On Thu, Oct 06, 2022 at 07:42:06PM -0300, Guilherme G. Piccoli wrote:
> Currently this tuning is only exposed as a filesystem option,
> but most Linux distros automatically mount pstore, hence changing
> this setting requires remounting it. Also, if that mount option
> wasn't explicitly set it doesn't show up in mount information,
> so users cannot check what is the current value of kmsg_bytes.
>
> Let's then expose it as a module parameter, allowing both user
> visibility at all times (even if not manually set) and also the
> possibility of setting that as a boot/module parameter.
I've been meaning to do this too. :)
>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx>
> ---
> fs/pstore/platform.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index c32957e4b256..be05090076ce 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -89,6 +89,11 @@ static char *compress =
> module_param(compress, charp, 0444);
> MODULE_PARM_DESC(compress, "compression to use");
>
> +/* How much of the kernel log to snapshot */
> +unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
> +module_param(kmsg_bytes, ulong, 0444);
> +MODULE_PARM_DESC(kmsg_bytes, "amount of kernel log to snapshot (in bytes)");
> +
> /* Compression parameters */
> static struct crypto_comp *tfm;
>
> @@ -100,9 +105,6 @@ struct pstore_zbackend {
> static char *big_oops_buf;
> static size_t big_oops_buf_sz;
>
> -/* How much of the console log to snapshot */
> -unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
> -
> void pstore_set_kmsg_bytes(int bytes)
> {
> kmsg_bytes = bytes;
> --
> 2.38.0
Doing a mount will override the result, so I wonder if there should be
two variables, etc... not a concern for the normal use case.
Also, I've kind of wanted to get rid of a "default" for this and instead
use a value based on the compression vs record sizes, etc. But I didn't
explore it.
--
Kees Cook
