Re: fishy ->put_inode usage in ntfs

[Anton Altaparmakov <aia21@cam.ac.uk>]

On Thu, 2005-02-10 at 14:48 +0000, Anton Altaparmakov wrote:
> On Thu, 2005-02-10 at 15:42 +0100, Christoph Hellwig wrote:
> > On Thu, Feb 10, 2005 at 02:40:39PM +0000, Anton Altaparmakov wrote:
> > > I am not sure what you mean.  The VFS layer does reference counting on
> > > inodes.  I have no choice in the matter.
> > > 
> > > > Can someone ever grab a reference separate from it's master inode?
> > > 
> > > Again, not sure what you mean.  Could you elaborate?
> > 
> > ntfs_read_locked_attr_inode() does igrab on the 'parent' inode
> > currently.  What do you need this for exactly - the attr inode
> > goes away anyway when clear_inode is called on that 'parent' inode
> > (in my scheme).
> 
> If the igrab() were not done, it would be possible for clear_inode to be
> called on the 'parent' inode whilst at the same time one or more attr
> inodes (belonging to this 'parent') are in use and Bad Things(TM) would
> happen...

The igrab() effectively guarantees that iput() is called on all attr
inodes before clear_inode on the 'parent' can be invoked.

Best regards,

        Anton
-- 
Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK
Linux NTFS maintainer / IRC: #ntfs on irc.freenode.net
WWW: http://linux-ntfs.sf.net/ & http://www-stu.christs.cam.ac.uk/~aia21/