On Wed, Sep 14, 2016 at 3:43 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> copy_file_range syscall returns -EXDEV if src and dest
> file are not on the same file system.
> The vfs_copy_file_range() helper, however, knows how to copy
> across file systems with do_splice_direct().
>
> Move the enforcement of same file system from the vfs helper
> to the syscall code.
>
> A following patch is going to use the vfs_copy_file_range()
> helper in overlayfs to copy up between lower and upper
> not on the same file system.
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/read_write.c | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 9dc6e52..6975fe8 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1502,10 +1502,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> (file_out->f_flags & O_APPEND))
> return -EBADF;
>
> - /* this could be relaxed once a method supports cross-fs copies */
> - if (inode_in->i_sb != inode_out->i_sb)
> - return -EXDEV;
> -
> if (len == 0)
> return 0;
>
> @@ -1514,7 +1510,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> return ret;
>
> ret = -EOPNOTSUPP;
> - if (file_out->f_op->copy_file_range)
> + /* copy_file_range() method does not support cross-fs copies */
> + if (inode_in->i_sb == inode_out->i_sb &&
> + file_out->f_op->copy_file_range)
> ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out,
> pos_out, len, flags);
> if (ret == -EOPNOTSUPP)
> @@ -1569,6 +1567,14 @@ SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user *, off_in,
> pos_out = f_out.file->f_pos;
> }
>
> + /*
> + * vfs_copy_file_range() can do cross-fs copy, but we want to
> + * fulfill the guaranty to userland that copy_file_range syscall
> + * does not allow cross-fs copy
> + */
> + if (file_inode(f_in.file)->i_sb != file_inode(f_out.file)->i_sb)
> + return -EXDEV;
Oops, that was supposed to be goto out;
Anyway, I am holding back on the vfs_copy_file_range() patches sub set
until I have a reliable test on xfs to fall back from clone to copy range
> +
> ret = vfs_copy_file_range(f_in.file, pos_in, f_out.file, pos_out, len,
> flags);
> if (ret > 0) {
> --
> 2.7.4
>
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