1 files changed, 184 insertions, 87 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0b4e2af7954d..a872b48be0ae 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -67,7 +67,7 @@ static void free_fs_devices(struct btrfs_fs_devices *fs_devices)
 	kfree(fs_devices);
 }
 
-int btrfs_cleanup_fs_uuids(void)
+void btrfs_cleanup_fs_uuids(void)
 {
 	struct btrfs_fs_devices *fs_devices;
 
@@ -77,7 +77,6 @@ int btrfs_cleanup_fs_uuids(void)
 		list_del(&fs_devices->list);
 		free_fs_devices(fs_devices);
 	}
-	return 0;
 }
 
 static noinline struct btrfs_device *__find_device(struct list_head *head,
@@ -130,7 +129,7 @@ static void requeue_list(struct btrfs_pending_bios *pending_bios,
  * the list if the block device is congested.  This way, multiple devices
  * can make progress from a single worker thread.
  */
-static noinline int run_scheduled_bios(struct btrfs_device *device)
+static noinline void run_scheduled_bios(struct btrfs_device *device)
 {
 	struct bio *pending;
 	struct backing_dev_info *bdi;
@@ -316,7 +315,6 @@ loop_lock:
 
 done:
 	blk_finish_plug(&plug);
-	return 0;
 }
 
 static void pending_bios_fn(struct btrfs_work *work)
@@ -455,16 +453,27 @@ error:
 	return ERR_PTR(-ENOMEM);
 }
 
-int btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices)
+void btrfs_close_extra_devices(struct btrfs_fs_devices *fs_devices)
 {
 	struct btrfs_device *device, *next;
 
+	struct block_device *latest_bdev = NULL;
+	u64 latest_devid = 0;
+	u64 latest_transid = 0;
+
 	mutex_lock(&uuid_mutex);
 again:
 	/* This is the initialized path, it is safe to release the devices. */
 	list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
-		if (device->in_fs_metadata)
+		if (device->in_fs_metadata) {
+			if (!latest_transid ||
+			    device->generation > latest_transid) {
+				latest_devid = device->devid;
+				latest_transid = device->generation;
+				latest_bdev = device->bdev;
+			}
 			continue;
+		}
 
 		if (device->bdev) {
 			blkdev_put(device->bdev, device->mode);
@@ -487,8 +496,11 @@ again:
 		goto again;
 	}
 
+	fs_devices->latest_bdev = latest_bdev;
+	fs_devices->latest_devid = latest_devid;
+	fs_devices->latest_trans = latest_transid;
+
 	mutex_unlock(&uuid_mutex);
-	return 0;
 }
 
 static void __free_device(struct work_struct *work)
@@ -537,10 +549,10 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
 			fs_devices->num_can_discard--;
 
 		new_device = kmalloc(sizeof(*new_device), GFP_NOFS);
-		BUG_ON(!new_device);
+		BUG_ON(!new_device); /* -ENOMEM */
 		memcpy(new_device, device, sizeof(*new_device));
 		new_device->name = kstrdup(device->name, GFP_NOFS);
-		BUG_ON(device->name && !new_device->name);
+		BUG_ON(device->name && !new_device->name); /* -ENOMEM */
 		new_device->bdev = NULL;
 		new_device->writeable = 0;
 		new_device->in_fs_metadata = 0;
@@ -610,6 +622,8 @@ static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 			printk(KERN_INFO "open %s failed\n", device->name);
 			goto error;
 		}
+		filemap_write_and_wait(bdev->bd_inode->i_mapping);
+		invalidate_bdev(bdev);
 		set_blocksize(bdev, 4096);
 
 		bh = btrfs_read_dev_super(bdev);
@@ -1024,8 +1038,10 @@ again:
 		leaf = path->nodes[0];
 		extent = btrfs_item_ptr(leaf, path->slots[0],
 					struct btrfs_dev_extent);
+	} else {
+		btrfs_error(root->fs_info, ret, "Slot search failed");
+		goto out;
 	}
-	BUG_ON(ret);
 
 	if (device->bytes_used > 0) {
 		u64 len = btrfs_dev_extent_length(leaf, extent);
@@ -1035,7 +1051,10 @@ again:
 		spin_unlock(&root->fs_info->free_chunk_lock);
 	}
 	ret = btrfs_del_item(trans, root, path);
-
+	if (ret) {
+		btrfs_error(root->fs_info, ret,
+			    "Failed to remove dev extent item");
+	}
 out:
 	btrfs_free_path(path);
 	return ret;
@@ -1063,7 +1082,8 @@ int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
 	key.type = BTRFS_DEV_EXTENT_KEY;
 	ret = btrfs_insert_empty_item(trans, root, path, &key,
 				      sizeof(*extent));
-	BUG_ON(ret);
+	if (ret)
+		goto out;
 
