dovecot-2.0: lib-index: When creating dovecot.index.backup files...

[dovecot at dovecot.org]

details:   http://hg.dovecot.org/dovecot-2.0/rev/f08bf97278ac
changeset: 12886:f08bf97278ac
user:      Timo Sirainen <tss at iki.fi>
date:      Tue Aug 23 23:25:14 2011 +0300
description:
lib-index: When creating dovecot.index.backup files, fdatasync() them first.
Otherwise if the dovecot.index file had been written to recently, it could
lose both the new and the old backup data.

diffstat:

 src/lib-index/mail-index-write.c |  10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diffs (20 lines):

diff -r de0ea56932e5 -r f08bf97278ac src/lib-index/mail-index-write.c
--- a/src/lib-index/mail-index-write.c	Tue Aug 23 23:03:41 2011 +0300
+++ b/src/lib-index/mail-index-write.c	Tue Aug 23 23:25:14 2011 +0300
@@ -18,6 +18,16 @@
 	const char *backup_path, *tmp_backup_path;
 	int ret;
 
+	if (index->fd != -1) {
+		/* we very much want to avoid creating a backup file that
+		   hasn't been written to disk yet */
+		if (fdatasync(index->fd) < 0) {
+			mail_index_set_error(index, "fdatasync(%s) failed: %m",
+					     tmp_backup_path);
+			return -1;
+		}
+	}
+
 	backup_path = t_strconcat(index->filepath, ".backup", NULL);
 	tmp_backup_path = t_strconcat(backup_path, ".tmp", NULL);
 	ret = link(index->filepath, tmp_backup_path);