Commit ba346b35 authored by Gerhard Heift's avatar Gerhard Heift Committed by Chris Mason
Browse files

btrfs: tree_search, search_ioctl: direct copy to userspace 



By copying each found item seperatly to userspace, we do not need extra
buffer in the kernel.

Signed-off-by: default avatarGerhard Heift <Gerhard@Heift.Name>
Signed-off-by: default avatarChris Mason <clm@fb.com>
Acked-by: default avatarDavid Sterba <dsterba@suse.cz>
parent 550ac1d8

fs/btrfs/ioctl.c

+33 −15
Original line number Diff line number Diff line
@@ -1958,7 +1958,7 @@ static noinline int copy_to_sk(struct btrfs_root *root, 
			       struct btrfs_key *key,

			       struct btrfs_ioctl_search_key *sk,

			       size_t *buf_size,

			       char *buf,

			       char __user *ubuf,

			       unsigned long *sk_offset,

			       int *num_found)

{
@@ -2018,14 +2018,22 @@ static noinline int copy_to_sk(struct btrfs_root *root, 
		sh.transid = found_transid;



		/* copy search result header */

		memcpy(buf + *sk_offset, &sh, sizeof(sh));

		if (copy_to_user(ubuf + *sk_offset, &sh, sizeof(sh))) {

			ret = -EFAULT;

			goto out;

		}



		*sk_offset += sizeof(sh);



		if (item_len) {

			char *p = buf + *sk_offset;

			char __user *up = ubuf + *sk_offset;

			/* copy the item */

			read_extent_buffer(leaf, p,

					   item_off, item_len);

			if (read_extent_buffer_to_user(leaf, up,

						       item_off, item_len)) {

				ret = -EFAULT;

				goto out;

			}



			*sk_offset += item_len;

		}

		(*num_found)++;
@@ -2052,13 +2060,22 @@ static noinline int copy_to_sk(struct btrfs_root *root, 
	} else

		ret = 1;

out:

	/*

	 *  0: all items from this leaf copied, continue with next

	 *  1: * more items can be copied, but unused buffer is too small

	 *     * all items were found

	 *     Either way, it will stops the loop which iterates to the next

	 *     leaf

	 *  -EOVERFLOW: item was to large for buffer

	 *  -EFAULT: could not copy extent buffer back to userspace

	 */

	return ret;

}



static noinline int search_ioctl(struct inode *inode,

				 struct btrfs_ioctl_search_key *sk,

				 size_t *buf_size,

				 char *buf)

				 char __user *ubuf)

{

	struct btrfs_root *root;

	struct btrfs_key key;
@@ -2106,7 +2123,7 @@ static noinline int search_ioctl(struct inode *inode, 
				ret = 0;

			goto err;

		}

		ret = copy_to_sk(root, path, &key, sk, buf_size, buf,

		ret = copy_to_sk(root, path, &key, sk, buf_size, ubuf,

				 &sk_offset, &num_found);

		btrfs_release_path(path);

		if (ret)
@@ -2124,7 +2141,8 @@ static noinline int search_ioctl(struct inode *inode, 
static noinline int btrfs_ioctl_tree_search(struct file *file,

					   void __user *argp)

{

	struct btrfs_ioctl_search_args *args;

	struct btrfs_ioctl_search_args __user *uargs;

	struct btrfs_ioctl_search_key sk;

	struct inode *inode;

	int ret;

	size_t buf_size;
@@ -2132,14 +2150,15 @@ static noinline int btrfs_ioctl_tree_search(struct file *file, 
	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	args = memdup_user(argp, sizeof(*args));

	if (IS_ERR(args))

		return PTR_ERR(args);

	uargs = (struct btrfs_ioctl_search_args __user *)argp;



	buf_size = sizeof(args->buf);

	if (copy_from_user(&sk, &uargs->key, sizeof(sk)))

		return -EFAULT;



	buf_size = sizeof(uargs->buf);



	inode = file_inode(file);

	ret = search_ioctl(inode, &args->key, &buf_size, args->buf);

	ret = search_ioctl(inode, &sk, &buf_size, uargs->buf);



	/*

	 * In the origin implementation an overflow is handled by returning a
@@ -2148,9 +2167,8 @@ static noinline int btrfs_ioctl_tree_search(struct file *file, 
	if (ret == -EOVERFLOW)

		ret = 0;



	if (ret == 0 && copy_to_user(argp, args, sizeof(*args)))

	if (ret == 0 && copy_to_user(&uargs->key, &sk, sizeof(sk)))

		ret = -EFAULT;

	kfree(args);

	return ret;

}