Re: [PATCH 1/4] btrfs: stop checking for NULL return from btrfs_get_extent()

[Filipe Manana <fdmanana@kernel.org>]

On Fri, Feb 04, 2022 at 08:19:08AM +0000, Johannes Thumshirn wrote:
> On 03/02/2022 16:37, fdmanana@kernel.org wrote:
> > From: Filipe Manana <fdmanana@suse.com>
> > 
> > At extent_io.c, in the read page and write page code paths, we are testing
> > if the return value from btrfs_get_extent() can be NULL. However that is
> > not possible, as btrfs_get_extent() always returns either an error pointer
> > or a (non-NULL) pointer to an extent map structure.
> > 
> > Eveywhere else outside extent_io.c we never check for NULL, we always
> > treat any returned value as a non-NULL pointer if it does not encode an
> > error.
> > 
> > So check only for the IS_ERR() case at extent_io.c.
> > 
> 
> Isn't the same true for btrfs_get_extent_fiemap()? In get_extent_skip_holes() 
> we're also checking for IS_ERR_OR_NULL() but AFAICS btrfs_get_extent_fiemap()
> will never return NULL only a valid em or an error pointer.

Yep.
I was focused on the read and write page paths, due to the next change, so I
missed that one.

I can send another patch to fix that one, or if you want to do it yourself,
please go ahead.

Thanks.

> 
> Anyways for this patch:
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>