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From:   Christoph Hellwig <hch@lst.de>
To:     Mikulas Patocka <mpatocka@redhat.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Jan Kara <jack@suse.cz>,
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        Theodore Ts'o <tytso@mit.edu>,
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        Matthew Wilcox <willy@infradead.org>,
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        linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 2/2] xfs: don't update mtime on COW faults
Message-ID: <20200907064758.GA19384@lst.de>
References: <alpine.LRH.2.02.2009031328040.6929@file01.intranet.prod.int.rdu2.redhat.com> <alpine.LRH.2.02.2009041200570.27312@file01.intranet.prod.int.rdu2.redhat.com> <alpine.LRH.2.02.2009050805250.12419@file01.intranet.prod.int.rdu2.redhat.com> <alpine.LRH.2.02.2009050812060.12419@file01.intranet.prod.int.rdu2.redhat.com>
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> +static bool
> +xfs_is_write_fault(
> +	struct vm_fault		*vmf)
> +{
> +	return vmf->flags & FAULT_FLAG_WRITE && vmf->vma->vm_flags & VM_SHARED;
> +}

This function does not look xfs specific at all.  Why isn't it it in
fs.h?  While we're at it the name sounds rather generic, and there are
no good comments.

Maybe we just need to split FAULT_FLAG_WRITE into two and check those
instead of such crazy workarounds?