		    array.raid_disks !=
+		    (info->array.raid_disks + info->delta_disks)) {
+			array.raid_disks += info->delta_disks;
+			if (md_set_array_info(fd, &array) != 0) {
+				pr_err("failed to set raid disks\n");
+				goto release;
+			} else if (verbose >= 0) {
+				printf("raid_disks for %s set to %d\n",
+				       devname, array.raid_disks);
+			}
+		}
+		if (info->new_chunk != 0 &&
+		    info->new_chunk != array.chunk_size) {
+			if (sysfs_set_num(info, NULL,
+					  "chunk_size", info->new_chunk) != 0) {
+				pr_err("failed to set chunk size\n");
+				goto release;
+			} else if (verbose >= 0)
+				printf("chunk size for %s set to %d\n",
+				       devname, info->new_chunk);
+		}
+		unfreeze(st);
+		return 0;
+	}
+
+	/*
+	 * There are three possibilities.
+	 * 1/ The array will shrink.
+	 *    We need to ensure the reshape will pause before reaching
+	 *    the 'critical section'.  We also need to fork and wait for
+	 *    that to happen.  When it does we
+	 *       suspend/backup/complete/unfreeze
+	 *
+	 * 2/ The array will not change size.
+	 *    This requires that we keep a backup of a sliding window
+	 *    so that we can restore data after a crash.  So we need
+	 *    to fork and monitor progress.
+	 *    In future we will allow the data_offset to change, so
+	 *    a sliding backup becomes unnecessary.
+	 *
+	 * 3/ The array will grow. This is relatively easy.
+	 *    However the kernel's restripe routines will cheerfully
+	 *    overwrite some early data before it is safe.  So we
+	 *    need to make a backup of the early parts of the array
+	 *    and be ready to restore it if rebuild aborts very early.
+	 *    For externally managed metadata, we still need a forked
+	 *    child to monitor the reshape and suspend IO over the region
+	 *    that is being reshaped.
+	 *
+	 *    We backup data by writing it to one spare, or to a
+	 *    file which was given on command line.
+	 *
+	 * In each case, we first make sure that storage is available
+	 * for the required backup.
+	 * Then we:
+	 *   -  request the shape change.
+	 *   -  fork to handle backup etc.
+	 */
+	/* Check that we can hold all the data */
+	get_dev_size(fd, NULL, &array_size);
+	if (reshape.new_size < (array_size/512)) {
+		pr_err("this change will reduce the size of the array.\n"
+		       "       use --grow --array-size first to truncate array.\n"
+		       "       e.g. mdadm --grow %s --array-size %llu\n",
+		       devname, reshape.new_size/2);
+		goto release;
+	}
+
+	if (array.level == 10) {
+		/* Reshaping RAID10 does not require any data backup by
+		 * user-space.  Instead it requires that the data_offset
+		 * is changed to avoid the need for backup.
+		 * So this is handled very separately
+		 */
+		if (restart)
+			/* Nothing to do. */
+			return 0;
+		return raid10_reshape(container, fd, devname, st, info,
+				      &reshape, data_offset, force, verbose);
+	}
+	sra = sysfs_read(fd, NULL,
+			 GET_COMPONENT|GET_DEVS|GET_OFFSET|GET_STATE|GET_CHUNK|
+			 GET_CACHE);
+	if (!sra) {
+		pr_err("%s: Cannot get array details from sysfs\n",
+			devname);
+		goto release;
+	}
+
+	if (!backup_file)
+		switch(set_new_data_offset(sra, st, devname,
+					   reshape.after.data_disks - reshape.before.data_disks,
+					   data_offset,
+					   reshape.min_offset_change, 1)) {
+	case -1:
+		goto release;
+	case 0:
+		/* Updated data_offset, so it's easy now */
+		update_cache_size(container, sra, info,
+				  min(reshape.before.data_disks,
+				      reshape.after.data_disks),
+				  reshape.backup_blocks);
+
+		/* Right, everything seems fine. Let's kick things off.
+		 */
+		sync_metadata(st);
+
+		if (impose_reshape(sra, info, st, fd, restart,
+				   devname, container, &reshape) < 0)
+			goto release;
+		if (sysfs_set_str(sra, NULL, "sync_action", "reshape") < 0) {
+			struct mdinfo *sd;
+			if (errno != EINVAL) {
+				pr_err("Failed to initiate reshape!\n");
+				goto release;
+			}
+			/* revert data_offset and try the old way */
+			for (sd = sra->devs; sd; sd = sd->next) {
+				sysfs_set_num(sra, sd, "new_offset",
+					      sd->data_offset);
+				sysfs_set_str(sra, NULL, "reshape_direction",
+					      "forwards");
+			}
+			break;
+		}
+		if (info->new_level == reshape.level)
+			return 0;
+		/* need to adjust level when reshape completes */
+		switch(fork()) {
+		case -1: /* ignore error, but don't wait */
+			return 0;
+		default: /* parent */
+			return 0;
+		case 0:
+			manage_fork_fds(0);
+			map_fork();
+			break;
+		}
+		close(fd);
+		wait_reshape(sra);
+		fd = open_dev(sra->sys_name);
+		if (fd >= 0)
+			impose_level(fd, info->new_level, devname, verbose);
+		return 0;
+	case 1: /* Couldn't set data_offset, try the old way */
+		if (data_offset != INVALID_SECTORS) {
+			pr_err("Cannot update data_offset on this array\n");
+			goto release;
+		}
+		break;
+	}
+
+started:
+	/* Decide how many blocks (sectors) for a reshape
+	 * unit.  The number we have so far is just a minimum
+	 */
+	blocks = reshape.backup_blocks;
+	if (reshape.before.data_disks ==
+	    reshape.after.data_disks) {
+		/* Make 'blocks' bigger for better throughput, but
+		 * not so big that we reject it below.
+		 * Try for 16 megabytes
+		 */
+		while (blocks * 32 < sra->component_size && blocks < 16*1024*2)
+			blocks *= 2;
+	} else
+		pr_err("Need to backup %luK of critical section..\n", blocks/2);
+
+	if (blocks >= sra->component_size/2) {
+		pr_err("%s: Something wrong - reshape aborted\n", devname);
+		goto release;
+	}
+
+	/* Now we need to open all these devices so we can read/write.
+	 */
+	nrdisks = max(reshape.before.data_disks,
+		      reshape.after.data_disks) + reshape.parity
+		+ sra->array.spare_disks;
+	fdlist = xcalloc((1+nrdisks), sizeof(int));
+	offsets = xcalloc((1+nrdisks), sizeof(offsets[0]));
+
+	odisks = reshape.before.data_disks + reshape.parity;
+	d = reshape_prepare_fdlist(devname, sra, odisks, nrdisks, blocks,
+				   backup_file, fdlist, offsets);
+	if (d < odisks) {
+		goto release;
+	}
+	if ((st->ss->manage_reshape == NULL) ||
+	    (st->ss->recover_backup == NULL)) {
+		if (backup_file == NULL) {
+			if (reshape.after.data_disks <=
+			    reshape.before.data_disks) {
+				pr_err("%s: Cannot grow - need backup-file\n",
+				       devname);
+				pr_err(" Please provide one with \"--backup=...\"\n");
+				goto release;
+			} else if (d == odisks) {
+				pr_err("%s: Cannot grow - need a spare or backup-file to backup critical section\n", devname);
+				goto release;
+			}
+		} else {
+			if (!reshape_open_backup_file(backup_file, fd, devname,
+						      (signed)blocks,
+						      fdlist+d, offsets+d,
+						      sra->sys_name, restart)) {
+				goto release;
+			}
+			d++;
+		}
+	}
+
+	update_cache_size(container, sra, info,
+			  min(reshape.before.data_disks,
+			      reshape.after.data_disks), blocks);
+
+	/* Right, everything seems fine. Let's kick things off.
+	 * If only changing raid_disks, use ioctl, else use
+	 * sysfs.
+	 */
+	sync_metadata(st);
+
+	if (impose_reshape(sra, info, st, fd, restart,
+			   devname, container, &reshape) < 0)
+		goto release;
+
+	err = start_reshape(sra, restart, reshape.before.data_disks,
+			    reshape.after.data_disks, st);
+	if (err) {
+		pr_err("Cannot %s reshape for %s\n",
+		       restart ? "continue" : "start", devname);
+		goto release;
+	}
+	if (restart)
+		sysfs_set_str(sra, NULL, "array_state", "active");
+	if (freeze_reshape) {
+		free(fdlist);
+		free(offsets);
+		sysfs_free(sra);
+		pr_err("Reshape has to be continued from location %llu when root filesystem has been mounted.\n",
+			sra->reshape_progress);
+		return 1;
+	}
+
+	if (!forked)
+		if (continue_via_systemd(container ?: sra->sys_name,
+					 GROW_SERVICE)) {
+			free(fdlist);
+			free(offsets);
+			sysfs_free(sra);
+			return 0;
+		}
+
+	close(fd);
+	/* Now we just need to kick off the reshape and watch, while
+	 * handling backups of the data...
