From 4defc641a2da2b20898f15eb1c9234dcc1cbeb38 Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Wed, 20 Oct 2021 14:36:05 -0400
Subject: [PATCH] Have ShareFile only write a new lease if there is room for it

StorageServer passes available space down so it can make the decision.
ShareFile has to do it because `add_or_renew_lease` only *sometimes* adds a
lease and only ShareFile knows when that is.
---
 src/allmydata/storage/immutable.py | 20 ++++++++++++++++++--
 src/allmydata/storage/server.py    |  2 +-
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/allmydata/storage/immutable.py b/src/allmydata/storage/immutable.py
index 55bcdda64..ad2d19f5f 100644
--- a/src/allmydata/storage/immutable.py
+++ b/src/allmydata/storage/immutable.py
@@ -21,6 +21,7 @@ from zope.interface import implementer
 from allmydata.interfaces import (
     RIBucketWriter, RIBucketReader, ConflictingWriteError,
     DataTooLargeError,
+    NoSpace,
 )
 from allmydata.util import base32, fileutil, log
 from allmydata.util.assertutil import precondition
@@ -249,14 +250,29 @@ class ShareFile(object):
                 return
         raise IndexError("unable to renew non-existent lease")
 
-    def add_or_renew_lease(self, lease_info):
+    def add_or_renew_lease(self, available_space, lease_info):
+        """
+        Renew an existing lease if possible, otherwise allocate a new one.
+
+        :param int available_space: The maximum number of bytes of storage to
+            commit in this operation.  If more than this number of bytes is
+            required, raise ``NoSpace`` instead.
+
+        :param LeaseInfo lease_info: The details of the lease to renew or add.
+
+        :raise NoSpace: If more than ``available_space`` bytes is required to
+            complete the operation.  In this case, no lease is added.
+
+        :return: ``None``
+        """
         try:
             self.renew_lease(lease_info.renew_secret,
                              lease_info.expiration_time)
         except IndexError:
+            if lease_info.immutable_size() > available_space:
+                raise NoSpace()
             self.add_lease(lease_info)
 
-
     def cancel_lease(self, cancel_secret):
         """Remove a lease with the given cancel_secret. If the last lease is
         cancelled, the file will be removed. Return the number of bytes that
diff --git a/src/allmydata/storage/server.py b/src/allmydata/storage/server.py
index 21c612a59..66d9df998 100644
--- a/src/allmydata/storage/server.py
+++ b/src/allmydata/storage/server.py
@@ -618,7 +618,7 @@ class StorageServer(service.MultiService, Referenceable):
         :param LeaseInfo lease_info: The lease to put on the shares.
         """
         for share in shares:
-            share.add_or_renew_lease(lease_info)
+            share.add_or_renew_lease(self.get_available_space(), lease_info)
 
     def slot_testv_and_readv_and_writev(  # type: ignore # warner/foolscap#78
             self,