[Libguestfs] [libnbd PATCH v2 1/5] lib: Refactor state event into command_common

[Eric Blake]

The next patch wants to make queuing commands smarter; rather than
duplicating the logic at each command's call site, it's better to
centralize things in command_common, and to also make this helper
routine visible for use in NBD_CMD_DISC.
---
 lib/disconnect.c | 17 +++--------------
 lib/internal.h   |  6 ++++++
 lib/rw.c         | 19 +++----------------
 3 files changed, 12 insertions(+), 30 deletions(-)

diff --git a/lib/disconnect.c b/lib/disconnect.c
index bc43b4c..26d7298 100644
--- a/lib/disconnect.c
+++ b/lib/disconnect.c
@@ -62,25 +62,14 @@ nbd_unlocked_aio_disconnect (struct nbd_connection *conn)
 {
   struct command_in_flight *cmd;

-  cmd = malloc (sizeof *cmd);
-  if (cmd == NULL) {
-    set_error (errno, "malloc");
+  cmd = command_common (conn, 0, NBD_CMD_DISC, 0, 0, NULL);
+  if (cmd == NULL)
     return -1;
-  }
-  cmd->flags = 0;
-  cmd->type = NBD_CMD_DISC;
-  cmd->handle = conn->h->unique++;
-  cmd->offset = 0;
-  cmd->count = 0;
-  cmd->data = NULL;
-
-  cmd->next = conn->cmds_to_issue;
-  conn->cmds_to_issue = cmd;

   /* This will leave the command on the in-flight list.  Is this a
    * problem?  Probably it isn't.  If it is, we could add a flag to
    * the command struct to tell SEND_REQUEST not to add it to the
    * in-flight list.
    */
-  return nbd_internal_run (conn->h, conn, cmd_issue);
+  return 0;
 }
diff --git a/lib/internal.h b/lib/internal.h
index 3f2b729..67bd52a 100644
--- a/lib/internal.h
+++ b/lib/internal.h
@@ -265,6 +265,12 @@ extern void nbd_internal_set_last_error (int errnum, char *error);
 extern int nbd_internal_errno_of_nbd_error (uint32_t error);
 extern const char *nbd_internal_name_of_nbd_cmd (uint16_t type);

+/* rw.c */
+extern struct command_in_flight *command_common (struct nbd_connection *conn,
+                                                 uint16_t flags, uint16_t type,
+                                                 uint64_t offset,
+                                                 uint64_t count, void *data);
+
 /* socket.c */
 struct socket *nbd_internal_socket_create (int fd);

diff --git a/lib/rw.c b/lib/rw.c
index 9dfce97..a7587e9 100644
--- a/lib/rw.c
+++ b/lib/rw.c
@@ -241,7 +241,7 @@ nbd_unlocked_block_status (struct nbd_handle *h,
   return r == -1 ? -1 : 0;
 }

-static struct command_in_flight *
+struct command_in_flight *
 command_common (struct nbd_connection *conn,
                 uint16_t flags, uint16_t type,
                 uint64_t offset, uint64_t count, void *data)
@@ -298,6 +298,8 @@ command_common (struct nbd_connection *conn,

   cmd->next = conn->cmds_to_issue;
   conn->cmds_to_issue = cmd;
+  if (nbd_internal_run (conn->h, conn, cmd_issue) == -1)
+    return NULL;

   return cmd;
 }
@@ -311,8 +313,6 @@ nbd_unlocked_aio_pread (struct nbd_connection *conn, void *buf,
   cmd = command_common (conn, 0, NBD_CMD_READ, offset, count, buf);
   if (!cmd)
     return -1;
-  if (nbd_internal_run (conn->h, conn, cmd_issue) == -1)
-    return -1;

   return cmd->handle;
 }
@@ -344,8 +344,6 @@ nbd_unlocked_aio_pwrite (struct nbd_connection *conn, const void *buf,
                         (void *) buf);
   if (!cmd)
     return -1;
-  if (nbd_internal_run (conn->h, conn, cmd_issue) == -1)
-    return -1;

   return cmd->handle;
 }
@@ -363,8 +361,6 @@ nbd_unlocked_aio_flush (struct nbd_connection *conn)
   cmd = command_common (conn, 0, NBD_CMD_FLUSH, 0, 0, NULL);
   if (!cmd)
     return -1;
-  if (nbd_internal_run (conn->h, conn, cmd_issue) == -1)
-    return -1;

   return cmd->handle;
 }
@@ -400,8 +396,6 @@ nbd_unlocked_aio_trim (struct nbd_connection *conn,
   cmd = command_common (conn, flags, NBD_CMD_TRIM, offset, count, NULL);
   if (!cmd)
     return -1;
-  if (nbd_internal_run (conn->h, conn, cmd_issue) == -1)
-    return -1;

   return cmd->handle;
 }
@@ -424,8 +418,6 @@ nbd_unlocked_aio_cache (struct nbd_connection *conn,
   cmd = command_common (conn, 0, NBD_CMD_CACHE, offset, count, NULL);
   if (!cmd)
     return -1;
-  if (nbd_internal_run (conn->h, conn, cmd_issue) == -1)
-    return -1;

   return cmd->handle;
 }
@@ -461,8 +453,6 @@ nbd_unlocked_aio_zero (struct nbd_connection *conn,
   cmd = command_common (conn, flags, NBD_CMD_WRITE_ZEROES, offset, count, NULL);
   if (!cmd)
     return -1;
-  if (nbd_internal_run (conn->h, conn, cmd_issue) == -1)
-    return -1;

   return cmd->handle;
 }
@@ -505,8 +495,5 @@ nbd_unlocked_aio_block_status (struct nbd_connection *conn,
   cmd->extent_fn = extent;
   cmd->extent_id = id;

-  if (nbd_internal_run (conn->h, conn, cmd_issue) == -1)
-    return -1;
-
   return cmd->handle;
 }
-- 
2.20.1