+	 * This is all done by a forked background process.
+	 */
+	switch(forked ? 0 : fork()) {
+	case -1:
+		pr_err("Cannot run child to monitor reshape: %s\n",
+			strerror(errno));
+		abort_reshape(sra);
+		goto release;
+	default:
+		free(fdlist);
+		free(offsets);
+		sysfs_free(sra);
+		return 0;
+	case 0:
+		map_fork();
+		break;
+	}
+
+	/* If another array on the same devices is busy, the
+	 * reshape will wait for them.  This would mean that
+	 * the first section that we suspend will stay suspended
+	 * for a long time.  So check on that possibility
+	 * by looking for "DELAYED" in /proc/mdstat, and if found,
+	 * wait a while
+	 */
+	do {
+		struct mdstat_ent *mds, *m;
+		delayed = 0;
+		mds = mdstat_read(1, 0);
+		for (m = mds; m; m = m->next)
+			if (strcmp(m->devnm, sra->sys_name) == 0) {
+				if (m->resync && m->percent == RESYNC_DELAYED)
+					delayed = 1;
+				if (m->resync == 0)
+					/* Haven't started the reshape thread
+					 * yet, wait a bit
+					 */
+					delayed = 2;
+				break;
+			}
+		free_mdstat(mds);
+		if (delayed == 1 && get_linux_version() < 3007000) {
+			pr_err("Reshape is delayed, but cannot wait carefully with this kernel.\n"
+			       "       You might experience problems until other reshapes complete.\n");
+			delayed = 0;
+		}
+		if (delayed)
+			mdstat_wait(30 - (delayed-1) * 25);
+	} while (delayed);
+	mdstat_close();
+	if (check_env("MDADM_GROW_VERIFY"))
+		fd = open(devname, O_RDONLY | O_DIRECT);
+	else
+		fd = -1;
+	mlockall(MCL_FUTURE);
+
+	signal(SIGTERM, catch_term);
+
+	if (st->ss->external) {
+		/* metadata handler takes it from here */
+		done = st->ss->manage_reshape(
+			fd, sra, &reshape, st, blocks,
+			fdlist, offsets, d - odisks, fdlist + odisks,
+			offsets + odisks);
+	} else
+		done = child_monitor(
+			fd, sra, &reshape, st, blocks, fdlist, offsets,
+			d - odisks, fdlist + odisks, offsets + odisks);
+
+	free(fdlist);
+	free(offsets);
+
+	if (backup_file && done) {
+		char *bul;
+		bul = make_backup(sra->sys_name);
+		if (bul) {
+			char buf[1024];
+			int l = readlink(bul, buf, sizeof(buf) - 1);
+			if (l > 0) {
+				buf[l]=0;
+				unlink(buf);
+			}
+			unlink(bul);
+			free(bul);
+		}
+		unlink(backup_file);
+	}
+	if (!done) {
+		abort_reshape(sra);
+		goto out;
+	}
+
+	if (!st->ss->external &&
+	    !(reshape.before.data_disks != reshape.after.data_disks &&
+	      info->custom_array_size) && info->new_level == reshape.level &&
+	    !forked) {
+		/* no need to wait for the reshape to finish as
+		 * there is nothing more to do.
+		 */
+		sysfs_free(sra);
+		exit(0);
+	}
+	wait_reshape(sra);
+
+	if (st->ss->external) {
+		/* Re-load the metadata as much could have changed */
+		int cfd = open_dev(st->container_devnm);
+		if (cfd >= 0) {
+			flush_mdmon(container);
+			st->ss->free_super(st);
+			st->ss->load_container(st, cfd, container);
+			close(cfd);
+		}
+	}
+
+	/* set new array size if required customer_array_size is used
+	 * by this metadata.
+	 */
+	if (reshape.before.data_disks != reshape.after.data_disks &&
+	    info->custom_array_size)
+		set_array_size(st, info, info->text_version);
+
+	if (info->new_level != reshape.level) {
+		if (fd < 0)
+			fd = open(devname, O_RDONLY);
+		impose_level(fd, info->new_level, devname, verbose);
+		close(fd);
+		if (info->new_level == 0)
+			st->update_tail = NULL;
+	}
+out:
+	sysfs_free(sra);
+	if (forked)
+		return 0;
+	unfreeze(st);
+	exit(0);
+
+release:
+	free(fdlist);
+	free(offsets);
+	if (orig_level != UnSet && sra) {
+		c = map_num(pers, orig_level);
+		if (c && sysfs_set_str(sra, NULL, "level", c) == 0)
+			pr_err("aborting level change\n");
+	}
+	sysfs_free(sra);
+	if (!forked)
+		unfreeze(st);
+	return 1;
+}
+
+/* mdfd handle is passed to be closed in child process (after fork).
+ */
+int reshape_container(char *container, char *devname,
+		      int mdfd,
+		      struct supertype *st,
+		      struct mdinfo *info,
+		      int force,
+		      char *backup_file, int verbose,
+		      int forked, int restart, int freeze_reshape)
+{
+	struct mdinfo *cc = NULL;
+	int rv = restart;
+	char last_devnm[32] = "";
+
+	/* component_size is not meaningful for a container,
+	 * so pass '0' meaning 'no change'
+	 */
+	if (!restart &&
+	    reshape_super(st, 0, info->new_level,
+			  info->new_layout, info->new_chunk,
+			  info->array.raid_disks, info->delta_disks,
+			  backup_file, devname, APPLY_METADATA_CHANGES,
+			  verbose)) {
+		unfreeze(st);
+		return 1;
+	}
+
+	sync_metadata(st);
+
+	/* ping monitor to be sure that update is on disk
+	 */
+	ping_monitor(container);
+
+	if (!forked && !freeze_reshape)
+		if (continue_via_systemd(container, GROW_SERVICE))
+			return 0;
+
+	switch (forked ? 0 : fork()) {
+	case -1: /* error */
+		perror("Cannot fork to complete reshape\n");
+		unfreeze(st);
+		return 1;
+	default: /* parent */
+		if (!freeze_reshape)
+			printf("%s: multi-array reshape continues in background\n", Name);
+		return 0;
+	case 0: /* child */
+		manage_fork_fds(0);
+		map_fork();
+		break;
+	}
+
+	/* close unused handle in child process
+	 */
+	if (mdfd > -1)
+		close(mdfd);
+
+	while(1) {
+		/* For each member array with reshape_active,
+		 * we need to perform the reshape.
+		 * We pick the first array that needs reshaping and
+		 * reshape it.  reshape_array() will re-read the metadata
+		 * so the next time through a different array should be
+		 * ready for reshape.
+		 * It is possible that the 'different' array will not
+		 * be assembled yet.  In that case we simple exit.
+		 * When it is assembled, the mdadm which assembles it
+		 * will take over the reshape.
+		 */
+		struct mdinfo *content;
+		int fd;
+		struct mdstat_ent *mdstat;
+		char *adev;
+		dev_t devid;
+
+		sysfs_free(cc);
+
+		cc = st->ss->container_content(st, NULL);
+
+		for (content = cc; content ; content = content->next) {
+			char *subarray;
+			if (!content->reshape_active)
+				continue;
+
+			subarray = strchr(content->text_version+1, '/')+1;
+			mdstat = mdstat_by_subdev(subarray, container);
+			if (!mdstat)
+				continue;
+			if (mdstat->active == 0) {
+				pr_err("Skipping inactive array %s.\n",
+				       mdstat->devnm);
+				free_mdstat(mdstat);
+				mdstat = NULL;
+				continue;
+			}
+			break;
+		}
+		if (!content)
+			break;
+
+		devid = devnm2devid(mdstat->devnm);
+		adev = map_dev(major(devid), minor(devid), 0);
+		if (!adev)
+			adev = content->text_version;
+
+		fd = open_dev(mdstat->devnm);
+		if (fd < 0) {
+			pr_err("Device %s cannot be opened for reshape.\n",
+			       adev);
+			break;
+		}
+
+		if (strcmp(last_devnm, mdstat->devnm) == 0) {
+			/* Do not allow for multiple reshape_array() calls for
+			 * the same array.
+			 * It can happen when reshape_array() returns without
+			 * error, when reshape is not finished (wrong reshape
+			 * starting/continuation conditions).  Mdmon doesn't
+			 * switch to next array in container and reentry
+			 * conditions for the same array occur.
+			 * This is possibly interim until the behaviour of
+			 * reshape_array is resolved().
