Improve detection of external changes affecting internal cache.

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.01.08 - 
 ================================
+  Improve detection of external changes affecting internal cache.
   Add 'already in device cache' debug message.
   Add -a to pvdisplay -C.
   Avoid rmdir opendir error messsages when dir was already removed.

lib/cache/lvmcache.c

@@ -104,10 +104,30 @@ struct lvmcache_vginfo *vginfo_from_vgname(const char *vgname)
 const struct format_type *fmt_from_vgname(const char *vgname)
 {
 	struct lvmcache_vginfo *vginfo;
+	struct label *label;
+	struct list *ih, *devh, *tmp;
+	struct list devs;
+	struct device_list *devl;
 
 	if (!(vginfo = vginfo_from_vgname(vgname)))
 		return NULL;
 
+	/* This function is normally called before reading metadata so
+ 	 * we check cached labels here. Unfortunately vginfo is volatile. */
+	list_init(&devs);
+	list_iterate(ih, &vginfo->infos) {
+		devl = malloc(sizeof(*devl));
+		devl->dev = list_item(ih, struct lvmcache_info)->dev;
+		list_add(&devs, &devl->list);
+	}
+
+	list_iterate_safe(devh, tmp, &devs) {
+		devl = list_item(devh, struct device_list);
+		label_read(devl->dev, &label);
+		list_del(&devl->list);
+		free(devl);
+	}
+
 	return vginfo->fmt;
 }
 
@@ -403,6 +423,9 @@ int lvmcache_update_vgname(struct lvmcache_info *info, const char *vgname)
 	/* FIXME Check consistency of list! */
 	vginfo->fmt = info->fmt;
 
+	log_debug("lvmcache: %s now %s%s", dev_name(info->dev),
+		  *vgname ? "in VG " : "orphaned", vgname);
+
 	return 1;
 }
 
@@ -551,6 +574,8 @@ static void _lvmcache_destroy_lockname(int present)
 
 void lvmcache_destroy(void)
 {
+	log_verbose("Wiping internal VG cache");
+
 	_has_scanned = 0;
 
 	if (_vgid_hash) {

lib/device/dev-cache.c

@@ -21,6 +21,7 @@
 #include "lvm-types.h"
 #include "btree.h"
 #include "filter.h"
+#include "filter-persistent.h"
 
 #include <unistd.h>
 #include <sys/param.h>
@@ -368,6 +369,7 @@ static void _full_scan(int dev_scan)
 	};
 
 	_cache.has_scanned = 1;
+	init_full_scan_done(1);
 }
 
 int dev_cache_has_scanned(void)
@@ -379,15 +381,14 @@ void dev_cache_scan(int do_scan)
 {
 	if (!do_scan)
 		_cache.has_scanned = 1;
-	else {
-		_cache.has_scanned = 0;
+	else
 		_full_scan(1);
-	}
 }
 
 int dev_cache_init(void)
 {
 	_cache.names = NULL;
+	_cache.has_scanned = 0;
 
 	if (!(_cache.mem = pool_create("dev_cache", 10 * 1024))) {
 		stack;
@@ -549,7 +550,14 @@ struct dev_iter *dev_iter_create(struct dev_filter *f, int dev_scan)
 		return NULL;
 	}
 
-	_full_scan(dev_scan);
+
+	if (dev_scan) {
+		/* Flag gets reset between each command */
+		if (!full_scan_done())
+			persistent_filter_wipe(f); /* Calls _full_scan(1) */
+	} else
+		_full_scan(0);
+
 	di->current = btree_first(_cache.devices);
 	di->filter = f;
 

lib/filters/filter-persistent.c

@@ -53,7 +53,9 @@ int persistent_filter_wipe(struct dev_filter *f)
 {
 	struct pfilter *pf = (struct pfilter *) f->private;
 
+	log_verbose("Wiping cache of LVM-capable devices");
 	hash_wipe(pf->devices);
+
 	/* Trigger complete device scan */
 	dev_cache_scan(1);
 

lib/format_text/format-text.c

@@ -188,6 +188,7 @@ static struct raw_locn *_find_vg_rlocn(struct device_area *dev_area,
 	size_t len;
 	char vgnamebuf[NAME_LEN + 2];
 	struct raw_locn *rlocn;
+	struct lvmcache_info *info;
 
 	rlocn = mdah->raw_locns;
 
