Re: [PATCH -V16 07/12] vfs: Support null pathname in linkat

["Aneesh Kumar K. V" <aneesh.kumar@linux.vnet.ibm.com>]

On Mon, 12 Jul 2010 10:05:39 +0200, Miklos Szeredi <miklos@szeredi.hu> wrote:
> On Mon, 12 Jul 2010, Aneesh Kumar K.V wrote:
> > This enables to use linkat to create hardlinks from a
> > file descriptor pointing to the file. This can be used
> > with open_by_handle syscall that returns a file descriptor.
> 
> This needs more thought, filesystems don't usually tolerate
> resurrecting a file which has already been unlinked (i_nlink == 0).
> 

We get -ENOENT error when we do that on ext*

open("test", O_RDONLY)                  = 3
unlink("test")                          = 0
linkat(3, NULL, AT_FDCWD, "test3", 0)   = -1 ENOENT (No such file or directory)

ext4_link does the below

/*
 * Return -ENOENT if we've raced with unlink and i_nlink is 0.  Doing
 * otherwise has the potential to corrupt the orphan inode list.
 */
if (inode->i_nlink == 0)
	return -ENOENT;

I can move this check to VFS so that we do it for all file systems. 

-aneesh