Linux-EROFS Archive on lore.kernel.org
 help / color / Atom feed
From: Gao Xiang <gaoxiang25@huawei.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: devel@driverdev.osuosl.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Miao Xie <miaoxie@huawei.com>,
	LKML <linux-kernel@vger.kernel.org>,
	weidu.du@huawei.com, Joe Perches <joe@perches.com>,
	linux-erofs@lists.ozlabs.org,
	Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [PATCH v3 7/7] erofs: redundant assignment in __erofs_get_meta_page()
Date: Sat, 31 Aug 2019 00:48:27 +0800
Message-ID: <20190830164827.GA107220@architecture4> (raw)
In-Reply-To: <20190830162812.GA10694@infradead.org>

Hi Christoph,

On Fri, Aug 30, 2019 at 09:28:12AM -0700, Christoph Hellwig wrote:
> > -		err = bio_add_page(bio, page, PAGE_SIZE, 0);
> > -		if (err != PAGE_SIZE) {
> > +		if (bio_add_page(bio, page, PAGE_SIZE, 0) != PAGE_SIZE) {
> >  			err = -EFAULT;
> >  			goto err_out;
> >  		}
> 
> This patch looks like an improvement.  But looking at that whole
> area just makes me cringe.

OK, I agree with you, I will improve it or just kill them all with
new iomap approach after it supports tail-end packing inline.

> 
> Why is there __erofs_get_meta_page with the two weird booleans instead
> of a single erofs_get_meta_page that gets and gfp_t for additional
> flags and an unsigned int for additional bio op flags.

I agree with you. Thanks for your suggestion.

> 
> Why do need ioprio support to start with?  Seeing that in a new
> fs look kinda odd.  Do you have benchmarks that show the difference?

I don't have some benchmark for all of these, can I just set
REQ_PRIO for all metadata? is that reasonable?
Could you kindly give some suggestion on this?

> 
> That function then calls erofs_grab_bio, which tries to handle a
> bio_alloc failure, except that the function will not actually fail
> due the mempool backing it.  It also seems like and awfully
> huge function to inline.

OK, I will simplify it. Thanks for your suggestion.

> 
> Why is there __submit_bio which really just obsfucates what is
> going on?  Also why is __submit_bio using bio_set_op_attrs instead
> of opencode it as the comment right next to it asks you to?

Originally, mainly due to backport consideration since some
of our smartphones use 3.x kernel as well...

> 
> Also I really don't understand why you can't just use read_cache_page
> or even read_cache_page_gfp instead of __erofs_get_meta_page.
> That function is a whole lot of duplication of functionality shared
> by a lot of other file systems.

OK, I have to admit, that code was originally just copied from f2fs
with some modification (maybe it's not a good example for us).

Thanks,
Gao Xiang


  reply index

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-30  3:00 [PATCH v2 1/7] erofs: on-disk format should have explicitly assigned numbers Gao Xiang
2019-08-30  3:00 ` [PATCH v2 2/7] erofs: some marcos are much more readable as a function Gao Xiang
2019-08-30  3:16   ` Joe Perches
2019-08-30  3:20     ` Gao Xiang
2019-08-30  3:36       ` [PATCH v3 1/7] erofs: on-disk format should have explicitly assigned numbers Gao Xiang
2019-08-30  3:36         ` [PATCH v3 2/7] erofs: some macros are much more readable as a function Gao Xiang
2019-08-30  3:38           ` [PATCH v4 " Gao Xiang
2019-08-30  6:11           ` [PATCH v3 " Chao Yu
2019-08-30  3:36         ` [PATCH v3 3/7] erofs: use a better form for complicated on-disk fields Gao Xiang
2019-08-30  3:36         ` [PATCH v3 4/7] erofs: kill __packed for on-disk structures Gao Xiang
2019-08-30  6:16           ` Chao Yu
2019-08-30  3:36         ` [PATCH v3 5/7] erofs: kill erofs_{init,exit}_inode_cache Gao Xiang
2019-08-30  6:17           ` Chao Yu
2019-08-30  3:36         ` [PATCH v3 6/7] erofs: remove all likely/unlikely annotations Gao Xiang
2019-08-30  6:25           ` Chao Yu
2019-08-30  6:31             ` Gao Xiang
2019-08-30  6:43               ` Chao Yu
2019-08-30 11:55             ` Dan Carpenter
2019-08-30 11:30           ` Dan Carpenter
2019-08-30 12:06             ` Gao Xiang via Linux-erofs
2019-08-30 15:46           ` Christoph Hellwig
2019-08-30 16:04             ` Gao Xiang
2019-08-31 10:57               ` Dan Carpenter
2019-08-30  3:36         ` [PATCH v3 7/7] erofs: redundant assignment in __erofs_get_meta_page() Gao Xiang
2019-08-30  6:25           ` Chao Yu
2019-08-30 16:28           ` Christoph Hellwig
2019-08-30 16:48             ` Gao Xiang [this message]
2019-08-30 15:25         ` [PATCH v3 1/7] erofs: on-disk format should have explicitly assigned numbers Gao Xiang
2019-08-30 15:45     ` [PATCH v2 2/7] erofs: some marcos are much more readable as a function Christoph Hellwig
2019-08-30 15:52       ` Gao Xiang
2019-08-30 15:56         ` Gao Xiang
2019-08-30  3:00 ` [PATCH v2 3/7] erofs: use a better form for complicated on-disk fields Gao Xiang
2019-08-30  3:29   ` Chao Yu
2019-08-30  3:00 ` [PATCH v2 4/7] erofs: kill __packed for on-disk structures Gao Xiang
2019-08-30  3:00 ` [PATCH v2 5/7] erofs: kill erofs_{init,exit}_inode_cache Gao Xiang
2019-08-30  3:00 ` [PATCH v2 6/7] erofs: remove all likely/unlikely annotations Gao Xiang
2019-08-30  3:00 ` [PATCH v2 7/7] erofs: reduntant assignment in __erofs_get_meta_page() Gao Xiang
2019-08-30  3:28 ` [PATCH v2 1/7] erofs: on-disk format should have explicitly assigned numbers Chao Yu

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=20190830164827.GA107220@architecture4 \
    --to=gaoxiang25@huawei.com \
    --cc=dan.carpenter@oracle.com \
    --cc=devel@driverdev.osuosl.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=hch@infradead.org \
    --cc=joe@perches.com \
    --cc=linux-erofs@lists.ozlabs.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=miaoxie@huawei.com \
    --cc=weidu.du@huawei.com \
    /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

Linux-EROFS Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-erofs/0 linux-erofs/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-erofs linux-erofs/ https://lore.kernel.org/linux-erofs \
		linux-erofs@lists.ozlabs.org linux-erofs@ozlabs.org
	public-inbox-index linux-erofs

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.ozlabs.lists.linux-erofs


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git