From bdb3d504dcfc11d44d6a4e6d2d099dffb933fb47 Mon Sep 17 00:00:00 2001
From: Roman Sofin <roma.sofin@gmail.com>
Date: Mon, 25 Aug 2025 10:09:58 +0300
Subject: [PATCH 1/2] io_u: make should_fsync() take a const

Make should_fsync() safer by using a pointer to a constant thread_data
structure instance.

Signed-off-by: Roman Sofin roma.sofin@gmail.com
---
 fio.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fio.h b/fio.h
index 4bb6cfa7f3..14163e2d2b 100644
--- a/fio.h
+++ b/fio.h
@@ -628,7 +628,7 @@ static inline bool multi_range_trim(struct thread_data *td, struct io_u *io_u)
 	return false;
 }
 
-static inline bool should_fsync(struct thread_data *td)
+static inline bool should_fsync(const struct thread_data *td)
 {
 	if (ddir_sync(td->last_ddir_issued))
 		return false;

From 7b7f18c1e33c7223788bfd42490d673150b30079 Mon Sep 17 00:00:00 2001
From: Roman Sofin <roma.sofin@gmail.com>
Date: Mon, 8 Sep 2025 11:44:29 +0300
Subject: [PATCH 2/2] io_u/backend: fix missing final fsync() when using
 fsync=N

When fsync=N is specified and the final I/O issued happens to be the Nth, the
following fsync() is missed.

This update checks if it needs to loop again in do_io() to issue that final
fsync when all the IO work is done.

Signed-off-by: Roman Sofin roma.sofin@gmail.com
---
 backend.c |  7 ++++---
 io_u.c    | 37 +++++++++++++++++++++++++------------
 io_u.h    |  2 ++
 3 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/backend.c b/backend.c
index fe03eab387..5704cb7db9 100644
--- a/backend.c
+++ b/backend.c
@@ -1000,7 +1000,8 @@ static void do_io(struct thread_data *td, uint64_t *bytes_done)
 
 	while ((td->o.read_iolog_file && !flist_empty(&td->io_log_list)) ||
 		(!flist_empty(&td->trim_list)) || !io_issue_bytes_exceeded(td) ||
-		td->o.time_based) {
+		td->o.time_based ||
+		(should_fsync(td) && ddir_is_sync(td))) {
 		struct timespec comp_time;
 		struct io_u *io_u;
 		int full;
@@ -1032,8 +1033,8 @@ static void do_io(struct thread_data *td, uint64_t *bytes_done)
 		 */
 		if (bytes_issued >= total_bytes &&
 		    !td->o.read_iolog_file &&
-		    (!td->o.time_based ||
-		     (td->o.time_based && td->o.verify != VERIFY_NONE)))
+		    ((!td->o.time_based && !(should_fsync(td) && ddir_is_sync(td))) ||
+		      (td->o.time_based && td->o.verify != VERIFY_NONE)))
 			break;
 
 		io_u = get_io_u(td);
diff --git a/io_u.c b/io_u.c
index f81086b658..21b7f2a334 100644
--- a/io_u.c
+++ b/io_u.c
@@ -742,19 +742,8 @@ static enum fio_ddir rate_ddir(struct thread_data *td, enum fio_ddir ddir)
 	return ddir;
 }
 
-/*
- * Return the data direction for the next io_u. If the job is a
- * mixed read/write workload, check the rwmix cycle and switch if
- * necessary.
- */
-static enum fio_ddir get_rw_ddir(struct thread_data *td)
+static inline enum fio_ddir get_sync_ddir(const struct thread_data *td)
 {
-	enum fio_ddir ddir;
-
-	/*
-	 * See if it's time to fsync/fdatasync/sync_file_range first,
-	 * and if not then move on to check regular I/Os.
-	 */
 	if (should_fsync(td) && td->last_ddir_issued == DDIR_WRITE) {
 		if (td->o.fsync_blocks && td->io_issues[DDIR_WRITE] &&
 		    !(td->io_issues[DDIR_WRITE] % td->o.fsync_blocks))
@@ -768,6 +757,30 @@ static enum fio_ddir get_rw_ddir(struct thread_data *td)
 		    !(td->io_issues[DDIR_WRITE] % td->sync_file_range_nr))
 			return DDIR_SYNC_FILE_RANGE;
 	}
+	return DDIR_INVAL;
+}
+
+bool ddir_is_sync(const struct thread_data *td)
+{
+	return get_sync_ddir(td) != DDIR_INVAL;
+}
+
+/*
+ * Return the data direction for the next io_u. If the job is a
+ * mixed read/write workload, check the rwmix cycle and switch if
+ * necessary.
+ */
+static enum fio_ddir get_rw_ddir(struct thread_data *td)
+{
+	enum fio_ddir ddir;
+
+	/*
+	 * See if it's time to fsync/fdatasync/sync_file_range first,
+	 * and if not then move on to check regular I/Os.
+	 */
+	ddir = get_sync_ddir(td);
+	if (ddir != DDIR_INVAL)
+		return ddir;
 
 	if (td_rw(td)) {
 		/*
diff --git a/io_u.h b/io_u.h
index ab93d50f96..25a0c0e865 100644
--- a/io_u.h
+++ b/io_u.h
@@ -169,6 +169,8 @@ bool queue_full(const struct thread_data *);
 int do_io_u_sync(const struct thread_data *, struct io_u *);
 int do_io_u_trim(struct thread_data *, struct io_u *);
 
+bool ddir_is_sync(const struct thread_data *);
+
 #ifdef FIO_INC_DEBUG
 static inline void dprint_io_u(struct io_u *io_u, const char *p)
 {