linux-kernel - Re: xfs: commit 6552321831dc "xfs: remove i_iolock and use i_rwsem in the VFS inode instead" change causes hang

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Message-ID: <20170108145200.GA29570@lst.de>
Date:   Sun, 8 Jan 2017 15:52:00 +0100
From:   Christoph Hellwig <hch@....de>
To:     Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:     linux-xfs@...r.kernel.org, Christoph Hellwig <hch@....de>,
        Dave Chinner <david@...morbit.com>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Al Viro <viro@...IV.linux.org.uk>
Subject: Re: xfs:  commit 6552321831dc "xfs: remove i_iolock and use
        i_rwsem in the VFS inode instead"  change causes hang

On Sun, Jan 08, 2017 at 09:48:44AM -0500, Mimi Zohar wrote:
> IMA takes the i_rwsem (fomerly i_mutex) before reading the file to
> synchronize calculating the file hash and validating the file's
> hash/signature stored as security.ima xattr

Well, it shouldn't do that.  In the I/O path i_rwsem is up to the
fs to use.  Various other file systems also take it internally for
reads, although mostly only for direct I/O.

So the answer here is that ima needs to stop playing with i_rwsem.