 	leaf = path->nodes[0];
 	extent = btrfs_item_ptr(leaf, path->slots[0],
@@ -1078,6 +1098,7 @@ int btrfs_alloc_dev_extent(struct btrfs_trans_handle *trans,
 
 	btrfs_set_dev_extent_length(leaf, extent, num_bytes);
 	btrfs_mark_buffer_dirty(leaf);
+out:
 	btrfs_free_path(path);
 	return ret;
 }
@@ -1103,7 +1124,7 @@ static noinline int find_next_chunk(struct btrfs_root *root,
 	if (ret < 0)
 		goto error;
 
-	BUG_ON(ret == 0);
+	BUG_ON(ret == 0); /* Corruption */
 
 	ret = btrfs_previous_item(root, path, 0, BTRFS_CHUNK_ITEM_KEY);
 	if (ret) {
@@ -1147,7 +1168,7 @@ static noinline int find_next_devid(struct btrfs_root *root, u64 *objectid)
 	if (ret < 0)
 		goto error;
 
-	BUG_ON(ret == 0);
+	BUG_ON(ret == 0); /* Corruption */
 
 	ret = btrfs_previous_item(root, path, BTRFS_DEV_ITEMS_OBJECTID,
 				  BTRFS_DEV_ITEM_KEY);
@@ -1335,6 +1356,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 		}
 
 		set_blocksize(bdev, 4096);
+		invalidate_bdev(bdev);
 		bh = btrfs_read_dev_super(bdev);
 		if (!bh) {
 			ret = -EINVAL;
@@ -1581,7 +1603,7 @@ next_slot:
 				   (unsigned long)btrfs_device_fsid(dev_item),
 				   BTRFS_UUID_SIZE);
 		device = btrfs_find_device(root, devid, dev_uuid, fs_uuid);
-		BUG_ON(!device);
+		BUG_ON(!device); /* Logic error */
 
 		if (device->fs_devices->seeding) {
 			btrfs_set_device_generation(leaf, dev_item,
@@ -1691,7 +1713,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 	if (seeding_dev) {
 		sb->s_flags &= ~MS_RDONLY;
 		ret = btrfs_prepare_sprout(root);
-		BUG_ON(ret);
+		BUG_ON(ret); /* -ENOMEM */
 	}
 
 	device->fs_devices = root->fs_info->fs_devices;
@@ -1729,11 +1751,15 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 
 	if (seeding_dev) {
 		ret = init_first_rw_device(trans, root, device);
-		BUG_ON(ret);
+		if (ret)
+			goto error_trans;
 		ret = btrfs_finish_sprout(trans, root);
-		BUG_ON(ret);
+		if (ret)
+			goto error_trans;
 	} else {
 		ret = btrfs_add_device(trans, root, device);
+		if (ret)
+			goto error_trans;
 	}
 
 	/*
@@ -1743,17 +1769,31 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 	btrfs_clear_space_info_full(root->fs_info);
 
 	unlock_chunks(root);
-	btrfs_commit_transaction(trans, root);
+	ret = btrfs_commit_transaction(trans, root);
 
 	if (seeding_dev) {
 		mutex_unlock(&uuid_mutex);
 		up_write(&sb->s_umount);
 
+		if (ret) /* transaction commit */
+			return ret;
+
 		ret = btrfs_relocate_sys_chunks(root);
-		BUG_ON(ret);
+		if (ret < 0)
+			btrfs_error(root->fs_info, ret,
+				    "Failed to relocate sys chunks after "
+				    "device initialization. This can be fixed "
+				    "using the \"btrfs balance\" command.");
 	}
 
 	return ret;
+
+error_trans:
+	unlock_chunks(root);
+	btrfs_abort_transaction(trans, root, ret);
+	btrfs_end_transaction(trans, root);
+	kfree(device->name);
+	kfree(device);
 error:
 	blkdev_put(bdev, FMODE_EXCL);
 	if (seeding_dev) {
@@ -1861,10 +1901,20 @@ static int btrfs_free_chunk(struct btrfs_trans_handle *trans,
 	key.type = BTRFS_CHUNK_ITEM_KEY;
 
