Messages in this thread | | | Date | Wed, 30 Aug 2023 12:27:41 +0100 | From | Jonathan Cameron <> | Subject | Re: [PATCH RFC v2 13/18] dax/bus: Factor out dev dax resize logic |
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On Mon, 28 Aug 2023 22:21:04 -0700 Ira Weiny <ira.weiny@intel.com> wrote:
> Dynamic Capacity regions must limit dev dax resources to those areas > which have extents backing real memory. Four alternatives were > considered to manage the intersection of region space and extents: > > 1) Create a single region resource child on region creation which > reserves the entire region. Then as extents are added punch holes in > this reservation. This requires new resource manipulation to punch > the holes and still requires an additional iteration over the extent > areas which may already have existing dev dax resources used. > > 2) Maintain an ordered xarray of extents which can be queried while > processing the resize logic. The issue is that existing region->res > children may artificially limit the allocation size sent to > alloc_dev_dax_range(). IE the resource children can't be directly > used in the resize logic to find where space in the region is. > > 3) Maintain a separate resource tree with extents. This option is the > same as 2) but with a different data structure. Most ideally we have > some unified representation of the resource tree. > > 4) Create region resource children for each extent. Manage the dax dev > resize logic in the same way as before but use a region child > (extent) resource as the parents to find space within each extent. > > Option 4 can leverage the existing resize algorithm to find space within > the extents. > > In preparation for this change, factor out the dev_dax_resize logic. > For static regions use dax_region->res as the parent to find space for > the dax ranges. Future patches will use the same algorithm with > individual extent resources as the parent. > > Signed-off-by: Ira Weiny <ira.weiny@intel.com> Hi Ira,
Some trivial comments on comments, but in general this indeed seems to be doing what you say and factoring out the static allocation part.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> --- > drivers/dax/bus.c | 128 +++++++++++++++++++++++++++++++++--------------------- > 1 file changed, 79 insertions(+), 49 deletions(-) > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > index b76e49813a39..ea7ae82b4687 100644 > --- a/drivers/dax/bus.c > +++ b/drivers/dax/bus.c > @@ -817,11 +817,10 @@ static int devm_register_dax_mapping(struct dev_dax *dev_dax, int range_id) > return 0; > } >
> -static ssize_t dev_dax_resize(struct dax_region *dax_region, > - struct dev_dax *dev_dax, resource_size_t size) > +/*
/**
Suitable builds will then check this doc matches the function etc even if this is never included into any of the docs build.
> + * dev_dax_resize_static - Expand the device into the unused portion of the > + * region. This may involve adjusting the end of an existing resource, or > + * allocating a new resource. > + * > + * @parent: parent resource to allocate this range in. > + * @dev_dax: DAX device we are creating this range for
Trivial: Doesn't seem to be consistent on . or not
> + * @to_alloc: amount of space to alloc; must be <= space available in @parent > + * > + * Return the amount of space allocated or -ERRNO on failure > + */ > +static ssize_t dev_dax_resize_static(struct resource *parent, > + struct dev_dax *dev_dax, > + resource_size_t to_alloc)
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