[ndctl PATCH v3 7/9] libcxl: Add extent functionality to DC regions

[Ira Weiny <ira.weiny@intel.com>]

DCD regions have 0 or more extents.  The ability to list those and their
properties is useful to end users.

Add extent scanning and reporting functionality to libcxl.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes:
[djiang: report strerror() on opendir() error]
[djiang: Fix up strtoull() error checking]
[Alison: Enhance man page]
[Alison: Enhance extent processing debug]
[Alison: Fix up libcxl export symbols]
[Alison/iweiny: Add documentation]
---
 Documentation/cxl/lib/libcxl.txt |  27 ++++++++
 cxl/lib/libcxl.c                 | 138 +++++++++++++++++++++++++++++++++++++++
 cxl/lib/libcxl.sym               |   5 ++
 cxl/lib/private.h                |  11 ++++
 cxl/libcxl.h                     |  11 ++++
 5 files changed, 192 insertions(+)

diff --git a/Documentation/cxl/lib/libcxl.txt b/Documentation/cxl/lib/libcxl.txt
index abca08fc81e6e84d176facafad6decae2f875880..0b53cf9a3a09a3e8c9059f796823b52d22d1077f 100644
--- a/Documentation/cxl/lib/libcxl.txt
+++ b/Documentation/cxl/lib/libcxl.txt
@@ -632,6 +632,33 @@ Regions now have a mode distinct from decoders.  cxl_region_get_mode() is
 deprecated in favor of cxl_region_get_region_mode().  Dynamic capacity regions
 require the use of cxl_region_get_region_mode().
 
+EXTENTS
+-------
+
+=== EXTENT: Enumeration
+----
+struct cxl_region_extent;
+struct cxl_region_extent *cxl_extent_get_first(struct cxl_region *region);
+struct cxl_region_extent *cxl_extent_get_next(struct cxl_region_extent *extent);
+#define cxl_extent_foreach(region, extent) \
+        for (extent = cxl_extent_get_first(region); \
+             extent != NULL; \
+             extent = cxl_extent_get_next(extent))
+
+----
+
+=== EXTENT: Attributes
+----
+unsigned long long cxl_extent_get_offset(struct cxl_region_extent *extent);
+unsigned long long cxl_extent_get_length(struct cxl_region_extent *extent);
+void cxl_extent_get_tag(struct cxl_region_extent *extent, uuid_t tag);
+----
+
+Extents represent available memory within a dynamic capacity region.  Extent
+objects are available for informational purposes to aid in allocation of
+memory.
+
+
 include::../../copyright.txt[]
 
 SEE ALSO
diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c
index df250db9dbacb2f0f34e8a592ce194159584fe4f..a029b14dcccf038b02b28d05df6f0dc71557df5e 100644
--- a/cxl/lib/libcxl.c
+++ b/cxl/lib/libcxl.c
@@ -568,6 +568,7 @@ static void *add_cxl_region(void *parent, int id, const char *cxlregion_base)
 	region->ctx = ctx;
 	region->decoder = decoder;
 	list_head_init(&region->mappings);
+	list_head_init(&region->extents);
 
 	region->dev_path = strdup(cxlregion_base);
 	if (!region->dev_path)
@@ -1178,6 +1179,143 @@ cxl_mapping_get_next(struct cxl_memdev_mapping *mapping)
 	return list_next(&region->mappings, mapping, list);
 }
 
