[PATCH] md: allow md intent bitmap to be stored near the superblock.
This provides an alternate to storing the bitmap in a separate file. The
bitmap can be stored at a given offset from the superblock. Obviously the
creator of the array must make sure this doesn't intersect with data....
After is good for version-0.90 superblocks.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/raid/bitmap.h b/include/linux/raid/bitmap.h
index cfe60cf..e24b74b 100644
--- a/include/linux/raid/bitmap.h
+++ b/include/linux/raid/bitmap.h
@@ -217,6 +217,7 @@
/* bitmap spinlock */
spinlock_t lock;
+ long offset; /* offset from superblock if file is NULL */
struct file *file; /* backing disk file */
struct page *sb_page; /* cached copy of the bitmap file superblock */
struct page **filemap; /* list of cache pages for the file */
@@ -255,6 +256,7 @@
int bitmap_update_sb(struct bitmap *bitmap);
int bitmap_setallbits(struct bitmap *bitmap);
+void bitmap_write_all(struct bitmap *bitmap);
/* these are exported */
int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sectors);
diff --git a/include/linux/raid/md.h b/include/linux/raid/md.h
index 75f41d8..ffa316c 100644
--- a/include/linux/raid/md.h
+++ b/include/linux/raid/md.h
@@ -60,7 +60,14 @@
*/
#define MD_MAJOR_VERSION 0
#define MD_MINOR_VERSION 90
-#define MD_PATCHLEVEL_VERSION 1
+/*
+ * MD_PATCHLEVEL_VERSION indicates kernel functionality.
+ * >=1 means different superblock formats are selectable using SET_ARRAY_INFO
+ * and major_version/minor_version accordingly
+ * >=2 means that Internal bitmaps are supported by setting MD_SB_BITMAP_PRESENT
+ * in the super status byte
+ */
+#define MD_PATCHLEVEL_VERSION 2
extern int register_md_personality (int p_num, mdk_personality_t *p);
extern int unregister_md_personality (int p_num);
@@ -78,6 +85,12 @@
extern void md_print_devices (void);
+extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
+ sector_t sector, int size, struct page *page);
+extern int sync_page_io(struct block_device *bdev, sector_t sector, int size,
+ struct page *page, int rw);
+
+
#define MD_BUG(x...) { printk("md: bug in file %s, line %d\n", __FILE__, __LINE__); md_print_devices(); }
#endif
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 3e97702..a3725b57 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -273,6 +273,10 @@
struct bitmap *bitmap; /* the bitmap for the device */
struct file *bitmap_file; /* the bitmap file */
+ long bitmap_offset; /* offset from superblock of
+ * start of bitmap. May be
+ * negative, but not '0'
+ */
struct list_head all_mddevs;
};
diff --git a/include/linux/raid/md_p.h b/include/linux/raid/md_p.h
index 8ba95d6..8e592a2 100644
--- a/include/linux/raid/md_p.h
+++ b/include/linux/raid/md_p.h
@@ -96,6 +96,7 @@
#define MD_SB_CLEAN 0
#define MD_SB_ERRORS 1
+#define MD_SB_BITMAP_PRESENT 8 /* bitmap may be present nearby */
typedef struct mdp_superblock_s {
/*
* Constant generic information
@@ -184,7 +185,7 @@
/* constant array information - 128 bytes */
__u32 magic; /* MD_SB_MAGIC: 0xa92b4efc - little endian */
__u32 major_version; /* 1 */
- __u32 feature_map; /* 0 for now */
+ __u32 feature_map; /* bit 0 set if 'bitmap_offset' is meaningful */
__u32 pad0; /* always set to 0 when writing */
__u8 set_uuid[16]; /* user-space generated. */
@@ -197,6 +198,10 @@
__u32 chunksize; /* in 512byte sectors */
__u32 raid_disks;
+ __u32 bitmap_offset; /* sectors after start of superblock that bitmap starts
+ * NOTE: signed, so bitmap can be before superblock
+ * only meaningful of feature_map[0] is set.
+ */
__u8 pad1[128-96]; /* set to 0 when written */
/* constant this-device information - 64 bytes */