Grow: lack of head/tail space not fatal for RAID5 etc.

For RAID10, we must have head/tail space for reshape.
For RAID4/5/6 we can use a spare or a backup file.

So make that distinction.

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

diff --git a/Grow.c b/Grow.c
index d939850c5e92b9a3c2d9ef6a26c0bbc69e4c2715..8e4594d61a814c62c597da7d59c78127af2bbff9 100644 (file)
--- a/Grow.c
+++ b/Grow.c
@@ -2202,7 +2202,8 @@ static unsigned long long choose_offset(unsigned long long lo,
 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)
+                              unsigned long long min,
+                              int can_fallback)
 {
        struct mdinfo *sd;
        int dir = 0;
@@ -2298,6 +2299,8 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
                } 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;
@@ -2328,6 +2331,8 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
                        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;
@@ -2348,6 +2353,8 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
                        } else {
                                /* Decrease data offset */
                                if (before < min) {
+                                       if (can_fallback)
+                                               goto fallback;
                                        pr_err("insufficient head-room on %s\n",
                                                dn);
                                        goto release;
@@ -2402,6 +2409,9 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
        return err;
 release:
        return -1;
+fallback:
+       /* Just use a backup file */
+       return 1;
 }
 
 static int raid10_reshape(char *container, int fd, char *devname,
@@ -2458,7 +2468,7 @@ static int raid10_reshape(char *container, int fd, char *devname,
                }
        }
        err = set_new_data_offset(sra, st, devname, info->delta_disks, data_offset,
-                                 min);
+                                 min, 0);
        if (err == 1) {
                pr_err("Cannot set new_data_offset: RAID10 reshape not\n");
                cont_err("supported on this kernel\n");
@@ -3048,7 +3058,7 @@ static int reshape_array(char *container, int fd, char *devname,
                switch(set_new_data_offset(sra, st, devname,
                                           reshape.after.data_disks - reshape.before.data_disks,
                                           data_offset,
-                                          reshape.min_offset_change)) {
+                                          reshape.min_offset_change, 1)) {
        case -1:
                goto release;
        case 0: