qemu-ga: add hook to quiesce the guest on fsfreeze-freeze/thaw

Adds sample hook scripts for --fsfreeze-hook option of qemu-ga.
- fsfreeze-hook : execute scripts in fsfreeze-hook.d/
- fsfreeze-hook.d/mysql-flush.sh.sample : quiesce MySQL before snapshot

Signed-off-by Tomoki Sekiyama <[email protected]>

---
 .gitignore                                         |    1 
 Makefile                                           |    2 -
 scripts/qemu-guest-agent/fsfreeze-hook             |   33 ++++++++++++
 .../fsfreeze-hook.d/mysql-flush.sh.sample          |   56 ++++++++++++++++++++
 4 files changed, 91 insertions(+), 1 deletion(-)
 create mode 100755 scripts/qemu-guest-agent/fsfreeze-hook
 create mode 100755 scripts/qemu-guest-agent/fsfreeze-hook.d/mysql-flush.sh.sample

.gitignore +1 -0

index bd6ba1c..6456e9d 100644
@@ -68,6 +68,7 @@ fsdev/virtfs-proxy-helper.pod
 *.tp
 *.vr
 *.d
+!scripts/qemu-guest-agent/fsfreeze-hook.d
 *.o
 *.lo
 *.la

Makefile +1 -1

index 9ecbcbb..466dcd7 100644
@@ -248,7 +248,7 @@ clean:
 # avoid old build problems by removing potentially incorrect old files
 	rm -f config.mak op-i386.h opc-i386.h gen-op-i386.h op-arm.h opc-arm.h gen-op-arm.h
 	rm -f qemu-options.def
-	find . -name '*.[od]' -exec rm -f {} +
+	find . -name '*.[od]' -type f -exec rm -f {} +
 	rm -f *.a *.lo $(TOOLS) $(HELPERS-y) qemu-ga TAGS cscope.* *.pod *~ */*~
 	rm -Rf .libs
 	rm -f qemu-img-cmds.h

scripts/qemu-guest-agent/fsfreeze-hook new file +33 -0

new file mode 100755
index 0000000..c27b29f
@@ -0,0 +1,33 @@
+#!/bin/sh
+
+# This script is executed when a guest agent receives fsfreeze-freeze and
+# fsfreeze-thaw command, if it is specified in --fsfreeze-hook (-F)
+# option of qemu-ga or placed in default path (/etc/qemu/fsfreeze-hook).
+# When the agent receives fsfreeze-freeze request, this script is issued with
+# "freeze" argument before the filesystem is frozen. And for fsfreeze-thaw
+# request, it is issued with "thaw" argument after filesystem is thawed.
+
+LOGFILE=/var/log/qga-fsfreeze-hook.log
+FSFREEZE_D=$(dirname -- "$0")/fsfreeze-hook.d
+
+# Check whether file $1 is a backup or rpm-generated file and should be ignored
+is_ignored_file() {
+    case "$1" in
+        *~ | *.bak | *.orig | *.rpmnew | *.rpmorig | *.rpmsave | *.sample)
+            return 0 ;;
+    esac
+    return 1
+}
+
+# Iterate executables in directory "fsfreeze-hook.d" with the specified args
+[ ! -d "$FSFREEZE_D" ] && exit 0
+for file in "$FSFREEZE_D"/* ; do
+    is_ignored_file "$file" && continue
+    [ -x "$file" ] || continue
+    printf "$(date): execute $file $@\n" >>$LOGFILE
+    "$file" "$@" >>$LOGFILE 2>&1
+    STATUS=$?
+    printf "$(date): $file finished with status=$STATUS\n" >>$LOGFILE
+done
+
+exit 0

scripts/qemu-guest-agent/fsfreeze-hook.d/mysql-flush.sh.sample new file +56 -0

new file mode 100755
index 0000000..2b4fa3a
@@ -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

Hi,

This is version 8 of the qemu-ga fsfreeze hook patchset.

*Changes from v7: ( http://patchwork.ozlabs.org/patch/204426/ )
1/2: Not changed.
2/2: Moved .gitignore exception for fsfreeze-hook.d right below "*.d".
Make fsfreeze success even if fsfreeze-hook.d doesn't exist. Use printf(1) instead of echo to output logs.
Use "$MYSQL" $MYSQL_OPTS instead of $MYSQL_CMD for safety. Improve signal handling in flush-mysql.sh.
Fix misspelling.

This patchset depends on Luiz Capitulino's patchset to improve error handling, which is available at:
https://lists.gnu.org/archive/html/qemu-devel/2012-11/msg03016.html
---
Tomoki Sekiyama (2):
qemu-ga: execute hook to quiesce the guest on fsfreeze-freeze/thaw
qemu-ga: sample fsfreeze hooks

 .gitignore                                         |    1 
 Makefile                                           |    2 -
 qemu-ga.c                                          |   42 ++++++++++++
 qga/commands-posix.c                               |   69 ++++++++++++++++++++
 qga/guest-agent-core.h                             |    1 
 scripts/qemu-guest-agent/fsfreeze-hook             |   33 ++++++++++
 .../fsfreeze-hook.d/mysql-flush.sh.sample          |   56 ++++++++++++++++
 7 files changed, 202 insertions(+), 2 deletions(-)
 create mode 100755 scripts/qemu-guest-agent/fsfreeze-hook
 create mode 100755 scripts/qemu-guest-agent/fsfreeze-hook.d/mysql-flush.sh.sample

Thanks,

Signature · 3 lines

Tomoki Sekiyama <[email protected]>
Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory