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 <[email protected]> --- 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
