[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>

1 files changed, 38 insertions, 2 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 7075bebb7f37..fde8acfac320 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -337,7 +337,7 @@ static int bi_complete(struct bio *bio, unsigned int bytes_done, int error)
         return 0;
 }
 
-static int sync_page_io(struct block_device *bdev, sector_t sector, int size,
+int sync_page_io(struct block_device *bdev, sector_t sector, int size,
                    struct page *page, int rw)
 {
         struct bio *bio = bio_alloc(GFP_NOIO, 1);
@@ -609,6 +609,17 @@ static int super_90_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                 memcpy(mddev->uuid+12,&sb->set_uuid3, 4);
 
                 mddev->max_disks = MD_SB_DISKS;
+
+                if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
+                    mddev->bitmap_file == NULL) {
+                        if (mddev->level != 1) {
+                                /* FIXME use a better test */
+                                printk(KERN_WARNING "md: bitmaps only support for raid1\n");
+                                return -EINVAL;
+                        }
+                        mddev->bitmap_offset = (MD_SB_BYTES >> 9);
+                }
+
         } else if (mddev->pers == NULL) {
                 /* Insist on good event counter while assembling */
                 __u64 ev1 = md_event(sb);
@@ -702,6 +713,9 @@ static void super_90_sync(mddev_t *mddev, mdk_rdev_t *rdev)
         sb->layout = mddev->layout;
         sb->chunk_size = mddev->chunk_size;
 
+        if (mddev->bitmap && mddev->bitmap_file == NULL)
+                sb->state |= (1<<MD_SB_BITMAP_PRESENT);
+
         sb->disks[0].state = (1<<MD_DISK_REMOVED);
         ITERATE_RDEV(mddev,rdev2,tmp) {
                 mdp_disk_t *d;
@@ -898,6 +912,15 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
                 memcpy(mddev->uuid, sb->set_uuid, 16);
 
                 mddev->max_disks =  (4096-256)/2;
+
+                if ((le32_to_cpu(sb->feature_map) & 1) &&
+                    mddev->bitmap_file == NULL ) {
+                        if (mddev->level != 1) {
+                                printk(KERN_WARNING "md: bitmaps only supported for raid1\n");
+                                return -EINVAL;
+                        }
+                        mddev->bitmap_offset = (__s32)le32_to_cpu(sb->bitmap_offset);
+                }
         } else if (mddev->pers == NULL) {
                 /* Insist of good event counter while assembling */
                 __u64 ev1 = le64_to_cpu(sb->events);
@@ -960,6 +983,11 @@ static void super_1_sync(mddev_t *mddev, mdk_rdev_t *rdev)
         else
                 sb->resync_offset = cpu_to_le64(0);
 
+        if (mddev->bitmap && mddev->bitmap_file == NULL) {
+                sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_offset);
+                sb->feature_map = cpu_to_le32(1);
+        }
+
         max_dev = 0;
         ITERATE_RDEV(mddev,rdev2,tmp)
                 if (rdev2->desc_nr+1 > max_dev)
@@ -2406,7 +2434,8 @@ static int set_bitmap_file(mddev_t *mddev, int fd)
                         mdname(mddev));
                 fput(mddev->bitmap_file);
                 mddev->bitmap_file = NULL;
-        }
+        } else
+                mddev->bitmap_offset = 0; /* file overrides offset */
         return err;
 }
 
@@ -3774,6 +3803,13 @@ void md_check_recovery(mddev_t *mddev)
                         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
                         if (!spares)
                                 set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+                        if (spares && mddev->bitmap && ! mddev->bitmap->file) {
+                                /* We are adding a device or devices to an array
+                                 * which has the bitmap stored on all devices.
+                                 * So make sure all bitmap pages get written
+                                 */
+                                bitmap_write_all(mddev->bitmap);
+                        }
                         mddev->sync_thread = md_register_thread(md_do_sync,
                                                                 mddev,
                                                                 "%s_resync");