On Sun, May 26, 2019 at 09:10:52AM +0300, Amir Goldstein wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> Right now if vfs_copy_file_range() does not use any offload
> mechanism, it falls back to calling do_splice_direct(). This fails
> to do basic sanity checks on the files being copied. Before we
> start adding this necessarily functionality to the fallback path,
> separate it out into generic_copy_file_range().
>
> generic_copy_file_range() has the same prototype as
> ->copy_file_range() so that filesystems can use it in their custom
> ->copy_file_range() method if they so choose.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> fs/read_write.c | 35 ++++++++++++++++++++++++++++++++---
> include/linux/fs.h | 3 +++
> 2 files changed, 35 insertions(+), 3 deletions(-)
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index c543d965e288..676b02fae589 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1565,6 +1565,36 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd,
> }
> #endif
>
> +/**
> + * generic_copy_file_range - copy data between two files
> + * @file_in: file structure to read from
> + * @pos_in: file offset to read from
> + * @file_out: file structure to write data to
> + * @pos_out: file offset to write data to
> + * @len: amount of data to copy
> + * @flags: copy flags
> + *
> + * This is a generic filesystem helper to copy data from one file to another.
> + * It has no constraints on the source or destination file owners - the files
> + * can belong to different superblocks and different filesystem types. Short
> + * copies are allowed.
> + *
> + * This should be called from the @file_out filesystem, as per the
> + * ->copy_file_range() method.
> + *
> + * Returns the number of bytes copied or a negative error indicating the
> + * failure.
> + */
> +
> +ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
> + struct file *file_out, loff_t pos_out,
> + size_t len, unsigned int flags)
> +{
> + return do_splice_direct(file_in, &pos_in, file_out, &pos_out,
> + len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
> +}
> +EXPORT_SYMBOL(generic_copy_file_range);
> +
> /*
> * copy_file_range() differs from regular file read and write in that it
> * specifically allows return partial success. When it does so is up to
> @@ -1632,9 +1662,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> goto done;
> }
>
> - ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out,
> - len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0);
> -
> + ret = generic_copy_file_range(file_in, pos_in, file_out, pos_out, len,
> + flags);
> done:
> if (ret > 0) {
> fsnotify_access(file_in);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index f7fdfe93e25d..ea17858310ff 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1889,6 +1889,9 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
> unsigned long, loff_t *, rwf_t);
> extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
> loff_t, size_t, unsigned int);
> +extern ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
> + struct file *file_out, loff_t pos_out,
> + size_t len, unsigned int flags);
> extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
> struct file *file_out, loff_t pos_out,
> loff_t *count,
> --
> 2.17.1
>
