Re: historical question: nfs_rename()

[Peter Staubach <staubach@redhat.com>]

Trond Myklebust wrote:

>m=E5 den 17.10.2005 klokka 12:12 (-0700) skreiv Lever, Charles:
> =20
>
>>a customer recently pointed out that the rename(2) system call does not
>>allow replacing directories, even if they are empty.  RFC1813 at least
>>suggests that the server and protocol do allow directory replacement, a=
s
>>long as the target is empty.
>>
>>the culprit appears to be this check in nfs_rename()
>>
>>        if (S_ISDIR(new_inode->i_mode))
>>                goto out;
>>
>>which causes nfs_rename() to return -EBUSY if the target is a directory.
>>
>>is there a historical reason why the Linux NFS client does not allow
>>directory replacement?  shouldn't the error code be -EISDIR for this
>>case?
>>   =20
>>
>
>Yes, the error should be EISDIR. I'm not sure that I agree with your
>assertion that rename failing is an NFS-only issue, though. The attached
>testcase fails on both XFS and ext3 too with the error "Rename failed:
>Is a directory".
>
>Cheers,
>  Trond
>
> =20
>
>------------------------------------------------------------------------
>
>#include <sys/types.h>
>#include <sys/stat.h>
>#include <fcntl.h>
>#include <stdio.h>
>#include <stdlib.h>
>
>#define FILENAME "gnurr"
>#define DIRNAME "gnarg"
>
>void die(char *errmsg)
>{
>	perror(errmsg);
>	exit(1);
>}
>
>int main()
>{
>	int fd;
>	int err;
>
>	fd =3D open(FILENAME, O_CREAT|O_EXCL|O_RDWR, 0644);
>	if (fd < 0)
>		die("File creation failed");
>	close(fd);
>	err =3D mkdir(DIRNAME, 0700);
>	if (err !=3D 0)
>		die("Directory creation failed");
>	err =3D rename("gnurr", "gnarg");
>	if (err !=3D 0)
>		die("Rename failed");
>}
> =20
>

Actually, this case should fail with EISDIR, as it does.  Mixing
directory and files in a rename(2) will fail with EISDIR or ENOTDIR.

However, renaming one directory to another directory, when the target
directory is "empty", should not fail.

       ps


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