dm stats: report precise_timestamps and histogram in @stats_list output

If the user selected the precise_timestamps or histogram options, report
it in the @stats_list message output.

If the user didn't select these options, no extra tokens are reported,
thus it is backward compatible with old software that doesn't know about
precise timestamps and histogram.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 4.2

3 files changed, 19 insertions, 3 deletions

diff --git a/Documentation/device-mapper/statistics.txt b/Documentation/device-mapper/statistics.txt
index 4919b2dfd1b3..6f5ef944ca4c 100644
--- a/Documentation/device-mapper/statistics.txt
+++ b/Documentation/device-mapper/statistics.txt
@@ -121,6 +121,10 @@ Messages
 
         Output format:
           <region_id>: <start_sector>+<length> <step> <program_id> <aux_data>
+                precise_timestamps histogram:n1,n2,n3,...
+
+        The strings "precise_timestamps" and "histogram" are printed only
+        if they were specified when creating the region.
 
     @stats_print <region_id> [<starting_line> <number_of_lines>]
 
diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index 8a8b48fa901a..8289804ccd99 100644
--- a/drivers/md/dm-stats.c
+++ b/drivers/md/dm-stats.c
@@ -457,12 +457,24 @@ static int dm_stats_list(struct dm_stats *stats, const char *program,
         list_for_each_entry(s, &stats->list, list_entry) {
                 if (!program || !strcmp(program, s->program_id)) {
                         len = s->end - s->start;
-                        DMEMIT("%d: %llu+%llu %llu %s %s\n", s->id,
+                        DMEMIT("%d: %llu+%llu %llu %s %s", s->id,
                                 (unsigned long long)s->start,
                                 (unsigned long long)len,
                                 (unsigned long long)s->step,
                                 s->program_id,
                                 s->aux_data);
+                        if (s->stat_flags & STAT_PRECISE_TIMESTAMPS)
+                                DMEMIT(" precise_timestamps");
+                        if (s->n_histogram_entries) {
+                                unsigned i;
+                                DMEMIT(" histogram:");
+                                for (i = 0; i < s->n_histogram_entries; i++) {
+                                        if (i)
+                                                DMEMIT(",");
+                                        DMEMIT("%llu", s->histogram_boundaries[i]);
+                                }
+                        }
+                        DMEMIT("\n");
                 }
         }
         mutex_unlock(&stats->mutex);
diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h
index 061aca3a962d..d34611e35a30 100644
--- a/include/uapi/linux/dm-ioctl.h
+++ b/include/uapi/linux/dm-ioctl.h
@@ -267,9 +267,9 @@ enum {
 #define DM_DEV_SET_GEOMETRY     _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
 
 #define DM_VERSION_MAJOR        4
-#define DM_VERSION_MINOR        32
+#define DM_VERSION_MINOR        33
 #define DM_VERSION_PATCHLEVEL   0
-#define DM_VERSION_EXTRA        "-ioctl (2015-6-26)"
+#define DM_VERSION_EXTRA        "-ioctl (2015-8-18)"
 
 /* Status bits */
 #define DM_READONLY_FLAG        (1 << 0) /* In/Out */