qga: add guest-get-diskstats command for Linux guests

Add a new 'guest-get-diskstats' command for report disk io statistics
for Linux guests. This can be useful for getting io flow or handling
IO fault, no need to enter guests.

Signed-off-by: luzhipeng <luzhipeng@cestc.cn>
Message-Id: <20220520021935.676-1-luzhipeng@cestc.cn>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>

1 files changed, 123 insertions, 0 deletions

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 69f209af87..12b50b7124 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -2783,6 +2783,122 @@ GuestMemoryBlockInfo *qmp_guest_get_memory_block_info(Error **errp)
     return info;
 }
 
+#define MAX_NAME_LEN 128
+static GuestDiskStatsInfoList *guest_get_diskstats(Error **errp)
+{
+#ifdef CONFIG_LINUX
+    GuestDiskStatsInfoList *head = NULL, **tail = &head;
+    const char *diskstats = "/proc/diskstats";
+    FILE *fp;
+    size_t n;
+    char *line = NULL;
+
+    fp = fopen(diskstats, "r");
+    if (fp  == NULL) {
+        error_setg_errno(errp, errno, "open(\"%s\")", diskstats);
+        return NULL;
+    }
+
+    while (getline(&line, &n, fp) != -1) {
+        g_autofree GuestDiskStatsInfo *diskstatinfo = NULL;
+        g_autofree GuestDiskStats *diskstat = NULL;
+        char dev_name[MAX_NAME_LEN];
+        unsigned int ios_pgr, tot_ticks, rq_ticks, wr_ticks, dc_ticks, fl_ticks;
+        unsigned long rd_ios, rd_merges_or_rd_sec, rd_ticks_or_wr_sec, wr_ios;
+        unsigned long wr_merges, rd_sec_or_wr_ios, wr_sec;
+        unsigned long dc_ios, dc_merges, dc_sec, fl_ios;
+        unsigned int major, minor;
+        int i;
+
+        i = sscanf(line, "%u %u %s %lu %lu %lu"
+                   "%lu %lu %lu %lu %u %u %u %u"
+                   "%lu %lu %lu %u %lu %u",
+                   &major, &minor, dev_name,
+                   &rd_ios, &rd_merges_or_rd_sec, &rd_sec_or_wr_ios,
+                   &rd_ticks_or_wr_sec, &wr_ios, &wr_merges, &wr_sec,
+                   &wr_ticks, &ios_pgr, &tot_ticks, &rq_ticks,
+                   &dc_ios, &dc_merges, &dc_sec, &dc_ticks,
+                   &fl_ios, &fl_ticks);
+
+        if (i < 7) {
+            continue;
+        }
+
+        diskstatinfo = g_new0(GuestDiskStatsInfo, 1);
+        diskstatinfo->name = g_strdup(dev_name);
+        diskstatinfo->major = major;
+        diskstatinfo->minor = minor;
+
+        diskstat = g_new0(GuestDiskStats, 1);
+        if (i == 7) {
+            diskstat->has_read_ios = true;
+            diskstat->read_ios = rd_ios;
+            diskstat->has_read_sectors = true;
+            diskstat->read_sectors = rd_merges_or_rd_sec;
+            diskstat->has_write_ios = true;
+            diskstat->write_ios = rd_sec_or_wr_ios;
+            diskstat->has_write_sectors = true;
+            diskstat->write_sectors = rd_ticks_or_wr_sec;
+        }
+        if (i >= 14) {
+            diskstat->has_read_ios = true;
+            diskstat->read_ios = rd_ios;
+            diskstat->has_read_sectors = true;
+            diskstat->read_sectors = rd_sec_or_wr_ios;
+            diskstat->has_read_merges = true;
+            diskstat->read_merges = rd_merges_or_rd_sec;
+            diskstat->has_read_ticks = true;
+            diskstat->read_ticks = rd_ticks_or_wr_sec;
+            diskstat->has_write_ios = true;
+            diskstat->write_ios = wr_ios;
+            diskstat->has_write_sectors = true;
+            diskstat->write_sectors = wr_sec;
+            diskstat->has_write_merges = true;
+            diskstat->write_merges = wr_merges;
+            diskstat->has_write_ticks = true;
+            diskstat->write_ticks = wr_ticks;
+            diskstat->has_ios_pgr = true;
+            diskstat->ios_pgr = ios_pgr;
+            diskstat->has_total_ticks = true;
+            diskstat->total_ticks = tot_ticks;
+            diskstat->has_weight_ticks = true;
+            diskstat->weight_ticks = rq_ticks;
+        }
+        if (i >= 18) {
+            diskstat->has_discard_ios = true;
+            diskstat->discard_ios = dc_ios;
+            diskstat->has_discard_merges = true;
+            diskstat->discard_merges = dc_merges;
+            diskstat->has_discard_sectors = true;
+            diskstat->discard_sectors = dc_sec;
+            diskstat->has_discard_ticks = true;
+            diskstat->discard_ticks = dc_ticks;
+        }
+        if (i >= 20) {
+            diskstat->has_flush_ios = true;
+            diskstat->flush_ios = fl_ios;
+            diskstat->has_flush_ticks = true;
+            diskstat->flush_ticks = fl_ticks;
+        }
+
+        diskstatinfo->stats = g_steal_pointer(&diskstat);
+        QAPI_LIST_APPEND(tail, diskstatinfo);
+        diskstatinfo = NULL;
+    }
+    free(line);
+    fclose(fp);
+    return head;
+#else
+    g_debug("disk stats reporting available only for Linux");
+    return NULL;
+#endif
+}
+
+GuestDiskStatsInfoList *qmp_guest_get_diskstats(Error **errp)
+{
+    return guest_get_diskstats(errp);
+}
+
 #else /* defined(__linux__) */
 
 void qmp_guest_suspend_disk(Error **errp)
@@ -3131,6 +3247,13 @@ GuestDiskInfoList *qmp_guest_get_disks(Error **errp)
     return NULL;
 }
 
+GuestDiskStatsInfoList *qmp_guest_get_diskstats(Error **errp)
+{
+    error_setg(errp, QERR_UNSUPPORTED);
+    return NULL;
+}
+
+
 #endif /* CONFIG_FSFREEZE */
 
 #if !defined(CONFIG_FSTRIM)