From: Hanna Reitz <hreitz@redhat.com>
To: Vivek Goyal <vgoyal@redhat.com>, Max Reitz <mreitz@redhat.com>
Cc: virtio-fs@redhat.com, qemu-devel@nongnu.org,
Stefan Hajnoczi <stefanha@redhat.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH v3 10/10] virtiofsd: Add lazy lo_do_find()
Date: Tue, 10 Aug 2021 10:38:32 +0200 [thread overview]
Message-ID: <dfebe39a-35d4-1e1c-c63f-2312586aa97d@redhat.com> (raw)
In-Reply-To: <YRF9Q+MSjrbeybd2@redhat.com>
On 09.08.21 21:08, Vivek Goyal wrote:
> On Fri, Jul 30, 2021 at 05:01:34PM +0200, Max Reitz wrote:
>> lo_find() right now takes two lookup keys for two maps, namely the file
>> handle for inodes_by_handle and the statx information for inodes_by_ids.
>> However, we only need the statx information if looking up the inode by
>> the file handle failed.
>>
>> There are two callers of lo_find(): The first one, lo_do_lookup(), has
>> both keys anyway, so passing them does not incur any additional cost.
>> The second one, lookup_name(), though, needs to explicitly invoke
>> name_to_handle_at() (through get_file_handle()) and statx() (through
>> do_statx()). We need to try to get a file handle as the primary key, so
>> we cannot get rid of get_file_handle(), but we only need the statx
>> information if looking up an inode by handle failed; so we can defer
>> that until the lookup has indeed failed.
> So IIUC, this patch seems to be all about avoiding do_statx()
> call in lookup_name() if file handle could be successfully
> generated.
>
> So can't we just not modify lookup_name() to not call statx()
> if file handle could be generated. And also modfiy lo_find()
> to use st/mnt_id only if fhandle==NULL.
>
> That probably is much simpler change as compared to passing function
> pointers around.
Definitely, but I don’t know whether it’s correct.
Or, we can just drop this patch and say that we don’t need to
over-optimize C virtiofsd.
Hanna
next prev parent reply other threads:[~2021-08-10 8:39 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-30 15:01 [PATCH v3 00/10] virtiofsd: Allow using file handles instead of O_PATH FDs Max Reitz
2021-07-30 15:01 ` [PATCH v3 01/10] virtiofsd: Limit setxattr()'s creds-dropped region Max Reitz
2021-08-06 14:16 ` Vivek Goyal
2021-08-09 10:30 ` Max Reitz
2021-07-30 15:01 ` [PATCH v3 02/10] virtiofsd: Add TempFd structure Max Reitz
2021-08-06 14:41 ` Vivek Goyal
2021-08-09 10:44 ` Max Reitz
2021-07-30 15:01 ` [PATCH v3 03/10] virtiofsd: Use lo_inode_open() instead of openat() Max Reitz
2021-08-06 15:42 ` Vivek Goyal
2021-07-30 15:01 ` [PATCH v3 04/10] virtiofsd: Add lo_inode_fd() helper Max Reitz
2021-08-06 18:25 ` Vivek Goyal
2021-08-09 10:48 ` Max Reitz
2021-07-30 15:01 ` [PATCH v3 05/10] virtiofsd: Let lo_fd() return a TempFd Max Reitz
2021-07-30 15:01 ` [PATCH v3 06/10] virtiofsd: Let lo_inode_open() " Max Reitz
2021-08-06 19:55 ` Vivek Goyal
2021-08-09 13:40 ` Max Reitz
2021-07-30 15:01 ` [PATCH v3 07/10] virtiofsd: Add lo_inode.fhandle Max Reitz
2021-08-09 15:21 ` Vivek Goyal
2021-08-09 16:41 ` Hanna Reitz
2021-07-30 15:01 ` [PATCH v3 08/10] virtiofsd: Add inodes_by_handle hash table Max Reitz
2021-08-09 16:10 ` Vivek Goyal
2021-08-09 16:47 ` Hanna Reitz
2021-08-10 14:07 ` Vivek Goyal
2021-08-10 14:13 ` Hanna Reitz
2021-08-10 17:51 ` Vivek Goyal
2021-07-30 15:01 ` [PATCH v3 09/10] virtiofsd: Optionally fill lo_inode.fhandle Max Reitz
2021-08-09 18:41 ` Vivek Goyal
2021-08-10 8:32 ` Hanna Reitz
2021-08-10 15:23 ` Vivek Goyal
2021-08-10 15:26 ` Hanna Reitz
2021-08-10 15:57 ` Vivek Goyal
2021-08-11 6:41 ` Hanna Reitz
2021-08-16 19:44 ` Vivek Goyal
2021-08-17 8:27 ` Hanna Reitz
2021-08-17 19:45 ` Vivek Goyal
2021-08-18 0:14 ` Vivek Goyal
2021-08-18 13:32 ` Vivek Goyal
2021-08-18 13:48 ` Hanna Reitz
2021-08-19 16:38 ` Dr. David Alan Gilbert
2021-07-30 15:01 ` [PATCH v3 10/10] virtiofsd: Add lazy lo_do_find() Max Reitz
2021-08-09 19:08 ` Vivek Goyal
2021-08-10 8:38 ` Hanna Reitz [this message]
2021-08-10 14:12 ` Vivek Goyal
2021-08-10 14:17 ` Hanna Reitz
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=dfebe39a-35d4-1e1c-c63f-2312586aa97d@redhat.com \
--to=hreitz@redhat.com \
--cc=dgilbert@redhat.com \
--cc=mreitz@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@redhat.com \
--cc=vgoyal@redhat.com \
--cc=virtio-fs@redhat.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
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).