Grow: allow for different sized devices when updating data_offset.

It is possible that the devices in an array have different sizes, and
different data_offsets.  So the 'before_space' and 'after_space' may
be different from drive to drive.
Any decisions about how much to change the data_offset must work on
all devices, so must be based on the minimum available space on
any devices.

So find this minimum first, then do the calculation.

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

diff --git a/Grow.c b/Grow.c
index 2eb8c7ce042bd6b224547e1d9eb2b3cd8aec30fe..5e214f12aa461893133f66ce29ee6994a2b19f55 100644 (file)
--- a/Grow.c
+++ b/Grow.c
@@ -24,6 +24,7 @@
 #include       "mdadm.h"
 #include       "dlink.h"
 #include       <sys/mman.h>
+#include       <stdint.h>
 
 #if ! defined(__BIG_ENDIAN) && ! defined(__LITTLE_ENDIAN)
 #error no endian defined
@@ -2152,7 +2153,13 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
        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;
@@ -2186,6 +2193,38 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
                        /* Metadata doesn't support data_offset changes */
                        return 1;
                }
+               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);
+
+               struct mdinfo info2;
                if (delta_disks < 0) {
                        /* Don't need any space as array is shrinking
                         * just move data_offset up by min
@@ -2202,7 +2241,7 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
                        }
                } else if (delta_disks > 0) {
                        /* need space before */
-                       if (info2.space_before < min) {
+                       if (before < min) {
                                pr_err("Insufficient head-space for reshape on %s\n",
                                        dn);
                                goto release;
@@ -2219,25 +2258,21 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
                        }
                } else {
                        if (dir == 0) {
-                               /* can move up or down. 'data_offset'
-                                * might guide us, otherwise choose
-                                * direction with most space
+                               /* can move up or down.  If 'data_offset'
+                                * was set we would have already decided,
+                                * so just choose direction with most space.
                                 */
-                               if (data_offset == INVALID_SECTORS) {
-                                       if (info2.space_before > info2.space_after)
-                                               dir = -1;
-                                       else
-                                               dir = 1;
-                               } else if (data_offset < info2.data_offset)
+                               if (info2.space_before > info2.space_after)
                                        dir = -1;
                                else
                                        dir = 1;
                                sysfs_set_str(sra, NULL, "reshape_direction",
                                              dir == 1 ? "backwards" : "forwards");
                        }
+
                        switch (dir) {
                        case 1: /* Increase data offset */
-                               if (info2.space_after < min) {
+                               if (after < min) {
                                        pr_err("Insufficient tail-space for reshape on %s\n",
                                                dn);
                                        goto release;
@@ -2251,8 +2286,7 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
                                if (data_offset != INVALID_SECTORS)
                                        info2.new_data_offset = data_offset;
                                else {
-                                       unsigned long long off =
-                                               info2.space_after / 2;
+                                       unsigned long long off = after / 2;
                                        off &= ~7ULL;
                                        if (off < min)
                                                off = min;
@@ -2261,7 +2295,7 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
                                }
                                break;
                        case -1: /* Decrease data offset */
-                               if (info2.space_before < min) {
+                               if (before < min) {
                                        pr_err("insufficient head-room on %s\n",
                                                dn);
                                        goto release;
@@ -2275,8 +2309,7 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
                                if (data_offset != INVALID_SECTORS)
                                        info2.new_data_offset = data_offset;
                                else {
-                                       unsigned long long off =
-                                               info2.space_before / 2;
+                                       unsigned long long off = before / 2;
                                        off &= ~7ULL;
                                        if (off < min)
                                                off = min;