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From: Christoph Hellwig <hch@lst.de>
To: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>,
	"Darrick J . Wong" <djwong@kernel.org>,
	linux-xfs@vger.kernel.org,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	cluster-devel <cluster-devel@redhat.com>,
	stable <stable@vger.kernel.org>
Subject: Re: [5.15 REGRESSION] iomap: Fix inline extent handling in iomap_readpage
Date: Thu, 11 Nov 2021 08:25:06 +0100	[thread overview]
Message-ID: <20211111072506.GB30478@lst.de> (raw)
In-Reply-To: <CAHc6FU49TnYvrL-FU5oz9th6STuQ=eYokjsD+0QpbkdHedRd9w@mail.gmail.com>

On Wed, Nov 10, 2021 at 03:52:01PM +0100, Andreas Gruenbacher wrote:
> Hmm, that doesn't make sense to me: the filesystem doesn't know that
> iomap_readpage will pad to page boundaries. This happens at the iomap
> layer, so the iomap layer should also deal with the consequences.
> We're using different alignment rules here and for direct I/O, so that
> makes fake-aligning the extent size in iomap_begin even more
> questionable.
> 
> "Fixing" the extent size the filesystem returns would also break
> direct I/O. We could add some additional padding code to
> iomap_dio_inline_iter to deal with that, but currently, there's no
> need for that.

The iomap mapping sizes are read-only to iomap for a good reason.  You
can't just break that design.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: cluster-devel.redhat.com
Subject: [Cluster-devel] [5.15 REGRESSION] iomap: Fix inline extent handling in iomap_readpage
Date: Thu, 11 Nov 2021 08:25:06 +0100	[thread overview]
Message-ID: <20211111072506.GB30478@lst.de> (raw)
In-Reply-To: <CAHc6FU49TnYvrL-FU5oz9th6STuQ=eYokjsD+0QpbkdHedRd9w@mail.gmail.com>

On Wed, Nov 10, 2021 at 03:52:01PM +0100, Andreas Gruenbacher wrote:
> Hmm, that doesn't make sense to me: the filesystem doesn't know that
> iomap_readpage will pad to page boundaries. This happens at the iomap
> layer, so the iomap layer should also deal with the consequences.
> We're using different alignment rules here and for direct I/O, so that
> makes fake-aligning the extent size in iomap_begin even more
> questionable.
> 
> "Fixing" the extent size the filesystem returns would also break
> direct I/O. We could add some additional padding code to
> iomap_dio_inline_iter to deal with that, but currently, there's no
> need for that.

The iomap mapping sizes are read-only to iomap for a good reason.  You
can't just break that design.



  reply	other threads:[~2021-11-11  7:25 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-10 11:38 [5.15 REGRESSION] iomap: Fix inline extent handling in iomap_readpage Andreas Gruenbacher
2021-11-10 11:38 ` [Cluster-devel] " Andreas Gruenbacher
2021-11-10 12:55 ` Christoph Hellwig
2021-11-10 12:55   ` [Cluster-devel] " Christoph Hellwig
2021-11-10 14:52   ` Andreas Gruenbacher
2021-11-10 14:52     ` [Cluster-devel] " Andreas Gruenbacher
2021-11-11  7:25     ` Christoph Hellwig [this message]
2021-11-11  7:25       ` Christoph Hellwig
2021-11-11 16:21       ` Andreas Grünbacher
2021-11-11 16:21         ` [Cluster-devel] " Andreas Grünbacher

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