From: Dominique Martinet <asmadeus@codewreck.org>
To: Jianyong Wu <jianyong.wu@arm.com>
Cc: ericvh@gmail.com, lucho@ionkov.net,
v9fs-developer@lists.sourceforge.net,
linux-kernel@vger.kernel.org, Steve.Capper@arm.com,
Kaly.Xin@arm.com, justin.he@arm.com, wei.chen@arm.com
Subject: Re: [PATCH v2] 9p: retrieve fid from file when file instance exist.
Date: Wed, 1 Jul 2020 12:59:27 +0200 [thread overview]
Message-ID: <20200701105927.GA20762@nautica> (raw)
In-Reply-To: <20200701023821.5387-1-jianyong.wu@arm.com>
Jianyong Wu wrote on Wed, Jul 01, 2020:
> In the current setattr implementation in 9p, fid is always retrieved
> from dentry no matter file instance exists or not. There may be
> some info related to opened file instance dropped. so it's better
> to retrieve fid from file instance if file instance is passed to setattr.
>
> for example:
> fd=open("tmp", O_RDWR);
> ftruncate(fd, 10);
>
> The file context related with fd will be lost as fid is always
> retrieved from dentry, then the backend can't get the info of
> file context. It is against the original intention of user and
> may lead to bug.
Thanks for the commit message - still feels a bit odd but at least
correct enough for me :)
> Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>
> ---
> fs/9p/vfs_inode.c | 6 +++++-
> fs/9p/vfs_inode_dotl.c | 6 +++++-
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
> index c9255d399917..b33574d347fa 100644
> --- a/fs/9p/vfs_inode.c
> +++ b/fs/9p/vfs_inode.c
> @@ -1100,7 +1100,11 @@ static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
>
> retval = -EPERM;
> v9ses = v9fs_dentry2v9ses(dentry);
> - fid = v9fs_fid_lookup(dentry);
> + if (iattr->ia_valid & ATTR_FILE) {
> + fid = iattr->ia_file->private_data;
> + WARN_ON(!fid);
That would crash in 9p_client_wstat a few lines below with the current
else ; so I'm not sure WARN_ON is appropriate with this code.
the snippet I had suggested had v9fs_fid_lookup in a different if, not
as a else statement to avoid this crash (and then warning is OK)
> + } else
> + fid = v9fs_fid_lookup(dentry);
--
Dominique
next prev parent reply other threads:[~2020-07-01 10:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-01 2:38 [PATCH v2] 9p: retrieve fid from file when file instance exist Jianyong Wu
2020-07-01 10:59 ` Dominique Martinet [this message]
2020-07-02 1:09 ` Jianyong Wu
2020-07-02 7:56 ` Dominique Martinet
2020-07-02 9:54 ` Jianyong Wu
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=20200701105927.GA20762@nautica \
--to=asmadeus@codewreck.org \
--cc=Kaly.Xin@arm.com \
--cc=Steve.Capper@arm.com \
--cc=ericvh@gmail.com \
--cc=jianyong.wu@arm.com \
--cc=justin.he@arm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=lucho@ionkov.net \
--cc=v9fs-developer@lists.sourceforge.net \
--cc=wei.chen@arm.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).