ocfs2-devel.oss.oracle.com archive mirror
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Cc: jack@suse.cz, darrick.wong@oracle.com, linux-nvdimm@lists.01.org,
	david@fromorbit.com, linux-kernel@vger.kernel.org,
	linux-xfs@vger.kernel.org, ocfs2-devel@oss.oracle.com,
	viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org,
	dan.j.williams@intel.com, linux-btrfs@vger.kernel.org
Subject: Re: [Ocfs2-devel] [PATCH v2 02/10] fsdax: Factor helper: dax_fault_actor()
Date: Wed, 3 Mar 2021 10:28:08 +0100	[thread overview]
Message-ID: <20210303092808.GC12784@lst.de> (raw)
In-Reply-To: <20210226002030.653855-3-ruansy.fnst@fujitsu.com>

On Fri, Feb 26, 2021 at 08:20:22AM +0800, Shiyang Ruan wrote:
> The core logic in the two dax page fault functions is similar. So, move
> the logic into a common helper function. Also, to facilitate the
> addition of new features, such as CoW, switch-case is no longer used to
> handle different iomap types.
> 
> Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
> ---
>  fs/dax.c | 211 ++++++++++++++++++++++++++++++-------------------------
>  1 file changed, 117 insertions(+), 94 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index 7031e4302b13..9dea1572868e 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1289,6 +1289,93 @@ static int dax_fault_cow_page(struct vm_fault *vmf, struct iomap *iomap,
>  	return 0;
>  }
>  
> +static vm_fault_t dax_fault_insert_pfn(struct vm_fault *vmf, pfn_t pfn,
> +		bool pmd, bool write)
> +{
> +	vm_fault_t ret;
> +
> +	if (!pmd) {
> +		struct vm_area_struct *vma = vmf->vma;
> +		unsigned long address = vmf->address;
> +
> +		if (write)
> +			ret = vmf_insert_mixed_mkwrite(vma, address, pfn);
> +		else
> +			ret = vmf_insert_mixed(vma, address, pfn);
> +	} else
> +		ret = vmf_insert_pfn_pmd(vmf, pfn, write);

What about simplifying this a little bit more, something like:

	if (pmd)
		return vmf_insert_pfn_pmd(vmf, pfn, write);

	if (write)
		return vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);
	return vmf_insert_mixed(vmf->vma, vmf->address, pfn);

also given that this only has a single user, why not keep open coding
it in the caller?

> +#ifdef CONFIG_FS_DAX_PMD
> +static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
> +		struct iomap *iomap, void **entry);
> +#else
> +static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
> +		struct iomap *iomap, void **entry)
> +{
> +	return VM_FAULT_FALLBACK;
> +}
> +#endif

Can we try to avoid the forward declaration?  Also is there a reason
dax_pmd_load_hole does not compile for the !CONFIG_FS_DAX_PMD case?
If it compiles fine we can just rely on IS_ENABLED() based dead code
elimination entirely.

> +	/* 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;
	}


> +	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!

_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel@oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel

  reply	other threads:[~2021-03-03  9:28 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-26  0:20 [Ocfs2-devel] [PATCH v2 00/10] fsdax, xfs: Add reflink&dedupe support for fsdax Shiyang Ruan
2021-02-26  0:20 ` [Ocfs2-devel] [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 ` [Ocfs2-devel] [PATCH v2 02/10] fsdax: Factor helper: dax_fault_actor() Shiyang Ruan
2021-03-03  9:28   ` Christoph Hellwig [this message]
2021-03-12  9:01     ` ruansy.fnst
2021-02-26  0:20 ` [Ocfs2-devel] [PATCH v2 03/10] fsdax: Output address in dax_iomap_pfn() and rename it Shiyang Ruan
2021-02-26  0:20 ` [Ocfs2-devel] [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 ` [Ocfs2-devel] [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
2021-03-03  8:45     ` ruansy.fnst
2021-03-03  9:04       ` Joe Perches
2021-03-03  9:39       ` hch
2021-03-03  9:46         ` ruansy.fnst
2021-03-04  5:42   ` [Ocfs2-devel] [RESEND PATCH v2.1 " Shiyang Ruan
2021-02-26  0:20 ` [Ocfs2-devel] [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 ` [Ocfs2-devel] [PATCH v2 10/10] fs/xfs: Add dedupe support for fsdax Shiyang Ruan
2021-02-26  9:45 ` [Ocfs2-devel] 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
     [not found] ` <20210226002030.653855-5-ruansy.fnst@fujitsu.com>
2021-03-03  9:29   ` [Ocfs2-devel] [PATCH v2 04/10] fsdax: Introduce dax_iomap_cow_copy() Christoph Hellwig
     [not found] ` <20210226002030.653855-7-ruansy.fnst@fujitsu.com>
2021-03-03  9:31   ` [Ocfs2-devel] [PATCH v2 06/10] fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero Christoph Hellwig
     [not found] ` <20210226002030.653855-8-ruansy.fnst@fujitsu.com>
2021-02-26  4:14   ` [Ocfs2-devel] [PATCH v2 07/10] iomap: Introduce iomap_apply2() for operations on two files Darrick J. Wong
2021-02-26  8:11     ` ruansy.fnst
2021-02-26  8:25   ` Shiyang Ruan
2021-03-04  5:41   ` [Ocfs2-devel] [RESEND PATCH v2.1 " Shiyang Ruan
2021-03-11 12:30     ` Christoph Hellwig
2021-03-09  6:36 ` [Ocfs2-devel] [PATCH v2 00/10] fsdax, xfs: Add reflink&dedupe support for fsdax Xiaoguang Wang
2021-03-10  1:32   ` ruansy.fnst
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210303092808.GC12784@lst.de \
    --to=hch@lst.de \
    --cc=dan.j.williams@intel.com \
    --cc=darrick.wong@oracle.com \
    --cc=david@fromorbit.com \
    --cc=jack@suse.cz \
    --cc=linux-btrfs@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nvdimm@lists.01.org \
    --cc=linux-xfs@vger.kernel.org \
    --cc=ocfs2-devel@oss.oracle.com \
    --cc=ruansy.fnst@fujitsu.com \
    --cc=viro@zeniv.linux.org.uk \
    --subject='Re: [Ocfs2-devel] [PATCH v2 02/10] fsdax: Factor helper: dax_fault_actor()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).