Commit c6aeae86 authored by David Sterba's avatar David Sterba
Browse files

btrfs: use on-stack variable for block reserve in btrfs_replace_file_extents() 



We can avoid potential memory allocation failure in
btrfs_replace_file_extents() as the block reserve lifetime is limited to
the scope of the function. This requires +48 bytes on stack.

Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 7ce22f62

fs/btrfs/file.c

+12 −17
Original line number Diff line number Diff line
@@ -2341,7 +2341,7 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode, 
	u64 min_size = btrfs_calc_insert_metadata_size(fs_info, 1);

	u64 ino_size = round_up(inode->vfs_inode.i_size, fs_info->sectorsize);

	struct btrfs_trans_handle *trans = NULL;

	struct btrfs_block_rsv *rsv;

	struct btrfs_block_rsv rsv;

	unsigned int rsv_count;

	u64 cur_offset;

	u64 len = end - start;
@@ -2350,13 +2350,9 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode, 
	if (end <= start)

		return -EINVAL;



	rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);

	if (!rsv) {

		ret = -ENOMEM;

		goto out;

	}

	rsv->size = btrfs_calc_insert_metadata_size(fs_info, 1);

	rsv->failfast = true;

	btrfs_init_metadata_block_rsv(fs_info, &rsv, BTRFS_BLOCK_RSV_TEMP);

	rsv.size = btrfs_calc_insert_metadata_size(fs_info, 1);

	rsv.failfast = true;



	/*

	 * 1 - update the inode
@@ -2373,14 +2369,14 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode, 
	if (IS_ERR(trans)) {

		ret = PTR_ERR(trans);

		trans = NULL;

		goto out_free;

		goto out_release;

	}



	ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv,

	ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, &rsv,

				      min_size, false);

	if (WARN_ON(ret))

		goto out_trans;

	trans->block_rsv = rsv;

	trans->block_rsv = &rsv;



	cur_offset = start;

	drop_args.path = path;
@@ -2496,10 +2492,10 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode, 
		}



		ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,

					      rsv, min_size, false);

					      &rsv, min_size, false);

		if (WARN_ON(ret))

			break;

		trans->block_rsv = rsv;

		trans->block_rsv = &rsv;



		cur_offset = drop_args.drop_end;

		len = end - cur_offset;
@@ -2576,16 +2572,15 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode, 


out_trans:

	if (!trans)

		goto out_free;

		goto out_release;



	trans->block_rsv = &fs_info->trans_block_rsv;

	if (ret)

		btrfs_end_transaction(trans);

	else

		*trans_out = trans;

out_free:

	btrfs_free_block_rsv(fs_info, rsv);

out:

out_release:

	btrfs_block_rsv_release(fs_info, &rsv, (u64)-1, NULL);

	return ret;

}