strlcpy() reads the entire source buffer first. This read may exceed
the destination size limit. This is both inefficient and can lead
to linear read overflows if a source string is not NUL-terminated[1].
Additionally, it returns the size of the source string, not the
resulting size of the destination string. In an effort to remove strlcpy()
completely[2], replace strlcpy() here with strscpy().

Nothing checks the return value here, so a direct replacement with
strspy() is possible.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1]
Link: https://github.com/KSPP/linux/issues/89 [2]
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Brian Foster <bfoster@redhat.com>
Cc:  <linux-bcachefs@vger.kernel.org>
Link: https://lore.kernel.org/r/20240110235438.work.385-kees@kernel.orgSigned-off-by: Kees Cook <keescook@chromium.org>