mdadm: write behind value does not have endian conversion

Neil,

The write behind value does not get converted to/from little endian which causes write behind not to work on big endian machines (RUN ARRAY fails with invalid argument error):

# mdadm -B /dev/md0 -l1 -n2 --write-behind=256 /dev/sdb10 --write-mostly /dev/nbd0 --bitmap=/bitmaps/test5
mdadm: RUN_ARRAY failed: Invalid argument

# tail /var/log/messages
Oct  6 13:14:48 caspian kernel:   daemon sleep: 5s
Oct  6 13:14:48 caspian kernel:      sync size: 1001456 KB
Oct  6 13:14:48 caspian kernel: max write behind: 65536
Oct  6 13:14:48 caspian kernel: md0: failed to create bitmap (-22)

Attached patch for mdadm fixes this.

Thanks,
Paul

@@ -33,6 +33,7 @@ inline void sb_le_to_cpu(bitmap_super_t 
 	sb->chunksize = __le32_to_cpu(sb->chunksize);
 	sb->daemon_sleep = __le32_to_cpu(sb->daemon_sleep);
 	sb->sync_size = __le64_to_cpu(sb->sync_size);
+	sb->write_behind = __le32_to_cpu(sb->sync_size);
 }
 
 inline void sb_cpu_to_le(bitmap_super_t *sb)

Thanks.
Applied and push out to git.

NeilBrown