Commit 8d8aafee authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
Browse files

btrfs: Simplify math in should_alloc chunk 



Currently should_alloc_chunk uses ->total_bytes - ->bytes_readonly to
signify the total amount of bytes in this space info. However, given
Jeff's patch which adds bytes_pinned and bytes_may_use to the calculation
of num_allocated it becomes a lot more clear to just eliminate num_bytes
altogether and add the bytes_readonly to the amount of used space. That
way we don't change the results of the following statements. In the
process also start using btrfs_space_info_used.

Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Signed-off-by: default avatarJeff Mahoney <jeffm@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent f44d2287

fs/btrfs/extent-tree.c

+4 −5
Original line number Diff line number Diff line
@@ -4418,8 +4418,7 @@ static int should_alloc_chunk(struct btrfs_fs_info *fs_info, 
			      struct btrfs_space_info *sinfo, int force)

{

	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;

	u64 num_bytes = sinfo->total_bytes - sinfo->bytes_readonly;

	u64 num_allocated = sinfo->bytes_used + sinfo->bytes_reserved + sinfo->bytes_pinned;

	u64 bytes_used = btrfs_space_info_used(sinfo, false);

	u64 thresh;



	if (force == CHUNK_ALLOC_FORCE)
@@ -4431,7 +4430,7 @@ static int should_alloc_chunk(struct btrfs_fs_info *fs_info, 
	 * global_rsv, it doesn't change except when the transaction commits.

	 */

	if (sinfo->flags & BTRFS_BLOCK_GROUP_METADATA)

		num_allocated += calc_global_rsv_need_space(global_rsv);

		bytes_used += calc_global_rsv_need_space(global_rsv);



	/*

	 * in limited mode, we want to have some free space up to
@@ -4441,11 +4440,11 @@ static int should_alloc_chunk(struct btrfs_fs_info *fs_info, 
		thresh = btrfs_super_total_bytes(fs_info->super_copy);

		thresh = max_t(u64, SZ_64M, div_factor_fine(thresh, 1));



		if (num_bytes - num_allocated < thresh)

		if (sinfo->total_bytes - bytes_used < thresh)

			return 1;

	}



	if (num_allocated + SZ_2M < div_factor(num_bytes, 8))

	if (bytes_used + SZ_2M < div_factor(sinfo->total_bytes, 8))

		return 0;

	return 1;

}

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