dissect-image: filter out enumerated or triggered devices without "partition" sysattr

This also adds more filters for device enumerator and monitor.
These newly added filters should be mostly redundant. But this hides
spurious error in sd_device_get_sysattr_value(). See,
https://github.com/systemd/systemd/pull/18684#discussion_r579700977

diff --git a/src/shared/dissect-image.c b/src/shared/dissect-image.c
index fabf3b2e2ec025424611ea4f9cf9c12c307bba41..fb8df16ebc3278b84cf5e58bab386f3881b28858 100644 (file)
--- a/src/shared/dissect-image.c
+++ b/src/shared/dissect-image.c
@@ -127,10 +127,18 @@ static int enumerator_for_parent(sd_device *d, sd_device_enumerator **ret) {
         if (r < 0)
                 return r;
 
+        r = sd_device_enumerator_add_match_subsystem(e, "block", true);
+        if (r < 0)
+                return r;
+
         r = sd_device_enumerator_add_match_parent(e, d);
         if (r < 0)
                 return r;
 
+        r = sd_device_enumerator_add_match_sysattr(e, "partition", NULL, true);
+        if (r < 0)
+                return r;
+
         *ret = TAKE_PTR(e);
         return 0;
 }
@@ -151,9 +159,6 @@ static int device_is_partition(sd_device *d, blkid_partition pp) {
                 return false;
 
         r = sd_device_get_sysattr_value(d, "partition", &v);
-        if (r == -ENOENT ||        /* Not a partition device */
-            ERRNO_IS_PRIVILEGE(r)) /* Not ready to access? */
-                return false;
         if (r < 0)
                 return r;
         r = safe_atoi(v, &partno);
@@ -313,6 +318,14 @@ static int wait_for_partition_device(
         if (r < 0)
                 return r;
 
+        r = sd_device_monitor_filter_add_match_parent(monitor, parent, true);
+        if (r < 0)
+                return r;
+
+        r = sd_device_monitor_filter_add_match_sysattr(monitor, "partition", NULL, true);
+        if (r < 0)
+                return r;
+
         r = sd_device_monitor_attach_event(monitor, event);
         if (r < 0)
                 return r;