[PATCH 6.19 720/844] ocfs2: fix reflink preserve cleanup issue

[Sasha Levin]

From: Heming Zhao <heming.zhao@xxxxxxxx>

[ Upstream commit 5138c936c2c82c9be8883921854bc6f7e1177d8c ]

commit c06c303832ec ("ocfs2: fix xattr array entry __counted_by error")
doesn't handle all cases and the cleanup job for preserved xattr entries
still has bug:
- the 'last' pointer should be shifted by one unit after cleanup
  an array entry.
- current code logic doesn't cleanup the first entry when xh_count is 1.

Note, commit c06c303832ec is also a bug fix for 0fe9b66c65f3.

Link: https://lkml.kernel.org/r/20251210015725.8409-2-heming.zhao@xxxxxxxx
Fixes: 0fe9b66c65f3 ("ocfs2: Add preserve to reflink.")
Signed-off-by: Heming Zhao <heming.zhao@xxxxxxxx>
Cc: Mark Fasheh <mark@xxxxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Cc: Joseph Qi <jiangqi903@xxxxxxxxx>
Cc: Changwei Ge <gechangwei@xxxxxxx>
Cc: Jun Piao <piaojun@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/ocfs2/xattr.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index 1b21fbc16d73a..1bff4f2d1345e 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -6394,6 +6394,10 @@ static int ocfs2_reflink_xattr_header(handle_t *handle,
 					(void *)last - (void *)xe);
 				memset(last, 0,
 				       sizeof(struct ocfs2_xattr_entry));
+				last = &new_xh->xh_entries[le16_to_cpu(new_xh->xh_count)] - 1;
+			} else {
+				memset(xe, 0, sizeof(struct ocfs2_xattr_entry));
+				last = NULL;
 			}
 
 			/*
-- 
2.51.0