Add --trustcache option to reporting commands in preparation for supporting

event-driven model.  Without changes to the way the cache gets updated, the
option is currently unreliable without a global lock to prevent any lvm2
commands from running concurrently.

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.02.08 - 
 ================================
+  Add unreliable --trustcache option to reporting commands.
   Fix locking for mimage removal.
   Fix clvmd_init_rhel4 'status' exit code.
 

lib/cache/lvmcache.c

@@ -241,7 +241,7 @@ int lvmcache_label_scan(struct cmd_context *cmd, int full_scan)
 		goto out;
 	}
 
-	if (!(iter = dev_iter_create(cmd->filter, (full_scan == 2) ? 1: 0))) {
+	if (!(iter = dev_iter_create(cmd->filter, (full_scan == 2) ? 1 : 0))) {
 		log_error("dev_iter creation failed");
 		goto out;
 	}

lib/device/dev-cache.c

@@ -645,8 +645,7 @@ struct dev_iter *dev_iter_create(struct dev_filter *f, int dev_scan)
 		return NULL;
 	}
 
-
-	if (dev_scan) {
+	if (dev_scan && !trust_cache()) {
 		/* Flag gets reset between each command */
 		if (!full_scan_done())
 			persistent_filter_wipe(f); /* Calls _full_scan(1) */

lib/format1/disk-rep.c

@@ -458,7 +458,7 @@ static void _add_pv_to_list(struct list *head, struct disk_list *data)
 
 /*
  * Build a list of pv_d's structures, allocated from mem.
- * We keep track of the first object allocated form the pool
+ * We keep track of the first object allocated from the pool
  * so we can free off all the memory if something goes wrong.
  */
 int read_pvs_in_vg(const struct format_type *fmt, const char *vg_name,

lib/log/log.c

@@ -32,6 +32,7 @@ static int _partial = 0;
 static int _md_filtering = 0;
 static int _pvmove = 0;
 static int _full_scan_done = 0;	/* Restrict to one full scan during each cmd */
+static int _trust_cache = 0; /* Don't scan when incomplete VGs encountered */
 static int _debug_level = 0;
 static int _syslog = 0;
 static int _log_to_file = 0;
@@ -163,6 +164,11 @@ void init_full_scan_done(int level)
 	_full_scan_done = level;
 }
 
+void init_trust_cache(int trustcache)
+{
+	_trust_cache = trustcache;
+}
+
 void init_ignorelockingfailure(int level)
 {
 	_ignorelockingfailure = level;
@@ -237,6 +243,11 @@ int full_scan_done()
 	return _full_scan_done;
 }
 
+int trust_cache()
+{
+	return _trust_cache;
+}
+
 int lockingfailed()
 {
 	return _lockingfailed;

lib/log/log.h

@@ -66,6 +66,7 @@ void init_partial(int level);
 void init_md_filtering(int level);
 void init_pvmove(int level);
 void init_full_scan_done(int level);
+void init_trust_cache(int trustcache);
 void init_debug(int level);
 void init_cmd_name(int status);
 void init_msg_prefix(const char *prefix);
@@ -83,6 +84,7 @@ int partial_mode(void);
 int md_filtering(void);
 int pvmove_mode(void);
 int full_scan_done(void);
+int trust_cache(void);
 int debug_level(void);
 int ignorelockingfailure(void);
 int lockingfailed(void);

tools/args.h

@@ -49,6 +49,7 @@ arg(nosync_ARG, '\0', "nosync", NULL)
 arg(corelog_ARG, '\0', "corelog", NULL)
 arg(monitor_ARG, '\0', "monitor", yes_no_arg)
 arg(config_ARG, '\0', "config", string_arg)
+arg(trustcache_ARG, '\0', "trustcache", NULL)
 
 /* Allow some variations */
 arg(resizable_ARG, '\0', "resizable", yes_no_arg)

tools/commands.h

@@ -343,6 +343,7 @@ xx(lvs,
    "\t[-P|--partial] " "\n"
    "\t[--segments]\n"
    "\t[--separator Separator]\n"
+   "\t[--trustcache]\n"
    "\t[--unbuffered]\n"
    "\t[--units hsbkmgtHKMGT]\n"
    "\t[-v|--verbose]\n"
@@ -351,7 +352,7 @@ xx(lvs,
 
    aligned_ARG, all_ARG, ignorelockingfailure_ARG, noheadings_ARG,
    nolocking_ARG, nosuffix_ARG, options_ARG, partial_ARG, segments_ARG,
-   separator_ARG, sort_ARG, unbuffered_ARG, units_ARG)
+   separator_ARG, sort_ARG, trustcache_ARG, unbuffered_ARG, units_ARG)
 
 xx(lvscan,
    "List all logical volumes in all volume groups",
@@ -527,6 +528,7 @@ xx(pvs,
    "\t[-P|--partial] " "\n"
    "\t[--segments]\n"
    "\t[--separator Separator]\n"
+   "\t[--trustcache]\n"
    "\t[--unbuffered]\n"
    "\t[--units hsbkmgtHKMGT]\n"
    "\t[-v|--verbose]\n"
@@ -535,7 +537,7 @@ xx(pvs,
 
    aligned_ARG, all_ARG, ignorelockingfailure_ARG, noheadings_ARG,
    nolocking_ARG, nosuffix_ARG, options_ARG, partial_ARG, segments_ARG,
-   separator_ARG, sort_ARG, unbuffered_ARG, units_ARG)
+   separator_ARG, sort_ARG, trustcache_ARG, unbuffered_ARG, units_ARG)
 
 xx(pvscan,
    "List all physical volumes",
@@ -819,6 +821,7 @@ xx(vgs,
    "\t[-O|--sort [+|-]key1[,[+|-]key2[,...]]]\n"
    "\t[-P|--partial] " "\n"
    "\t[--separator Separator]\n"
+   "\t[--trustcache]\n"
    "\t[--unbuffered]\n"
    "\t[--units hsbkmgtHKMGT]\n"
    "\t[-v|--verbose]\n"
@@ -827,7 +830,7 @@ xx(vgs,
 
    aligned_ARG, all_ARG, ignorelockingfailure_ARG, noheadings_ARG,
    nolocking_ARG, nosuffix_ARG, options_ARG, partial_ARG, separator_ARG,
-   sort_ARG, unbuffered_ARG, units_ARG)
+   sort_ARG, trustcache_ARG, unbuffered_ARG, units_ARG)
 
 xx(vgscan,
    "Search for all volume groups",

tools/lvmcmdline.c

@@ -707,6 +707,17 @@ static int _get_settings(struct cmd_context *cmd)
 			return EINVALID_CMD_LINE;
 		}
 
+	if (arg_count(cmd, trustcache_ARG)) {
+		if (arg_count(cmd, all_ARG)) {
+			log_error("--trustcache is incompatible with --all");
+			return EINVALID_CMD_LINE;
+		}
+		init_trust_cache(1);
+		log_print("WARNING: Cache file of PVs will be trusted.  "
+			  "New devices holding PVs may get ignored.");
+	} else
+		init_trust_cache(0);
+
 	/* Handle synonyms */
 	if (!_merge_synonym(cmd, resizable_ARG, resizeable_ARG) ||
 	    !_merge_synonym(cmd, allocation_ARG, allocatable_ARG) ||