kernel-ark/fs/xfs/xfs_globals.c
Brian Foster 2e22717874 xfs: export log_recovery_delay to delay mount time log recovery
XFS log recovery has been discovered to have race conditions with
buffers when I/O errors occur. External tools are available to simulate
I/O errors to XFS, but this alone is not sufficient for testing log
recovery. XFS unconditionally resets the inactive region of the log
prior to log recovery to avoid confusion over processing any partially
written log records that might have been written before an unclean
shutdown. Therefore, unconditional write I/O failures at mount time are
caught by the reset sequence rather than log recovery and hinder the
ability to test the latter.

The device-mapper dm-flakey module uses an up/down timer to define a
cycle for when to fail I/Os. Create a pre log recovery delay tunable
that can be used to coordinate XFS log recovery with I/O errors
simulated by dm-flakey. This facilitates coordination in userspace that
allows the reset of stale log blocks to succeed and writes due to log
recovery to fail. For example, define a dm-flakey instance with an
uptime long enough to allow log reset to succeed and a log recovery
delay long enough to allow the dm-flakey uptime to expire.

The 'log_recovery_delay' sysfs tunable is exported under
/sys/fs/xfs/debug and is only enabled for kernels compiled in XFS debug
mode. The value is exported in units of seconds and allows for a delay
of up to 60 seconds. Note that this is for XFS debug and test
instrumentation purposes only and should not be used by applications. No
delay is enabled by default.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
2014-09-09 11:56:13 +10:00

50 lines
1.7 KiB
C

/*
* Copyright (c) 2000-2005 Silicon Graphics, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "xfs.h"
#include "xfs_sysctl.h"
/*
* Tunable XFS parameters. xfs_params is required even when CONFIG_SYSCTL=n,
* other XFS code uses these values. Times are measured in centisecs (i.e.
* 100ths of a second) with the exception of eofb_timer, which is measured in
* seconds.
*/
xfs_param_t xfs_params = {
/* MIN DFLT MAX */
.sgid_inherit = { 0, 0, 1 },
.symlink_mode = { 0, 0, 1 },
.panic_mask = { 0, 0, 255 },
.error_level = { 0, 3, 11 },
.syncd_timer = { 1*100, 30*100, 7200*100},
.stats_clear = { 0, 0, 1 },
.inherit_sync = { 0, 1, 1 },
.inherit_nodump = { 0, 1, 1 },
.inherit_noatim = { 0, 1, 1 },
.xfs_buf_timer = { 100/2, 1*100, 30*100 },
.xfs_buf_age = { 1*100, 15*100, 7200*100},
.inherit_nosym = { 0, 0, 1 },
.rotorstep = { 1, 1, 255 },
.inherit_nodfrg = { 0, 1, 1 },
.fstrm_timer = { 1, 30*100, 3600*100},
.eofb_timer = { 1, 300, 3600*24},
};
struct xfs_globals xfs_globals = {
.log_recovery_delay = 0, /* no delay by default */
};