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In-Reply-To: <20201111230908.GC3576660@ZenIV.linux.org.uk>
From:   yulei zhang <yulei.kernel@gmail.com>
Date:   Thu, 12 Nov 2020 18:03:20 +0800
Message-ID: <CACZOiM0SH_Uo9F5jOGtpXSnkHarH=E-BA-7eUFFKsb2onP2yOw@mail.gmail.com>
Subject: Re: [PATCH 01/35] fs: introduce dmemfs module
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        kvm <kvm@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
        Wanpeng Li <kernellwp@gmail.com>,
        Haiwei Li <lihaiwei.kernel@gmail.com>,
        Yulei Zhang <yuleixzhang@tencent.com>,
        Xiao Guangrong <gloryxiao@tencent.com>
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On Thu, Nov 12, 2020 at 7:09 AM Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> On Wed, Nov 11, 2020 at 04:53:00PM +0800, yulei zhang wrote:
>
> > > ... same here, seeing that you only call that thing from the next two functions
> > > and you do *not* provide ->mknod() as a method (unsurprisingly - what would
> > > device nodes do there?)
> > >
> >
> > Thanks for pointing this out. we may need support the mknod method, otherwise
> > the dev is redundant  and need to be removed.
>
> I'd suggest turning that into (static) __create_file(....) with
>
> static int dmemfs_create(struct inode *dir, struct dentry *dentry,
>                          umode_t mode, bool excl)
> {
>         return __create_file(dir, dentry, mode | S_IFREG);
> }
>
> static int dmemfs_mkdir(struct inode *dir, struct dentry *dentry,
>                          umode_t mode)
> {
>         return __create_file(dir, dentry, mode | S_IFDIR);
> }
>
> (i.e. even inc_nlink() of parent folded into that).
>
> [snip]
>
> > Yes, we seperate the full implementation for dmemfs_file_mmap into
> > patch 05/35, it
> > will assign the interfaces to handle the page fault.
>
> It would be less confusing to move the introduction of ->mmap() to that patch,
> then.

Thanks for the suggestion. will refactor the patches accordingly.