+			 */
+			printf("%s: Multiple reshape execution detected for device  %s.\n", Name, adev);
+			close(fd);
+			break;
+		}
+		strcpy(last_devnm, mdstat->devnm);
+
+		if (sysfs_init(content, fd, mdstat->devnm)) {
+			pr_err("Unable to initialize sysfs for %s\n",
+			       mdstat->devnm);
+			rv = 1;
+			break;
+		}
+
+		if (mdmon_running(container))
+			flush_mdmon(container);
+
+		rv = reshape_array(container, fd, adev, st,
+				   content, force, NULL, INVALID_SECTORS,
+				   backup_file, verbose, 1, restart,
+				   freeze_reshape);
+		close(fd);
+
+		if (freeze_reshape) {
+			sysfs_free(cc);
+			exit(0);
+		}
+
+		restart = 0;
+		if (rv)
+			break;
+
+		if (mdmon_running(container))
+			flush_mdmon(container);
+	}
+	if (!rv)
+		unfreeze(st);
+	sysfs_free(cc);
+	exit(0);
+}
+
+/*
+ * We run a child process in the background which performs the following
+ * steps:
+ *   - wait for resync to reach a certain point
+ *   - suspend io to the following section
+ *   - backup that section
+ *   - allow resync to proceed further
+ *   - resume io
+ *   - discard the backup.
+ *
+ * When are combined in slightly different ways in the three cases.
+ * Grow:
+ *   - suspend/backup/allow/wait/resume/discard
+ * Shrink:
+ *   - allow/wait/suspend/backup/allow/wait/resume/discard
+ * same-size:
+ *   - wait/resume/discard/suspend/backup/allow
+ *
+ * suspend/backup/allow always come together
+ * wait/resume/discard do too.
+ * For the same-size case we have two backups to improve flow.
+ *
+ */
+
+int progress_reshape(struct mdinfo *info, struct reshape *reshape,
+		     unsigned long long backup_point,
+		     unsigned long long wait_point,
+		     unsigned long long *suspend_point,
+		     unsigned long long *reshape_completed, int *frozen)
+{
+	/* This function is called repeatedly by the reshape manager.
+	 * It determines how much progress can safely be made and allows
+	 * that progress.
+	 * - 'info' identifies the array and particularly records in
+	 *    ->reshape_progress the metadata's knowledge of progress
+	 *      This is a sector offset from the start of the array
+	 *      of the next array block to be relocated.  This number
+	 *      may increase from 0 or decrease from array_size, depending
+	 *      on the type of reshape that is happening.
+	 *    Note that in contrast, 'sync_completed' is a block count of the
+	 *    reshape so far.  It gives the distance between the start point
+	 *    (head or tail of device) and the next place that data will be
+	 *    written.  It always increases.
+	 * - 'reshape' is the structure created by analyse_change
+	 * - 'backup_point' shows how much the metadata manager has backed-up
+	 *   data.  For reshapes with increasing progress, it is the next address
+	 *   to be backed up, previous addresses have been backed-up.  For
+	 *   decreasing progress, it is the earliest address that has been
+	 *   backed up - later address are also backed up.
+	 *   So addresses between reshape_progress and backup_point are
+	 *   backed up providing those are in the 'correct' order.
+	 * - 'wait_point' is an array address.  When reshape_completed
+	 *   passes this point, progress_reshape should return.  It might
+	 *   return earlier if it determines that ->reshape_progress needs
+	 *   to be updated or further backup is needed.
+	 * - suspend_point is maintained by progress_reshape and the caller
+	 *   should not touch it except to initialise to zero.
+	 *   It is an array address and it only increases in 2.6.37 and earlier.
+	 *   This makes it difficult to handle reducing reshapes with
+	 *   external metadata.
+	 *   However:  it is similar to backup_point in that it records the
+	 *     other end of a suspended region from  reshape_progress.
+	 *     it is moved to extend the region that is safe to backup and/or
+	 *     reshape
+	 * - reshape_completed is read from sysfs and returned.  The caller
+	 *   should copy this into ->reshape_progress when it has reason to
+	 *   believe that the metadata knows this, and any backup outside this
+	 *   has been erased.
+	 *
+	 * Return value is:
+	 *   1 if more data from backup_point - but only as far as suspend_point,
+	 *     should be backed up
+	 *   0 if things are progressing smoothly
+	 *  -1 if the reshape is finished because it is all done,
+	 *  -2 if the reshape is finished due to an error.
+	 */
+
+	int advancing = (reshape->after.data_disks
+			 >= reshape->before.data_disks);
+	unsigned long long need_backup; /* All data between start of array and
+					 * here will at some point need to
+					 * be backed up.
+					 */
+	unsigned long long read_offset, write_offset;
+	unsigned long long write_range;
+	unsigned long long max_progress, target, completed;
+	unsigned long long array_size = (info->component_size
+					 * reshape->before.data_disks);
+	int fd;
+	char buf[20];
+
+	/* First, we unsuspend any region that is now known to be safe.
+	 * If suspend_point is on the 'wrong' side of reshape_progress, then
+	 * we don't have or need suspension at the moment.  This is true for
+	 * native metadata when we don't need to back-up.
+	 */
+	if (advancing) {
+		if (info->reshape_progress <= *suspend_point)
+			sysfs_set_num(info, NULL, "suspend_lo",
+				      info->reshape_progress);
+	} else {
+		/* Note: this won't work in 2.6.37 and before.
+		 * Something somewhere should make sure we don't need it!
+		 */
+		if (info->reshape_progress >= *suspend_point)
+			sysfs_set_num(info, NULL, "suspend_hi",
+				      info->reshape_progress);
+	}
+
+	/* Now work out how far it is safe to progress.
+	 * If the read_offset for ->reshape_progress is less than
+	 * 'blocks' beyond the write_offset, we can only progress as far
+	 * as a backup.
+	 * Otherwise we can progress until the write_offset for the new location
+	 * reaches (within 'blocks' of) the read_offset at the current location.
+	 * However that region must be suspended unless we are using native
+	 * metadata.
+	 * If we need to suspend more, we limit it to 128M per device, which is
+	 * rather arbitrary and should be some time-based calculation.
+	 */
+	read_offset = info->reshape_progress / reshape->before.data_disks;
+	write_offset = info->reshape_progress / reshape->after.data_disks;
+	write_range = info->new_chunk/512;
+	if (reshape->before.data_disks == reshape->after.data_disks)
+		need_backup = array_size;
+	else
+		need_backup = reshape->backup_blocks;
+	if (advancing) {
+		if (read_offset < write_offset + write_range)
+			max_progress = backup_point;
+		else
+			max_progress =
+				read_offset * reshape->after.data_disks;
+	} else {
+		if (read_offset > write_offset - write_range)
+			/* Can only progress as far as has been backed up,
+			 * which must be suspended */
+			max_progress = backup_point;
+		else if (info->reshape_progress <= need_backup)
+			max_progress = backup_point;
+		else {
+			if (info->array.major_version >= 0)
+				/* Can progress until backup is needed */
+				max_progress = need_backup;
+			else {
+				/* Can progress until metadata update is required */
+				max_progress =
+					read_offset * reshape->after.data_disks;
+				/* but data must be suspended */
+				if (max_progress < *suspend_point)
+					max_progress = *suspend_point;
+			}
+		}
+	}
+
+	/* We know it is safe to progress to 'max_progress' providing
+	 * it is suspended or we are using native metadata.
+	 * Consider extending suspend_point 128M per device if it
+	 * is less than 64M per device beyond reshape_progress.
+	 * But always do a multiple of 'blocks'
+	 * FIXME this is too big - it takes to long to complete
+	 * this much.
+	 */
+	target = 64*1024*2 * min(reshape->before.data_disks,
+				 reshape->after.data_disks);
+	target /= reshape->backup_blocks;
+	if (target < 2)
+		target = 2;
+	target *= reshape->backup_blocks;
+
+	/* For externally managed metadata we always need to suspend IO to
+	 * the area being reshaped so we regularly push suspend_point forward.
+	 * For native metadata we only need the suspend if we are going to do
+	 * a backup.
