From: "ruansy.fnst@fujitsu.com" <ruansy.fnst@fujitsu.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-xfs@vger.kernel.org" <linux-xfs@vger.kernel.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"darrick.wong@oracle.com" <darrick.wong@oracle.com>,
"willy@infradead.org" <willy@infradead.org>,
"jack@suse.cz" <jack@suse.cz>,
"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
"ocfs2-devel@oss.oracle.com" <ocfs2-devel@oss.oracle.com>,
"david@fromorbit.com" <david@fromorbit.com>,
"rgoldwyn@suse.de" <rgoldwyn@suse.de>
Subject: RE: [PATCH v2 02/10] fsdax: Factor helper: dax_fault_actor()
Date: Fri, 12 Mar 2021 09:01:15 +0000 [thread overview]
Message-ID: <OSBPR01MB29207FE4814F0FDA5C08676AF46F9@OSBPR01MB2920.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <20210303092808.GC12784@lst.de>
> > + /* if we are reading UNWRITTEN and HOLE, return a hole. */
> > + if (!write &&
> > + (iomap->type == IOMAP_UNWRITTEN || iomap->type ==
> IOMAP_HOLE)) {
> > + if (!pmd)
> > + return dax_load_hole(xas, mapping, &entry, vmf);
> > + else
> > + return dax_pmd_load_hole(xas, vmf, iomap, &entry);
> > + }
> > +
> > + if (iomap->type != IOMAP_MAPPED) {
> > + WARN_ON_ONCE(1);
> > + return VM_FAULT_SIGBUS;
> > + }
>
> Nit: I'd use a switch statement here for a clarity:
>
> switch (iomap->type) {
> case IOMAP_MAPPED:
> break;
> case IOMAP_UNWRITTEN:
> case IOMAP_HOLE:
> if (!write) {
> if (!pmd)
> return dax_load_hole(xas, mapping, &entry, vmf);
> return dax_pmd_load_hole(xas, vmf, iomap, &entry);
> }
> break;
> default:
> WARN_ON_ONCE(1);
> return VM_FAULT_SIGBUS;
> }
>
Hi, Christoph
I did not use a switch-case here is because that I still have to introduce a 'goto' for CoW(Writing on IOMAP_UNWRITTEN and the two different iomap indicate that it is a CoW operation. Then goto IOMAP_MAPPED branch to do the data copy and pfn insertion.) You said the 'goto' makes the code convoluted. So, I avoided to use it and refactored this part into so much if-else, which looks similar in dax_iomap_actor(). So, what's your opinion now?
--
Thanks,
Ruan Shiyang.
>
> > + err = dax_iomap_pfn(iomap, pos, size, &pfn);
> > + if (err)
> > + goto error_fault;
> > +
> > + entry = dax_insert_entry(xas, mapping, vmf, entry, pfn, 0,
> > + write && !sync);
> > +
> > + if (sync)
> > + return dax_fault_synchronous_pfnp(pfnp, pfn);
> > +
> > + ret = dax_fault_insert_pfn(vmf, pfn, pmd, write);
> > +
> > +error_fault:
> > + if (err)
> > + ret = dax_fault_return(err);
> > +
> > + return ret;
>
> It seems like the only place that sets err is the dax_iomap_pfn case above. So
> I'd move the dax_fault_return there, which then allows a direct return for
> everyone else, including the open coded version of dax_fault_insert_pfn.
>
> I really like where this is going!
