Merge branch 'map-pinning'

Toke Høiland-Jørgensen says:

====================
This series adds support to libbpf for reading 'pinning' settings from BTF-based
map definitions. It introduces a new open option which can set the pinning path;
if no path is set, /sys/fs/bpf is used as the default. Callers can customise the
pinning between open and load by setting the pin path per map, and still get the
automatic reuse feature.

The semantics of the pinning is similar to the iproute2 "PIN_GLOBAL" setting,
and the eventual goal is to move the iproute2 implementation to be based on
libbpf and the functions introduced in this series.

Changelog:

v6:
  - Fix leak of struct bpf_object in selftest
  - Make struct bpf_map arg const in bpf_map__is_pinned() and bpf_map__get_pin_path()

v5:
  - Don't pin maps with pinning set, but with a value of LIBBPF_PIN_NONE
  - Add a few more selftests:
    - Should not pin map with pinning set, but value LIBBPF_PIN_NONE
    - Should fail to load a map with an invalid pinning value
    - Should fail to re-use maps with parameter mismatch
  - Alphabetise libbpf.map
  - Whitespace and typo fixes

v4:
  - Don't check key_type_id and value_type_id when checking for map reuse
    compatibility.
  - Move building of map->pin_path into init_user_btf_map()
  - Get rid of 'pinning' attribute in struct bpf_map
  - Make sure we also create parent directory on auto-pin (new patch 3).
  - Abort the selftest on error instead of attempting to continue.
  - Support unpinning all pinned maps with bpf_object__unpin_maps(obj, NULL)
  - Support pinning at map->pin_path with bpf_object__pin_maps(obj, NULL)
  - Make re-pinning a map at the same path a noop
  - Rename the open option to pin_root_path
  - Add a bunch more self-tests for pin_maps(NULL) and unpin_maps(NULL)
  - Fix a couple of smaller nits

v3:
  - Drop bpf_object__pin_maps_opts() and just use an open option to customise
    the pin path; also don't touch bpf_object__{un,}pin_maps()
  - Integrate pinning and reuse into bpf_object__create_maps() instead of having
    multiple loops though the map structure
  - Make errors in map reuse and pinning fatal to the load procedure
  - Add selftest to exercise pinning feature
  - Rebase series to latest bpf-next

v2:
  - Drop patch that adds mounting of bpffs
  - Only support a single value of the pinning attribute
  - Add patch to fixup error handling in reuse_fd()
  - Implement the full automatic pinning and map reuse logic on load
====================

Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 210 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/pinning.c b/tools/testing/selftests/bpf/prog_tests/pinning.c
new file mode 100644
index 000000000000..525388971e08
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/pinning.c
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <test_progs.h>
+
+__u32 get_map_id(struct bpf_object *obj, const char *name)
+{
+	struct bpf_map_info map_info = {};
+	__u32 map_info_len, duration = 0;
+	struct bpf_map *map;
+	int err;
+
+	map_info_len = sizeof(map_info);
+
+	map = bpf_object__find_map_by_name(obj, name);
+	if (CHECK(!map, "find map", "NULL map"))
+		return 0;
+
+	err = bpf_obj_get_info_by_fd(bpf_map__fd(map),
+				     &map_info, &map_info_len);
+	CHECK(err, "get map info", "err %d errno %d", err, errno);
+	return map_info.id;
+}
+
+void test_pinning(void)
+{
+	const char *file_invalid = "./test_pinning_invalid.o";
+	const char *custpinpath = "/sys/fs/bpf/custom/pinmap";
+	const char *nopinpath = "/sys/fs/bpf/nopinmap";
+	const char *nopinpath2 = "/sys/fs/bpf/nopinmap2";
+	const char *custpath = "/sys/fs/bpf/custom";
+	const char *pinpath = "/sys/fs/bpf/pinmap";
+	const char *file = "./test_pinning.o";
+	__u32 map_id, map_id2, duration = 0;
+	struct stat statbuf = {};
+	struct bpf_object *obj;
+	struct bpf_map *map;
+	int err;
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
+		.pin_root_path = custpath,
+	);
+
+	/* check that opening fails with invalid pinning value in map def */
+	obj = bpf_object__open_file(file_invalid, NULL);
+	err = libbpf_get_error(obj);
+	if (CHECK(err != -EINVAL, "invalid open", "err %d errno %d\n", err, errno)) {
+		obj = NULL;
+		goto out;
+	}
+
+	/* open the valid object file  */
+	obj = bpf_object__open_file(file, NULL);
+	err = libbpf_get_error(obj);
+	if (CHECK(err, "default open", "err %d errno %d\n", err, errno)) {
+		obj = NULL;
+		goto out;
+	}
+
+	err = bpf_object__load(obj);
+	if (CHECK(err, "default load", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that pinmap was pinned */
+	err = stat(pinpath, &statbuf);
+	if (CHECK(err, "stat pinpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that nopinmap was *not* pinned */
+	err = stat(nopinpath, &statbuf);
+	if (CHECK(!err || errno != ENOENT, "stat nopinpath",
+		  "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that nopinmap2 was *not* pinned */
+	err = stat(nopinpath2, &statbuf);
+	if (CHECK(!err || errno != ENOENT, "stat nopinpath2",
+		  "err %d errno %d\n", err, errno))
+		goto out;
+
+	map_id = get_map_id(obj, "pinmap");
+	if (!map_id)
+		goto out;
+
+	bpf_object__close(obj);
+
+	obj = bpf_object__open_file(file, NULL);
+	if (CHECK_FAIL(libbpf_get_error(obj))) {
+		obj = NULL;
+		goto out;
+	}
+
+	err = bpf_object__load(obj);
+	if (CHECK(err, "default load", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that same map ID was reused for second load */
+	map_id2 = get_map_id(obj, "pinmap");
+	if (CHECK(map_id != map_id2, "check reuse",
+		  "err %d errno %d id %d id2 %d\n", err, errno, map_id, map_id2))
+		goto out;
+
+	/* should be no-op to re-pin same map */
+	map = bpf_object__find_map_by_name(obj, "pinmap");
+	if (CHECK(!map, "find map", "NULL map"))
+		goto out;
+
+	err = bpf_map__pin(map, NULL);
+	if (CHECK(err, "re-pin map", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* but error to pin at different location */
+	err = bpf_map__pin(map, "/sys/fs/bpf/other");
+	if (CHECK(!err, "pin map different", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* unpin maps with a pin_path set */
+	err = bpf_object__unpin_maps(obj, NULL);
+	if (CHECK(err, "unpin maps", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* and re-pin them... */
+	err = bpf_object__pin_maps(obj, NULL);
+	if (CHECK(err, "pin maps", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* set pinning path of other map and re-pin all */
+	map = bpf_object__find_map_by_name(obj, "nopinmap");
+	if (CHECK(!map, "find map", "NULL map"))
+		goto out;
+
+	err = bpf_map__set_pin_path(map, custpinpath);
+	if (CHECK(err, "set pin path", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* should only pin the one unpinned map */
+	err = bpf_object__pin_maps(obj, NULL);
+	if (CHECK(err, "pin maps", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that nopinmap was pinned at the custom path */
+	err = stat(custpinpath, &statbuf);
+	if (CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* remove the custom pin path to re-test it with auto-pinning below */
+	err = unlink(custpinpath);
+	if (CHECK(err, "unlink custpinpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+	err = rmdir(custpath);
+	if (CHECK(err, "rmdir custpindir", "err %d errno %d\n", err, errno))
+		goto out;
+
+	bpf_object__close(obj);
+
+	/* open the valid object file again */
+	obj = bpf_object__open_file(file, NULL);
+	err = libbpf_get_error(obj);
+	if (CHECK(err, "default open", "err %d errno %d\n", err, errno)) {
+		obj = NULL;
+		goto out;
+	}
+
+	/* swap pin paths of the two maps */
+	bpf_object__for_each_map(map, obj) {
+		if (!strcmp(bpf_map__name(map), "nopinmap"))
+			err = bpf_map__set_pin_path(map, pinpath);
+		else if (!strcmp(bpf_map__name(map), "pinmap"))
+			err = bpf_map__set_pin_path(map, NULL);
+		else
+			continue;
+
+		if (CHECK(err, "set pin path", "err %d errno %d\n", err, errno))
+			goto out;
+	}
+
+	/* should fail because of map parameter mismatch */
+	err = bpf_object__load(obj);
+	if (CHECK(err != -EINVAL, "param mismatch load", "err %d errno %d\n", err, errno))
+		goto out;
+
+	bpf_object__close(obj);
+
+	/* test auto-pinning at custom path with open opt */
+	obj = bpf_object__open_file(file, &opts);
+	if (CHECK_FAIL(libbpf_get_error(obj))) {
+		obj = NULL;
+		goto out;
+	}
+
+	err = bpf_object__load(obj);
+	if (CHECK(err, "custom load", "err %d errno %d\n", err, errno))
+		goto out;
+
+	/* check that pinmap was pinned at the custom path */
+	err = stat(custpinpath, &statbuf);
+	if (CHECK(err, "stat custpinpath", "err %d errno %d\n", err, errno))
+		goto out;
+
+out:
+	unlink(pinpath);
+	unlink(nopinpath);
+	unlink(nopinpath2);
+	unlink(custpinpath);
+	rmdir(custpath);
+	if (obj)
+		bpf_object__close(obj);
+}