libbtrfsutil: add btrfs_util_deleted_subvolumes()

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

libbtrfsutil/btrfsutil.h

@@ -580,6 +580,27 @@ enum btrfs_util_error btrfs_util_subvolume_iterator_next_info(struct btrfs_util_
 							      char **path_ret,
 							      struct btrfs_util_subvolume_info *subvol);
 
+/**
+ * btrfs_util_deleted_subvolumes() - Get a list of subvolume which have been
+ * deleted but not yet cleaned up.
+ * @path: Path on a Btrfs filesystem.
+ * @ids: Returned array of subvolume IDs.
+ * @n: Returned number of IDs in the @ids array.
+ *
+ * This requires appropriate privilege (CAP_SYS_ADMIN).
+ *
+ * Return: %BTRFS_UTIL_OK on success, non-zero error code on failure.
+ */
+enum btrfs_util_error btrfs_util_deleted_subvolumes(const char *path,
+						    uint64_t **ids,
+						    size_t *n);
+
+/**
+ * btrfs_util_deleted_subvolumes_fd() - See btrfs_util_deleted_subvolumes().
+ */
+enum btrfs_util_error btrfs_util_deleted_subvolumes_fd(int fd, uint64_t **ids,
+						       size_t *n);
+
 /**
  * btrfs_util_create_qgroup_inherit() - Create a qgroup inheritance specifier
  * for btrfs_util_create_subvolume() or btrfs_util_create_snapshot().

libbtrfsutil/python/btrfsutilpy.h

@@ -54,6 +54,8 @@ struct path_arg {
 int path_converter(PyObject *o, void *p);
 void path_cleanup(struct path_arg *path);
 
+PyObject *list_from_uint64_array(const uint64_t *arr, size_t n);
+
 void SetFromBtrfsUtilError(enum btrfs_util_error err);
 void SetFromBtrfsUtilErrorWithPath(enum btrfs_util_error err,
 				   struct path_arg *path);
@@ -75,6 +77,7 @@ PyObject *set_default_subvolume(PyObject *self, PyObject *args, PyObject *kwds);
 PyObject *create_subvolume(PyObject *self, PyObject *args, PyObject *kwds);
 PyObject *create_snapshot(PyObject *self, PyObject *args, PyObject *kwds);
 PyObject *delete_subvolume(PyObject *self, PyObject *args, PyObject *kwds);
+PyObject *deleted_subvolumes(PyObject *self, PyObject *args, PyObject *kwds);
 
 void add_module_constants(PyObject *m);
 

libbtrfsutil/python/module.c

@@ -125,6 +125,29 @@ err:
 	return 0;
 }
 
+PyObject *list_from_uint64_array(const uint64_t *arr, size_t n)
+{
+    PyObject *ret;
+    size_t i;
+
+    ret = PyList_New(n);
+    if (!ret)
+	    return NULL;
+
+    for (i = 0; i < n; i++) {
+	    PyObject *tmp;
+
+	    tmp = PyLong_FromUnsignedLongLong(arr[i]);
+	    if (!tmp) {
+		    Py_DECREF(ret);
+		    return NULL;
+	    }
+	    PyList_SET_ITEM(ret, i, tmp);
+    }
+
+    return ret;
+}
+
 void path_cleanup(struct path_arg *path)
 {
 	Py_CLEAR(path->object);
@@ -235,6 +258,13 @@ static PyMethodDef btrfsutil_methods[] = {
 	 "path -- string, bytes, or path-like object\n"
 	 "recursive -- if the given subvolume has child subvolumes, delete\n"
 	 "them instead of failing"},
+	{"deleted_subvolumes", (PyCFunction)deleted_subvolumes,
+	 METH_VARARGS | METH_KEYWORDS,
+	 "deleted_subvolumes(path)\n\n"
+	 "Get the list of subvolume IDs which have been deleted but not yet\n"
+	 "cleaned up\n\n"
+	 "Arguments:\n"
+	 "path -- string, bytes, path-like object, or open file descriptor"},
 	{},
 };
 

libbtrfsutil/python/qgroup.c

@@ -55,25 +55,12 @@ static PyObject *QgroupInherit_getattro(QgroupInherit *self, PyObject *nameobj)
     }
 
     if (strcmp(name, "groups") == 0) {
-	    PyObject *ret, *tmp;
 	    const uint64_t *arr;
-	    size_t n, i;
+	    size_t n;
 
 	    btrfs_util_qgroup_inherit_get_groups(self->inherit, &arr, &n);
-	    ret = PyList_New(n);
-	    if (!ret)
-		    return NULL;
 
-	    for (i = 0; i < n; i++) {
-		    tmp = PyLong_FromUnsignedLongLong(arr[i]);
-		    if (!tmp) {
-			    Py_DECREF(ret);
-			    return NULL;
-		    }
-		    PyList_SET_ITEM(ret, i, tmp);
-	    }
-
-	    return ret;
+	    return list_from_uint64_array(arr, n);
     } else {
 	    return PyObject_GenericGetAttr((PyObject *)self, nameobj);
     }

libbtrfsutil/python/subvolume.c

@@ -425,6 +425,36 @@ PyObject *delete_subvolume(PyObject *self, PyObject *args, PyObject *kwds)
 	Py_RETURN_NONE;
 }
 
