From 43a498e938887956f393b5e45ea6ac79cc5f4b84 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Thu, 15 Jun 2023 00:17:01 -0400
Subject: [PATCH] resize2fs: use Direct I/O when reading the superblock for
 online resizes

If the file system is mounted, the superblock can be changing while
resize2fs is trying to read the superblock, resulting in checksum
failures.  One way of avoiding this problem is read the superblock
using Direct I/O, since the kernel makes sure that what gets written
to disk is self-consistent.

Suggested-by: Krister Johansen <kjlx@templeofstupid.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 resize/main.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/resize/main.c b/resize/main.c
index 94f5ec6d..f914c050 100644
--- a/resize/main.c
+++ b/resize/main.c
@@ -403,6 +403,8 @@ int main (int argc, char ** argv)
 
 	if (!(mount_flags & EXT2_MF_MOUNTED))
 		io_flags = EXT2_FLAG_RW | EXT2_FLAG_EXCLUSIVE;
+	if (mount_flags & EXT2_MF_MOUNTED)
+		io_flags |= EXT2_FLAG_DIRECT_IO;
 
 	io_flags |= EXT2_FLAG_64BITS | EXT2_FLAG_THREADS;
 	if (undo_file) {
-- 
2.32.0

