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authorBrian Foster <bfoster@redhat.com>2014-09-09 11:56:13 +1000
committerDave Chinner <david@fromorbit.com>2014-09-09 11:56:13 +1000
commit2e2271787419a12496bf5da5c3028a9c73c9697f (patch)
treef4020fa97468fa93b3c387bc27102a5a3df87af8 /fs/xfs/xfs_sysfs.c
parent65b65735fede29b516fed1d8c2391e8bc373b805 (diff)
downloadlinux-2e2271787419a12496bf5da5c3028a9c73c9697f.tar.bz2
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>
Diffstat (limited to 'fs/xfs/xfs_sysfs.c')
-rw-r--r--fs/xfs/xfs_sysfs.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c
index 32ddf0c8c50e..aa03670851d8 100644
--- a/fs/xfs/xfs_sysfs.c
+++ b/fs/xfs/xfs_sysfs.c
@@ -54,7 +54,38 @@ struct kobj_type xfs_mp_ktype = {
#ifdef DEBUG
/* debug */
+STATIC ssize_t
+log_recovery_delay_store(
+ const char *buf,
+ size_t count,
+ void *data)
+{
+ int ret;
+ int val;
+
+ ret = kstrtoint(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ if (val < 0 || val > 60)
+ return -EINVAL;
+
+ xfs_globals.log_recovery_delay = val;
+
+ return count;
+}
+
+STATIC ssize_t
+log_recovery_delay_show(
+ char *buf,
+ void *data)
+{
+ return snprintf(buf, PAGE_SIZE, "%d\n", xfs_globals.log_recovery_delay);
+}
+XFS_SYSFS_ATTR_RW(log_recovery_delay);
+
static struct attribute *xfs_dbg_attrs[] = {
+ ATTR_LIST(log_recovery_delay),
NULL,
};