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-rwxr-xr-xqemu/scripts/qemu-guest-agent/fsfreeze-hook.d/mysql-flush.sh.sample56
1 files changed, 56 insertions, 0 deletions
diff --git a/qemu/scripts/qemu-guest-agent/fsfreeze-hook.d/mysql-flush.sh.sample b/qemu/scripts/qemu-guest-agent/fsfreeze-hook.d/mysql-flush.sh.sample
new file mode 100755
index 000000000..2b4fa3aeb
--- /dev/null
+++ b/qemu/scripts/qemu-guest-agent/fsfreeze-hook.d/mysql-flush.sh.sample
@@ -0,0 +1,56 @@
+#!/bin/sh
+
+# Flush MySQL tables to the disk before the filesystem is frozen.
+# At the same time, this keeps a read lock in order to avoid write accesses
+# from the other clients until the filesystem is thawed.
+
+MYSQL="/usr/bin/mysql"
+MYSQL_OPTS="-uroot" #"-prootpassword"
+FIFO=/var/run/mysql-flush.fifo
+
+# Check mysql is installed and the server running
+[ -x "$MYSQL" ] && "$MYSQL" $MYSQL_OPTS < /dev/null || exit 0
+
+flush_and_wait() {
+ printf "FLUSH TABLES WITH READ LOCK \\G\n"
+ trap 'printf "$(date): $0 is killed\n">&2' HUP INT QUIT ALRM TERM
+ read < $FIFO
+ printf "UNLOCK TABLES \\G\n"
+ rm -f $FIFO
+}
+
+case "$1" in
+ freeze)
+ mkfifo $FIFO || exit 1
+ flush_and_wait | "$MYSQL" $MYSQL_OPTS &
+ # wait until every block is flushed
+ while [ "$(echo 'SHOW STATUS LIKE "Key_blocks_not_flushed"' |\
+ "$MYSQL" $MYSQL_OPTS | tail -1 | cut -f 2)" -gt 0 ]; do
+ sleep 1
+ done
+ # for InnoDB, wait until every log is flushed
+ INNODB_STATUS=$(mktemp /tmp/mysql-flush.XXXXXX)
+ [ $? -ne 0 ] && exit 2
+ trap "rm -f $INNODB_STATUS; exit 1" HUP INT QUIT ALRM TERM
+ while :; do
+ printf "SHOW ENGINE INNODB STATUS \\G" |\
+ "$MYSQL" $MYSQL_OPTS > $INNODB_STATUS
+ LOG_CURRENT=$(grep 'Log sequence number' $INNODB_STATUS |\
+ tr -s ' ' | cut -d' ' -f4)
+ LOG_FLUSHED=$(grep 'Log flushed up to' $INNODB_STATUS |\
+ tr -s ' ' | cut -d' ' -f5)
+ [ "$LOG_CURRENT" = "$LOG_FLUSHED" ] && break
+ sleep 1
+ done
+ rm -f $INNODB_STATUS
+ ;;
+
+ thaw)
+ [ ! -p $FIFO ] && exit 1
+ echo > $FIFO
+ ;;
+
+ *)
+ exit 1
+ ;;
+esac