 	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
-	BUG_ON(ret);
+	if (ret < 0)
+		goto out;
+	else if (ret > 0) { /* Logic error or corruption */
+		btrfs_error(root->fs_info, -ENOENT,
+			    "Failed lookup while freeing chunk.");
+		ret = -ENOENT;
+		goto out;
+	}
 
 	ret = btrfs_del_item(trans, root, path);
-
+	if (ret < 0)
+		btrfs_error(root->fs_info, ret,
+			    "Failed to delete chunk item.");
+out:
 	btrfs_free_path(path);
 	return ret;
 }
@@ -1953,7 +2003,7 @@ static int btrfs_relocate_chunk(struct btrfs_root *root,
 	em = lookup_extent_mapping(em_tree, chunk_offset, 1);
 	read_unlock(&em_tree->lock);
 
-	BUG_ON(em->start > chunk_offset ||
+	BUG_ON(!em || em->start > chunk_offset ||
 	       em->start + em->len < chunk_offset);
 	map = (struct map_lookup *)em->bdev;
 
@@ -2026,7 +2076,7 @@ again:
 		ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0);
 		if (ret < 0)
 			goto error;
-		BUG_ON(ret == 0);
+		BUG_ON(ret == 0); /* Corruption */
 
 		ret = btrfs_previous_item(chunk_root, path, key.objectid,
 					  key.type);
@@ -2235,15 +2285,13 @@ static void unset_balance_control(struct btrfs_fs_info *fs_info)
  * Balance filters.  Return 1 if chunk should be filtered out
  * (should not be balanced).
  */
-static int chunk_profiles_filter(u64 chunk_profile,
+static int chunk_profiles_filter(u64 chunk_type,
 				 struct btrfs_balance_args *bargs)
 {
-	chunk_profile &= BTRFS_BLOCK_GROUP_PROFILE_MASK;
+	chunk_type = chunk_to_extended(chunk_type) &
+				BTRFS_EXTENDED_PROFILE_MASK;
 
-	if (chunk_profile == 0)
-		chunk_profile = BTRFS_AVAIL_ALLOC_BIT_SINGLE;
-
-	if (bargs->profiles & chunk_profile)
+	if (bargs->profiles & chunk_type)
 		return 0;
 
 	return 1;
@@ -2350,18 +2398,16 @@ static int chunk_vrange_filter(struct extent_buffer *leaf,
 	return 1;
 }
 
-static int chunk_soft_convert_filter(u64 chunk_profile,
+static int chunk_soft_convert_filter(u64 chunk_type,
 				     struct btrfs_balance_args *bargs)
 {
 	if (!(bargs->flags & BTRFS_BALANCE_ARGS_CONVERT))
 		return 0;
 
-	chunk_profile &= BTRFS_BLOCK_GROUP_PROFILE_MASK;
-
-	if (chunk_profile == 0)
-		chunk_profile = BTRFS_AVAIL_ALLOC_BIT_SINGLE;
+	chunk_type = chunk_to_extended(chunk_type) &
+				BTRFS_EXTENDED_PROFILE_MASK;
 
-	if (bargs->target & chunk_profile)
+	if (bargs->target == chunk_type)
 		return 1;
 
 	return 0;
@@ -2587,6 +2633,30 @@ error:
 	return ret;
 }
 
+/**
+ * alloc_profile_is_valid - see if a given profile is valid and reduced
+ * @flags: profile to validate
+ * @extended: if true @flags is treated as an extended profile
+ */
+static int alloc_profile_is_valid(u64 flags, int extended)
+{
+	u64 mask = (extended ? BTRFS_EXTENDED_PROFILE_MASK :
+			       BTRFS_BLOCK_GROUP_PROFILE_MASK);
+
+	flags &= ~BTRFS_BLOCK_GROUP_TYPE_MASK;
+
+	/* 1) check that all other bits are zeroed */
+	if (flags & ~mask)
+		return 0;
+
+	/* 2) see if profile is reduced */
+	if (flags == 0)
+		return !extended; /* "0" is valid for usual profiles */
+
+	/* true if exactly one bit set */
+	return (flags & (flags - 1)) == 0;
+}
+
 static inline int balance_need_close(struct btrfs_fs_info *fs_info)
 {
 	/* cancel requested || normal exit path */
@@ -2615,6 +2685,7 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
 {
 	struct btrfs_fs_info *fs_info = bctl->fs_info;
 	u64 allowed;
+	int mixed = 0;
 	int ret;
 
 	if (btrfs_fs_closing(fs_info) ||
@@ -2624,13 +2695,16 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
 		goto out;
 	}
 
