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From: Dave Chinner <david@fromorbit.com>
To: Mark Tinguely <tinguely@sgi.com>
Cc: XFS Mailing List <xfs@oss.sgi.com>
Subject: Re: [RFC] libxfs: adding attribute fork frees xfs_inode ptr
Date: Thu, 24 Apr 2014 08:22:15 +1000	[thread overview]
Message-ID: <20140423222215.GT18672@dastard> (raw)
In-Reply-To: <20140423210445.700477624@sgi.com>

On Wed, Apr 23, 2014 at 04:04:35PM -0500, Mark Tinguely wrote:
> User space does not currently perform any attribute adding/deleting,
> but if we do want to fix attributes or use them for parent inode
> pointers, user space should support attributes.
> 
> The adding an attribute fork is done in an embedded transaction
> inside xfs_attr_set_int(). The xfs_trans_commit in xfs_bmap_add_attrfork()
> will free the xfs_inode pointer causing xfs_attr_calc_size() in
> xfs_attr_set_int() to fail.

It shouldn't. xfs_bmap_add_attrfork() does:

	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);

which in the kernel code sets:

	iip->ili_lock_flags = lock_flags;


The libxfs code doesn't do that, so when xfs_trans_commit() gets
to inode_item_unlock():


        if (!iip->ili_lock_flags)
                libxfs_iput(ip, 0);
        else
                iip->ili_lock_flags = 0;

It frees the inode rather than just returning it with the lock
flags cleared.

Note that libxfs still has libxfs_trans_ijoin_ref() which sets the
lock flags, but this has been removed from the kernel code. IOWs,
this is a libxfs/trans.c::xfs_trans_ijoin() bug, not something that
needs fixing in the shared kernel/user libxfs code.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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  reply	other threads:[~2014-04-23 22:22 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20140423210034.892939354@sgi.com>
2014-04-23 21:04 ` [RFC] libxfs: adding attribute fork frees xfs_inode ptr Mark Tinguely
2014-04-23 22:22   ` Dave Chinner [this message]
2014-04-24 17:11     ` Mark Tinguely
2014-04-24 20:59       ` Mark Tinguely
2014-04-25  5:40         ` Christoph Hellwig
2014-04-25 13:18           ` Mark Tinguely

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