* [PATCH nbdinfo proposal] info: Add a --map option for displaying allocation metadata.
2020-09-26 14:36 [PATCH nbdinfo proposal] info: Add a --map option for displaying allocation metadata Richard W.M. Jones
@ 2020-09-26 14:36 ` Richard W.M. Jones
0 siblings, 0 replies; 2+ messages in thread
From: Richard W.M. Jones @ 2020-09-26 14:36 UTC (permalink / raw)
To: libguestfs; +Cc: vsementsov, pkrempa, qemu-devel
---
info/nbdinfo.c | 132 ++++++++++++++++++++++++++++++++++++++++++++---
info/nbdinfo.pod | 39 +++++++++++++-
2 files changed, 164 insertions(+), 7 deletions(-)
diff --git a/info/nbdinfo.c b/info/nbdinfo.c
index 647a24c..d1648b8 100644
--- a/info/nbdinfo.c
+++ b/info/nbdinfo.c
@@ -34,6 +34,7 @@
static bool list_all = false;
static bool probe_content, content_flag, no_content_flag;
static bool json_output = false;
+static const char *map = NULL;
static bool size_only = false;
static struct export_list {
@@ -49,6 +50,10 @@ static void list_one_export (struct nbd_handle *nbd, const char *desc,
static void list_all_exports (struct nbd_handle *nbd1, const char *uri);
static void print_json_string (const char *);
static char *get_content (struct nbd_handle *, int64_t size);
+static int extent_callback (void *user_data, const char *metacontext,
+ uint64_t offset,
+ uint32_t *entries, size_t nr_entries,
+ int *error);
static void __attribute__((noreturn))
usage (FILE *fp, int exitcode)
@@ -60,6 +65,7 @@ usage (FILE *fp, int exitcode)
" nbdinfo nbd://localhost\n"
" nbdinfo \"nbd+unix:///?socket=/tmp/unixsock\"\n"
" nbdinfo --size nbd://example.com\n"
+" nbdinfo --map nbd://example.com\n"
" nbdinfo --json nbd://example.com\n"
" nbdinfo --list nbd://example.com\n"
"\n"
@@ -85,6 +91,7 @@ main (int argc, char *argv[])
CONTENT_OPTION,
NO_CONTENT_OPTION,
JSON_OPTION,
+ MAP_OPTION,
SIZE_OPTION,
};
const char *short_options = "LV";
@@ -95,6 +102,7 @@ main (int argc, char *argv[])
{ "json", no_argument, NULL, JSON_OPTION },
{ "list", no_argument, NULL, 'L' },
{ "long-options", no_argument, NULL, LONG_OPTIONS },
+ { "map", optional_argument, NULL, MAP_OPTION },
{ "short-options", no_argument, NULL, SHORT_OPTIONS },
{ "size", no_argument, NULL, SIZE_OPTION },
{ "version", no_argument, NULL, 'V' },
@@ -143,6 +151,10 @@ main (int argc, char *argv[])
no_content_flag = true;
break;
+ case MAP_OPTION:
+ map = optarg ? optarg : "base:allocation";
+ break;
+
case SIZE_OPTION:
size_only = true;
break;
@@ -164,10 +176,11 @@ main (int argc, char *argv[])
if (argc - optind != 1)
usage (stderr, EXIT_FAILURE);
- /* You can combine certain options. */
- if (list_all && size_only) {
- fprintf (stderr, "%s: you cannot use %s and %s together.\n",
- argv[0], "--list", "--size");
+ /* You cannot combine certain options. */
+ if (!!list_all + !!map + !!size_only > 1) {
+ fprintf (stderr,
+ "%s: you cannot use --list, --map and --size together.\n",
+ argv[0]);
exit (EXIT_FAILURE);
}
if (content_flag && no_content_flag) {
@@ -182,6 +195,8 @@ main (int argc, char *argv[])
probe_content = true;
if (no_content_flag)
probe_content = false;
+ if (map)
+ probe_content = false;
/* Open the NBD side. */
nbd = nbd_create ();
@@ -191,11 +206,13 @@ main (int argc, char *argv[])
}
nbd_set_uri_allow_local_file (nbd, true); /* Allow ?tls-psk-file. */
- /* If using --list then we need opt mode in the handle. */
+ /* Set optional modes in the handle. */
if (list_all)
nbd_set_opt_mode (nbd, true);
- if (!size_only)
+ if (!map && !size_only)
nbd_set_full_info (nbd, true);
+ if (map)
+ nbd_add_meta_context (nbd, map);
if (nbd_connect_uri (nbd, argv[optind]) == -1) {
fprintf (stderr, "%s\n", nbd_get_error ());
@@ -225,6 +242,43 @@ main (int argc, char *argv[])
printf ("%" PRIi64 "\n", size);
}
+ else if (map) {
+ uint64_t offset, prev_offset;
+
+ /* Did we get the requested map? */
+ if (!nbd_can_meta_context (nbd, map)) {
+ fprintf (stderr,
+ "%s: --map: server does not support metadata context \"%s\"\n",
+ argv[0], map);
+ exit (EXIT_FAILURE);
+ }
+
+ size = nbd_get_size (nbd);
+ if (size == -1) {
+ fprintf (stderr, "%s\n", nbd_get_error ());
+ exit (EXIT_FAILURE);
+ }
+
+ for (offset = 0; offset < size;) {
+ prev_offset = offset;
+ if (nbd_block_status (nbd, size - offset, offset,
+ (nbd_extent_callback) { .callback = extent_callback,
+ .user_data = &offset },
+ 0) == -1) {
+ fprintf (stderr, "%s\n", nbd_get_error ());
+ exit (EXIT_FAILURE);
+ }
+ /* We expect extent_callback to increment the offset. If it did
+ * not then probably the server is not returning any extents.
