[Libguestfs] [libnbd PATCH 3/3] nbdinfo: Expose block size constraints

[Eric Blake]

Now that we have an API, it's time to put it to use.
---
 info/nbdinfo.pod |  6 ++++++
 info/nbdinfo.c   | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/info/nbdinfo.pod b/info/nbdinfo.pod
index 9761551..d0d20a9 100644
--- a/info/nbdinfo.pod
+++ b/info/nbdinfo.pod
@@ -45,6 +45,9 @@ L<https://github.com/NetworkBlockDevice/nbd/blob/master/doc/uri.md>):
          can_multi_conn: true
          can_trim: true
          can_zero: true
+         block_size_minimum: 1
+         block_size_preferred: 4096
+         block_size_maximum: 33554432

 To display only the size in bytes of the NBD export (useful for
 scripting) use the I<--size> parameter:
@@ -73,6 +76,9 @@ the I<--json> parameter:
        "can_multi_conn": true,
        "can_trim": false,
        "can_zero": false,
+       "block_size_minimum": 1,
+       "block_size_preferred": 4096,
+       "block_size_maximum": 33554432,
        "export-size": 2125119488
      }
    ]
diff --git a/info/nbdinfo.c b/info/nbdinfo.c
index 455cfc8..4c58815 100644
--- a/info/nbdinfo.c
+++ b/info/nbdinfo.c
@@ -264,6 +264,7 @@ list_one_export (struct nbd_handle *nbd)
   int is_rotational, is_read_only;
   int can_cache, can_df, can_fast_zero, can_flush, can_fua,
     can_multi_conn, can_trim, can_zero;
+  int64_t block_minimum, block_preferred, block_maximum;

   /* Collect the metadata we are going to display. */
   size = nbd_get_size (nbd);
@@ -288,6 +289,9 @@ list_one_export (struct nbd_handle *nbd)
   can_multi_conn = nbd_can_multi_conn (nbd);
   can_trim = nbd_can_trim (nbd);
   can_zero = nbd_can_zero (nbd);
+  block_minimum = nbd_get_block_size (nbd, LIBNBD_SIZE_MINIMUM);
+  block_preferred = nbd_get_block_size (nbd, LIBNBD_SIZE_PREFERRED);
+  block_maximum = nbd_get_block_size (nbd, LIBNBD_SIZE_MAXIMUM);

   if (!json_output) {
     printf ("export=");
@@ -317,6 +321,12 @@ list_one_export (struct nbd_handle *nbd)
       printf ("\t%s: %s\n", "can_trim", can_trim ? "true" : "false");
     if (can_zero >= 0)
       printf ("\t%s: %s\n", "can_zero", can_zero ? "true" : "false");
+    if (block_minimum > 0)
+      printf ("\t%s: %" PRId64 "\n", "block_size_minimum", block_minimum);
+    if (block_preferred > 0)
+      printf ("\t%s: %" PRId64 "\n", "block_size_preferred", block_preferred);
+    if (block_maximum > 0)
+      printf ("\t%s: %" PRId64 "\n", "block_size_maximum", block_maximum);
   }
   else {
     printf ("\"exports\": [\n");
@@ -363,6 +373,14 @@ list_one_export (struct nbd_handle *nbd)
       printf ("\t\"%s\": %s,\n",
               "can_zero", can_zero ? "true" : "false");

+    if (block_minimum > 0)
+      printf ("\t\"%s\": %" PRId64 ",\n", "block_size_minimum", block_minimum);
+    if (block_preferred > 0)
+      printf ("\t\"%s\": %" PRId64 ",\n", "block_size_preferred",
+              block_preferred);
+    if (block_maximum > 0)
+      printf ("\t\"%s\": %" PRId64 ",\n", "block_size_maximum", block_maximum);
+
     /* Put this one at the end because of the stupid comma thing in JSON. */
     printf ("\t\"export-size\": %" PRIi64 "\n", size);

-- 
2.27.0