#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:
* 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:
*
__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:
* (1) This event counter is updated before the eventcounter in the md superblock
* When a bitmap is loaded, it is only accepted if this event counter is equal
* to, or one greater than, the event counter in the superblock.
- * (2) This event counter is updated when the other one is *if*and*only*if* the
+ * (2) This event counter is updated when the other one is *if*and*only*if* the
* array is not degraded. As bits are not cleared when the array is degraded,
* this represents the last time that any bits were cleared.
* If a device is being added that has an event count with this value or
unsigned int hijacked;
/*
* count of dirty bits on the page
- */
+ */
int count;
};