On Mon, Jul 18, 2016 at 12:13:38AM +0200, Adam Borowski wrote:
> Instead of checking the mode of the file descriptor, let's check whether it
> could have been opened rw. This allows fixing intermittent exec failures
> when deduping a live system: anyone trying to exec a file currently being
> deduped gets ETXTBSY.
>
> Issuing this ioctl on a ro file was already allowed for root/cap.
>
> Tested on btrfs and not-yet-merged xfs, as only them implement this ioctl.
>
> Signed-off-by: Adam Borowski <kilobyte@xxxxxxxxxx>
Could you please send an xfstest to test this aspect of the dedupe ioctl?
--D
> ---
> fs/read_write.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 933b53a..df59dc6 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1723,7 +1723,7 @@ int vfs_dedupe_file_range(struct file *file, struct file_dedupe_range *same)
>
> if (info->reserved) {
> info->status = -EINVAL;
> - } else if (!(is_admin || (dst_file->f_mode & FMODE_WRITE))) {
> + } else if (!(is_admin || !inode_permission(dst, MAY_WRITE))) {
> info->status = -EINVAL;
> } else if (file->f_path.mnt != dst_file->f_path.mnt) {
> info->status = -EXDEV;
> --
> 2.8.1
>
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