#!/bin/bash
#
# usage: debug_upcall.sh <lctl-dk-log-file>
#
# Dumps locks to the Lustre kernel ring buffer and then appends the contents of
# the Lustre kernel ring buffer to the given debug log file.
#
# This is meant to be set as the debug_log_upcall, which is called by Lustre
# after dumping logs with libcfs_debug_dumplog_internal().  Lustre passes the
# upcall the name of the file to which the trace buffer was dumped.
#
# To set the Lustre debug_upcall to this script, set the debug_upcall to the
# path to this script using "lctl set_param" as follows:
#
# # lctl set_param debug_log_upcall=/path/to/this/script

debugLogFile="$1"

# Enable dlmtrace to get locks dumped, but save the old state first
oldDebug=$(lctl get_param -n debug)
lctl set_param debug=+dlmtrace
lctl set_param ldlm.dump_namespaces=1

# Dump logs in raw form
tmpLockDump=$(mktemp /tmp/lustre-ldlm-dump.XXXXX)
lctl dk $tmpLockDump 1
# Remove the line indicating how many lines were dumped
sed '/^Debug log:/d' $tmpLockDump >> $debugLogFile
rm $tmpLockDump

# Restore the old debug state
lctl set_param debug="$oldDebug"