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Re: [RFC] guarantee inode of alias's parent

From Al Viro <viro@ZenIV.linux.org.uk>
Newsgroups linux.kernel
Subject Re: [RFC] guarantee inode of alias's parent
Date 2017-07-07 16:20 +0200
Message-ID <u0CgW-5bd-13@gated-at.bofh.it> (permalink)
References <u0Bux-4As-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Fri, Jul 07, 2017 at 03:28:11PM +0200, Gioh Kim wrote:

> Before __d_unalias(), the dentry and parent of the dentry
> are locked. But I wonder how I can assure of existence of the
> alias and the parent of the alias.
> 
> Where is the code to lock alias and alias->d_parent?

Nowhere.  Why the hell would you want to lock them?

> What will happend if alias->d_parent be deleted by another process?

Huh?  As soon as you've grabbed ->s_vfs_rename_mutex, ->d_parent of everything on
that filesystem is stable - and positive.  Moreover, any positive dentry with
references held (in particular, anyone's parent) is going to remain such for
as long as those references are held.

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[RFC] guarantee inode of alias's parent Gioh Kim <gi-oh.kim@profitbricks.com> - 2017-07-07 15:30 +0200
  Re: [RFC] guarantee inode of alias's parent Al Viro <viro@ZenIV.linux.org.uk> - 2017-07-07 16:20 +0200

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