+	allowed = btrfs_super_incompat_flags(fs_info->super_copy);
+	if (allowed & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
+		mixed = 1;
+
 	/*
 	 * In case of mixed groups both data and meta should be picked,
 	 * and identical options should be given for both of them.
 	 */
-	allowed = btrfs_super_incompat_flags(fs_info->super_copy);
-	if ((allowed & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS) &&
-	    (bctl->flags & (BTRFS_BALANCE_DATA | BTRFS_BALANCE_METADATA))) {
+	allowed = BTRFS_BALANCE_DATA | BTRFS_BALANCE_METADATA;
+	if (mixed && (bctl->flags & allowed)) {
 		if (!(bctl->flags & BTRFS_BALANCE_DATA) ||
 		    !(bctl->flags & BTRFS_BALANCE_METADATA) ||
 		    memcmp(&bctl->data, &bctl->meta, sizeof(bctl->data))) {
@@ -2641,14 +2715,6 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
 		}
 	}
 
-	/*
-	 * Profile changing sanity checks.  Skip them if a simple
-	 * balance is requested.
-	 */
-	if (!((bctl->data.flags | bctl->sys.flags | bctl->meta.flags) &
-	      BTRFS_BALANCE_ARGS_CONVERT))
-		goto do_balance;
-
 	allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE;
 	if (fs_info->fs_devices->num_devices == 1)
 		allowed |= BTRFS_BLOCK_GROUP_DUP;
@@ -2658,24 +2724,27 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
 		allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
 				BTRFS_BLOCK_GROUP_RAID10);
 
-	if (!profile_is_valid(bctl->data.target, 1) ||
-	    bctl->data.target & ~allowed) {
+	if ((bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
+	    (!alloc_profile_is_valid(bctl->data.target, 1) ||
+	     (bctl->data.target & ~allowed))) {
 		printk(KERN_ERR "btrfs: unable to start balance with target "
 		       "data profile %llu\n",
 		       (unsigned long long)bctl->data.target);
 		ret = -EINVAL;
 		goto out;
 	}
-	if (!profile_is_valid(bctl->meta.target, 1) ||
-	    bctl->meta.target & ~allowed) {
+	if ((bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
+	    (!alloc_profile_is_valid(bctl->meta.target, 1) ||
+	     (bctl->meta.target & ~allowed))) {
 		printk(KERN_ERR "btrfs: unable to start balance with target "
 		       "metadata profile %llu\n",
 		       (unsigned long long)bctl->meta.target);
 		ret = -EINVAL;
 		goto out;
 	}
-	if (!profile_is_valid(bctl->sys.target, 1) ||
-	    bctl->sys.target & ~allowed) {
+	if ((bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
+	    (!alloc_profile_is_valid(bctl->sys.target, 1) ||
+	     (bctl->sys.target & ~allowed))) {
 		printk(KERN_ERR "btrfs: unable to start balance with target "
 		       "system profile %llu\n",
 		       (unsigned long long)bctl->sys.target);
@@ -2683,7 +2752,9 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
 		goto out;
 	}
 
-	if (bctl->data.target & BTRFS_BLOCK_GROUP_DUP) {
+	/* allow dup'ed data chunks only in mixed mode */
+	if (!mixed && (bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT) &&
+	    (bctl->data.target & BTRFS_BLOCK_GROUP_DUP)) {
 		printk(KERN_ERR "btrfs: dup for data is not allowed\n");
 		ret = -EINVAL;
 		goto out;
@@ -2709,7 +2780,6 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
 		}
 	}
 
-do_balance:
 	ret = insert_balance_item(fs_info->tree_root, bctl);
 	if (ret && ret != -EEXIST)
 		goto out;
@@ -2952,7 +3022,7 @@ again:
 	key.offset = (u64)-1;
 	key.type = BTRFS_DEV_EXTENT_KEY;
 
-	while (1) {
+	do {
 		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 		if (ret < 0)
 			goto done;
@@ -2994,8 +3064,7 @@ again:
 			goto done;
 		if (ret == -ENOSPC)
 			failed++;
-		key.offset -= 1;
-	}
+	} while (key.offset-- > 0);
 
 	if (failed && !retried) {
 		failed = 0;
@@ -3113,11 +3182,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	int i;
 	int j;
 
