From db722158867b3b7541ed788b0a0f42a29a839ee4 Mon Sep 17 00:00:00 2001
From: qihao <qihao_yewu@cmss.chinamobile.com>
Date: Fri, 16 Aug 2024 17:51:45 +0800
Subject: [PATCH] vvfat: Fix bug in writing to middle of file

cheery-pick from b881cf00c99e03bc8a3648581f97736ff275b18b

Before this commit, the behavior when calling `commit_one_file` for
example with `offset=0x2000` (second cluster), what will happen is that
we won't fetch the next cluster from the fat, and instead use the first
cluster for the read operation.

This is due to off-by-one error here, where `i=0x2000 !< offset=0x2000`,
thus not fetching the next cluster.

Signed-off-by: Amjad Alsharafi <amjadsharafi10@gmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Tested-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <b97c1e1f1bc2f776061ae914f95d799d124fcd73.1721470238.git.amjadsharafi10@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: qihao_yewu <qihao_yewu@cmss.chinamobile.com>
---
 block/vvfat.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/vvfat.c b/block/vvfat.c
index 9d050ba3ae..9010f3f33f 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -2525,7 +2525,7 @@ commit_one_file(BDRVVVFATState* s, int dir_index, uint32_t offset)
         return -1;
     }
 
-    for (i = s->cluster_size; i < offset; i += s->cluster_size)
+    for (i = 0; i < offset; i += s->cluster_size)
         c = modified_fat_get(s, c);
 
     fd = qemu_open_old(mapping->path, O_RDWR | O_CREAT | O_BINARY, 0666);
-- 
2.41.0.windows.1