+	 */
+	if (advancing) {
+		if ((need_backup > info->reshape_progress ||
+		     info->array.major_version < 0) &&
+		    *suspend_point < info->reshape_progress + target) {
+			if (need_backup < *suspend_point + 2 * target)
+				*suspend_point = need_backup;
+			else if (*suspend_point + 2 * target < array_size)
+				*suspend_point += 2 * target;
+			else
+				*suspend_point = array_size;
+			sysfs_set_num(info, NULL, "suspend_hi", *suspend_point);
+			if (max_progress > *suspend_point)
+				max_progress = *suspend_point;
+		}
+	} else {
+		if (info->array.major_version >= 0) {
+			/* Only need to suspend when about to backup */
+			if (info->reshape_progress < need_backup * 2 &&
+			    *suspend_point > 0) {
+				*suspend_point = 0;
+				sysfs_set_num(info, NULL, "suspend_lo", 0);
+				sysfs_set_num(info, NULL, "suspend_hi",
+					      need_backup);
+			}
+		} else {
+			/* Need to suspend continually */
+			if (info->reshape_progress < *suspend_point)
+				*suspend_point = info->reshape_progress;
+			if (*suspend_point + target < info->reshape_progress)
+				/* No need to move suspend region yet */;
+			else {
+				if (*suspend_point >= 2 * target)
+					*suspend_point -= 2 * target;
+				else
+					*suspend_point = 0;
+				sysfs_set_num(info, NULL, "suspend_lo",
+					      *suspend_point);
+			}
+			if (max_progress < *suspend_point)
+				max_progress = *suspend_point;
+		}
+	}
+
+	/* now set sync_max to allow that progress. sync_max, like
+	 * sync_completed is a count of sectors written per device, so
+	 * we find the difference between max_progress and the start point,
+	 * and divide that by after.data_disks to get a sync_max
+	 * number.
+	 * At the same time we convert wait_point to a similar number
+	 * for comparing against sync_completed.
+	 */
+	/* scale down max_progress to per_disk */
+	max_progress /= reshape->after.data_disks;
+	/*
+	 * Round to chunk size as some kernels give an erroneously
+	 * high number
+	 */
+	max_progress /= info->new_chunk/512;
+	max_progress *= info->new_chunk/512;
+	/* And round to old chunk size as the kernel wants that */
+	max_progress /= info->array.chunk_size/512;
+	max_progress *= info->array.chunk_size/512;
+	/* Limit progress to the whole device */
+	if (max_progress > info->component_size)
+		max_progress = info->component_size;
+	wait_point /= reshape->after.data_disks;
+	if (!advancing) {
+		/* switch from 'device offset' to 'processed block count' */
+		max_progress = info->component_size - max_progress;
+		wait_point = info->component_size - wait_point;
+	}
+
+	if (!*frozen)
+		sysfs_set_num(info, NULL, "sync_max", max_progress);
+
+	/* Now wait.  If we have already reached the point that we were
+	 * asked to wait to, don't wait at all, else wait for any change.
+	 * We need to select on 'sync_completed' as that is the place that
+	 * notifications happen, but we are really interested in
+	 * 'reshape_position'
+	 */
+	fd = sysfs_get_fd(info, NULL, "sync_completed");
+	if (fd < 0)
+		goto check_progress;
+
+	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
+		 */
+		char action[20];
+		if (sysfs_get_str(info, NULL, "sync_action", action, 20) <= 0 ||
+		    strncmp(action, "reshape", 7) != 0)
+			break;
+		/* Some kernels reset 'sync_completed' to zero
+		 * before setting 'sync_action' to 'idle'.
+		 * So we need these extra tests.
+		 */
+		if (completed == 0 && advancing &&
+		    strncmp(action, "idle", 4) == 0 &&
+		    info->reshape_progress > 0)
+			break;
+		if (completed == 0 && !advancing &&
+		    strncmp(action, "idle", 4) == 0 &&
+		    info->reshape_progress <
+		    (info->component_size * reshape->after.data_disks))
+			break;
+		sysfs_wait(fd, NULL);
+		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.
+	 * So in that case, read 'reshape_position' from sysfs.
+	 */
+	if (completed == 0) {
+		unsigned long long reshapep;
+		char action[20];
+		if (sysfs_get_str(info, NULL, "sync_action", action, 20) > 0 &&
+		    strncmp(action, "idle", 4) == 0 &&
+		    sysfs_get_ll(info, NULL,
+				 "reshape_position", &reshapep) == 0)
+			*reshape_completed = reshapep;
+	} else {
+		/* some kernels can give an incorrectly high
+		 * 'completed' number, so round down */
+		completed /= (info->new_chunk/512);
+		completed *= (info->new_chunk/512);
+		/* Convert 'completed' back in to a 'progress' number */
+		completed *= reshape->after.data_disks;
+		if (!advancing)
+			completed = (info->component_size
+				     * reshape->after.data_disks
+				     - completed);
+		*reshape_completed = completed;
+	}
+
+	close(fd);
+
+	/* We return the need_backup flag.  Caller will decide
+	 * how much - a multiple of ->backup_blocks up to *suspend_point
+	 */
+	if (advancing)
+		return need_backup > info->reshape_progress;
+	else
+		return need_backup >= info->reshape_progress;
+
+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.
+	 */
+	if (sysfs_get_str(info, NULL, "reshape_position", buf,
+			  sizeof(buf)) < 0 || strncmp(buf, "none", 4) != 0) {
+		/* The abort might only be temporary.  Wait up to 10
+		 * seconds for fd to contain a valid number again.
+		 */
+		int wait = 10000;
+		int rv = -2;
+		unsigned long long new_sync_max;
+		while (fd >= 0 && rv < 0 && wait > 0) {
+			if (sysfs_wait(fd, &wait) != 1)
+				break;
+			switch (sysfs_fd_get_ll(fd, &completed)) {
+			case 0:
+				/* all good again */
+				rv = 1;
+				/* If "sync_max" is no longer max_progress
+				 * we need to freeze things
+				 */
+				sysfs_get_ll(info, NULL, "sync_max",
+					     &new_sync_max);
+				*frozen = (new_sync_max != max_progress);
+				break;
+			case -2: /* read error - abort */
+				wait = 0;
+				break;
+			}
+		}
+		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)
+			return -2; /* abort */
+		return -1; /* complete */
+	}
+}
+
+/* FIXME return status is never checked */
+static int grow_backup(struct mdinfo *sra,
+		unsigned long long offset, /* per device */
+		unsigned long stripes, /* per device, in old chunks */
+		int *sources, unsigned long long *offsets,
+		int disks, int chunk, int level, int layout,
+		int dests, int *destfd, unsigned long long *destoffsets,
+		int part, int *degraded,
+		char *buf)
+{
+	/* Backup 'blocks' sectors at 'offset' on each device of the array,
+	 * to storage 'destfd' (offset 'destoffsets'), after first
+	 * suspending IO.  Then allow resync to continue
+	 * over the suspended section.
+	 * Use part 'part' of the backup-super-block.
+	 */
+	int odata = disks;
+	int rv = 0;
+	int i;
+	unsigned long long ll;
+	int new_degraded;
+	//printf("offset %llu\n", offset);
+	if (level >= 4)
+		odata--;
+	if (level == 6)
+		odata--;
+
+	/* Check that array hasn't become degraded, else we might backup the wrong data */
+	if (sysfs_get_ll(sra, NULL, "degraded", &ll) < 0)
+		return -1; /* FIXME this error is ignored */
+	new_degraded = (int)ll;
+	if (new_degraded != *degraded) {
+		/* check each device to ensure it is still working */
+		struct mdinfo *sd;
+		for (sd = sra->devs ; sd ; sd = sd->next) {
+			if (sd->disk.state & (1<<MD_DISK_FAULTY))
+				continue;
+			if (sd->disk.state & (1<<MD_DISK_SYNC)) {
+				char sbuf[100];
+
+				if (sysfs_get_str(sra, sd, "state",
+						  sbuf, sizeof(sbuf)) < 0 ||
+				    strstr(sbuf, "faulty") ||
+				    strstr(sbuf, "in_sync") == NULL) {
+					/* this device is dead */
+					sd->disk.state = (1<<MD_DISK_FAULTY);
+					if (sd->disk.raid_disk >= 0 &&
+					    sources[sd->disk.raid_disk] >= 0) {
+						close(sources[sd->disk.raid_disk]);
+						sources[sd->disk.raid_disk] = -1;
+					}
+				}
+			}
+		}
+		*degraded = new_degraded;
+	}
+	if (part) {
+		bsb.arraystart2 = __cpu_to_le64(offset * odata);
+		bsb.length2 = __cpu_to_le64(stripes * (chunk/512) * odata);
+	} else {
+		bsb.arraystart = __cpu_to_le64(offset * odata);
+		bsb.length = __cpu_to_le64(stripes * (chunk/512) * odata);
+	}
+	if (part)
+		bsb.magic[15] = '2';
+	for (i = 0; i < dests; i++)
+		if (part)
+			lseek64(destfd[i], destoffsets[i] +
+				__le64_to_cpu(bsb.devstart2)*512, 0);
+		else
+			lseek64(destfd[i], destoffsets[i], 0);
+
+	rv = save_stripes(sources, offsets, disks, chunk, level, layout,
+			  dests, destfd, offset * 512 * odata,
+			  stripes * chunk * odata, buf);
+
+	if (rv)
+		return rv;
+	bsb.mtime = __cpu_to_le64(time(0));
+	for (i = 0; i < dests; i++) {
+		bsb.devstart = __cpu_to_le64(destoffsets[i]/512);
+
+		bsb.sb_csum = bsb_csum((char*)&bsb,
+				       ((char*)&bsb.sb_csum)-((char*)&bsb));
+		if (memcmp(bsb.magic, "md_backup_data-2", 16) == 0)
+			bsb.sb_csum2 = bsb_csum((char*)&bsb,
+						((char*)&bsb.sb_csum2)-((char*)&bsb));
+
+		rv = -1;
+		if ((unsigned long long)lseek64(destfd[i],
+						destoffsets[i] - 4096, 0) !=
+		    destoffsets[i] - 4096)
+			break;
+		if (write(destfd[i], &bsb, 512) != 512)
+			break;
+		if (destoffsets[i] > 4096) {
+			if ((unsigned long long)lseek64(destfd[i], destoffsets[i]+stripes*chunk*odata, 0) !=
+			    destoffsets[i]+stripes*chunk*odata)
+				break;
+			if (write(destfd[i], &bsb, 512) != 512)
+				break;
+		}
+		fsync(destfd[i]);
+		rv = 0;
+	}
+
+	return rv;
+}
+
+/* in 2.6.30, the value reported by sync_completed can be
+ * less that it should be by one stripe.
