File mirrored_log_fixed_when_double_fault_occurs.diff of Package lvm2

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File mirrored_log_fixed_when_double_fault_occurs.diff of Package lvm2 (Revision 926875da861d2f5807c528e44590ddfb)

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From 54c73b7723713f43413584d59ca0bdd42c1d8241 Mon Sep 17 00:00:00 2001
From: Jonathan Brassow <jbrassow@redhat.com>
Date: Wed, 14 Nov 2012 14:58:47 -0600
Subject: mirror: Mirrored log should be fixed before mirror when double fault
 occurs
Git-repo: https://git.fedorahosted.org/git/lvm2.git
Git-commit: 54c73b7723713f43413584d59ca0bdd42c1d8241

This patch is intended to fix bug 825323 - FS turns read-only during a double
 fault of a mirror leg and mirrored log's leg at the same time.  It only
 affects a 2-way mirror with a mirrored log.  3+-way mirrors and mirrors
 without a mirrored log are not affected.

The problem resulted from the fact that the top level mirror was not
 using 'noflush' when suspending before its "down-convert".  When a
 mirror image fails, the bios are queue until a suspend is recieved.  If
 it is a 'noflush' suspend, the bios can be safely requeued in the DM
 core.  If 'noflush' is not used, the bios must be pushed through the
 target and if a device is failed for a mirror, that means issuing an
 error.  When an error is received by a file system, it results in it
 turning read-only (depending on the FS).

Part of the problem was is due to the nature of the stacking involved in
 using a mirror as a mirror's log.  When an image in each fail, the top
 level mirror stalls because it is waiting for a log flush.  The other
 stalls waiting for corrective action.  When the repair command is issued,
 the entire stacked arrangement is collapsed to a linear LV.  The log
 flush then fails (somewhat uncleanly) and the top-level mirror is suspended
 without 'noflush' because it is a linear device.

This patch allows the log to be repaired first, which in turn allows the
 top-level mirror's log flush to complete cleanly.  The top-level mirror
 is then secondarily reduced to a linear device - at which time this mirror
 is suspended properly with 'noflush'.
---

tools/lvconvert.c |    8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/tools/lvconvert.c b/tools/lvconvert.c
index f23fc4b..27d8181 100644
--- a/tools/lvconvert.c
+++ b/tools/lvconvert.c
@@ -1341,10 +1341,6 @@ int mirror_remove_missing(struct cmd_context *cmd,
 	if (!(failed_pvs = _failed_pv_list(lv->vg)))
 		return_0;
 
-	/* No point in keeping a log if the result is not a mirror */
-	if (_failed_mirrors_count(lv) + 1 >= lv_mirror_count(lv))
-		log_count = 0;
-
         if (force && _failed_mirrors_count(lv) == lv_mirror_count(lv)) {
 		log_error("No usable images left in %s.", lv->name);
 		return lv_remove_with_dependencies(cmd, lv, DONT_PROMPT, 0);
@@ -1363,8 +1359,8 @@ int mirror_remove_missing(struct cmd_context *cmd,
 			       _is_partial_lv, NULL, 0))
 		return 0;
 
-	if (!_lv_update_log_type(cmd, NULL, lv, failed_pvs,
-				 log_count))
+	if (lv_is_mirrored(lv) &&
+	    !_lv_update_log_type(cmd, NULL, lv, failed_pvs, log_count))
 		return 0;
 
 	if (!_reload_lv(cmd, lv->vg, lv))

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File mirrored_log_fixed_when_double_fault_occurs.diff of Package lvm2 (Revision 926875da861d2f5807c528e44590ddfb)

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