super1: reserve at least 2 chunks for reshape headroom.

sometimes 0.1% isn't enough, though mostly only in testing.

We need one chunk for a successful reshape, so reserve 2.

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

diff --git a/super1.c b/super1.c
index 54bd5b3268ccec91f8a4e63e341f80e77b355617..8f5f3071bb1c018801effd24839fad457e452a8e 100644 (file)
--- a/super1.c
+++ b/super1.c
@@ -1330,11 +1330,15 @@ static int write_init_super1(struct supertype *st)
                /* We try to leave 0.1% at the start for reshape
                 * operations, but limit this to 128Meg (0.1% of 10Gig)
                 * which is plenty for efficient reshapes
+                * However we make it at least 2 chunks as one chunk
+                * is minimum needed for reshape.
                 */
                headroom = 128 * 1024 * 2;
-               while  (headroom << 10 > array_size)
+               while  (headroom << 10 > array_size &&
+                       headroom/2 >= __le32_to_cpu(sb->chunksize) * 2)
                        headroom >>= 1;
 
+
                switch(st->minor_version) {
                case 0:
                        sb_offset = dsize;
@@ -1685,8 +1689,8 @@ static struct supertype *match_metadata_desc1(char *arg)
  * superblock type st, and reserving 'reserve' sectors for
  * a possible bitmap
  */
-static __u64 avail_size1(struct supertype *st, __u64 devsize,
-                        unsigned long long data_offset)
+static __u64 _avail_size1(struct supertype *st, __u64 devsize,
+                         unsigned long long data_offset, int chunksize)
 {
        struct mdp_superblock_1 *super = st->sb;
        int bmspace = 0;
@@ -1734,7 +1738,9 @@ static __u64 avail_size1(struct supertype *st, __u64 devsize,
                 * Limit slack to 128M, but aim for about 0.1%
                 */
                unsigned long long headroom = 128*1024*2;
-               while ((headroom << 10) > devsize)
+               while ((headroom << 10) > devsize &&
+                      (chunksize == 0 ||
+                       headroom / 2 >= ((unsigned)chunksize*2)*2))
                        headroom >>= 1;
                devsize -= headroom;
        }
@@ -1751,6 +1757,11 @@ static __u64 avail_size1(struct supertype *st, __u64 devsize,
        }
        return 0;
 }
+static __u64 avail_size1(struct supertype *st, __u64 devsize,
+                        unsigned long long data_offset)
+{
+       return _avail_size1(st, devsize, data_offset, 0);
+}
 
 static int
 add_internal_bitmap1(struct supertype *st,
@@ -2010,7 +2021,7 @@ static int validate_geometry1(struct supertype *st, int level,
        }
        close(fd);
 
-       *freesize = avail_size1(st, ldsize >> 9, data_offset);
+       *freesize = _avail_size1(st, ldsize >> 9, data_offset, *chunk);
        return 1;
 }
 #endif /* MDASSEMBLE */