From: Amjad Alsharafi <amjadsharafi10@gmail.com>

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>
(cherry picked from commit b881cf00c99e03bc8a3648581f97736ff275b18b)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/block/vvfat.c b/block/vvfat.c
index 723c91216e..741fdb0341 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -2522,8 +2522,9 @@ static int commit_one_file(BDRVVVFATState* s,
         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);
     if (fd < 0) {
-- 
2.39.2