From: Amir Goldstein <amir73il@gmail.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>, linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [GIT PULL] Fsnotify cleanups
Date: Sat, 9 Jun 2018 21:46:01 +0300 [thread overview]
Message-ID: <CAOQ4uxj9EU+CTveKqQN1QDHAC-to6aS7uKUkfr_+pk3S_riHaA@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFx8YyVLaPXfpbp=omega0NsHJ1vbBBUOKEZjFkyPsBa9A@mail.gmail.com>
On Sat, Jun 9, 2018 at 8:30 PM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> On Fri, Jun 8, 2018 at 11:57 PM Amir Goldstein <amir73il@gmail.com> wrote:
>>
>> We embed fsnotify_obj in struct inode and fsnotify_obj_mask in struct mount.
>
> So I'd *really* like to see just a pointer, not an embedded struct.
>
> Yes, if you get rid of the mask from the embedded struct (so that it
> only contains a pointer), you do get rid of the odd alignment issues
> and the need for "packed".
>
> But from previous experience, once you embed a structure, that
> structure tends to grow. Because it can, and it's so convenient.
> Suddently it has a spinlock in it too etc.
>
Fair enough.
> So if you can make do with just the pointer, it would actually be
> nicer to expose it as such. Then you can also avoid the header file
> dependency chain, because you can just pre-declare the structure (like
> it does now) and
>
> struct fsnotify_mark_connector;
> ..
> struct fsnotify_mark_connector __rcu *i_fsnotify_marks;
>
> in the inode. That way the core header files don't need to worry about
> the fsnotify details, and don't need to include fsnotify headers.
>
> And we can do inode packing without having to know (not that it
> happens all that often - everybody would *love* to shrink the inode
> structure, but it's just hard. Because everybody also wants to put
> their own data into the inode ..)
>
> Can't the generalization code just take a pointer to a __rcu pointer
> to fsnotify_mark_connector, obviating the need for the fsnotify_obj
> structure definition?
>
Well, if Jan agrees with me that using 2 bits for FS_ACCESS and
FS_EVENT_ON_CHILD on pointer is enough for the purpose of
optimizing pointer dereference, then we can have generalized code
with just the pointer in struct inode/mount.
Thanks,
Amir.
next prev parent reply other threads:[~2018-06-09 18:46 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-07 15:02 [GIT PULL] Fsnotify cleanups Jan Kara
2018-06-07 16:34 ` Linus Torvalds
2018-06-08 13:27 ` Jan Kara
2018-06-08 20:34 ` Linus Torvalds
2018-06-09 6:57 ` Amir Goldstein
2018-06-09 8:00 ` Amir Goldstein
2018-06-11 16:12 ` Jan Kara
2018-06-11 16:31 ` Amir Goldstein
2018-06-09 17:30 ` Linus Torvalds
2018-06-09 18:46 ` Amir Goldstein [this message]
2018-06-10 17:49 ` Amir Goldstein
2018-06-11 13:36 ` Jan Kara
2018-06-11 13:58 ` Amir Goldstein
2018-06-11 16:03 ` Jan Kara
2018-06-11 16:38 ` Amir Goldstein
2018-06-11 19:51 ` Amir Goldstein
2018-06-13 13:21 ` Jan Kara
2018-06-13 13:56 ` Amir Goldstein
2018-06-13 22:17 ` Amir Goldstein
2018-06-22 16:44 ` Jan Kara
2018-06-23 7:42 ` Amir Goldstein
2018-06-11 11:08 ` Jan Kara
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=CAOQ4uxj9EU+CTveKqQN1QDHAC-to6aS7uKUkfr_+pk3S_riHaA@mail.gmail.com \
--to=amir73il@gmail.com \
--cc=jack@suse.cz \
--cc=linux-fsdevel@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).