linux-ext4 - [PATCH 02/10] libext2fs: always fsync the device when closing the unix IO manager

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Message-ID: <174787198103.1484572.14307160616313425545.stgit@frogsfrogsfrogs>
Date: Wed, 21 May 2025 17:08:45 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: tytso@....edu
Cc: John@...ves.net, linux-ext4@...r.kernel.org, miklos@...redi.hu,
 joannelkoong@...il.com, bernd@...ernd.com, linux-fsdevel@...r.kernel.org
Subject: [PATCH 02/10] libext2fs: always fsync the device when closing the
 unix IO manager

From: Darrick J. Wong <djwong@...nel.org>

unix_close is the last chance that libext2fs has to report write
failures to users.  Although it's likely that ext2fs_close already
called ext2fs_flush and told the IO manager to flush, we could do one
more sync before we close the file descriptor.  Also don't override the
fsync's errno with the close's errno.

Signed-off-by: "Darrick J. Wong" <djwong@...nel.org>
---
 lib/ext2fs/unix_io.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 40fd9cc1427c31..7c5cb075d6b6b6 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -1136,8 +1136,11 @@ static errcode_t unix_close(io_channel channel)
 #ifndef NO_IO_CACHE
 	retval = flush_cached_blocks(channel, data, 0);
 #endif
+	/* always fsync the device, even if flushing our own cache failed */
+	if (fsync(data->dev) != 0 && !retval)
+		retval = errno;

-	if (close(data->dev) < 0)
+	if (close(data->dev) < 0 && !retval)
 		retval = errno;
 	free_cache(data);
 	free(data->cache);