From mboxrd@z Thu Jan 1 00:00:00 1970 From: jbrassow@sourceware.org Date: 26 Aug 2010 14:21:53 -0000 Subject: LVM2 ./WHATS_NEW lib/activate/dev_manager.c Message-ID: <20100826142153.7885.qmail@sourceware.org> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit CVSROOT: /cvs/lvm2 Module name: LVM2 Changes by: jbrassow at sourceware.org 2010-08-26 14:21:52 Modified files: . : WHATS_NEW lib/activate : dev_manager.c Log message: 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. Patches: http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/WHATS_NEW.diff?cvsroot=lvm2&r1=1.1724&r2=1.1725 http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/lib/activate/dev_manager.c.diff?cvsroot=lvm2&r1=1.201&r2=1.202 --- LVM2/WHATS_NEW 2010/08/26 12:08:19 1.1724 +++ LVM2/WHATS_NEW 2010/08/26 14:21:50 1.1725 @@ -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. --- LVM2/lib/activate/dev_manager.c 2010/08/17 19:25:05 1.201 +++ LVM2/lib/activate/dev_manager.c 2010/08/26 14:21:51 1.202 @@ -175,6 +175,21 @@ 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? */