From a71d6051ed3d72af6895733c599cc44b49f24dbb Mon Sep 17 00:00:00 2001 From: Jonathan Earl Brassow Date: Thu, 26 Aug 2010 14:21:50 +0000 Subject: [PATCH] This patch fixes a potential for I/O to hang and LVM commands to block when a mirror under a snapshot suffers a failure. The problem has to do with label scanning. When a mirror suffers a failure, the kernel blocks I/O to prevent corruption. When LVM attempts to repair the mirror, it scans the devices on the system for LVM labels. While mirrors are skipped during this scanning process, snapshot-origins are not. When the origin is scanned, it kicks up I/O to the mirror (which is blocked) underneath - causing the label scan (an thus the repair operation) to hang. This patch simply bypasses snapshot-origin devices when doing labels scans (while ignore_suspended_devices() is set). This fixes the issue. --- WHATS_NEW | 1 + lib/activate/dev_manager.c | 15 +++++++++++++++ 2 files changed, 16 insertions(+) diff --git a/WHATS_NEW b/WHATS_NEW index cf98cdfa2..36d166c05 100644 --- a/WHATS_NEW +++ b/WHATS_NEW @@ -1,5 +1,6 @@ Version 2.02.74 - ================================== + Like mirrors, don't scan origins if ignore_suspended_devices() is set. Fix return type qualifier to avoid compiler warning. (2.02.69) Automatically generate LSB Requires-Start for clvmd init script. Fix return code of pvmove --abort PV. diff --git a/lib/activate/dev_manager.c b/lib/activate/dev_manager.c index 853a7be30..cee8f104f 100644 --- a/lib/activate/dev_manager.c +++ b/lib/activate/dev_manager.c @@ -175,6 +175,21 @@ int device_is_usable(struct device *dev) log_debug("%s: Mirror device %s not usable.", dev_name(dev), name); goto out; } + + /* + * Snapshot origin could be sitting on top of a mirror which + * could be blocking I/O. Skip snapshot origins entirely for + * now. + * + * FIXME: rather than skipping origin, check if mirror is + * underneath and if the mirror is blocking I/O. + */ + if (target_type && !strcmp(target_type, "snapshot-origin") && + ignore_suspended_devices()) { + log_debug("%s: Snapshot-origin device %s not usable.", + dev_name(dev), name); + goto out; + } } while (next); /* FIXME Also check dependencies? */