Commit d8ccbd21 authored by Filipe Manana's avatar Filipe Manana Committed by David Sterba
Browse files

btrfs: remove BUG_ON()'s in add_new_free_space() 



At add_new_free_space() we have these BUG_ON()'s that are there to deal
with any failure to add free space to the in memory free space cache.
Such failures are mostly -ENOMEM that should be very rare. However there's
no need to have these BUG_ON()'s, we can just return any error to the
caller and all callers and their upper call chain are already dealing with
errors.

So just make add_new_free_space() return any errors, while removing the
BUG_ON()'s, and returning the total amount of added free space to an
optional u64 pointer argument.

Reported-by: default avatar <syzbot+3ba856e07b7127889d8c@syzkaller.appspotmail.com>
Link: https://lore.kernel.org/linux-btrfs/000000000000e9cb8305ff4e8327@google.com/


Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 8dbfc14f

fs/btrfs/block-group.c

+34 −17
Original line number Diff line number Diff line
@@ -499,12 +499,16 @@ static void fragment_free_space(struct btrfs_block_group *block_group) 
 * used yet since their free space will be released as soon as the transaction

 * commits.

 */

u64 add_new_free_space(struct btrfs_block_group *block_group, u64 start, u64 end)

int add_new_free_space(struct btrfs_block_group *block_group, u64 start, u64 end,

		       u64 *total_added_ret)

{

	struct btrfs_fs_info *info = block_group->fs_info;

	u64 extent_start, extent_end, size, total_added = 0;

	u64 extent_start, extent_end, size;

	int ret;



	if (total_added_ret)

		*total_added_ret = 0;



	while (start < end) {

		ret = find_first_extent_bit(&info->excluded_extents, start,

					    &extent_start, &extent_end,
@@ -517,10 +521,12 @@ u64 add_new_free_space(struct btrfs_block_group *block_group, u64 start, u64 end 
			start = extent_end + 1;

		} else if (extent_start > start && extent_start < end) {

			size = extent_start - start;

			total_added += size;

			ret = btrfs_add_free_space_async_trimmed(block_group,

								 start, size);

			BUG_ON(ret); /* -ENOMEM or logic error */

			if (ret)

				return ret;

			if (total_added_ret)

				*total_added_ret += size;

			start = extent_end + 1;

		} else {

			break;
@@ -529,13 +535,15 @@ u64 add_new_free_space(struct btrfs_block_group *block_group, u64 start, u64 end 


	if (start < end) {

		size = end - start;

		total_added += size;

		ret = btrfs_add_free_space_async_trimmed(block_group, start,

							 size);

		BUG_ON(ret); /* -ENOMEM or logic error */

		if (ret)

			return ret;

		if (total_added_ret)

			*total_added_ret += size;

	}



	return total_added;

	return 0;

}



/*
@@ -779,8 +787,13 @@ static int load_extent_tree_free(struct btrfs_caching_control *caching_ctl) 


		if (key.type == BTRFS_EXTENT_ITEM_KEY ||

		    key.type == BTRFS_METADATA_ITEM_KEY) {

			total_found += add_new_free_space(block_group, last,

							  key.objectid);

			u64 space_added;



			ret = add_new_free_space(block_group, last, key.objectid,

						 &space_added);

			if (ret)

				goto out;

			total_found += space_added;

			if (key.type == BTRFS_METADATA_ITEM_KEY)

				last = key.objectid +

					fs_info->nodesize;
@@ -795,11 +808,10 @@ static int load_extent_tree_free(struct btrfs_caching_control *caching_ctl) 
		}

		path->slots[0]++;

	}

	ret = 0;



	total_found += add_new_free_space(block_group, last,

				block_group->start + block_group->length);



	ret = add_new_free_space(block_group, last,

				 block_group->start + block_group->length,

				 NULL);

out:

	btrfs_free_path(path);

	return ret;
@@ -2294,9 +2306,11 @@ static int read_one_block_group(struct btrfs_fs_info *info, 
		btrfs_free_excluded_extents(cache);

	} else if (cache->used == 0) {

		cache->cached = BTRFS_CACHE_FINISHED;

		add_new_free_space(cache, cache->start,

				   cache->start + cache->length);

		ret = add_new_free_space(cache, cache->start,

					 cache->start + cache->length, NULL);

		btrfs_free_excluded_extents(cache);

		if (ret)

			goto error;

	}



	ret = btrfs_add_block_group_cache(info, cache);
@@ -2740,9 +2754,12 @@ struct btrfs_block_group *btrfs_make_block_group(struct btrfs_trans_handle *tran 
		return ERR_PTR(ret);

	}



	add_new_free_space(cache, chunk_offset, chunk_offset + size);



	ret = add_new_free_space(cache, chunk_offset, chunk_offset + size, NULL);

	btrfs_free_excluded_extents(cache);

	if (ret) {

		btrfs_put_block_group(cache);

		return ERR_PTR(ret);

	}



	/*

	 * Ensure the corresponding space_info object is created and

fs/btrfs/block-group.h

+2 −2
Original line number Diff line number Diff line
@@ -289,8 +289,8 @@ int btrfs_cache_block_group(struct btrfs_block_group *cache, bool wait); 
void btrfs_put_caching_control(struct btrfs_caching_control *ctl);

struct btrfs_caching_control *btrfs_get_caching_control(

		struct btrfs_block_group *cache);

u64 add_new_free_space(struct btrfs_block_group *block_group,

		       u64 start, u64 end);

int add_new_free_space(struct btrfs_block_group *block_group,

		       u64 start, u64 end, u64 *total_added_ret);

struct btrfs_trans_handle *btrfs_start_trans_remove_block_group(

				struct btrfs_fs_info *fs_info,

				const u64 chunk_offset);

fs/btrfs/free-space-tree.c

+17 −7
Original line number Diff line number Diff line
@@ -1515,9 +1515,13 @@ static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl, 
			if (prev_bit == 0 && bit == 1) {

				extent_start = offset;

			} else if (prev_bit == 1 && bit == 0) {

				total_found += add_new_free_space(block_group,

								  extent_start,

								  offset);

				u64 space_added;



				ret = add_new_free_space(block_group, extent_start,

							 offset, &space_added);

				if (ret)

					goto out;

				total_found += space_added;

				if (total_found > CACHING_CTL_WAKE_UP) {

					total_found = 0;

					wake_up(&caching_ctl->wait);
@@ -1529,8 +1533,9 @@ static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl, 
		}

	}

	if (prev_bit == 1) {

		total_found += add_new_free_space(block_group, extent_start,

						  end);

		ret = add_new_free_space(block_group, extent_start, end, NULL);

		if (ret)

			goto out;

		extent_count++;

	}
@@ -1569,6 +1574,8 @@ static int load_free_space_extents(struct btrfs_caching_control *caching_ctl, 
	end = block_group->start + block_group->length;



	while (1) {

		u64 space_added;



		ret = btrfs_next_item(root, path);

		if (ret < 0)

			goto out;
@@ -1583,8 +1590,11 @@ static int load_free_space_extents(struct btrfs_caching_control *caching_ctl, 
		ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);

		ASSERT(key.objectid < end && key.objectid + key.offset <= end);



		total_found += add_new_free_space(block_group, key.objectid,

						  key.objectid + key.offset);

		ret = add_new_free_space(block_group, key.objectid,

					 key.objectid + key.offset, &space_added);

		if (ret)

			goto out;

		total_found += space_added;

		if (total_found > CACHING_CTL_WAKE_UP) {

			total_found = 0;

			wake_up(&caching_ctl->wait);