+ */
+ if (offset <= prev_offset) {
+ fprintf (stderr, "%s: --map: server did not return any extents\n",
+ argv[0]);
+ exit (EXIT_FAILURE);
+ }
+ }
+ if (json_output) printf ("\n");
+ }
else {
/* Print per-connection fields. */
protocol = nbd_get_protocol (nbd);
@@ -591,3 +645,69 @@ get_content (struct nbd_handle *nbd, int64_t size)
free (cmd);
return ret; /* caller frees */
}
+
+/* Callback handling --map. */
+static const char *
+extent_description (const char *metacontext, uint32_t type)
+{
+ if (strcmp (metacontext, "base:allocation") == 0) {
+ switch (type) {
+ case 0: return "allocated";
+ case 1: return "zero";
+ case 2: return "hole";
+ case 3: return "hole,zero";
+ }
+ }
+ else if (strcmp (metacontext, "qemu:dirty-bitmap") == 0) {
+ switch (type) {
+ case 0: return "dirty";
+ case 1: return "clean";
+ }
+ }
+
+ return "unknown";
+}
+
+static int
+extent_callback (void *user_data, const char *metacontext,
+ uint64_t offset,
+ uint32_t *entries, size_t nr_entries,
+ int *error)
+{
+ size_t i;
+ uint64_t *ret_offset = user_data;
+ static bool comma = false;
+
+ if (strcmp (metacontext, map) != 0)
+ return 0;
+
+ /* Print the entries received. */
+ for (i = 0; i < nr_entries; i += 2) {
+ const char *descr = extent_description (map, entries[i+1]);
+
+ if (!json_output) {
+ printf ("%" PRIu64 " "
+ "%" PRIu32 " "
+ "%" PRIu32 " "
+ "%s\n",
+ offset, entries[i], entries[i+1], descr);
+ }
+ else {
+ if (comma)
+ printf (",\n");
+
+ printf ("[%" PRIu64 ", "
+ "%" PRIu32 ", "
+ "%" PRIu32 ", ",
+ offset, entries[i], entries[i+1]);
+ print_json_string (descr);
+ printf ("]");
+ comma = true;
+ }
+
+ offset += entries[i];
+ }
+
+ *ret_offset = offset;
+ return 0;
+}
diff --git a/info/nbdinfo.pod b/info/nbdinfo.pod
index 19305bf..dbfb62f 100644
--- a/info/nbdinfo.pod
+++ b/info/nbdinfo.pod
@@ -4,7 +4,7 @@ nbdinfo - display information and metadata about NBD servers and exports
=head1 SYNOPSIS
- nbdinfo [--json] [--size] NBD-URI
+ nbdinfo [--json] [--map] [--size] NBD-URI
nbdinfo -L|--list NBD-URI
@@ -20,6 +20,8 @@ nbdinfo - display information and metadata about NBD servers and exports
nbdinfo --size nbd://example.com
+ nbdinfo --map nbd://example.com
+
nbdinfo --json nbd://example.com
nbdinfo --list nbd://example.com
@@ -84,6 +86,32 @@ the I<--json> parameter:
]
}
+=head3 Map
+
+To show a map which areas of the disk are allocated and sparse, use
+the I<--map> option:
+
+ $ nbdinfo --map nbd://localhost/
+ 0 1048576 0 allocated
+ 1048576 2097152 3 hole,zero
+
+The fields are: start size type description.
+
+The type field is an integer showing the raw value from the NBD
+protocol. For some maps nbdinfo knows how to translate the type into
+a printable description.
+
+By default this shows the C<"base:allocation"> map, but you can show
+other maps too:
+
+ $ nbdinfo --map=qemu:dirty-bitmap nbd://localhost/
+ 0 1048576 dirty
+
+For more information on NBD maps, see I<Metadata querying> in the NBD
+protocol. I<--json> can also be used here for parsable JSON output.
+
+=head3 List of exports
+
To list all the exports available on an NBD server use the I<--list>
(I<-L>) option.
@@ -122,6 +150,15 @@ use I<--list --content>.
The output is displayed in JSON format.
+=item B<--map>
+
+=item B<--map=>MAP
+
+Display the map (usually whether parts of the disk are allocated or
+sparse) of the given export. This displays the C<"base:allocation">
+map by default, you can choose a different map with the optional
+parameter.
+
=item B<-L>
=item B<--list>
--
2.27.0
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