@@ -196,7 +197,7 @@ static struct raw_locn *_find_vg_rlocn(struct device_area *dev_area,
 		if (!dev_read(dev_area->dev, dev_area->start + rlocn->offset,
 			      sizeof(vgnamebuf), vgnamebuf)) {
 			stack;
-			return NULL;
+			goto error;
 		}
 		if (!strncmp(vgnamebuf, vgname, len = strlen(vgname)) &&
 		    (isspace(vgnamebuf[len]) || vgnamebuf[len] == '{')) {
@@ -205,6 +206,10 @@ static struct raw_locn *_find_vg_rlocn(struct device_area *dev_area,
 		rlocn++;
 	}
 
+      error:
+	if ((info = info_from_pvid(dev_area->dev->pvid)))
+		lvmcache_update_vgname(info, ORPHAN);
+
 	return NULL;
 }
 
@@ -264,7 +269,7 @@ static struct volume_group *_vg_read_raw_area(struct format_instance *fid,
 	}
 
 	if (!(rlocn = _vg_posn(fid, area, vgname))) {
-		stack;
+		log_debug("VG %s not found on %s", vgname, dev_name(area->dev));
 		goto out;
 	}
 
@@ -1183,8 +1188,8 @@ static int _pv_read(const struct format_type *fmt, const char *pv_name,
 		return 1;
 	}
 
-	/* Perform full scan and try again */
-	if (!memlock()) {
+	/* Perform full scan (just the first time) and try again */
+	if (!memlock() && !full_scan_done()) {
 		lvmcache_label_scan(fmt->cmd, 2);
 
 		if (info->vginfo && info->vginfo->vgname &&

lib/label/label.c

@@ -117,12 +117,17 @@ static struct labeller *_find_labeller(struct device *dev, char *buf,
 	struct labeller_i *li;
 	struct labeller *r = NULL;
 	struct label_header *lh;
+	struct lvmcache_info *info;
 	uint64_t sector;
 	int found = 0;
 	char readbuf[LABEL_SCAN_SIZE];
 
 	if (!dev_open(dev)) {
 		stack;
+
+		if ((info = info_from_pvid(dev->pvid)))
+			lvmcache_update_vgname(info, ORPHAN);
+
 		return NULL;
 	}
 
@@ -182,10 +187,13 @@ static struct labeller *_find_labeller(struct device *dev, char *buf,
 		}
 	}
 
-	if (!found)
-		log_very_verbose("%s: No label detected", dev_name(dev));
-
       out:
+	if (!found) {
+		if ((info = info_from_pvid(dev->pvid)))
+			lvmcache_update_vgname(info, ORPHAN);
+		log_very_verbose("%s: No label detected", dev_name(dev));
+	}
+
 	if (!dev_close(dev))
 		stack;
 

lib/log/log.c

@@ -30,6 +30,7 @@ static int _test = 0;
 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 _debug_level = 0;
 static int _syslog = 0;
 static int _log_to_file = 0;
@@ -149,6 +150,11 @@ void init_pvmove(int level)
 	_pvmove = level;
 }
 
+void init_full_scan_done(int level)
+{
+	_full_scan_done = level;
+}
+
 void init_ignorelockingfailure(int level)
 {
 	_ignorelockingfailure = level;
@@ -203,6 +209,11 @@ int pvmove_mode()
 	return _pvmove;
 }
 
+int full_scan_done()
+{
+	return _full_scan_done;
+}
+
 int ignorelockingfailure()
 {
 	return _ignorelockingfailure;

lib/log/log.h

@@ -65,6 +65,7 @@ void init_test(int level);
 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_debug(int level);
 void init_cmd_name(int status);
 void init_msg_prefix(const char *prefix);
@@ -78,6 +79,7 @@ int test_mode(void);
 int partial_mode(void);
 int md_filtering(void);
 int pvmove_mode(void);
+int full_scan_done(void);
 int debug_level(void);
 int ignorelockingfailure(void);
 int security_level(void);

lib/metadata/metadata.c

@@ -687,10 +687,46 @@ struct volume_group *vg_read(struct cmd_context *cmd, const char *vgname,
 		}
 	}
 
