From: Bruce Fields <bfields@fieldses.org>
To: Chuck Lever <chuck.lever@oracle.com>
Cc: Anna Schumaker <schumaker.anna@gmail.com>,
Bruce Fields <bfields@redhat.com>,
Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v4 2/5] NFSD: Add READ_PLUS data support
Date: Fri, 4 Sep 2020 10:29:23 -0400 [thread overview]
Message-ID: <20200904142923.GE26706@fieldses.org> (raw)
In-Reply-To: <164C37D9-8044-4CF4-99A1-5FB722A16B8E@oracle.com>
On Fri, Sep 04, 2020 at 10:07:22AM -0400, Chuck Lever wrote:
> My primary concern is that the result of a file copy operation should
> look the same on NFS/TCP (with READ_PLUS) and NFS/RDMA (with SEEK_DATA/HOLE).
I'm not sure what you mean.
I don't see the spec providing any guarantee of consistency between
READ_PLUS and SEEK. It also doesn't guarantee that the results tell you
anything about how the file is actually stored--a returned "hole" could
represent an unallocated segment, or a fully allocated segment that's
filled with zeroes, or some combination.
So, for example, if you implemented an optimized copy that used
ALLOCATE, DEALLOCATE, SEEK and/or READ_PLUS to avoid reading and writing
a lot of zeroes--there's no guarantee that the target file would end up
allocated in the same way as the source.
--b.
next prev parent reply other threads:[~2020-09-04 14:29 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-17 16:53 [PATCH v4 0/5] NFSD: Add support for the v4.2 READ_PLUS operation schumaker.anna
2020-08-17 16:53 ` [PATCH v4 1/5] SUNRPC/NFSD: Implement xdr_reserve_space_vec() schumaker.anna
2020-08-17 16:53 ` [PATCH v4 2/5] NFSD: Add READ_PLUS data support schumaker.anna
2020-08-28 21:25 ` J. Bruce Fields
2020-08-28 21:56 ` J. Bruce Fields
2020-08-31 18:16 ` Anna Schumaker
2020-09-01 16:49 ` J. Bruce Fields
2020-09-01 17:40 ` Anna Schumaker
2020-09-01 19:18 ` J. Bruce Fields
2020-09-04 13:52 ` J. Bruce Fields
2020-09-04 13:56 ` Chuck Lever
2020-09-04 14:03 ` Bruce Fields
2020-09-04 14:07 ` Chuck Lever
2020-09-04 14:29 ` Bruce Fields [this message]
2020-09-04 14:36 ` Chuck Lever
2020-09-04 14:49 ` J. Bruce Fields
2020-09-04 14:58 ` Chuck Lever
2020-09-04 15:24 ` Bruce Fields
2020-09-04 16:17 ` Chuck Lever
2020-09-04 16:26 ` Bruce Fields
2020-09-04 16:30 ` Chuck Lever
2020-08-17 16:53 ` [PATCH v4 3/5] NFSD: Add READ_PLUS hole segment encoding schumaker.anna
2020-08-17 16:53 ` [PATCH v4 4/5] NFSD: Return both a hole and a data segment schumaker.anna
2020-08-28 22:18 ` J. Bruce Fields
2020-08-31 18:15 ` Anna Schumaker
2020-08-17 16:53 ` [PATCH v4 5/5] NFSD: Encode a full READ_PLUS reply schumaker.anna
2020-08-19 17:07 ` [PATCH v4 0/5] NFSD: Add support for the v4.2 READ_PLUS operation Chuck Lever
2020-08-26 21:54 ` J. Bruce Fields
2020-08-31 18:33 ` Anna Schumaker
2020-09-04 15:56 ` J. Bruce Fields
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