Re: [PATCH] Add option to fsfreeze to call syncfs() prior to freezing.

Alun
2012-12-07T11:17:23Z

Dear all,

Very sorry - I made a small mistake in the previous patch, which
resulted in syncfs() always being called rather than only when -s
was specified.

Signed-off-by: Alun Jones <alun.linux@ty-penguin.org.uk>

diff --git a/sys-utils/fsfreeze.8 b/sys-utils/fsfreeze.8
index 7693861..0d73afe 100644
--- a/sys-utils/fsfreeze.8
+++ b/sys-utils/fsfreeze.8
@@ -1,5 +1,5 @@
.\" -*- nroff -*-
-.TH FSFREEZE 8 "May 2010" "util-linux" "System Administration"
+.TH FSFREEZE 8 "December 2012" "util-linux" "System Administration"
.SH NAME
fsfreeze \- suspend access to a filesystem (Linux Ext3/4, ReiserFS, JFS, XFS)
.SH SYNOPSIS
@@ -9,6 +9,9 @@ fsfreeze \- suspend access to a filesystem (Linux Ext3/4, ReiserFS, JFS, XFS)
.B fsfreeze \-u
.I mountpoint

+.B fsfreeze \-s
+.I mountpoint
+
.SH DESCRIPTION
.B fsfreeze
suspends and resumes access to an filesystem
@@ -53,6 +56,14 @@ or a clean mount of the snapshot is complete.
This option is used to un-freeze the filesystem and allow operations to
continue. Any filesystem modifications that were blocked by the freeze are
unblocked and allowed to complete.
+.IP "\fB\-s, \-\-sync\fP
+This option, if specified, will cause fsfreeze to call syncfs() on the
+filesystem. It can be combined with -f to force dirty data to be written prior
+to the freeze operation. On a filesystem with heavy write load, adding this
+option will very likely reduce the time during which writes are suspended,
+at the cost of a delay before suspending writes. Therefore, if it's critical
+to reduce the time for which the filesystem is frozen, use this option; if
+it's critical to freeze the filesystem at a specific moment, don't use it.
.SH AUTHOR
.PP
Written by Hajime Taira.
diff --git a/sys-utils/fsfreeze.c b/sys-utils/fsfreeze.c
index 7161442..6e8fc82 100644
--- a/sys-utils/fsfreeze.c
+++ b/sys-utils/fsfreeze.c
@@ -44,6 +44,7 @@ static void __attribute__((__noreturn__)) usage(FILE *out)

fputs(_("\nOptions:\n"), out);
fputs(_(" -h, --help this help\n"
+ " -s, --sync sync the filesystem\n"
" -f, --freeze freeze the filesystem\n"
" -u, --unfreeze unfreeze the filesystem\n"), out);

@@ -56,6 +57,7 @@ int main(int argc, char **argv)
{
int fd = -1, c;
int freeze = -1, rc = EXIT_FAILURE;
+ int dosync = -1;
char *path;
struct stat sb;

@@ -63,6 +65,7 @@ int main(int argc, char **argv)
{ "help", 0, 0, 'h' },
{ "freeze", 0, 0, 'f' },
{ "unfreeze", 0, 0, 'u' },
+ { "sync", 0, 0, 's' },
{ NULL, 0, 0, 0 }
};

@@ -71,7 +74,7 @@ int main(int argc, char **argv)
textdomain(PACKAGE);
atexit(close_stdout);

- while ((c = getopt_long(argc, argv, "hfu", longopts, NULL)) != -1) {
+ while ((c = getopt_long(argc, argv, "hfus", longopts, NULL)) != -1) {
switch(c) {
case 'h':
usage(stdout);
@@ -82,13 +85,16 @@ int main(int argc, char **argv)
case 'u':
freeze = FALSE;
break;
+ case 's':
+ dosync = TRUE;
+ break;
default:
usage(stderr);
break;
}
}

- if (freeze == -1)
+ if (freeze == -1 && dosync == -1)
errx(EXIT_FAILURE, _("no action specified"));
if (optind == argc)
errx(EXIT_FAILURE, _("no filename specified"));
@@ -113,12 +119,19 @@ int main(int argc, char **argv)
goto done;
}

- if (freeze) {
+ if (dosync == TRUE) {
+ if (syncfs(fd)) {
+ warn(_("%s: syncfs failed"), path);
+ goto done;
+ }
+ }
+
+ if (freeze == TRUE) {
if (freeze_f(fd)) {
warn(_("%s: freeze failed"), path);
goto done;
}
- } else {
+ } else if (freeze == FALSE) {
if (unfreeze_f(fd)) {
warn(_("%s: unfreeze failed"), path);
goto done;