Re: [PATCH 3/7] btrfs: take into account global rsv in need_preemptive_reclaim

[David Sterba <dsterba@suse.cz>]

On Thu, Apr 29, 2021 at 10:03:10PM +0200, David Sterba wrote:
> On Wed, Apr 28, 2021 at 01:38:44PM -0400, Josef Bacik wrote:
> > Global rsv can't be used for normal allocations, and for very full file
> > systems we can decide to try and async flush constantly even though
> > there's really not a lot of space to reclaim.  Deal with this by
> > including the global block rsv size in the "total used" calculation.
> > 
> > Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> > ---
> >  fs/btrfs/space-info.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
> > index 33edab17af0d..e341f995a7dd 100644
> > --- a/fs/btrfs/space-info.c
> > +++ b/fs/btrfs/space-info.c
> > @@ -792,12 +792,14 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
> >  static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
> >  				    struct btrfs_space_info *space_info)
> >  {
> > +	u64 global_rsv_size = fs_info->global_block_rsv.reserved;
> >  	u64 ordered, delalloc;
> >  	u64 thresh = div_factor_fine(space_info->total_bytes, 98);
> >  	u64 used;
> >  
> >  	/* If we're just plain full then async reclaim just slows us down. */
> > -	if ((space_info->bytes_used + space_info->bytes_reserved) >= thresh)
> > +	if ((space_info->bytes_used + space_info->bytes_reserved +
> > +	     global_rsv_size) >= thresh)
> 
> That's an extra variable for one time use. Do you have plans to use it
> in further patches? Regarding readability, it has to be put on a
> separate line anyway so there's space for the whole identifier bit if
> you intend to use it then it's ok to keep it.

Never mind, I got fooled by the diff -p that shows the name of the
previous function (btrfs_calc_reclaim_metadata_size) and not the actual
function where it is being added (need_preemptive_reclaim) in case it's
in the hunk context.