[PATCH] smb/client: fix nlink of an overwritten open file

[Steve French <smfrench@gmail.com>]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

Reproducer:

  1. server: systemctl start ksmbd
  2. client: mount with `posix` option
     mount -t cifs -o posix //${server_ip}/export /mnt
  3. client: touch /mnt/file1 /mnt/file2
  4. client: C program: int fd = open("/mnt/file2", O_RDONLY);
  5. client: C program: rename("/mnt/file1", "/mnt/file2");
  6. client: C program: struct stat stbuf; fstat(fd, &stbuf);
                        stbuf.st_nlink is 1, should be 0

This patch fixes xfstests generic/035 when mounted with `posix` option.

Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/smb/client/inode.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c
index b2806371bfde..1dc511272f2a 100644
--- a/fs/smb/client/inode.c
+++ b/fs/smb/client/inode.c
@@ -2648,11 +2648,8 @@ cifs_rename2(struct mnt_idmap *idmap, struct inode *source_dir,
 	if (d_really_is_positive(target_dentry)) {
 		if (!rc) {
 			struct inode *inode = d_inode(target_dentry);
-			/*
-			 * Samba and ksmbd servers allow renaming a target
-			 * directory that is open, so make sure to update
-			 * ->i_nlink and then mark it as delete pending.
-			 */
+
+			/* Update the target link count after rename. */
 			if (S_ISDIR(inode->i_mode)) {
 				drop_cached_dir_by_name(xid, tcon, to_name, cifs_sb);
 				spin_lock(&inode->i_lock);
@@ -2663,6 +2660,10 @@ cifs_rename2(struct mnt_idmap *idmap, struct inode *source_dir,
 				CIFS_I(inode)->time = 0; /* force reval */
 				inode_set_ctime_current(inode);
 				inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
+			} else {
+				cifs_mark_open_handles_for_deleted_file(inode, to_name);
+				cifs_drop_nlink(inode);
+				inode_set_ctime_current(inode);
 			}
 		} else if (rc == -EACCES || rc == -EEXIST) {
 			/*
-- 
2.53.0