-	if ((type & BTRFS_BLOCK_GROUP_RAID1) &&
-	    (type & BTRFS_BLOCK_GROUP_DUP)) {
-		WARN_ON(1);
-		type &= ~BTRFS_BLOCK_GROUP_DUP;
-	}
+	BUG_ON(!alloc_profile_is_valid(type, 0));
 
 	if (list_empty(&fs_devices->alloc_list))
 		return -ENOSPC;
@@ -3313,13 +3378,15 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	write_lock(&em_tree->lock);
 	ret = add_extent_mapping(em_tree, em);
 	write_unlock(&em_tree->lock);
-	BUG_ON(ret);
 	free_extent_map(em);
+	if (ret)
+		goto error;
 
 	ret = btrfs_make_block_group(trans, extent_root, 0, type,
 				     BTRFS_FIRST_CHUNK_TREE_OBJECTID,
 				     start, num_bytes);
-	BUG_ON(ret);
+	if (ret)
+		goto error;
 
 	for (i = 0; i < map->num_stripes; ++i) {
 		struct btrfs_device *device;
@@ -3332,7 +3399,10 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 				info->chunk_root->root_key.objectid,
 				BTRFS_FIRST_CHUNK_TREE_OBJECTID,
 				start, dev_offset, stripe_size);
-		BUG_ON(ret);
+		if (ret) {
+			btrfs_abort_transaction(trans, extent_root, ret);
+			goto error;
+		}
 	}
 
 	kfree(devices_info);
@@ -3368,7 +3438,8 @@ static int __finish_chunk_alloc(struct btrfs_trans_handle *trans,
 		device = map->stripes[index].dev;
 		device->bytes_used += stripe_size;
 		ret = btrfs_update_device(trans, device);
-		BUG_ON(ret);
+		if (ret)
+			goto out_free;
 		index++;
 	}
 
@@ -3405,16 +3476,19 @@ static int __finish_chunk_alloc(struct btrfs_trans_handle *trans,
 	key.offset = chunk_offset;
 
 	ret = btrfs_insert_item(trans, chunk_root, &key, chunk, item_size);
-	BUG_ON(ret);
 
-	if (map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
+	if (ret == 0 && map->type & BTRFS_BLOCK_GROUP_SYSTEM) {
+		/*
+		 * TODO: Cleanup of inserted chunk root in case of
+		 * failure.
+		 */
 		ret = btrfs_add_system_chunk(chunk_root, &key, chunk,
 					     item_size);
-		BUG_ON(ret);
 	}
 
+out_free:
 	kfree(chunk);
-	return 0;
+	return ret;
 }
 
 /*
@@ -3446,7 +3520,8 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 
 	ret = __finish_chunk_alloc(trans, extent_root, map, chunk_offset,
 				   chunk_size, stripe_size);
-	BUG_ON(ret);
+	if (ret)
+		return ret;
 	return 0;
 }
 
@@ -3478,7 +3553,8 @@ static noinline int init_first_rw_device(struct btrfs_trans_handle *trans,
 
 	ret = __btrfs_alloc_chunk(trans, extent_root, &map, &chunk_size,
 				  &stripe_size, chunk_offset, alloc_profile);
-	BUG_ON(ret);
+	if (ret)
+		return ret;
 
 	sys_chunk_offset = chunk_offset + chunk_size;
 
@@ -3489,10 +3565,12 @@ static noinline int init_first_rw_device(struct btrfs_trans_handle *trans,
 	ret = __btrfs_alloc_chunk(trans, extent_root, &sys_map,
 				  &sys_chunk_size, &sys_stripe_size,
 				  sys_chunk_offset, alloc_profile);
-	BUG_ON(ret);
+	if (ret)
+		goto abort;
 
 	ret = btrfs_add_device(trans, fs_info->chunk_root, device);
-	BUG_ON(ret);
+	if (ret)
+		goto abort;
 
 	/*
 	 * Modifying chunk tree needs allocating new blocks from both
@@ -3502,13 +3580,20 @@ static noinline int init_first_rw_device(struct btrfs_trans_handle *trans,
 	 */
 	ret = __finish_chunk_alloc(trans, extent_root, map, chunk_offset,
 				   chunk_size, stripe_size);
-	BUG_ON(ret);
+	if (ret)
+		goto abort;
 
 	ret = __finish_chunk_alloc(trans, extent_root, sys_map,
 				   sys_chunk_offset, sys_chunk_size,
 				   sys_stripe_size);
-	BUG_ON(ret);
+	if (ret)
+		goto abort;
+
 	return 0;
+
+abort:
+	btrfs_abort_transaction(trans, root, ret);
+	return ret;
 }
 
