From 95e4b3413aca7d8c8c8cdec5a83b76214d0d1a64 Mon Sep 17 00:00:00 2001
From: Eduard Shishkin <edward6@linux.ibm.com>
Date: Fri, 16 May 2025 14:24:24 +0200
Subject: [PATCH] zipl/src: Prepare for global sync(2) removal
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zipl tool calls sync(2) before exit, which may hang on attempts to
flush not relevant problematic mounts (e.g. nfs) [1].

Complete any modification performed by zipl(8) tool with calling
fsync(2), or syncfs(2). This allows to get rid of the mentioned
sync(2) call.

[1] https://github.com/openshift/os/issues/1720
Github-ID: https://github.com/ibm-s390-linux/s390-tools/pull/186
Signed-off-by: Eduard Shishkin <edward6@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
---
 zipl/include/misc.h |  1 +
 zipl/src/bootmap.c  | 31 +++++++++++++++++++++++++++----
 zipl/src/install.c  |  4 +++-
 zipl/src/misc.c     | 10 ++++++++++
 4 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/zipl/include/misc.h b/zipl/include/misc.h
index 01f3a323..4b29adff 100644
--- a/zipl/include/misc.h
+++ b/zipl/include/misc.h
@@ -34,6 +34,7 @@ int misc_asprintf(char **out, const char *fmt, ...);
 void* misc_calloc(size_t n, size_t size);
 char* misc_strdup(const char* s);
 int misc_open_device(const char *filename, struct misc_fd *mfd, int simulate);
+int misc_fsync(struct misc_fd *mfd, const char *filename);
 int misc_read(int fd, void* buffer, size_t count);
 int misc_read_file(const char* filename, char** buffer, size_t* size,
 		   int nil_terminate);
diff --git a/zipl/src/bootmap.c b/zipl/src/bootmap.c
index ed3834b7..9b9136c6 100644
--- a/zipl/src/bootmap.c
+++ b/zipl/src/bootmap.c
@@ -1617,6 +1617,11 @@ static int finalize_create_file(struct job_data *job, struct install_set *bis)
 {
 	char *final_name;
 
+	/*
+	 * Sync the file before rename
+	 */
+	if (misc_fsync(&bis->mfd, bis->filename))
+		return -1;
 	final_name = misc_make_path(job->target.bootmap_dir, BOOTMAP_FILENAME);
 	if (!final_name)
 		return -1;
@@ -1632,6 +1637,18 @@ static int finalize_create_file(struct job_data *job, struct install_set *bis)
 	 * from the semantic volume
 	 */
 	bis->tmp_filename_created = 0;
+	/*
+	 * Sync meta-data and the parent directory of the new object.
+	 * For this, sync the whole file system, using the descriptor
+	 * obtained for the file with the old name.
+	 */
+	if (syncfs(bis->mfd.fd)) {
+		error_reason(strerror(errno));
+		error_text("Could not sync fs containing '%s'",
+			   final_name);
+		free(final_name);
+		return -1;
+	}
 	free(final_name);
 	return 0;
 }
@@ -1698,7 +1715,11 @@ static int ngdump_create_meta(const char *path)
 	rc = fclose(fp);
 	if (rc < 0)
 		return -1;
-
+	/*
+	 * In case of dry-run the meta-file will be removed.
+	 * Otherwise it will be written to disk when unmounting
+	 * the ngdump.
+	 */
 	return 0;
 }
 
@@ -1861,13 +1882,15 @@ int prepare_bootloader(struct job_data *job, struct install_set *bis)
  */
 int post_install_bootloader(struct job_data *job, struct install_set *bis)
 {
+	if (dry_run)
+		return 0;
 	if (job->id == job_dump_partition) {
 		if (job_dump_is_ngdump(job))
-			return dry_run ? 0 : finalize_create_file(job, bis);
+			return finalize_create_file(job, bis);
 		else
-			return 0;
+			return misc_fsync(&bis->mfd, bis->filename);
 	} else {
-		return dry_run ? 0 : finalize_create_file(job, bis);
+		return finalize_create_file(job, bis);
 	}
 }
 
diff --git a/zipl/src/install.c b/zipl/src/install.c
index 31e9c486..137793af 100644
--- a/zipl/src/install.c
+++ b/zipl/src/install.c
@@ -784,6 +784,8 @@ install_tapeloader(const char* device, const char* image, const char* parmline,
 		error_text("Could not rewind tape device '%s' to tape", device);
 		rc = -1;
 	}
+	if (!dry_run && fsync(fd))
+		error_text("Could not sync device file '%s'", device);
 	close(fd);
 	return rc;
 }
@@ -1139,7 +1141,7 @@ install_dump(const char *device, struct job_target_data *target, uint64_t mem,
 			error_text("Could not install dump record on tape "
 				   "device '%s'", device);
 		} else {
-			if (verbose) {
+			if (!misc_fsync(&mfd, device) && verbose) {
 				printf("Dump record successfully installed on "
 				       "tape device '%s'.\n", device);
 			}
diff --git a/zipl/src/misc.c b/zipl/src/misc.c
index b2d7fa29..f0a83dec 100644
--- a/zipl/src/misc.c
+++ b/zipl/src/misc.c
@@ -131,6 +131,16 @@ int misc_open_device(const char *filename, struct misc_fd *mfd, int simulate)
 	return mfd->fd;
 }
 
+int misc_fsync(struct misc_fd *mfd, const char *filename)
+{
+	if (fsync(mfd->fd)) {
+		error_reason(strerror(errno));
+		error_text("Could not sync file '%s'", filename);
+		return -1;
+	}
+	return 0;
+}
+
 /* Read COUNT bytes of data from file identified by file descriptor FD to
  * memory at location BUFFER. Return 0 when all bytes were successfully read,
  * non-zero otherwise. */