X-Git-Url: http://git.ipfire.org/?a=blobdiff_plain;f=bitmap.h;h=055661d1da81f8f91f861c5c031b05090493a786;hb=e39b673e4892ef0085a8e59eee89d42e6191a688;hp=17027e083cf82d7b5d1c03fc30b7cf35e9ef27c5;hpb=c82f047cfceb479c9c6b56b44c196018af050e45;p=thirdparty%2Fmdadm.git

diff --git a/bitmap.h b/bitmap.h
index 17027e08..055661d1 100644
--- a/bitmap.h
+++ b/bitmap.h
@@ -6,8 +6,14 @@
 #ifndef BITMAP_H
 #define BITMAP_H 1
 
-#define BITMAP_MAJOR 3
-#define BITMAP_MINOR 38
+#define BITMAP_MAJOR_LO 3
+/* version 4 insists the bitmap is in little-endian order
+ * with version 3, it is host-endian which is non-portable
+ */
+#define BITMAP_MAJOR_HI 4
+#define	BITMAP_MAJOR_HOSTENDIAN 3
+
+#define BITMAP_MINOR 39
 
 /*
  * in-memory bitmap:
@@ -43,6 +49,13 @@
  * When we set a bit, or in the counter (to start a write), if the fields is
  * 0, we first set the disk bit and set the counter to 1.
  *
+ * If the counter is 0, the on-disk bit is clear and the stipe is clean
+ * Anything that dirties the stipe pushes the counter to 2 (at least)
+ * and sets the on-disk bit (lazily).
+ * If a periodic sweep find the counter at 2, it is decremented to 1.
+ * If the sweep find the counter at 1, the on-disk bit is cleared and the
+ * counter goes to zero.
+ *
  * Also, we'll hijack the "map" pointer itself and use it as two 16 bit block
  * counters as a fallback when "page" memory cannot be allocated:
  *
@@ -140,8 +153,9 @@ typedef struct bitmap_super_s {
 	__u32 state;        /* 48  bitmap state information */
 	__u32 chunksize;    /* 52  the bitmap chunk size in bytes */
 	__u32 daemon_sleep; /* 56  seconds between disk flushes */
+	__u32 write_behind; /* 60  number of outstanding write-behind writes */
 
-	__u8  pad[4096 - 60]; /* set to zero */
+	__u8  pad[256 - 64]; /* set to zero */
 } bitmap_super_t;
 
 /* notes: