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From: Christoph Hellwig <hch@infradead.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	David Howells <dhowells@redhat.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Dave Wysochanski <dwysocha@redhat.com>,
	Dominique Martinet <asmadeus@codewreck.org>,
	Jeff Layton <jlayton@kernel.org>,
	Latchesar Ionkov <lucho@ionkov.net>,
	Marc Dionne <marc.dionne@auristor.com>,
	Omar Sandoval <osandov@osandov.com>,
	Shyam Prasad N <nspmangalore@gmail.com>,
	Steve French <sfrench@samba.org>,
	Trond Myklebust <trondmy@hammerspace.com>,
	Peter Zijlstra <peterz@infradead.org>,
	ceph-devel@vger.kernel.org, linux-afs@lists.infradead.org,
	linux-cachefs@redhat.com, CIFS <linux-cifs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	"open list:NFS, SUNRPC, AND..." <linux-nfs@vger.kernel.org>,
	v9fs-developer@lists.sourceforge.net,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Out of order read() completion and buffer filling beyond returned amount
Date: Mon, 17 Jan 2022 23:25:14 -0800	[thread overview]
Message-ID: <YeZrWoQY/3dKZHfT@infradead.org> (raw)
In-Reply-To: <YeVvXToTxCsMzHZv@casper.infradead.org>

On Mon, Jan 17, 2022 at 01:30:05PM +0000, Matthew Wilcox wrote:
> I think for DIO, you're sacrificing the entire buffer with any filesystem.
> If the underlying file is split across multiple drives, or is even
> just fragmented on a single drive, we'll submit multiple BIOs which
> will complete independently (even for SCSI which writes sequentially;
> never mind NVMe which can DMA blocks asynchronously).  It might be
> more apparent in a networking situation where errors are more common,
> but it's always been a possibility since Linux introduced DIO.

Yes.  Probably because of that we also never allow short reads or writes
due to I/O errrors but always fail the whole I/O.

      reply	other threads:[~2022-01-18  7:26 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-17  9:57 Out of order read() completion and buffer filling beyond returned amount David Howells
2022-01-17 10:19 ` Linus Torvalds
2022-01-17 13:30   ` Matthew Wilcox
2022-01-18  7:25     ` Christoph Hellwig [this message]

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