+static void cxl_extents_init(struct cxl_region *region)
+{
+	const char *devname = cxl_region_get_devname(region);
+	struct cxl_ctx *ctx = cxl_region_get_ctx(region);
+	char *extent_path, *dax_region_path;
+	struct dirent *de;
+	DIR *dir = NULL;
+
+	if (region->extents_init)
+		return;
+	region->extents_init = 1;
+
+	dax_region_path = calloc(1, strlen(region->dev_path) + 64);
+	if (!dax_region_path) {
+		err(ctx, "%s: allocation failure\n", devname);
+		return;
+	}
+
+	extent_path = calloc(1, strlen(region->dev_path) + 100);
+	if (!extent_path) {
+		err(ctx, "%s: allocation failure\n", devname);
+		free(dax_region_path);
+		return;
+	}
+
+	sprintf(dax_region_path, "%s/dax_region%d",
+		region->dev_path, region->id);
+	dir = opendir(dax_region_path);
+	if (!dir) {
+		err(ctx, "no extents found (%s): %s\n",
+			strerror(errno), dax_region_path);
+		free(extent_path);
+		free(dax_region_path);
+		return;
+	}
+
+	while ((de = readdir(dir)) != NULL) {
+		struct cxl_region_extent *extent;
+		char buf[SYSFS_ATTR_SIZE];
+		u64 offset, length;
+		int id, region_id;
+
+		if (sscanf(de->d_name, "extent%d.%d", &region_id, &id) != 2)
+			continue;
+
+		sprintf(extent_path, "%s/extent%d.%d/offset",
+			dax_region_path, region_id, id);
+		if (sysfs_read_attr(ctx, extent_path, buf) < 0) {
+			err(ctx, "%s: failed to read extent%d.%d/offset\n",
+				devname, region_id, id);
+			continue;
+		}
+
+		offset = strtoull(buf, NULL, 0);
+		if (offset == ULLONG_MAX) {
+			err(ctx, "%s extent%d.%d: failed to read offset\n",
+				devname, region_id, id);
+			continue;
+		}
+
+		sprintf(extent_path, "%s/extent%d.%d/length",
+			dax_region_path, region_id, id);
+		if (sysfs_read_attr(ctx, extent_path, buf) < 0) {
+			err(ctx, "%s: failed to read extent%d.%d/length\n",
+				devname, region_id, id);
+			continue;
+		}
+
+		length = strtoull(buf, NULL, 0);
+		if (length == ULLONG_MAX) {
+			err(ctx, "%s extent%d.%d: failed to read length\n",
+				devname, region_id, id);
+			continue;
+		}
+
+		sprintf(extent_path, "%s/extent%d.%d/tag",
+			dax_region_path, region_id, id);
+		buf[0] = '\0';
+		if (sysfs_read_attr(ctx, extent_path, buf) != 0)
+			dbg(ctx, "%s extent%d.%d: failed to read tag\n",
+				devname, region_id, id);
+
+		extent = calloc(1, sizeof(*extent));
+		if (!extent) {
+			err(ctx, "%s extent%d.%d: allocation failure\n",
+				devname, region_id, id);
+			continue;
+		}
+		if (strlen(buf) && uuid_parse(buf, extent->tag) < 0)
+			err(ctx, "%s:%s\n", extent_path, buf);
+		extent->region = region;
+		extent->offset = offset;
+		extent->length = length;
+
+		list_node_init(&extent->list);
+		list_add(&region->extents, &extent->list);
+		dbg(ctx, "%s added extent%d.%d\n", devname, region_id, id);
+	}
+	free(dax_region_path);
+	free(extent_path);
+	closedir(dir);
+}
+
+CXL_EXPORT struct cxl_region_extent *
+cxl_extent_get_first(struct cxl_region *region)
+{
+	cxl_extents_init(region);
+
+	return list_top(&region->extents, struct cxl_region_extent, list);
+}
+
+CXL_EXPORT struct cxl_region_extent *
+cxl_extent_get_next(struct cxl_region_extent *extent)
+{
+	struct cxl_region *region = extent->region;
+
+	return list_next(&region->extents, extent, list);
+}
+
+CXL_EXPORT unsigned long long
+cxl_extent_get_offset(struct cxl_region_extent *extent)
+{
+	return extent->offset;
+}
+
+CXL_EXPORT unsigned long long
+cxl_extent_get_length(struct cxl_region_extent *extent)
+{
+	return extent->length;
+}
+
+CXL_EXPORT void
+cxl_extent_get_tag(struct cxl_region_extent *extent, uuid_t tag)
+{
+	memcpy(tag, extent->tag, sizeof(uuid_t));
+}
+
 CXL_EXPORT struct cxl_decoder *
 cxl_mapping_get_decoder(struct cxl_memdev_mapping *mapping)
 {
diff --git a/cxl/lib/libcxl.sym b/cxl/lib/libcxl.sym
index fdb227789985443a13c72751bbd42ab383db5f97..d8e8dbc7e091792fe48faa4657ab7cf1d795efdd 100644
--- a/cxl/lib/libcxl.sym
+++ b/cxl/lib/libcxl.sym
@@ -295,4 +295,9 @@ global:
 	cxl_memdev_get_dc_size;
 	cxl_decoder_is_dc_capable;
 	cxl_decoder_create_dc_region;
+	cxl_extent_get_first;
+	cxl_extent_get_next;
+	cxl_extent_get_offset;
+	cxl_extent_get_length;
+	cxl_extent_get_tag;
 } LIBECXL_8;
diff --git a/cxl/lib/private.h b/cxl/lib/private.h
index 3efa230bfb632e6c6048aadd18f799b07d4bdfd3..62278ec79963c198dcca490015e4c3f7621109b2 100644
--- a/cxl/lib/private.h
+++ b/cxl/lib/private.h
@@ -164,6 +164,7 @@ struct cxl_region {
 	struct cxl_decoder *decoder;
 	struct list_node list;
 	int mappings_init;
+	int extents_init;
 	struct cxl_ctx *ctx;
 	void *dev_buf;
 	size_t buf_len;
@@ -179,6 +180,7 @@ struct cxl_region {
 	struct daxctl_region *dax_region;
 	struct kmod_module *module;
 	struct list_head mappings;
+	struct list_head extents;
 };
 
