[Libguestfs] [PATCH libnbd 2/7] lib: Allow retired commands to use free_callback on their buffer.

[Richard W.M. Jones]

When retiring a command test for a free_callback associated with their
buffer.  If there is one call it.  This allows language bindings to
use this mechanism to automatically decrement a reference to the
persistent buffer (note: this patch does not implement this).

The vast majority of this change is simply passing around the handle
so we have it when we call nbd_internal_free_callback in lib/aio.c.
---
 generator/states-reply.c |  2 +-
 generator/states.c       |  2 +-
 lib/aio.c                | 10 ++++++++--
 lib/handle.c             | 10 +++++-----
 lib/internal.h           |  3 ++-
 5 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/generator/states-reply.c b/generator/states-reply.c
index 09adfed..389317e 100644
--- a/generator/states-reply.c
+++ b/generator/states-reply.c
@@ -194,7 +194,7 @@ save_reply_state (struct nbd_handle *h)
     h->cmds_in_flight = cmd->next;
   cmd->next = NULL;
   if (retire)
-    nbd_internal_retire_and_free_command (cmd);
+    nbd_internal_retire_and_free_command (h, cmd);
   else {
     if (h->cmds_done_tail != NULL)
       h->cmds_done_tail = h->cmds_done_tail->next = cmd;
diff --git a/generator/states.c b/generator/states.c
index 9ed57ae..a11c1d1 100644
--- a/generator/states.c
+++ b/generator/states.c
@@ -142,7 +142,7 @@ void abort_commands (struct nbd_handle *h,
     if (cmd->error == 0)
       cmd->error = ENOTCONN;
     if (retire)
-      nbd_internal_retire_and_free_command (cmd);
+      nbd_internal_retire_and_free_command (h, cmd);
     else {
       cmd->next = NULL;
       if (h->cmds_done_tail)
diff --git a/lib/aio.c b/lib/aio.c
index c141de6..1d26be9 100644
--- a/lib/aio.c
+++ b/lib/aio.c
@@ -29,7 +29,8 @@
 
 /* Internal function which retires and frees a command. */
 void
-nbd_internal_retire_and_free_command (struct command *cmd)
+nbd_internal_retire_and_free_command (struct nbd_handle *h,
+                                      struct command *cmd)
 {
   /* Free the callbacks. */
   if (cmd->type == NBD_CMD_BLOCK_STATUS && cmd->cb.fn.extent)
@@ -42,6 +43,11 @@ nbd_internal_retire_and_free_command (struct command *cmd)
     cmd->cb.completion (LIBNBD_CALLBACK_FREE, cmd->cb.user_data,
                         NULL);
 
+  /* Free the persistent buffer if there is one and if there's an
+   * associated free callback.
+   */
+  nbd_internal_free_callback (h, cmd->data);
+
   free (cmd);
 }
 
@@ -109,7 +115,7 @@ nbd_unlocked_aio_command_completed (struct nbd_handle *h,
   else
     h->cmds_done = cmd->next;
 
-  nbd_internal_retire_and_free_command (cmd);
+  nbd_internal_retire_and_free_command (h, cmd);
 
   /* If the command was successful, return true. */
   if (error == 0)
diff --git a/lib/handle.c b/lib/handle.c
index ae0d196..0f50e38 100644
--- a/lib/handle.c
+++ b/lib/handle.c
@@ -32,13 +32,13 @@
 #include "internal.h"
 
 static void
-free_cmd_list (struct command *list)
+free_cmd_list (struct nbd_handle *h, struct command *list)
 {
   struct command *cmd, *cmd_next;
 
   for (cmd = list; cmd != NULL; cmd = cmd_next) {
     cmd_next = cmd->next;
-    nbd_internal_retire_and_free_command (cmd);
+    nbd_internal_retire_and_free_command (h, cmd);
   }
 }
 
@@ -123,9 +123,9 @@ nbd_close (struct nbd_handle *h)
     free (m->name);
     free (m);
   }
-  free_cmd_list (h->cmds_to_issue);
-  free_cmd_list (h->cmds_in_flight);
-  free_cmd_list (h->cmds_done);
+  free_cmd_list (h, h->cmds_to_issue);
+  free_cmd_list (h, h->cmds_in_flight);
+  free_cmd_list (h, h->cmds_done);
 
   /* Any remaining free callbacks indicate an error. */
   if (h->nr_free_callbacks != 0)
diff --git a/lib/internal.h b/lib/internal.h
index d8b0eed..42e6921 100644
--- a/lib/internal.h
+++ b/lib/internal.h
@@ -288,7 +288,8 @@ struct command {
 };
 
 /* aio.c */
-extern void nbd_internal_retire_and_free_command (struct command *);
+extern void nbd_internal_retire_and_free_command (struct nbd_handle *,
+                                                  struct command *);
 
 /* crypto.c */
 extern struct socket *nbd_internal_crypto_create_session (struct nbd_handle *, struct socket *oldsock);
-- 
2.22.0