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next prev parent reply other threads:[~2021-03-12 9:01 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 0:20 [PATCH v2 00/10] fsdax,xfs: Add reflink&dedupe support for fsdax Shiyang Ruan
2021-02-26 0:20 ` [PATCH v2 01/10] fsdax: Factor helpers to simplify dax fault code Shiyang Ruan
2021-03-03 9:13 ` Christoph Hellwig
2021-02-26 0:20 ` [PATCH v2 02/10] fsdax: Factor helper: dax_fault_actor() Shiyang Ruan
2021-03-03 9:28 ` Christoph Hellwig
2021-03-12 9:01 ` ruansy.fnst [this message]
2021-02-26 0:20 ` [PATCH v2 03/10] fsdax: Output address in dax_iomap_pfn() and rename it Shiyang Ruan
2021-02-26 0:20 ` [PATCH v2 04/10] fsdax: Introduce dax_iomap_cow_copy() Shiyang Ruan
2021-03-03 9:29 ` Christoph Hellwig
2021-02-26 0:20 ` [PATCH v2 05/10] fsdax: Replace mmap entry in case of CoW Shiyang Ruan
2021-03-03 9:30 ` Christoph Hellwig
2021-03-03 9:41 ` ruansy.fnst
2021-03-03 9:44 ` Christoph Hellwig
2021-03-03 9:48 ` Christoph Hellwig
2021-02-26 0:20 ` [PATCH v2 06/10] fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero Shiyang Ruan
2021-03-03 9:31 ` Christoph Hellwig
2021-02-26 0:20 ` [PATCH v2 07/10] iomap: Introduce iomap_apply2() for operations on two files Shiyang Ruan
2021-02-26 4:14 ` Darrick J. Wong
2021-02-26 8:11 ` ruansy.fnst
2021-02-26 8:25 ` Shiyang Ruan
2021-03-04 5:41 ` [RESEND PATCH v2.1 " Shiyang Ruan
2021-03-11 12:30 ` Christoph Hellwig
2021-02-26 0:20 ` [PATCH v2 08/10] fsdax: Dedup file range to use a compare function Shiyang Ruan
2021-02-26 8:28 ` Shiyang Ruan
2021-03-03 8:20 ` Joe Perches
2021-03-04 5:42 ` [RESEND PATCH v2.1 " Shiyang Ruan
2021-02-26 0:20 ` [PATCH v2 09/10] fs/xfs: Handle CoW for fsdax write() path Shiyang Ruan
2021-03-03 9:43 ` Christoph Hellwig
2021-03-03 9:57 ` ruansy.fnst
2021-03-03 10:43 ` Christoph Hellwig
2021-03-04 1:35 ` ruansy.fnst
2021-02-26 0:20 ` [PATCH v2 10/10] fs/xfs: Add dedupe support for fsdax Shiyang Ruan
2021-02-26 9:45 ` Question about the "EXPERIMENTAL" tag for dax in XFS ruansy.fnst
2021-02-26 19:04 ` Darrick J. Wong
2021-02-26 19:24 ` Dan Williams
2021-02-26 20:51 ` Dave Chinner
2021-02-26 20:59 ` Dan Williams
2021-02-26 21:27 ` Dave Chinner
2021-02-26 22:41 ` Dan Williams
2021-02-27 22:36 ` Dave Chinner
2021-02-27 23:40 ` Dan Williams
2021-02-28 22:38 ` Dave Chinner
2021-03-01 20:55 ` Dan Williams
2021-03-01 22:46 ` Dave Chinner
2021-03-02 0:32 ` Dan Williams
2021-03-02 2:42 ` Dave Chinner
2021-03-02 3:33 ` Dan Williams
2021-03-02 5:38 ` Dave Chinner
2021-03-02 5:50 ` Dan Williams
2021-03-02 3:28 ` Darrick J. Wong
2021-03-02 5:41 ` Dan Williams
2021-03-02 7:57 ` Dave Chinner
2021-03-02 17:49 ` Dan Williams
2021-03-04 23:40 ` Darrick J. Wong
2021-03-01 7:26 ` Yasunori Goto
2021-03-01 21:34 ` Dan Williams
2021-03-09 6:36 ` [PATCH v2 00/10] fsdax,xfs: Add reflink&dedupe support for fsdax Xiaoguang Wang
2021-03-09 16:19 ` Goldwyn Rodrigues
2021-03-10 1:26 ` ruansy.fnst
2021-03-10 12:30 ` Neal Gompa
2021-03-10 13:02 ` Matthew Wilcox
2021-03-10 13:36 ` Neal Gompa
2021-03-10 13:55 ` Matthew Wilcox
2021-03-10 14:21 ` Goldwyn Rodrigues
2021-03-10 14:26 ` Matthew Wilcox
2021-03-10 17:04 ` Goldwyn Rodrigues
2021-03-11 0:53 ` Dan Williams
2021-03-11 8:26 ` Neal Gompa
2021-03-13 13:07 ` Adam Borowski
2021-03-13 16:24 ` Neal Gompa
2021-03-13 22:00 ` Adam Borowski
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