linux-ext4 - /fs/ext4/namei.c ext4_find_dest

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Date:   Sun, 3 May 2020 14:00:25 +0100
From:   Jonny Grant <jg@...k.org>
To:     linux-ext4@...r.kernel.org
Subject: /fs/ext4/namei.c ext4_find_dest_de()

Hi

I noticed that mkdir() returns EEXIST if a directory already exists. 
strerror(EEXIST) text is "File exists"

Can ext4_find_dest_de() be amended to return EISDIR if a directory 
already exists? This will make the error message clearer.

This is the line of code from ext4_find_dest_de():

if (ext4_match(dir, fname, de))
			return -EEXIST;

I propose to change to something like the following:

int ext4_match_result = ext4_match(dir, fname, de);

		nlen = EXT4_DIR_REC_LEN(de->name_len);
		rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
		if ((de->inode ? rlen - nlen : rlen) >= reclen)
			break;
		de = (struct ext4_dir_entry_2 *)((char *)de + rlen);

if (ext4_match_result)
{
     if(EXT4_FT_DIR == de->file_type)
     {
         return -EISDIR;
     }
     else
     {
	return -EEXIST;
     }
}

Let me know if this would be supported, and I can prepare a patch.

Cheers
Jonny