Re: [PATCH] btrfs: Improve error reporting in lookup_inline_extent_backref

[Filipe Manana <fdmanana@kernel.org>]

On Wed, Apr 20, 2022 at 04:52:04PM +0200, David Sterba wrote:
> On Wed, Apr 20, 2022 at 02:54:00PM +0300, Nikolay Borisov wrote:
> > When iterating the backrefs in an extent item if the ptr to the
> > 'current' backref record goes beyond the extent item a warning is
> > generated and -ENOENT is returned. However what's more appropriate to
> > debug such cases would be to return EUCLEAN and also print the in-memory
> > state of the offending leaf.

How does printing only the leaf helps debugging anything?

You get the leaf dumped, but how do you know what you should be looking for?
Which key in the leaf, and for which inline backref are we searching for?

Dumping the leaf alone is not really useful, unless we also mention what we
are searching for...

So this should print as well:

1) The key, which tells us which key to look at, the extent's bytenr, type
   and size or owner;

2) The type of reference we are looking for, stored in the variable 'want';

3) The values of the variables 'root_objectid', 'parent' and 'offset'.
   These are used to search for the backreference we want, once we find
   one with the type we want.

Thanks.

> 
> Agreed, EUCLEAN makese sense. Added to misc-next, thanks.