+ * This only happens when reshape hits sync_max and pauses.
+ * So allow wait_backup to either extent sync_max further
+ * than strictly necessary, or return before the
+ * sync has got quite as far as we would really like.
+ * This is what 'blocks2' is for.
+ * The various caller give appropriate values so that
+ * every works.
+ */
+/* FIXME return value is often ignored */
+static int forget_backup(int dests, int *destfd,
+			 unsigned long long *destoffsets,
+			 int part)
+{
+	/*
+	 * Erase backup 'part' (which is 0 or 1)
+	 */
+	int i;
+	int rv;
+
+	if (part) {
+		bsb.arraystart2 = __cpu_to_le64(0);
+		bsb.length2 = __cpu_to_le64(0);
+	} else {
+		bsb.arraystart = __cpu_to_le64(0);
+		bsb.length = __cpu_to_le64(0);
+	}
+	bsb.mtime = __cpu_to_le64(time(0));
+	rv = 0;
+	for (i = 0; i < dests; i++) {
+		bsb.devstart = __cpu_to_le64(destoffsets[i]/512);
+		bsb.sb_csum = bsb_csum((char*)&bsb,
+				       ((char*)&bsb.sb_csum)-((char*)&bsb));
+		if (memcmp(bsb.magic, "md_backup_data-2", 16) == 0)
+			bsb.sb_csum2 = bsb_csum((char*)&bsb,
+						((char*)&bsb.sb_csum2)-((char*)&bsb));
+		if ((unsigned long long)lseek64(destfd[i], destoffsets[i]-4096, 0) !=
+		    destoffsets[i]-4096)
+			rv = -1;
+		if (rv == 0 && write(destfd[i], &bsb, 512) != 512)
+			rv = -1;
+		fsync(destfd[i]);
+	}
+	return rv;
+}
+
+static void fail(char *msg)
+{
+	int rv;
+	rv = (write(2, msg, strlen(msg)) != (int)strlen(msg));
+	rv |= (write(2, "\n", 1) != 1);
+	exit(rv ? 1 : 2);
+}
+
+static char *abuf, *bbuf;
+static unsigned long long abuflen;
+static void validate(int afd, int bfd, unsigned long long offset)
+{
+	/* check that the data in the backup against the array.
+	 * This is only used for regression testing and should not
+	 * be used while the array is active
+	 */
+	if (afd < 0)
+		return;
+	lseek64(bfd, offset - 4096, 0);
+	if (read(bfd, &bsb2, 512) != 512)
+		fail("cannot read bsb");
+	if (bsb2.sb_csum != bsb_csum((char*)&bsb2,
+				     ((char*)&bsb2.sb_csum)-((char*)&bsb2)))
+		fail("first csum bad");
+	if (memcmp(bsb2.magic, "md_backup_data", 14) != 0)
+		fail("magic is bad");
+	if (memcmp(bsb2.magic, "md_backup_data-2", 16) == 0 &&
+	    bsb2.sb_csum2 != bsb_csum((char*)&bsb2,
+				      ((char*)&bsb2.sb_csum2)-((char*)&bsb2)))
+		fail("second csum bad");
+
+	if (__le64_to_cpu(bsb2.devstart)*512 != offset)
+		fail("devstart is wrong");
+
+	if (bsb2.length) {
+		unsigned long long len = __le64_to_cpu(bsb2.length)*512;
+
+		if (abuflen < len) {
+			free(abuf);
+			free(bbuf);
+			abuflen = len;
+			if (posix_memalign((void**)&abuf, 4096, abuflen) ||
+			    posix_memalign((void**)&bbuf, 4096, abuflen)) {
+				abuflen = 0;
+				/* just stop validating on mem-alloc failure */
+				return;
+			}
+		}
+
+		lseek64(bfd, offset, 0);
+		if ((unsigned long long)read(bfd, bbuf, len) != len) {
+			//printf("len %llu\n", len);
+			fail("read first backup failed");
+		}
+		lseek64(afd, __le64_to_cpu(bsb2.arraystart)*512, 0);
+		if ((unsigned long long)read(afd, abuf, len) != len)
+			fail("read first from array failed");
+		if (memcmp(bbuf, abuf, len) != 0) {
+#if 0
+			int i;
+			printf("offset=%llu len=%llu\n",
+			       (unsigned long long)__le64_to_cpu(bsb2.arraystart)*512, len);
+			for (i=0; i<len; i++)
+				if (bbuf[i] != abuf[i]) {
+					printf("first diff byte %d\n", i);
+					break;
+				}
+#endif
+			fail("data1 compare failed");
+		}
+	}
+	if (bsb2.length2) {
+		unsigned long long len = __le64_to_cpu(bsb2.length2)*512;
+
+		if (abuflen < len) {
+			free(abuf);
+			free(bbuf);
+			abuflen = len;
+			abuf = xmalloc(abuflen);
+			bbuf = xmalloc(abuflen);
+		}
+
+		lseek64(bfd, offset+__le64_to_cpu(bsb2.devstart2)*512, 0);
+		if ((unsigned long long)read(bfd, bbuf, len) != len)
+			fail("read second backup failed");
+		lseek64(afd, __le64_to_cpu(bsb2.arraystart2)*512, 0);
+		if ((unsigned long long)read(afd, abuf, len) != len)
+			fail("read second from array failed");
+		if (memcmp(bbuf, abuf, len) != 0)
+			fail("data2 compare failed");
+	}
+}
+
+int child_monitor(int afd, struct mdinfo *sra, struct reshape *reshape,
+		  struct supertype *st, unsigned long blocks,
+		  int *fds, unsigned long long *offsets,
+		  int dests, int *destfd, unsigned long long *destoffsets)
+{
+	/* Monitor a reshape where backup is being performed using
+	 * 'native' mechanism - either to a backup file, or
+	 * to some space in a spare.
+	 */
+	char *buf;
+	int degraded = -1;
+	unsigned long long speed;
+	unsigned long long suspend_point, array_size;
+	unsigned long long backup_point, wait_point;
+	unsigned long long reshape_completed;
+	int done = 0;
+	int increasing = reshape->after.data_disks >=
+		reshape->before.data_disks;
+	int part = 0; /* The next part of the backup area to fill.  It
+		       * may already be full, so we need to check */
+	int level = reshape->level;
+	int layout = reshape->before.layout;
+	int data = reshape->before.data_disks;
+	int disks = reshape->before.data_disks + reshape->parity;
+	int chunk = sra->array.chunk_size;
+	struct mdinfo *sd;
+	unsigned long stripes;
+	int uuid[4];
+	int frozen = 0;
+
+	/* set up the backup-super-block.  This requires the
+	 * uuid from the array.
