linux-kernel - Re: [PATCH] btrfs: fiemap: make the assert more explicit after handling the error cases

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAL3q7H7g3xvs8TnSsYwaBP1n_EyRn1eC6SgeMP41G7BT=VZ2-A@mail.gmail.com>
Date: Wed, 23 Apr 2025 10:54:33 +0100
From: Filipe Manana <fdmanana@...nel.org>
To: Daniel Vacek <neelx@...e.com>
Cc: Chris Mason <clm@...com>, Josef Bacik <josef@...icpanda.com>, David Sterba <dsterba@...e.com>, 
	linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] btrfs: fiemap: make the assert more explicit after
 handling the error cases

On Wed, Apr 23, 2025 at 10:48 AM Daniel Vacek <neelx@...e.com> wrote:
>
> On Wed, 23 Apr 2025 at 11:04, Filipe Manana <fdmanana@...nel.org> wrote:
> >
> > On Wed, Apr 23, 2025 at 9:10 AM Daniel Vacek <neelx@...e.com> wrote:
> > >
> > > Let's not assert the errors and clearly state the expected result only
> > > after eventual error handling. It makes a bit more sense this way.
> >
> > It doesn't make more sense to me...
> > I prefer to assert expected results right after the function call.
>
> Oh well, if an error is expected then I get it. Is an error likely
> here?

The assertion serves to state what is never expected, and not what is
likely or unlikely.
It's about stating that an exact match shouldn't happen, i.e. ret == 0.

We do this sort of asserts in many places, and I find it more clear this way.

> I understood the comment says there can't be a file extent item
> at offset (u64)-1 which implies a strict return value of 1 and not an
> error or something >1. So that's why. And it's still quite after the
> function call.
>
> But I'm happy to scratch it if you don't like it.
>
> > Thanks.
> >
> > >
> > > Signed-off-by: Daniel Vacek <neelx@...e.com>
> > > ---
> > >  fs/btrfs/fiemap.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/fs/btrfs/fiemap.c b/fs/btrfs/fiemap.c
> > > index b80c07ad8c5e7..034f832e10c1a 100644
> > > --- a/fs/btrfs/fiemap.c
> > > +++ b/fs/btrfs/fiemap.c
> > > @@ -568,10 +568,10 @@ static int fiemap_find_last_extent_offset(struct btrfs_inode *inode,
> > >          * there might be preallocation past i_size.
> > >          */
> > >         ret = btrfs_lookup_file_extent(NULL, root, path, ino, (u64)-1, 0);
> > > -       /* There can't be a file extent item at offset (u64)-1 */
> > > -       ASSERT(ret != 0);
> > >         if (ret < 0)
> > >                 return ret;
> > > +       /* There can't be a file extent item at offset (u64)-1 */
> > > +       ASSERT(ret == 1);
> > >
> > >         /*
> > >          * For a non-existing key, btrfs_search_slot() always leaves us at a
> > > --
> > > 2.47.2
> > >
> > >