Enable loading of bitmaps for dm-md-raid1.

This is also a hack for systems with junk in the rest of the bitmap super (instead of zeroes) to boot. This is done by checking mddev->sync_super (which is exclusively set by dm-raid) is null.

These changes also include zeroing of most bitmap pages while allocating so we are sure that the junk is not coming from memory.

References: https://bugzilla.kernel.org/show_bug.cgi?id=100491

Signed-off-by Neil Brown <[email protected]>

Signed-off-by Goldwyn Rodrigues <[email protected]>

---

drivers/md/bitmap.c +13 -5

index 135a090..dfa5ef3 100644
@@ -494,7 +494,7 @@ static int bitmap_new_disk_sb(struct bitmap *bitmap)
 	bitmap_super_t *sb;
 	unsigned long chunksize, daemon_sleep, write_behind;
 
-	bitmap->storage.sb_page = alloc_page(GFP_KERNEL);
+	bitmap->storage.sb_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
 	if (bitmap->storage.sb_page == NULL)
 		return -ENOMEM;
 	bitmap->storage.sb_page->index = 0;

@@ -541,6 +541,7 @@ static int bitmap_new_disk_sb(struct bitmap *bitmap)
 	sb->state = cpu_to_le32(bitmap->flags);
 	bitmap->events_cleared = bitmap->mddev->events;
 	sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
+	bitmap->mddev->bitmap_info.nodes = 0;
 
 	kunmap_atomic(sb);
 

@@ -568,7 +569,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
 		goto out_no_sb;
 	}
 	/* page 0 is the superblock, read it... */
-	sb_page = alloc_page(GFP_KERNEL);
+	sb_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
 	if (!sb_page)
 		return -ENOMEM;
 	bitmap->storage.sb_page = sb_page;

@@ -611,8 +612,15 @@ re_read:
 	daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
 	write_behind = le32_to_cpu(sb->write_behind);
 	sectors_reserved = le32_to_cpu(sb->sectors_reserved);
-	nodes = le32_to_cpu(sb->nodes);
-	strlcpy(bitmap->mddev->bitmap_info.cluster_name, sb->cluster_name, 64);
+	/* XXX: This is an ugly hack to ensure that we don't use clustering
+	   in case dm-raid is in use and the nodes written in bitmap_sb
+	   is erroneous.
+	*/
+	if (!bitmap->mddev->sync_super) {
+		nodes = le32_to_cpu(sb->nodes);
+		strlcpy(bitmap->mddev->bitmap_info.cluster_name,
+				sb->cluster_name, 64);
+	}
 
 	/* verify that the bitmap-specific fields are valid */
 	if (sb->magic != cpu_to_le32(BITMAP_MAGIC))

@@ -649,7 +657,7 @@ re_read:
 			goto out;
 		}
 		events = le64_to_cpu(sb->events);
-		if (!nodes && (events < bitmap->mddev->events)) {
+		if (err == 0 && !nodes && (events < bitmap->mddev->events)) {
 			printk(KERN_INFO
 			       "%s: bitmap file is out of date (%llu < %llu) "
 			       "-- forcing full recovery\n",

drivers/md/md.c +0 -0

index 4dbed4a..6bd8bc3 100644

Quoted 75 lines · On Mon, 20 Jul 2015 12:06:28 -0500 Goldwyn Rodrigues <[email protected]> wrote:

This is also a hack for systems with junk in the rest of the bitmap super (instead of zeroes) to boot. This is done by checking mddev->sync_super (which is exclusively set by dm-raid) is null.

These changes also include zeroing of most bitmap pages while allocating so we are sure that the junk is not coming from memory.

References: https://bugzilla.kernel.org/show_bug.cgi?id=100491

Signed-off-by Neil Brown <[email protected]>

Signed-off-by Goldwyn Rodrigues <[email protected]>

---

drivers/md/bitmap.c +13 -5

index 135a090..dfa5ef3 100644
@@ -494,7 +494,7 @@ static int bitmap_new_disk_sb(struct bitmap *bitmap)
  	bitmap_super_t *sb;
  	unsigned long chunksize, daemon_sleep, write_behind;
 
-	bitmap->storage.sb_page = alloc_page(GFP_KERNEL);
+	bitmap->storage.sb_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
  	if (bitmap->storage.sb_page == NULL)
  		return -ENOMEM;
  	bitmap->storage.sb_page->index = 0;

@@ -541,6 +541,7 @@ static int bitmap_new_disk_sb(struct bitmap *bitmap)
  	sb->state = cpu_to_le32(bitmap->flags);
  	bitmap->events_cleared = bitmap->mddev->events;
  	sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
+	bitmap->mddev->bitmap_info.nodes = 0;
 
  	kunmap_atomic(sb);
 

@@ -568,7 +569,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
  		goto out_no_sb;
  	}
  	/* page 0 is the superblock, read it... */
-	sb_page = alloc_page(GFP_KERNEL);
+	sb_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
  	if (!sb_page)
  		return -ENOMEM;
  	bitmap->storage.sb_page = sb_page;

@@ -611,8 +612,15 @@ re_read:
  	daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
  	write_behind = le32_to_cpu(sb->write_behind);
  	sectors_reserved = le32_to_cpu(sb->sectors_reserved);
-	nodes = le32_to_cpu(sb->nodes);
-	strlcpy(bitmap->mddev->bitmap_info.cluster_name, sb->cluster_name, 64);
+	/* XXX: This is an ugly hack to ensure that we don't use clustering
+	   in case dm-raid is in use and the nodes written in bitmap_sb
+	   is erroneous.
+	*/
+	if (!bitmap->mddev->sync_super) {
+		nodes = le32_to_cpu(sb->nodes);
+		strlcpy(bitmap->mddev->bitmap_info.cluster_name,
+				sb->cluster_name, 64);
+	}
 
  	/* verify that the bitmap-specific fields are valid */
  	if (sb->magic != cpu_to_le32(BITMAP_MAGIC))

@@ -649,7 +657,7 @@ re_read:
  			goto out;
  		}
  		events = le64_to_cpu(sb->events);
-		if (!nodes && (events < bitmap->mddev->events)) {
+		if (err == 0 && !nodes && (events < bitmap->mddev->events)) {
  			printk(KERN_INFO
  			       "%s: bitmap file is out of date (%llu < %llu) "
  			       "-- forcing full recovery\n",

drivers/md/md.c +0 -0

index 4dbed4a..6bd8bc3 100644

drivers/md/md.c int md_setup_cluster(struct mddev *mddev, int nodes) · line 7421

Quoted 8 lines

drivers/md/md.c +1 -1

@@ -7415,7 +7415,7 @@ int md_setup_cluster(struct mddev *mddev, int nodes)
  	err = request_module("md-cluster");
  	if (err) {
  		pr_err("md-cluster module not found.\n");
-		return err;
+		return -ENOENT;
  	}
 
  	spin_lock(&pers_lock);

Thanks... but I think this is about 3 patches.

The patch to md.c is because request_module() returns a status different from what the documentation says. And

Fixes edb39c9deda8 ("Introduce md_cluster_operations to handle cluster functions")

(though it doesn't need to go to stable.

Adding "err == 0 &&' test is ... why is that? It looks to me like err == -EINVAL at that point, always. Can you explain/

Using __GFP_ZERO in read_sb_page seems wrong and so misleading.

The rest are for the main bug you are trying to fix .. though I think it could be described better.

-------------------
There is a bug that the bitmap superblock isn't initialised properly for dm-raid, so a new field can have garbage in new fields. (dm-raid does initialisation in the kernel - md initialised the superblock in mdadm).
This means that for dm-raid we cannot currently trust the new ->nodes field.
So:
- use __GFP_ZERO to initialise the superblock properly for all new arrays
- initialise all field in bitmap_info in bitmap_new_disk_sb
- ignore ->nodes for dm arrays (yes, this is a hack)
-----------------

Could you make it 3 patches for me please?