Re: [PATCH] bcachefs: don't call sleeping funcs when handling inconsistency errors

[Bharadwaj Raju]

On Wed, Apr 2, 2025 at 10:08 PM Kent Overstreet
<kent.overstreet@xxxxxxxxx> wrote:
>
> On Wed, Apr 02, 2025 at 10:03:10PM +0530, Bharadwaj Raju wrote:
> > On Wed, Apr 2, 2025 at 9:47 PM Kent Overstreet
> > <kent.overstreet@xxxxxxxxx> wrote:
>
> If you're feeling particularly adventurous - print_string_as_lines() is
> a hack, I think we should be able to do something more robust by
> skipping printk (that's where the 1k limit comes from) and calling
> something lower level - that will require digging into the printk
> codepath and finding lower level we can call.

I tried looking into the printk codepath, namely vprintk_emit -> vprintk_store.
It doesn't seem like there's a convenient single lower-level
entrypoint we could
call which just avoids the 1k limit, rather there's a lot of internal
code mixed with
the truncation that we'd have to just copy if we want printk behavior.
I don't think that's a reasonable option for us.

> I also just noticed that print_string_as_lines() needs to check for
> being passed a NULL pointer - in case the printbuf memory allocation
> fails. Want to get that one too?

>From what I'm seeing __bch2_print_string_as_lines already checks
for the lines pointer being NULL. The only unchecked pointer is prefix,
which I don't think needs to be checked since it will be something constant
from kern_levels.h, not something which could be NULL.