md: Support write-intent bitmaps with externally managed metadata.
In this case, the metadata needs to not be in the same
sector as the bitmap.
md will not read/write any bitmap metadata. Config must be
done via sysfs and when a recovery makes the array non-degraded
again, writing 'true' to 'bitmap/can_clear' will allow bits in
the bitmap to be cleared again.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/bitmap.h b/drivers/md/bitmap.h
index 50ee424..cb821d7 100644
--- a/drivers/md/bitmap.h
+++ b/drivers/md/bitmap.h
@@ -118,16 +118,6 @@
(CHUNK_BLOCK_SHIFT(bitmap) + PAGE_COUNTER_SHIFT - 1)
#define PAGEPTR_BLOCK_MASK(bitmap) (PAGEPTR_BLOCK_RATIO(bitmap) - 1)
-/*
- * on-disk bitmap:
- *
- * Use one bit per "chunk" (block set). We do the disk I/O on the bitmap
- * file a page at a time. There's a superblock at the start of the file.
- */
-
-/* map chunks (bits) to file pages - offset by the size of the superblock */
-#define CHUNK_BIT_OFFSET(chunk) ((chunk) + (sizeof(bitmap_super_t) << 3))
-
#endif
/*
@@ -250,6 +240,7 @@
wait_queue_head_t write_wait;
wait_queue_head_t overflow_wait;
+ struct sysfs_dirent *sysfs_can_clear;
};
/* the bitmap API */
