[ndctl PATCH v2 14/18] cxl/region: Trim region size by max available extent

[Dan Williams]

When a size is not specified, limit the size to either the available DPA
capacity, or the max available extent in the root decoder, whichever is
smaller.

Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
 cxl/region.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/cxl/region.c b/cxl/region.c
index 36ebc8e5210f..286c358f1a34 100644
--- a/cxl/region.c
+++ b/cxl/region.c
@@ -544,6 +544,7 @@ static int create_region(struct cxl_ctx *ctx, int *count,
        unsigned long flags = UTIL_JSON_TARGETS;
        struct json_object *jregion;
        struct cxl_region *region;
+       bool default_size = true;
        int i, rc, granularity;
        u64 size, max_extent;
        const char *devname;
@@ -555,6 +556,7 @@ static int create_region(struct cxl_ctx *ctx, int *count,
 
        if (p->size) {
                size = p->size;
+               default_size = false;
        } else if (p->ep_min_size) {
                size = p->ep_min_size * p->ways;
        } else {
@@ -567,13 +569,16 @@ static int create_region(struct cxl_ctx *ctx, int *count,
                        cxl_decoder_get_devname(p->root_decoder));
                return -EINVAL;
        }
-       if (size > max_extent) {
+       if (!default_size && size > max_extent) {
                log_err(&rl,
                        "%s: region size %#lx exceeds max available space\n",
                        cxl_decoder_get_devname(p->root_decoder), size);
                return -ENOSPC;
        }
 
+       if (size > max_extent)
+               size = ALIGN_DOWN(max_extent, SZ_256M * p->ways);
+
        if (p->mode == CXL_DECODER_MODE_PMEM) {
                region = cxl_decoder_create_pmem_region(p->root_decoder);
                if (!region) {