[lvm-devel] master - lvmetad: Re-organise filters to properly avoid scans of component devices.

[Alasdair Kergon]

Gitweb:        http://git.fedorahosted.org/git/?p=lvm2.git;a=commitdiff;h=a7be3b12dfe7388d1648595e6cc4c7a1379bb8a7
Commit:        a7be3b12dfe7388d1648595e6cc4c7a1379bb8a7
Parent:        1f0c4c811da287e7fc28b8c31dcd03347b16d360
Author:        Petr Rockai <prockai at redhat.com>
AuthorDate:    Tue Sep 9 17:16:40 2014 +0200
Committer:     Alasdair G Kergon <agk at redhat.com>
CommitterDate: Wed Sep 10 22:58:02 2014 +0100

lvmetad: Re-organise filters to properly avoid scans of component devices.

If a PV label is exposed both through a composite device (MD for example) and
through its component devices, we always want the PV that lvmetad sees to be the
composite, since this is what all LVM commands (including activation) will then
use. If pvscan --cache is triggered for multiple clones of the same PV, the last
to finish wins. This patch basically re-arranges the filters so that
component-device filters are part of the global_filter chain, not of the
client-side filter chain. This has a subtle effect on filter evaluation order,
but should not alter visible semantics in the non-lvmetad case.
---
 lib/commands/toolcontext.c |   47 +++++++++++++++++++++----------------------
 1 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/lib/commands/toolcontext.c b/lib/commands/toolcontext.c
index fe79a81..5bf5cbf 100644
--- a/lib/commands/toolcontext.c
+++ b/lib/commands/toolcontext.c
@@ -861,11 +861,9 @@ static struct dev_filter *_init_filter_components(struct cmd_context *cmd)
 	}
 
 	/* regex filter. Optional. */
-	if (!(cn = find_config_tree_node(cmd, devices_filter_CFG, NULL)))
-		log_very_verbose("devices/filter not found in config file: "
-				 "no regex filter installed");
-	else if (!(filters[nr_filt] = regex_filter_create(cn->v))) {
-		log_error("Failed to create regex device filter");
+	if ((cn = find_config_tree_node(cmd, devices_global_filter_CFG, NULL)) &&
+	    !(filters[nr_filt] = regex_filter_create(cn->v))) {
+		log_error("Failed to create global regex device filter");
 		goto bad;
 	} else
 		nr_filt++;
@@ -918,16 +916,26 @@ static int _init_filters(struct cmd_context *cmd, unsigned load_persistent_cache
 
 	cmd->dump_filter = 0;
 
-	if (!(f3 = _init_filter_components(cmd)))
+	if (!(cmd->lvmetad_filter = _init_filter_components(cmd)))
 		goto_bad;
 
 	init_ignore_suspended_devices(find_config_tree_bool(cmd, devices_ignore_suspended_devices_CFG, NULL));
 	init_ignore_lvm_mirrors(find_config_tree_bool(cmd, devices_ignore_lvm_mirrors_CFG, NULL));
 
+	if ((cn = find_config_tree_node(cmd, devices_filter_CFG, NULL))) {
+		if (!(f3 = regex_filter_create(cn->v)))
+			goto_bad;
+		toplevel_components[0] = cmd->lvmetad_filter;
+		toplevel_components[1] = f3;
+		if (!(f4 = composite_filter_create(2, toplevel_components)))
+			goto_bad;
+	} else
+		f4 = cmd->lvmetad_filter;
+
 	if (!(dev_cache = find_config_tree_str(cmd, devices_cache_CFG, NULL)))
 		goto_bad;
 
-	if (!(f4 = persistent_filter_create(cmd->dev_types, f3, dev_cache))) {
+	if (!(cmd->filter = persistent_filter_create(cmd->dev_types, f4, dev_cache))) {
 		log_verbose("Failed to create persistent device filter.");
 		goto bad;
 	}
@@ -948,29 +956,20 @@ static int _init_filters(struct cmd_context *cmd, unsigned load_persistent_cache
 	    load_persistent_cache && !cmd->is_long_lived &&
 	    !stat(dev_cache, &st) &&
 	    (st.st_ctime > config_file_timestamp(cmd->cft)) &&
-	    !persistent_filter_load(f4, NULL))
+	    !persistent_filter_load(cmd->filter, NULL))
 		log_verbose("Failed to load existing device cache from %s",
 			    dev_cache);
 
-	if (!(cn = find_config_tree_node(cmd, devices_global_filter_CFG, NULL))) {
-		cmd->filter = f4;
-	} else if (!(cmd->lvmetad_filter = regex_filter_create(cn->v)))
-		goto_bad;
-	else {
-		toplevel_components[0] = cmd->lvmetad_filter;
-		toplevel_components[1] = f4;
-		if (!(cmd->filter = composite_filter_create(2, toplevel_components)))
-			goto_bad;
-	}
-
 	return 1;
 bad:
-	if (f4)
+	if (f4) /* kills both f3 and cmd->lvmetad_filter */
 		f4->destroy(f4);
-	else if (f3)
-		f3->destroy(f3);
-	if (toplevel_components[0])
-		toplevel_components[0]->destroy(toplevel_components[0]);
+	else {
+		if (f3)
+			f3->destroy(f3);
+		if (cmd->lvmetad_filter)
+			cmd->lvmetad_filter->destroy(cmd->lvmetad_filter);
+	}
 	return 0;
 }