linux-kernel - Re: [PATCH 01/14] sysfs: fix i

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Date:	Fri, 27 Apr 2007 10:29:46 -0500
From:	Eric Sandeen <sandeen@...deen.net>
To:	Tejun Heo <htejun@...il.com>
CC:	gregkh@...e.de, maneesh@...ibm.com, dmitry.torokhov@...il.com,
	cornelia.huck@...ibm.com, oneukum@...e.de, rpurdie@...ys.net,
	James.Bottomley@...elEye.com, stern@...land.harvard.edu,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/14] sysfs: fix i_ino handling in sysfs

Tejun Heo wrote:
> Inode number handling was incorrect in two ways.
> 
> 1. sysfs uses the inode number allocated by new_inode() and never
>    hashes it.  When reporting the inode number, it uses iunique() if
>    inode is inaccessible.  This is incorrect because iunique() assumes
>    the inodes are hashed.  This can cause duplicate inode numbers and
>    the condition is likely to happen because new_inode() and iunique()
>    use separate increasing static counters to scan for empty slot.
> 
> 2. sysfs_dirent->s_dentry can go away anytime and can't be referenced
>    unless the caller knows the dentry is not and not going to be
>    deleted.
> 
> This patch makes sysfs report the pointer to sysfs_dirent as ino.
> ino_t is always as big as or larger than unsigned long && sysfs_dirent
> hierarchy is the internal representation of the sysfs tree, so it
> makes sense and simple to implement.

what about 32-bit stats from 32-bit apps on 64-bit systems?  This will 
make 64-bit inode numbers commonplace in sysfs; will this cause 
problems?  it seems that if they get truncated to 32 bits the 
possibility of duplicate inode nrs will come back...

-Eric
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