+	 */
+	/* Find a superblock */
+	for (sd = sra->devs; sd; sd = sd->next) {
+		char *dn;
+		int devfd;
+		int ok;
+		if (sd->disk.state & (1<<MD_DISK_FAULTY))
+			continue;
+		dn = map_dev(sd->disk.major, sd->disk.minor, 1);
+		devfd = dev_open(dn, O_RDONLY);
+		if (devfd < 0)
+			continue;
+		ok = st->ss->load_super(st, devfd, NULL);
+		close(devfd);
+		if (ok == 0)
+			break;
+	}
+	if (!sd) {
+		pr_err("Cannot find a superblock\n");
+		return 0;
+	}
+
+	memset(&bsb, 0, 512);
+	memcpy(bsb.magic, "md_backup_data-1", 16);
+	st->ss->uuid_from_super(st, uuid);
+	memcpy(bsb.set_uuid, uuid, 16);
+	bsb.mtime = __cpu_to_le64(time(0));
+	bsb.devstart2 = blocks;
+
+	stripes = blocks / (sra->array.chunk_size/512) /
+		reshape->before.data_disks;
+
+	if (posix_memalign((void**)&buf, 4096, disks * chunk))
+		/* Don't start the 'reshape' */
+		return 0;
+	if (reshape->before.data_disks == reshape->after.data_disks) {
+		sysfs_get_ll(sra, NULL, "sync_speed_min", &speed);
+		sysfs_set_num(sra, NULL, "sync_speed_min", 200000);
+	}
+
+	if (increasing) {
+		array_size = sra->component_size * reshape->after.data_disks;
+		backup_point = sra->reshape_progress;
+		suspend_point = 0;
+	} else {
+		array_size = sra->component_size * reshape->before.data_disks;
+		backup_point = reshape->backup_blocks;
+		suspend_point = array_size;
+	}
+
+	while (!done) {
+		int rv;
+
+		/* Want to return as soon the oldest backup slot can
+		 * be released as that allows us to start backing up
+		 * some more, providing suspend_point has been
+		 * advanced, which it should have.
+		 */
+		if (increasing) {
+			wait_point = array_size;
+			if (part == 0 && __le64_to_cpu(bsb.length) > 0)
+				wait_point = (__le64_to_cpu(bsb.arraystart) +
+					      __le64_to_cpu(bsb.length));
+			if (part == 1 && __le64_to_cpu(bsb.length2) > 0)
+				wait_point = (__le64_to_cpu(bsb.arraystart2) +
+					      __le64_to_cpu(bsb.length2));
+		} else {
+			wait_point = 0;
+			if (part == 0 && __le64_to_cpu(bsb.length) > 0)
+				wait_point = __le64_to_cpu(bsb.arraystart);
+			if (part == 1 && __le64_to_cpu(bsb.length2) > 0)
+				wait_point = __le64_to_cpu(bsb.arraystart2);
+		}
+
+		reshape_completed = sra->reshape_progress;
+		rv = progress_reshape(sra, reshape,
+				      backup_point, wait_point,
+				      &suspend_point, &reshape_completed,
+				      &frozen);
+		/* external metadata would need to ping_monitor here */
+		sra->reshape_progress = reshape_completed;
+
+		/* Clear any backup region that is before 'here' */
+		if (increasing) {
+			if (__le64_to_cpu(bsb.length) > 0 &&
+			    reshape_completed >= (__le64_to_cpu(bsb.arraystart) +
+						  __le64_to_cpu(bsb.length)))
+				forget_backup(dests, destfd,
+					      destoffsets, 0);
+			if (__le64_to_cpu(bsb.length2) > 0 &&
+			    reshape_completed >= (__le64_to_cpu(bsb.arraystart2) +
+						  __le64_to_cpu(bsb.length2)))
+				forget_backup(dests, destfd,
+					      destoffsets, 1);
+		} else {
+			if (__le64_to_cpu(bsb.length) > 0 &&
+			    reshape_completed <= (__le64_to_cpu(bsb.arraystart)))
+				forget_backup(dests, destfd,
+					      destoffsets, 0);
+			if (__le64_to_cpu(bsb.length2) > 0 &&
+			    reshape_completed <= (__le64_to_cpu(bsb.arraystart2)))
+				forget_backup(dests, destfd,
+					      destoffsets, 1);
+		}
+		if (sigterm)
+			rv = -2;
+		if (rv < 0) {
+			if (rv == -1)
+				done = 1;
+			break;
+		}
+		if (rv == 0 && increasing && !st->ss->external) {
+			/* No longer need to monitor this reshape */
+			sysfs_set_str(sra, NULL, "sync_max", "max");
+			done = 1;
+			break;
+		}
+
+		while (rv) {
+			unsigned long long offset;
+			unsigned long actual_stripes;
+			/* Need to backup some data.
+			 * If 'part' is not used and the desired
+			 * backup size is suspended, do a backup,
+			 * then consider the next part.
+			 */
+			/* Check that 'part' is unused */
+			if (part == 0 && __le64_to_cpu(bsb.length) != 0)
+				break;
+			if (part == 1 && __le64_to_cpu(bsb.length2) != 0)
+				break;
+
+			offset = backup_point / data;
+			actual_stripes = stripes;
+			if (increasing) {
+				if (offset + actual_stripes * (chunk/512) >
+				    sra->component_size)
+					actual_stripes = ((sra->component_size - offset)
+							  / (chunk/512));
+				if (offset + actual_stripes * (chunk/512) >
+				    suspend_point/data)
+					break;
+			} else {
+				if (offset < actual_stripes * (chunk/512))
+					actual_stripes = offset / (chunk/512);
+				offset -= actual_stripes * (chunk/512);
+				if (offset < suspend_point/data)
+					break;
+			}
+			if (actual_stripes == 0)
+				break;
+			grow_backup(sra, offset, actual_stripes, fds, offsets,
+				    disks, chunk, level, layout, dests, destfd,
+				    destoffsets, part, &degraded, buf);
+			validate(afd, destfd[0], destoffsets[0]);
+			/* record where 'part' is up to */
+			part = !part;
+			if (increasing)
+				backup_point += actual_stripes * (chunk/512) * data;
+			else
+				backup_point -= actual_stripes * (chunk/512) * data;
+		}
+	}
+
+	/* FIXME maybe call progress_reshape one more time instead */
+	/* remove any remaining suspension */
+	sysfs_set_num(sra, NULL, "suspend_lo", 0x7FFFFFFFFFFFFFFFULL);
+	sysfs_set_num(sra, NULL, "suspend_hi", 0);
+	sysfs_set_num(sra, NULL, "suspend_lo", 0);
+	sysfs_set_num(sra, NULL, "sync_min", 0);
+
+	if (reshape->before.data_disks == reshape->after.data_disks)
+		sysfs_set_num(sra, NULL, "sync_speed_min", speed);
+	free(buf);
+	return done;
+}
+
+/*
+ * If any spare contains md_back_data-1 which is recent wrt mtime,
+ * write that data into the array and update the super blocks with
+ * the new reshape_progress
+ */
+int Grow_restart(struct supertype *st, struct mdinfo *info, int *fdlist,
+		 int cnt, char *backup_file, int verbose)
+{
+	int i, j;
+	int old_disks;
+	unsigned long long *offsets;
+	unsigned long long  nstripe, ostripe;
+	int ndata, odata;
+
+	odata = info->array.raid_disks - info->delta_disks - 1;
+	if (info->array.level == 6)
+		odata--; /* number of data disks */
+	ndata = info->array.raid_disks - 1;
+	if (info->new_level == 6)
+		ndata--;
+
+	old_disks = info->array.raid_disks - info->delta_disks;
+
+	if (info->delta_disks <= 0)
+		/* Didn't grow, so the backup file must have
+		 * been used
+		 */
+		old_disks = cnt;
+	for (i=old_disks-(backup_file?1:0); i<cnt; i++) {
+		struct mdinfo dinfo;
+		int fd;
+		int bsbsize;
+		char *devname, namebuf[20];
+		unsigned long long lo, hi;
+
+		/* This was a spare and may have some saved data on it.
+		 * Load the superblock, find and load the
+		 * backup_super_block.
+		 * If either fail, go on to next device.
+		 * If the backup contains no new info, just return
+		 * else restore data and update all superblocks
+		 */
+		if (i == old_disks-1) {
+			fd = open(backup_file, O_RDONLY);
+			if (fd<0) {
+				pr_err("backup file %s inaccessible: %s\n",
+					backup_file, strerror(errno));
+				continue;
+			}
+			devname = backup_file;
+		} else {
+			fd = fdlist[i];
+			if (fd < 0)
+				continue;
+			if (st->ss->load_super(st, fd, NULL))
+				continue;
+
+			st->ss->getinfo_super(st, &dinfo, NULL);
+			st->ss->free_super(st);
+
+			if (lseek64(fd,
+				    (dinfo.data_offset + dinfo.component_size - 8) <<9,
+				    0) < 0) {
+				pr_err("Cannot seek on device %d\n", i);
+				continue; /* Cannot seek */
+			}
+			sprintf(namebuf, "device-%d", i);
+			devname = namebuf;
+		}
+		if (read(fd, &bsb, sizeof(bsb)) != sizeof(bsb)) {
+			if (verbose)
+				pr_err("Cannot read from %s\n", devname);
+			continue; /* Cannot read */
+		}
+		if (memcmp(bsb.magic, "md_backup_data-1", 16) != 0 &&
+		    memcmp(bsb.magic, "md_backup_data-2", 16) != 0) {
+			if (verbose)
+				pr_err("No backup metadata on %s\n", devname);
+			continue;
+		}
+		if (bsb.sb_csum != bsb_csum((char*)&bsb, ((char*)&bsb.sb_csum)-((char*)&bsb))) {
+			if (verbose)
+				pr_err("Bad backup-metadata checksum on %s\n",
+				       devname);
+			continue; /* bad checksum */
+		}
+		if (memcmp(bsb.magic, "md_backup_data-2", 16) == 0 &&
+		    bsb.sb_csum2 != bsb_csum((char*)&bsb, ((char*)&bsb.sb_csum2)-((char*)&bsb))) {
+			if (verbose)
+				pr_err("Bad backup-metadata checksum2 on %s\n",
+				       devname);
+			continue; /* Bad second checksum */
+		}
+		if (memcmp(bsb.set_uuid,info->uuid, 16) != 0) {
+			if (verbose)
+				pr_err("Wrong uuid on backup-metadata on %s\n",
+				       devname);
+			continue; /* Wrong uuid */
+		}
+
+		/*
+		 * array utime and backup-mtime should be updated at
+		 * much the same time, but it seems that sometimes
+		 * they aren't... So allow considerable flexability in
+		 * matching, and allow this test to be overridden by
+		 * an environment variable.
+		 */
+		if(time_after(info->array.utime, (unsigned int)__le64_to_cpu(bsb.mtime) + 2*60*60) ||
+		   time_before(info->array.utime, (unsigned int)__le64_to_cpu(bsb.mtime) - 10*60)) {
+			if (check_env("MDADM_GROW_ALLOW_OLD")) {
+				pr_err("accepting backup with timestamp %lu for array with timestamp %lu\n",
+					(unsigned long)__le64_to_cpu(bsb.mtime),
+					(unsigned long)info->array.utime);
+			} else {
+				pr_err("too-old timestamp on backup-metadata on %s\n", devname);
+				pr_err("If you think it is should be safe, try 'export MDADM_GROW_ALLOW_OLD=1'\n");
+				continue; /* time stamp is too bad */
+			}
+		}
+
+		if (bsb.magic[15] == '1') {
+			if (bsb.length == 0)
+				continue;
+			if (info->delta_disks >= 0) {
+				/* reshape_progress is increasing */
+				if (__le64_to_cpu(bsb.arraystart)
+				    + __le64_to_cpu(bsb.length)
+				    < info->reshape_progress) {
+				nonew:
+					if (verbose)
+						pr_err("backup-metadata found on %s but is not needed\n", devname);
+					continue; /* No new data here */
+				}
+			} else {
+				/* reshape_progress is decreasing */
+				if (__le64_to_cpu(bsb.arraystart) >=
+				    info->reshape_progress)
+					goto nonew; /* No new data here */
+			}
+		} else {
+			if (bsb.length == 0 && bsb.length2 == 0)
+				continue;
+			if (info->delta_disks >= 0) {
+				/* reshape_progress is increasing */
+				if ((__le64_to_cpu(bsb.arraystart)
+				     + __le64_to_cpu(bsb.length)
+				     < info->reshape_progress) &&
+				    (__le64_to_cpu(bsb.arraystart2)
+				     + __le64_to_cpu(bsb.length2)
+				     < info->reshape_progress))
+					goto nonew; /* No new data here */
+			} else {
+				/* reshape_progress is decreasing */
+				if (__le64_to_cpu(bsb.arraystart) >=
+				    info->reshape_progress &&
+				    __le64_to_cpu(bsb.arraystart2) >=
+				    info->reshape_progress)
+					goto nonew; /* No new data here */
+			}
+		}
+		if (lseek64(fd, __le64_to_cpu(bsb.devstart)*512, 0)< 0) {
+		second_fail:
+			if (verbose)
+				pr_err("Failed to verify secondary backup-metadata block on %s\n",
+				       devname);
+			continue; /* Cannot seek */
+		}
+		/* There should be a duplicate backup superblock 4k before here */
+		if (lseek64(fd, -4096, 1) < 0 ||
+		    read(fd, &bsb2, sizeof(bsb2)) != sizeof(bsb2))
+			goto second_fail; /* Cannot find leading superblock */
+		if (bsb.magic[15] == '1')
+			bsbsize = offsetof(struct mdp_backup_super, pad1);
+		else
+			bsbsize = offsetof(struct mdp_backup_super, pad);
+		if (memcmp(&bsb2, &bsb, bsbsize) != 0)
+			goto second_fail; /* Cannot find leading superblock */
+
+		/* Now need the data offsets for all devices. */
+		offsets = xmalloc(sizeof(*offsets)*info->array.raid_disks);
+		for(j=0; j<info->array.raid_disks; j++) {
+			if (fdlist[j] < 0)
+				continue;
+			if (st->ss->load_super(st, fdlist[j], NULL))
+				/* FIXME should be this be an error */
+				continue;
+			st->ss->getinfo_super(st, &dinfo, NULL);
+			st->ss->free_super(st);
+			offsets[j] = dinfo.data_offset * 512;
+		}
+		printf("%s: restoring critical section\n", Name);
+
+		if (restore_stripes(fdlist, offsets, info->array.raid_disks,
+				    info->new_chunk, info->new_level,
+				    info->new_layout, fd,
+				    __le64_to_cpu(bsb.devstart)*512,
+				    __le64_to_cpu(bsb.arraystart)*512,
+				    __le64_to_cpu(bsb.length)*512, NULL)) {
+			/* didn't succeed, so giveup */
+			if (verbose)
+				pr_err("Error restoring backup from %s\n",
+					devname);
+			free(offsets);
+			return 1;
+		}
+
+		if (bsb.magic[15] == '2' &&
+		    restore_stripes(fdlist, offsets, info->array.raid_disks,
+				    info->new_chunk, info->new_level,
+				    info->new_layout, fd,
+				    __le64_to_cpu(bsb.devstart)*512 +
+				    __le64_to_cpu(bsb.devstart2)*512,
+				    __le64_to_cpu(bsb.arraystart2)*512,
+				    __le64_to_cpu(bsb.length2)*512, NULL)) {
+			/* didn't succeed, so giveup */
+			if (verbose)
+				pr_err("Error restoring second backup from %s\n",
+					devname);
+			free(offsets);
+			return 1;
+		}
+
+		free(offsets);
+
+		/* Ok, so the data is restored. Let's update those superblocks. */
+
+		lo = hi = 0;
+		if (bsb.length) {
+			lo = __le64_to_cpu(bsb.arraystart);
+			hi = lo + __le64_to_cpu(bsb.length);
+		}
+		if (bsb.magic[15] == '2' && bsb.length2) {
+			unsigned long long lo1, hi1;
+			lo1 = __le64_to_cpu(bsb.arraystart2);
+			hi1 = lo1 + __le64_to_cpu(bsb.length2);
+			if (lo == hi) {
+				lo = lo1;
+				hi = hi1;
+			} else if (lo < lo1)
+				hi = hi1;
+			else
+				lo = lo1;
+		}
+		if (lo < hi && (info->reshape_progress < lo ||
+				info->reshape_progress > hi))
+			/* backup does not affect reshape_progress*/ ;
+		else if (info->delta_disks >= 0) {
+			info->reshape_progress = __le64_to_cpu(bsb.arraystart) +
+				__le64_to_cpu(bsb.length);
+			if (bsb.magic[15] == '2') {
+				unsigned long long p2;
+
+				p2 = __le64_to_cpu(bsb.arraystart2) +
+					__le64_to_cpu(bsb.length2);
+				if (p2 > info->reshape_progress)
+					info->reshape_progress = p2;
+			}
+		} else {
+			info->reshape_progress = __le64_to_cpu(bsb.arraystart);
+			if (bsb.magic[15] == '2') {
+				unsigned long long p2;
+
+				p2 = __le64_to_cpu(bsb.arraystart2);
+				if (p2 < info->reshape_progress)
+					info->reshape_progress = p2;
+			}
+		}
+		for (j=0; j<info->array.raid_disks; j++) {
+			if (fdlist[j] < 0)
+				continue;
+			if (st->ss->load_super(st, fdlist[j], NULL))
+				continue;
+			st->ss->getinfo_super(st, &dinfo, NULL);
+			dinfo.reshape_progress = info->reshape_progress;
+			st->ss->update_super(st, &dinfo, "_reshape_progress",
+					     NULL,0, 0, NULL);
+			st->ss->store_super(st, fdlist[j]);
+			st->ss->free_super(st);
+		}
+		return 0;
+	}
+	/* Didn't find any backup data, try to see if any
+	 * was needed.
+	 */
+	if (info->delta_disks < 0) {
+		/* When shrinking, the critical section is at the end.
+		 * So see if we are before the critical section.
