From 3d6bcae84c5f55a82dc0056e3d7da33bee3f00b9 Mon Sep 17 00:00:00 2001
From: Ondrej Kozina <okozina@redhat.com>
Date: Wed, 17 Sep 2014 16:38:39 +0200
Subject: [PATCH] reencrypt: use fsync instead of O_DIRECT flag

O_DIRECT operations directed towards filesystem are problematic:
There's no sane way how to detect specific filesystem requirements
for such operations.

This patch is replacing O_DIRECT flag with O_SYNC flag for all
open() calls related to reencrypt log. The O_SYNC flag is used
when --use-fsync option is detected.

Man page is modified accordingly.
---
 man/cryptsetup-reencrypt.8 |  6 ++++--
 src/cryptsetup_reencrypt.c | 12 ++----------
 2 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/man/cryptsetup-reencrypt.8 b/man/cryptsetup-reencrypt.8
index b3c374c..e0de656 100644
--- a/man/cryptsetup-reencrypt.8
+++ b/man/cryptsetup-reencrypt.8
@@ -158,13 +158,15 @@ WARNING: This is destructive operation and cannot be reverted.
 
 .TP
 .B "\-\-use-directio"
-Use direct-io (O_DIRECT) for all read/write data operations.
+Use direct-io (O_DIRECT) for all read/write data operations related
+to block device undergoing reencryption.
 
 Useful if direct-io operations perform better than normal buffered
 operations (e.g. in virtual environments).
 .TP
 .B "\-\-use-fsync"
-Use fsync call after every written block.
+Use fsync call after every written block. This applies for reencryption
+log files as well.
 .TP
 .B "\-\-write-log"
 Update log file after every block write. This can slow down reencryption
diff --git a/src/cryptsetup_reencrypt.c b/src/cryptsetup_reencrypt.c
index 997c388..a1cc51d 100644
--- a/src/cryptsetup_reencrypt.c
+++ b/src/cryptsetup_reencrypt.c
@@ -76,7 +76,7 @@ struct reenc_ctx {
 	char crypt_path_org[PATH_MAX];
 	char crypt_path_new[PATH_MAX];
 	int log_fd;
-	char *log_buf;
+	char log_buf[SECTOR_SIZE];
 
 	struct {
 		char *password;
@@ -351,13 +351,11 @@ static void close_log(struct reenc_ctx *rc)
 	log_dbg("Closing LUKS reencryption log file %s.", rc->log_file);
 	if (rc->log_fd != -1)
 		close(rc->log_fd);
-	free(rc->log_buf);
-	rc->log_buf = NULL;
 }
 
 static int open_log(struct reenc_ctx *rc)
 {
-	int flags = opt_directio ? O_DIRECT : 0;
+	int flags = opt_fsync ? O_SYNC : 0;
 
 	rc->log_fd = open(rc->log_file, O_RDWR|O_EXCL|O_CREAT|flags, S_IRUSR|S_IWUSR);
 	if (rc->log_fd != -1) {
@@ -371,12 +369,6 @@ static int open_log(struct reenc_ctx *rc)
 	if (rc->log_fd == -1)
 		return -EINVAL;
 
-	if (posix_memalign((void *)&rc->log_buf, alignment(rc->log_fd), SECTOR_SIZE)) {
-		log_err(_("Allocation of aligned memory failed.\n"));
-		close_log(rc);
-		return -ENOMEM;
-	}
-
 	if (!rc->in_progress && write_log(rc) < 0) {
 		close_log(rc);
 		return -EIO;
-- 
1.9.3