+PyObject *deleted_subvolumes(PyObject *self, PyObject *args, PyObject *kwds)
+{
+	static char *keywords[] = {"path", NULL};
+	struct path_arg path = {.allow_fd = true};
+	PyObject *ret;
+	uint64_t *ids;
+	size_t n;
+	enum btrfs_util_error err;
+
+	if (!PyArg_ParseTupleAndKeywords(args, kwds, "O&:deleted_subvolumes",
+					 keywords, &path_converter, &path))
+		return NULL;
+
+	if (path.path)
+		err = btrfs_util_deleted_subvolumes(path.path, &ids, &n);
+	else
+		err = btrfs_util_deleted_subvolumes_fd(path.fd, &ids, &n);
+	if (err) {
+		SetFromBtrfsUtilErrorWithPath(err, &path);
+		path_cleanup(&path);
+		return NULL;
+	}
+
+	path_cleanup(&path);
+
+	ret = list_from_uint64_array(ids, n);
+	free(ids);
+	return ret;
+}
+
 typedef struct {
 	PyObject_HEAD
 	struct btrfs_util_subvolume_iterator *iter;

libbtrfsutil/python/tests/test_subvolume.py

@@ -318,6 +318,14 @@ class TestSubvolume(BtrfsTestCase):
         btrfsutil.delete_subvolume(subvol + '5', recursive=True)
         self.assertFalse(os.path.exists(subvol + '5'))
 
+    def test_deleted_subvolumes(self):
+        subvol = os.path.join(self.mountpoint, 'subvol')
+        btrfsutil.create_subvolume(subvol + '1')
+        btrfsutil.delete_subvolume(subvol + '1')
+        for arg in self.path_or_fd(self.mountpoint):
+            with self.subTest(type=type(arg)):
+                self.assertEqual(btrfsutil.deleted_subvolumes(arg), [256])
+
     def test_subvolume_iterator(self):
         pwd = os.getcwd()
         try:

libbtrfsutil/subvolume.c

@@ -1279,3 +1279,92 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_iterator_next_info(struct btrf
 
 	return btrfs_util_subvolume_info_fd(iter->fd, id, subvol);
 }
+
+PUBLIC enum btrfs_util_error btrfs_util_deleted_subvolumes(const char *path,
+							   uint64_t **ids,
+							   size_t *n)
+{
+	enum btrfs_util_error err;
+	int fd;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return BTRFS_UTIL_ERROR_OPEN_FAILED;
+
+	err = btrfs_util_deleted_subvolumes_fd(fd, ids, n);
+	SAVE_ERRNO_AND_CLOSE(fd);
+	return err;
+}
+
+PUBLIC enum btrfs_util_error btrfs_util_deleted_subvolumes_fd(int fd,
+							      uint64_t **ids,
+							      size_t *n)
+{
+	size_t capacity = 0;
+	struct btrfs_ioctl_search_args search = {
+		.key = {
+			.tree_id = BTRFS_ROOT_TREE_OBJECTID,
+			.min_objectid = BTRFS_ORPHAN_OBJECTID,
+			.max_objectid = BTRFS_ORPHAN_OBJECTID,
+			.min_type = BTRFS_ORPHAN_ITEM_KEY,
+			.max_type = BTRFS_ORPHAN_ITEM_KEY,
+			.min_offset = 0,
+			.max_offset = UINT64_MAX,
+			.min_transid = 0,
+			.max_transid = UINT64_MAX,
+			.nr_items = 0,
+		},
+	};
+	enum btrfs_util_error err;
+	size_t items_pos = 0, buf_off = 0;
+	int ret;
+
+	*ids = NULL;
+	*n = 0;
+	for (;;) {
+		const struct btrfs_ioctl_search_header *header;
+
+		if (items_pos >= search.key.nr_items) {
+			search.key.nr_items = 4096;
+			ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &search);
+			if (ret == -1) {
+				err = BTRFS_UTIL_ERROR_SEARCH_FAILED;
+				goto out;
+			}
+			items_pos = 0;
+			buf_off = 0;
+
+			if (search.key.nr_items == 0)
+				break;
+		}
+
+		header = (struct btrfs_ioctl_search_header *)(search.buf + buf_off);
+		if (*n >= capacity) {
+			size_t new_capacity = capacity ? capacity * 2 : 1;
+			uint64_t *new_ids;
+
+			new_ids = reallocarray(*ids, new_capacity,
+					       sizeof(**ids));
+			if (!new_ids)
+				return BTRFS_UTIL_ERROR_NO_MEMORY;
+
+			*ids = new_ids;
+			capacity = new_capacity;
+		}
+
+		(*ids)[(*n)++] = header->offset;
+
+		items_pos++;
+		buf_off += sizeof(*header) + header->len;
+		search.key.min_offset = header->offset + 1;
+	}
+
+	err = BTRFS_UTIL_OK;
+out:
+	if (err) {
+		free(*ids);
+		*ids = NULL;
+		*n = 0;
+	}
+	return err;
+}