exfat: fix referencing wrong parent directory information after renaming

During renaming, the parent directory information maybe
updated. But the file/directory still references to the
old parent directory information.

This bug will cause 2 problems.

(1) The renamed file can not be written.

    [10768.175172] exFAT-fs (sda1): error, failed to bmap (inode : 7afd50e4 iblock : 0, err : -5)
    [10768.184285] exFAT-fs (sda1): Filesystem has been set read-only
    ash: write error: Input/output error

(2) Some dentries of the renamed file/directory are not set
    to deleted after removing the file/directory.

exfat_update_parent_info() is a workaround for the wrong parent
directory information being used after renaming. Now that bug is
fixed, this is no longer needed, so remove it.

Fixes: 5f2aa07 ("exfat: add inode operations")
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Reviewed-by: Andy Wu <Andy.Wu@sony.com>
Reviewed-by: Aoyama Wataru <wataru.aoyama@sony.com>
Reviewed-by: Daniel Palmer <daniel.palmer@sony.com>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

Author: YuezhangMo

fs/exfat/namei.c

@@ -1080,6 +1080,7 @@ static int exfat_rename_file(struct inode *inode, struct exfat_chain *p_dir,
 
 		exfat_remove_entries(inode, p_dir, oldentry, 0,
 			num_old_entries);
+		ei->dir = *p_dir;
 		ei->entry = newentry;
 	} else {
 		if (exfat_get_entry_type(epold) == TYPE_FILE) {
@@ -1167,28 +1168,6 @@ static int exfat_move_file(struct inode *inode, struct exfat_chain *p_olddir,
 	return 0;
 }
 
-static void exfat_update_parent_info(struct exfat_inode_info *ei,
-		struct inode *parent_inode)
-{
-	struct exfat_sb_info *sbi = EXFAT_SB(parent_inode->i_sb);
-	struct exfat_inode_info *parent_ei = EXFAT_I(parent_inode);
-	loff_t parent_isize = i_size_read(parent_inode);
-
-	/*
-	 * the problem that struct exfat_inode_info caches wrong parent info.
-	 *
-	 * because of flag-mismatch of ei->dir,
-	 * there is abnormal traversing cluster chain.
-	 */
-	if (unlikely(parent_ei->flags != ei->dir.flags ||
-		     parent_isize != EXFAT_CLU_TO_B(ei->dir.size, sbi) ||
-		     parent_ei->start_clu != ei->dir.dir)) {
-		exfat_chain_set(&ei->dir, parent_ei->start_clu,
-			EXFAT_B_TO_CLU_ROUND_UP(parent_isize, sbi),
-			parent_ei->flags);
-	}
-}
-
 /* rename or move a old file into a new file */
 static int __exfat_rename(struct inode *old_parent_inode,
 		struct exfat_inode_info *ei, struct inode *new_parent_inode,
@@ -1219,8 +1198,6 @@ static int __exfat_rename(struct inode *old_parent_inode,
 		return -ENOENT;
 	}
 
-	exfat_update_parent_info(ei, old_parent_inode);
-
 	exfat_chain_dup(&olddir, &ei->dir);
 	dentry = ei->entry;
 
@@ -1241,8 +1218,6 @@ static int __exfat_rename(struct inode *old_parent_inode,
 			goto out;
 		}
 
-		exfat_update_parent_info(new_ei, new_parent_inode);
-
 		p_dir = &(new_ei->dir);
 		new_entry = new_ei->entry;
 		ep = exfat_get_dentry(sb, p_dir, new_entry, &new_bh);