[bug report] staging: erofs: introduce erofs_grab_bio

[Dan Carpenter]

On Wed, Aug 28, 2019 at 07:39:29PM +0800, Gao Xiang wrote:
> (p.s. It makes me little confused these subject prefixes are "[bug report]", if they are
> really bugs, that is fine... If it be something unconfirmed (need our confirmation..,),
> could you kindly change the prefix into some other representations...? I will still look
> into all of them at least... and that makes me feel a bit better and easy.... thanks...)

Of course I thought it *was* a bug...

I've sent probably 1800 of these emails.  It's a script but I look over
the email before sending.  Maybe when people start using the Link: tag
I will be able to make these show up as reply to an email.

Normally, I sent them out in a much more timely sort of way but all the
erofs warnings show up as new with the move out of staging so I have
been re-reviewing the warnings.

So last August when this code was new, I must have seen the warning but
read the code correctly.  I checked before I sent this email to make
sure we hadn't discusssed it before.

But this time I got confused by the DBG_BUGON().  I decided to treat it
as a no-op because it can be configured to do nothing if you have
CONFIG_EROFS_FS_DEBUG disabled.  Plus it has "DBG" in the name so it
felt like debug code.  But I ended up focussing on it instead of seeing
the "(nofail ? __GFP_NOFAIL : 0)" bit.  The DBG_BUGON() is unreachable
and misleading nonsense fluff.  :(

regards,
dan carpenter