From 38124a137974e1433d68732640ca7f88664557da Mon Sep 17 00:00:00 2001

From: "Richard W.M. Jones" <rjones@redhat.com>

Date: Fri, 22 Nov 2019 19:25:53 +0000

Subject: [PATCH] python: Implement can_fua and can_cache.

(cherry picked from commit 97c46f885edec5a61a96ac86eccb9d8c874c602e)

---

 plugins/python/nbdkit-python-plugin.pod | 18 +++++++-

 plugins/python/python.c                 | 58 +++++++++++++++++++++++++

 2 files changed, 74 insertions(+), 2 deletions(-)

diff --git a/plugins/python/nbdkit-python-plugin.pod b/plugins/python/nbdkit-python-plugin.pod

index b92bb56..4065ec7 100644

--- a/plugins/python/nbdkit-python-plugin.pod

+++ b/plugins/python/nbdkit-python-plugin.pod

@@ -229,6 +229,22 @@ contents will be garbage collected.

  def can_fast_zero(h):

    # return a boolean

+=item C<can_fua>

+

+(Optional)

+

+ def can_fua(h):

+   # return nbdkit.FUA_NONE or nbdkit.FUA_EMULATE

+   # or nbdkit.FUA_NATIVE

+

+=item C<can_cache>

+

+(Optional)

+

+ def can_cache(h):

+   # return nbdkit.CACHE_NONE or nbdkit.CACHE_EMULATE

+   # or nbdkit.CACHE_NATIVE

+

 =item C<pread>

 (Required)

@@ -345,8 +361,6 @@ C<longname>,

 C<description>,

 C<config_help>,

 C<magic_config_key>,

-C<can_fua>,

-C<can_cache>,

 C<can_extents>,

 C<extents>.

diff --git a/plugins/python/python.c b/plugins/python/python.c

index b186b99..5e2e526 100644

--- a/plugins/python/python.c

+++ b/plugins/python/python.c

@@ -815,6 +815,62 @@ py_can_fast_zero (void *handle)

   return boolean_callback (handle, "can_fast_zero", NULL);

 }

+static int

+py_can_fua (void *handle)

+{

+  PyObject *obj = handle;

+  PyObject *fn;

+  PyObject *r;

+  int ret;

+

+  if (callback_defined ("can_fua", &fn)) {

+    PyErr_Clear ();

+

+    r = PyObject_CallFunctionObjArgs (fn, obj, NULL);

+    Py_DECREF (fn);

+    if (check_python_failure ("can_fua") == -1)

+      return -1;

+    ret = PyLong_AsLong (r);

+    Py_DECREF (r);

+    return ret;

+  }

+  /* No Python ‘can_fua’, but check if there's a Python ‘flush’

+   * callback defined.  (In C modules, nbdkit would do this).

+   */

+  else if (callback_defined ("flush", NULL))

+    return NBDKIT_FUA_EMULATE;

+  else

+    return NBDKIT_FUA_NONE;

+}

+

+static int

+py_can_cache (void *handle)

+{

+  PyObject *obj = handle;

+  PyObject *fn;

+  PyObject *r;

+  int ret;

+

+  if (callback_defined ("can_cache", &fn)) {

+    PyErr_Clear ();

+

+    r = PyObject_CallFunctionObjArgs (fn, obj, NULL);

+    Py_DECREF (fn);

+    if (check_python_failure ("can_cache") == -1)

+      return -1;

+    ret = PyLong_AsLong (r);

+    Py_DECREF (r);

+    return ret;

+  }

+  /* No Python ‘can_cache’, but check if there's a Python ‘cache’

+   * callback defined.  (In C modules, nbdkit would do this).

+   */

+  else if (callback_defined ("cache", NULL))

+    return NBDKIT_CACHE_NATIVE;

+  else

+    return NBDKIT_CACHE_NONE;

+}

+

 #define py_config_help \

   "script=<FILENAME>     (required) The Python plugin to run.\n" \

   "[other arguments may be used by the plugin that you load]"

@@ -844,6 +900,8 @@ static struct nbdkit_plugin plugin = {

   .can_trim          = py_can_trim,

   .can_zero          = py_can_zero,

   .can_fast_zero     = py_can_fast_zero,

+  .can_fua           = py_can_fua,

+  .can_cache         = py_can_cache,

   .pread             = py_pread,

   .pwrite            = py_pwrite,

-- 

2.18.2