process_each_pv: do full scan earlier to find new devicesdev-dct-dev-cache-full-scan

Before commit c1f246fedfc349c25749da501e68a7f70bd122b0,
_get_all_devices() did a full device scan before
get_vgnameids() was called.  New devices would be
added to the dev-cache before label scanning done
by get_vgnameids.  So, labels would be read from
new devices by the first 'pvs' command.

After that commit, _get_all_devices() was called
after get_vgnameids() was finished with label scanning.
So, new devices would be missed by the label scanning,
and would not appear to be lvm devices to the first
'pvs' command.  A new device would be added to .cache
by the first command, so the second 'pvs' command would
scan labels from it in get_vgnameids().

Now, the full device scan is factored out of
get_all_devices() and called by itself at the
start of the command so that new devices will
be known before get_vgnameids() scans labels.

4 files changed, 28 insertions, 9 deletions

diff --git a/lib/cache/lvmcache.c b/lib/cache/lvmcache.c
index 799de6f6e..2a01ec2cb 100644
--- a/lib/cache/lvmcache.c
+++ b/lib/cache/lvmcache.c
@@ -749,6 +749,7 @@ int lvmcache_label_scan(struct cmd_context *cmd, int full_scan)
 	struct dev_iter *iter;
 	struct device *dev;
 	struct format_type *fmt;
+	int dev_count = 0;
 
 	int r = 0;
 
@@ -779,11 +780,17 @@ int lvmcache_label_scan(struct cmd_context *cmd, int full_scan)
 		goto out;
 	}
 
-	while ((dev = dev_iter_get(iter)))
+	log_very_verbose("Scanning device labels");
+
+	while ((dev = dev_iter_get(iter))) {
 		(void) label_read(dev, &label, UINT64_C(0));
+		dev_count++;
+	}
 
 	dev_iter_destroy(iter);
 
+	log_very_verbose("Scanned %d device labels", dev_count);
+
 	_has_scanned = 1;
 
 	/* Perform any format-specific scanning e.g. text files */
diff --git a/lib/device/dev-cache.c b/lib/device/dev-cache.c
index 7626cebbd..97165dbf8 100644
--- a/lib/device/dev-cache.c
+++ b/lib/device/dev-cache.c
@@ -1026,6 +1026,16 @@ struct device *dev_cache_get_by_devt(dev_t dev, struct dev_filter *f)
 		      f->passes_filter(f, d))) ? d : NULL;
 }
 
+void dev_cache_full_scan(struct dev_filter *f)
+{
+	if (f && f->wipe) {
+		f->wipe(f); /* might call _full_scan(1) */
+		if (!full_scan_done())
+			_full_scan(1);
+	} else
+		_full_scan(1);
+}
+
 struct dev_iter *dev_iter_create(struct dev_filter *f, int dev_scan)
 {
 	struct dev_iter *di = dm_malloc(sizeof(*di));
@@ -1037,14 +1047,8 @@ struct dev_iter *dev_iter_create(struct dev_filter *f, int dev_scan)
 
 	if (dev_scan && !trust_cache()) {
 		/* Flag gets reset between each command */
-		if (!full_scan_done()) {
-			if (f && f->wipe) {
-				f->wipe(f); /* might call _full_scan(1) */
-				if (!full_scan_done())
-					_full_scan(1);
-			} else
-				_full_scan(1);
-		}
+		if (!full_scan_done())
+			dev_cache_full_scan(f);
 	} else
 		_full_scan(0);
 
diff --git a/lib/device/dev-cache.h b/lib/device/dev-cache.h
index 4fca35885..4efe41fe5 100644
--- a/lib/device/dev-cache.h
+++ b/lib/device/dev-cache.h
@@ -45,6 +45,7 @@ int dev_cache_check_for_open_devices(void);
 /* Trigger(1) or avoid(0) a scan */
 void dev_cache_scan(int do_scan);
 int dev_cache_has_scanned(void);
+void dev_cache_full_scan(struct dev_filter *f);
 
 int dev_cache_add_dir(const char *path);
 int dev_cache_add_loopfile(const char *path);
diff --git a/tools/toollib.c b/tools/toollib.c
index e03aaf77f..fb6edadde 100644
--- a/tools/toollib.c
+++ b/tools/toollib.c
@@ -3340,6 +3340,13 @@ int process_each_pv(struct cmd_context *cmd,
 		return_ECMD_FAILED;
 
 	/*
+	 * This full scan would be done by _get_all_devices() if
+	 * it were not done here first.  It's called here first
+	 * so that get_vgnameids() will look at any new devices.
+	 */
+	dev_cache_full_scan(cmd->full_filter);
+
+	/*
 	 * Need pvid's set on all PVs before processing so that pvid's
 	 * can be compared to find duplicates while processing.
 	 */