 struct cxl_memdev_mapping {
@@ -188,6 +190,15 @@ struct cxl_memdev_mapping {
 	struct list_node list;
 };
 
+#define CXL_REGION_EXTENT_TAG 0x10
+struct cxl_region_extent {
+	struct cxl_region *region;
+	u64 offset;
+	u64 length;
+	uuid_t tag;
+	struct list_node list;
+};
+
 enum cxl_cmd_query_status {
 	CXL_CMD_QUERY_NOT_RUN = 0,
 	CXL_CMD_QUERY_OK,
diff --git a/cxl/libcxl.h b/cxl/libcxl.h
index d7f8a37816f236acd71fc834eae70a7a17a2721a..1d294ac0278d798214acb2f62e98aaaccaf60ea5 100644
--- a/cxl/libcxl.h
+++ b/cxl/libcxl.h
@@ -445,6 +445,17 @@ unsigned int cxl_mapping_get_position(struct cxl_memdev_mapping *mapping);
              mapping != NULL; \
              mapping = cxl_mapping_get_next(mapping))
 
+struct cxl_region_extent;
+struct cxl_region_extent *cxl_extent_get_first(struct cxl_region *region);
+struct cxl_region_extent *cxl_extent_get_next(struct cxl_region_extent *extent);
+#define cxl_extent_foreach(region, extent) \
+        for (extent = cxl_extent_get_first(region); \
+             extent != NULL; \
+             extent = cxl_extent_get_next(extent))
+unsigned long long cxl_extent_get_offset(struct cxl_region_extent *extent);
+unsigned long long cxl_extent_get_length(struct cxl_region_extent *extent);
+void cxl_extent_get_tag(struct cxl_region_extent *extent, uuid_t tag);
+
 struct cxl_cmd;
 const char *cxl_cmd_get_devname(struct cxl_cmd *cmd);
 struct cxl_cmd *cxl_cmd_new_raw(struct cxl_memdev *memdev, int opcode);

-- 
2.47.0