Re: [PATCH] fs: ext4: inode->i_generation not assigned 0.

From	"J. Bruce Fields" <bfields@fieldses.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] fs: ext4: inode->i_generation not assigned 0.
Date	2017-06-29 20:40 +0200
Message-ID	<tXMw9-2FO-3@gated-at.bofh.it> (permalink)
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On Thu, Jun 29, 2017 at 10:25:28AM -0700, Darrick J. Wong wrote:
> Was there ever a version of NFS (or more generally callers of the
> exportfs code) that couldn't deal with i_generation in the file handle,
> and therefore we invented this generation hack to work around the loss
> of the generation information?
> 
> There's a comment in xfs_fs_encode_fh about not supporting 64bit inodes
> with subtree_check (which seems to require one ino/gen pair for the file
> and a second pair for the file's parent) on NFSv2 because v2 doesn't
> provide enough space for all the file handle information, but that's the
> furthest I got with lazy-mining the git history. :)

There's a comment in fs/ext4/super.c:ext4_nfs_get_inode

	* Currently we don't know the generation for parent directory, so
	* a generation of 0 means "accept any"

But I don't see that used.

It was used once upon a time; I see it actually used in old 2.5 code in
nfsd_get_dentry.  Hm.

--b.

Thread

[PATCH] fs: ext4: inode->i_generation not assigned 0. Kyungchan Koh <kkc6196@fb.com> - 2017-06-29 00:10 +0200
  Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-06-29 02:50 +0200
    Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. William Koh <kkc6196@fb.com> - 2017-06-29 03:00 +0200
  Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. Andreas Dilger <adilger@dilger.ca> - 2017-06-29 04:40 +0200
    Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. William Koh <kkc6196@fb.com> - 2017-06-29 06:40 +0200
      Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-06-29 07:10 +0200
        Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. William Koh <kkc6196@fb.com> - 2017-06-29 16:30 +0200
        Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. "J. Bruce Fields" <bfields@fieldses.org> - 2017-06-29 16:40 +0200
          Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-06-29 19:30 +0200
            Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. "J. Bruce Fields" <bfields@fieldses.org> - 2017-06-29 20:40 +0200
              Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. "J. Bruce Fields" <bfields@fieldses.org> - 2017-06-29 21:00 +0200

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