super1: put bitmap on a 4K boundary when possible.

[thirdparty/mdadm.git] / super1.c

diff --git a/super1.c b/super1.c
index 40fbb81accb30a904f1f5fd20a5fb7306e720270..7861cf4455e39b64dd399eef6d2f234d15004b10 100644 (file)
--- a/super1.c
+++ b/super1.c
@@ -1445,8 +1445,8 @@ add_internal_bitmap1(struct supertype *st,
 
        switch(st->minor_version) {
        case 0:
-               /* either 3K after the superblock, or some amount of space
-                * before.
+               /* either 3K after the superblock (when hot-add),
+                * or some amount of space before.
                 */
                if (may_change) {
                        /* We are creating array, so we *know* how much room has
@@ -1454,11 +1454,6 @@ add_internal_bitmap1(struct supertype *st,
                         */
                        offset = 0;
                        room = choose_bm_space(__le64_to_cpu(sb->size));
-                       if (room == 4*2) {
-                               /* make it 3K after the superblock */
-                               room = 3*2;
-                               offset = 2;
-                       }
                } else {
                        room = __le64_to_cpu(sb->super_offset)
                                - __le64_to_cpu(sb->data_offset)
@@ -1519,8 +1514,12 @@ add_internal_bitmap1(struct supertype *st,
                return 0;
 
        if (offset == 0) {
+               /* start bitmap on a 4K boundary with enough space for
+                * the bitmap
+                */
                bits = (size*512) / chunk + 1;
-               room = ((bits+7)/8 + sizeof(bitmap_super_t) +511)/512;
+               room = ((bits+7)/8 + sizeof(bitmap_super_t) +4095)/4096;
+               room *= 8; /* convert 4K blocks to sectors */
                offset = -room;
        }