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Date: Sun, 28 Jan 2024 17:55:49 +0100
From: Christoph Hellwig <hch@lst.de>
To: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Chandan Babu R <chandan.babu@oracle.com>,
	"Darrick J. Wong" <djwong@kernel.org>,
	Hugh Dickins <hughd@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-xfs@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 16/21] xfs: improve detection of lost xfile contents
Message-ID: <20240128165549.GA5727@lst.de>
References: <20240126132903.2700077-1-hch@lst.de> <20240126132903.2700077-17-hch@lst.de> <ZbPe5FjDaQp1v8En@casper.infradead.org>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Fri, Jan 26, 2024 at 04:33:40PM +0000, Matthew Wilcox wrote:
> > +static inline bool
> > +xfile_has_lost_data(
> > +	struct inode		*inode,
> > +	struct folio		*folio)
> > +{
> > +	struct address_space	*mapping = inode->i_mapping;
> > +
> > +	/* This folio itself has been poisoned. */
> > +	if (folio_test_hwpoison(folio))
> > +		return true;
> > +
> > +	/* A base page under this large folio has been poisoned. */
> > +	if (folio_test_large(folio) && folio_test_has_hwpoisoned(folio))
> > +		return true;
> > +
> > +	/* Data loss has occurred anywhere in this shmem file. */
> > +	if (test_bit(AS_EIO, &mapping->flags))
> > +		return true;
> > +	if (filemap_check_wb_err(mapping, 0))
> > +		return true;
> > +
> > +	return false;
> > +}
> 
> This is too much.  filemap_check_wb_err() will do just fine for your
> needs unless you really want to get fine-grained and perhaps try to
> reconstruct the contents of the file.

As in only call filemap_check_wb_err and do away with all the
hwpoisoned checks and the extra AS_EIO check?