-	/* Failed to find VG */
+	/* Failed to find VG where we expected it - full scan and retry */
 	if (!correct_vg) {
-		stack;
-		return NULL;
+		inconsistent = 0;
+
+		lvmcache_label_scan(cmd, 2);
+		if (!(fmt = fmt_from_vgname(vgname))) {
+			stack;
+			return NULL;
+		}
+
+		/* create format instance with appropriate metadata area */
+		if (!(fid = fmt->ops->create_instance(fmt, vgname, NULL))) {
+			log_error("Failed to create format instance");
+			return NULL;
+		}
+
+		/* Ensure contents of all metadata areas match - else recover */
+		list_iterate(mdah, &fid->metadata_areas) {
+			mda = list_item(mdah, struct metadata_area);
+			if (!(vg = mda->ops->vg_read(fid, vgname, mda))) {
+				inconsistent = 1;
+				continue;
+			}
+			if (!correct_vg) {
+				correct_vg = vg;
+				continue;
+			}
+			/* FIXME Also ensure contents same - checksums same? */
+			if (correct_vg->seqno != vg->seqno) {
+				inconsistent = 1;
+				if (vg->seqno > correct_vg->seqno)
+					correct_vg = vg;
+			}
+		}
+
+		/* Give up looking */
+		if (!correct_vg) {
+			stack;
+			return NULL;
+		}
 	}
 
 	lvmcache_update_vg(correct_vg);

tools/lvmcmdline.c

@@ -753,6 +753,7 @@ static void _apply_settings(struct cmd_context *cmd)
 	init_debug(cmd->current_settings.debug);
 	init_verbose(cmd->current_settings.verbose + VERBOSE_BASE_LEVEL);
 	init_test(cmd->current_settings.test);
+	init_full_scan_done(0);
 
 	init_msg_prefix(cmd->default_settings.msg_prefix);
 	init_cmd_name(cmd->default_settings.cmd_name);

tools/polldaemon.c

@@ -138,8 +138,11 @@ static int _wait_for_single_mirror(struct cmd_context *cmd, const char *name,
 	while (!finished) {
 		/* FIXME Also needed in vg/lvchange -ay? */
 		/* FIXME Use alarm for regular intervals instead */
-		if (parms->interval && !parms->aborting)
+		if (parms->interval && !parms->aborting) {
 			sleep(parms->interval);
+			/* Devices might have changed while we slept */
+			init_full_scan_done(0);
+		}
 
 		/* Locks the (possibly renamed) VG again */
 		if (!(vg = parms->poll_fns->get_copy_vg(cmd, name))) {

tools/pvcreate.c

@@ -63,10 +63,10 @@ static int pvcreate_check(struct cmd_context *cmd, const char *name)
 	/* Is there an md superblock here? */
 	if (!dev && md_filtering()) {
 		unlock_vg(cmd, "");
-		log_verbose("Wiping cache of LVM-capable devices");
+
 		persistent_filter_wipe(cmd->filter);
-		log_verbose("Wiping internal cache");
 		lvmcache_destroy();
+
 		init_md_filtering(0);
 		if (!lock_vol(cmd, "", LCK_VG_WRITE)) {
 			log_error("Can't get lock for orphan PVs");

tools/pvscan.c

@@ -123,10 +123,7 @@ int pvscan(struct cmd_context *cmd, int argc, char **argv)
 			  arg_count(cmd, exported_ARG) ?
 			  "of exported volume group(s)" : "in no volume group");
 
-	log_verbose("Wiping cache of LVM-capable devices");
 	persistent_filter_wipe(cmd->filter);
-
-	log_verbose("Wiping internal cache");
 	lvmcache_destroy();
 
 	log_verbose("Walking through all physical volumes");

tools/vgscan.c

@@ -48,10 +48,7 @@ int vgscan(struct cmd_context *cmd, int argc, char **argv)
 		return EINVALID_CMD_LINE;
 	}
 
-	log_verbose("Wiping cache of LVM-capable devices");
 	persistent_filter_wipe(cmd->filter);
-
-	log_verbose("Wiping internal cache");
 	lvmcache_destroy();
 
 	log_print("Reading all physical volumes.  This may take a while...");