+		 */
+		unsigned long long first_block;
+		nstripe = ostripe = 0;
+		first_block = 0;
+		while (ostripe >= nstripe) {
+			ostripe += info->array.chunk_size / 512;
+			first_block = ostripe * odata;
+			nstripe = first_block / ndata / (info->new_chunk/512) *
+				(info->new_chunk/512);
+		}
+
+		if (info->reshape_progress >= first_block)
+			return 0;
+	}
+	if (info->delta_disks > 0) {
+		/* See if we are beyond the critical section. */
+		unsigned long long last_block;
+		nstripe = ostripe = 0;
+		last_block = 0;
+		while (nstripe >= ostripe) {
+			nstripe += info->new_chunk / 512;
+			last_block = nstripe * ndata;
+			ostripe = last_block / odata / (info->array.chunk_size/512) *
+				(info->array.chunk_size/512);
+		}
+
+		if (info->reshape_progress >= last_block)
+			return 0;
+	}
+	/* needed to recover critical section! */
+	if (verbose)
+		pr_err("Failed to find backup of critical section\n");
+	return 1;
+}
+
+int Grow_continue_command(char *devname, int fd,
+			  char *backup_file, int verbose)
+{
+	int ret_val = 0;
+	struct supertype *st = NULL;
+	struct mdinfo *content = NULL;
+	struct mdinfo array;
+	char *subarray = NULL;
+	struct mdinfo *cc = NULL;
+	struct mdstat_ent *mdstat = NULL;
+	int cfd = -1;
+	int fd2;
+
+	dprintf("Grow continue from command line called for %s\n", devname);
+
+	st = super_by_fd(fd, &subarray);
+	if (!st || !st->ss) {
+		pr_err("Unable to determine metadata format for %s\n", devname);
+		return 1;
+	}
+	dprintf("Grow continue is run for ");
+	if (st->ss->external == 0) {
+		int d;
+		int cnt = 5;
+		dprintf_cont("native array (%s)\n", devname);
+		if (md_get_array_info(fd, &array.array) < 0) {
+			pr_err("%s is not an active md array - aborting\n",
+			       devname);
+			ret_val = 1;
+			goto Grow_continue_command_exit;
+		}
+		content = &array;
+		sysfs_init(content, fd, NULL);
+		/* Need to load a superblock.
+		 * FIXME we should really get what we need from
+		 * sysfs
+		 */
+		do {
+			for (d = 0; d < MAX_DISKS; d++) {
+				mdu_disk_info_t disk;
+				char *dv;
+				int err;
+				disk.number = d;
+				if (md_get_disk_info(fd, &disk) < 0)
+					continue;
+				if (disk.major == 0 && disk.minor == 0)
+					continue;
+				if ((disk.state & (1 << MD_DISK_ACTIVE)) == 0)
+					continue;
+				dv = map_dev(disk.major, disk.minor, 1);
+				if (!dv)
+					continue;
+				fd2 = dev_open(dv, O_RDONLY);
+				if (fd2 < 0)
+					continue;
+				err = st->ss->load_super(st, fd2, NULL);
+				close(fd2);
+				if (err)
+					continue;
+				break;
+			}
+			if (d == MAX_DISKS) {
+				pr_err("Unable to load metadata for %s\n",
+				       devname);
+				ret_val = 1;
+				goto Grow_continue_command_exit;
+			}
+			st->ss->getinfo_super(st, content, NULL);
+			if (!content->reshape_active)
+				sleep(3);
+			else
+				break;
+		} while (cnt-- > 0);
+	} else {
+		char *container;
+
+		if (subarray) {
+			dprintf_cont("subarray (%s)\n", subarray);
+			container = st->container_devnm;
+			cfd = open_dev_excl(st->container_devnm);
+		} else {
+			container = st->devnm;
+			close(fd);
+			cfd = open_dev_excl(st->devnm);
+			dprintf_cont("container (%s)\n", container);
+			fd = cfd;
+		}
+		if (cfd < 0) {
+			pr_err("Unable to open container for %s\n", devname);
+			ret_val = 1;
+			goto Grow_continue_command_exit;
+		}
+
+		/* find in container array under reshape
+		 */
+		ret_val = st->ss->load_container(st, cfd, NULL);
+		if (ret_val) {
+			pr_err("Cannot read superblock for %s\n", devname);
+			ret_val = 1;
+			goto Grow_continue_command_exit;
+		}
+
+		cc = st->ss->container_content(st, subarray);
+		for (content = cc; content ; content = content->next) {
+			char *array_name;
+			int allow_reshape = 1;
+
+			if (content->reshape_active == 0)
+				continue;
+			/* The decision about array or container wide
+			 * reshape is taken in Grow_continue based
+			 * content->reshape_active state, therefore we
+			 * need to check_reshape based on
+			 * reshape_active and subarray name
+			 */
+			if (content->array.state & (1<<MD_SB_BLOCK_VOLUME))
+				allow_reshape = 0;
+			if (content->reshape_active == CONTAINER_RESHAPE &&
+			    (content->array.state
+			     & (1<<MD_SB_BLOCK_CONTAINER_RESHAPE)))
+				allow_reshape = 0;
+
+			if (!allow_reshape) {
+				pr_err("cannot continue reshape of an array in container with unsupported metadata: %s(%s)\n",
+				       devname, container);
+				ret_val = 1;
+				goto Grow_continue_command_exit;
+			}
+
+			array_name = strchr(content->text_version+1, '/')+1;
+			mdstat = mdstat_by_subdev(array_name, container);
+			if (!mdstat)
+				continue;
+			if (mdstat->active == 0) {
+				pr_err("Skipping inactive array %s.\n",
+				       mdstat->devnm);
+				free_mdstat(mdstat);
+				mdstat = NULL;
+				continue;
+			}
+			break;
+		}
+		if (!content) {
+			pr_err("Unable to determine reshaped array for %s\n", devname);
+			ret_val = 1;
+			goto Grow_continue_command_exit;
+		}
+		fd2 = open_dev(mdstat->devnm);
+		if (fd2 < 0) {
+			pr_err("cannot open (%s)\n", mdstat->devnm);
+			ret_val = 1;
+			goto Grow_continue_command_exit;
+		}
+
+		if (sysfs_init(content, fd2, mdstat->devnm)) {
+			pr_err("Unable to initialize sysfs for %s, Grow cannot continue.\n",
+			       mdstat->devnm);
+			ret_val = 1;
+			close(fd2);
+			goto Grow_continue_command_exit;
+		}
+
+		close(fd2);
+
+		/* start mdmon in case it is not running
+		 */
+		if (!mdmon_running(container))
+			start_mdmon(container);
+		ping_monitor(container);
+
+		if (mdmon_running(container))
+			st->update_tail = &st->updates;
+		else {
+			pr_err("No mdmon found. Grow cannot continue.\n");
+			ret_val = 1;
+			goto Grow_continue_command_exit;
+		}
+	}
+
+	/* verify that array under reshape is started from
+	 * correct position
+	 */
+	if (verify_reshape_position(content, content->array.level) < 0) {
+		ret_val = 1;
+		goto Grow_continue_command_exit;
+	}
+
+	/* continue reshape
+	 */
+	ret_val = Grow_continue(fd, st, content, backup_file, 1, 0);
+
+Grow_continue_command_exit:
+	if (cfd > -1)
+		close(cfd);
+	st->ss->free_super(st);
+	free_mdstat(mdstat);
+	sysfs_free(cc);
+	free(subarray);
+
+	return ret_val;
+}
+
+int Grow_continue(int mdfd, struct supertype *st, struct mdinfo *info,
+		  char *backup_file, int forked, int freeze_reshape)
+{
+	int ret_val = 2;
+
+	if (!info->reshape_active)
+		return ret_val;
+
+	if (st->ss->external) {
+		int cfd = open_dev(st->container_devnm);
+
+		if (cfd < 0)
+			return 1;
+
+		st->ss->load_container(st, cfd, st->container_devnm);
+		close(cfd);
+		ret_val = reshape_container(st->container_devnm, NULL, mdfd,
+					    st, info, 0, backup_file, 0,
+					    forked, 1 | info->reshape_active,
+					    freeze_reshape);
+	} else
+		ret_val = reshape_array(NULL, mdfd, "array", st, info, 1,
+					NULL, INVALID_SECTORS, backup_file,
+					0, forked, 1 | info->reshape_active,
+					freeze_reshape);
+
+	return ret_val;
+}
+
+char *make_backup(char *name)
+{
+	char *base = "backup_file-";
+	int len;
+	char *fname;
+
+	len = strlen(MAP_DIR) + 1 + strlen(base) + strlen(name)+1;
+	fname = xmalloc(len);
+	sprintf(fname, "%s/%s%s", MAP_DIR, base, name);
+	return fname;
+}
+
+char *locate_backup(char *name)
+{
+	char *fl = make_backup(name);
+	struct stat stb;
+
+	if (stat(fl, &stb) == 0 && S_ISREG(stb.st_mode))
+		return fl;
+
+	free(fl);
+	return NULL;
+}