Re: [PATCH 13/35] fallthru: ext2 fallthru support

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, Apr 19, Jamie Lokier wrote:

> Jan Blunck wrote:
> > On Mon, Apr 19, David Woodhouse wrote:
> > 
> > > On Mon, 2010-04-19 at 14:40 +0200, Jan Blunck wrote:
> > > > On Thu, Apr 15, Valerie Aurora wrote:
> > > > 
> > > > > Add support for fallthru directory entries to ext2.
> > > > > 
> > > > > XXX - Makes up inode number for fallthru entry
> > > > > XXX - Might be better implemented as special symlinks
> > > > 
> > > > Better not. David Woodhouse actually convinced me of moving away from the
> > > > special symlink approach. The whiteouts have been implemented as special
> > > > symlinks before.
> > > 
> > > I certainly asked whether you really need a real 'struct inode' for
> > > whiteouts, and suggested that they should be represented _purely_ as a
> > > dentry with type DT_WHT.
> > > 
> > > I don't much like the manifestation of that in this patch though,
> > > especially with the made-up inode number. (ISTR I had other
> > > jffs2-specific objections too, which I'll dig out and forward).
> > 
> > Yes, this patches still have issues that Val and me are aware off. I can't
> > remember anything jffs2-specific though.
> > 
> > We return that inode number because we don't want to lookup the name on the
> > other filesystem during readdir. Therefore returning DT_UNKNOWN to let the
> > userspace decide if it needs to stat the file was the easiest workaround. I
> > know that POSIX requires d_ino and d_name but on the other hand it does not
> > require anything more on how long d_ino is valid.
> 
> Although the lifetime of d_ino might very, I know some programs (not
> public) that will break if they see a d_ino which is wrongly matching
> the st_ino of another file somewhere on the same st_dev.  They will
> assume the name is a hard link to the other file, without calling
> stat(), which I think is a reasonable assumption and a useful optimisation.
> 
> So the made-up d_ino should at least be careful to not match an inode
> number of another file which has a stable st_ino.
> 
> Why not zero for d_ino?
> 

Hmm, why not. Or even the ino of the directory we are reading from ...

Regards,
	Jan

-- 
Jan Blunck <jblunck@xxxxxxx>
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux