imsm: catch attempt to auto-layout zero-length arrays

When -z is omitted reserve_space() looks to satisfy a zero length
allocation which lo and behold is equal to the amount of free space on a
full disk.  So, catch maxsize == 0 and simplify the return value from
merge_extents() to always equal amount of free space (no benefit to
having a special case ~0ULL == error).

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/super-intel.c b/super-intel.c
index 2e119f831fc5d260ccc253d399058142b428304d..6fe5e0db89474623038622831cf5de8b5732cd28 100644 (file)
--- a/super-intel.c
+++ b/super-intel.c
@@ -3333,7 +3333,7 @@ static unsigned long long merge_extents(struct intel_super *super, int sum_exten
        unsigned long reserve;
 
        if (!e)
-               return ~0ULL; /* error */
+               return 0;
 
        /* coalesce and sort all extents. also, check to see if we need to
         * reserve space between member arrays
@@ -3376,17 +3376,23 @@ static unsigned long long merge_extents(struct intel_super *super, int sum_exten
        } while (e[i-1].size);
        free(e);
 
+       if (maxsize == 0)
+               return 0;
+
+       /* FIXME assumes volume at offset 0 is the first volume in a
+        * container
+        */
        if (start_extent > 0)
                reserve = IMSM_RESERVED_SECTORS; /* gap between raid regions */
        else
                reserve = 0;
 
        if (maxsize < reserve)
-               return ~0ULL;
+               return 0;
 
        super->create_offset = ~((__u32) 0);
        if (start + reserve > super->create_offset)
-               return ~0ULL; /* start overflows create_offset */
+               return 0; /* start overflows create_offset */
        super->create_offset = start + reserve;
 
        return maxsize - reserve;
@@ -3569,15 +3575,11 @@ static int validate_geometry_imsm_volume(struct supertype *st, int level,
                        i += dl->extent_cnt;
 
        maxsize = merge_extents(super, i);
-       if (maxsize < size) {
+       if (maxsize < size || maxsize == 0) {
                if (verbose)
                        fprintf(stderr, Name ": not enough space after merge (%llu < %llu)\n",
                                maxsize, size);
                return 0;
-       } else if (maxsize == ~0ULL) {
-               if (verbose)
-                       fprintf(stderr, Name ": failed to merge %d extents\n", i);
-               return 0;
        }
 
        *freesize = maxsize;
@@ -3634,7 +3636,8 @@ static int reserve_space(struct supertype *st, int raiddisks,
 
        if (cnt < raiddisks ||
            (super->orom && used && used != raiddisks) ||
-           maxsize < minsize) {
+           maxsize < minsize ||
+           maxsize == 0) {
                fprintf(stderr, Name ": not enough devices with space to create array.\n");
                return 0; /* No enough free spaces large enough */
        }