 int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset)
@@ -3859,7 +3944,7 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
 		do_div(length, map->num_stripes);
 
 	buf = kzalloc(sizeof(u64) * map->num_stripes, GFP_NOFS);
-	BUG_ON(!buf);
+	BUG_ON(!buf); /* -ENOMEM */
 
 	for (i = 0; i < map->num_stripes; i++) {
 		if (devid && map->stripes[i].dev->devid != devid)
@@ -3952,7 +4037,7 @@ struct async_sched {
  * This will add one bio to the pending list for a device and make sure
  * the work struct is scheduled.
  */
-static noinline int schedule_bio(struct btrfs_root *root,
+static noinline void schedule_bio(struct btrfs_root *root,
 				 struct btrfs_device *device,
 				 int rw, struct bio *bio)
 {
@@ -3964,7 +4049,7 @@ static noinline int schedule_bio(struct btrfs_root *root,
 		bio_get(bio);
 		btrfsic_submit_bio(rw, bio);
 		bio_put(bio);
-		return 0;
+		return;
 	}
 
 	/*
@@ -3998,7 +4083,6 @@ static noinline int schedule_bio(struct btrfs_root *root,
 	if (should_queue)
 		btrfs_queue_worker(&root->fs_info->submit_workers,
 				   &device->work);
-	return 0;
 }
 
 int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
@@ -4021,7 +4105,8 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
 
 	ret = btrfs_map_block(map_tree, rw, logical, &map_length, &bbio,
 			      mirror_num);
-	BUG_ON(ret);
+	if (ret) /* -ENOMEM */
+		return ret;
 
 	total_devs = bbio->num_stripes;
 	if (map_length < length) {
@@ -4040,7 +4125,7 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
 	while (dev_nr < total_devs) {
 		if (dev_nr < total_devs - 1) {
 			bio = bio_clone(first_bio, GFP_NOFS);
-			BUG_ON(!bio);
+			BUG_ON(!bio); /* -ENOMEM */
 		} else {
 			bio = first_bio;
 		}
@@ -4194,13 +4279,13 @@ static int read_one_chunk(struct btrfs_root *root, struct btrfs_key *key,
 	write_lock(&map_tree->map_tree.lock);
 	ret = add_extent_mapping(&map_tree->map_tree, em);
 	write_unlock(&map_tree->map_tree.lock);
-	BUG_ON(ret);
+	BUG_ON(ret); /* Tree corruption */
 	free_extent_map(em);
 
 	return 0;
 }
 
-static int fill_device_from_item(struct extent_buffer *leaf,
+static void fill_device_from_item(struct extent_buffer *leaf,
 				 struct btrfs_dev_item *dev_item,
 				 struct btrfs_device *device)
 {
@@ -4217,8 +4302,6 @@ static int fill_device_from_item(struct extent_buffer *leaf,
 
 	ptr = (unsigned long)btrfs_device_uuid(dev_item);
 	read_extent_buffer(leaf, device->uuid, ptr, BTRFS_UUID_SIZE);
-
-	return 0;
 }
 
 static int open_seed_devices(struct btrfs_root *root, u8 *fsid)
@@ -4356,6 +4439,20 @@ int btrfs_read_sys_array(struct btrfs_root *root)
 		return -ENOMEM;
 	btrfs_set_buffer_uptodate(sb);
 	btrfs_set_buffer_lockdep_class(root->root_key.objectid, sb, 0);
+	/*
+	 * The sb extent buffer is artifical and just used to read the system array.
+	 * btrfs_set_buffer_uptodate() call does not properly mark all it's
+	 * pages up-to-date when the page is larger: extent does not cover the
+	 * whole page and consequently check_page_uptodate does not find all
+	 * the page's extents up-to-date (the hole beyond sb),
+	 * write_extent_buffer then triggers a WARN_ON.
+	 *
+	 * Regular short extents go through mark_extent_buffer_dirty/writeback cycle,
+	 * but sb spans only this function. Add an explicit SetPageUptodate call
+	 * to silence the warning eg. on PowerPC 64.
+	 */
+	if (PAGE_CACHE_SIZE > BTRFS_SUPER_INFO_SIZE)
+		SetPageUptodate(sb->pages[0]);
 
 	write_extent_buffer(sb, super_copy, 0, BTRFS_SUPER_INFO_SIZE);
 	array_size = btrfs_super_sys_array_size(super_copy);