Messages in this thread | | | Date | Fri, 18 Sep 2009 10:05:20 +0800 | Subject | Re: [PATCH 3/3][mmotm] updateing size of kcore | From | Américo Wang <> |
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On Thu, Sep 17, 2009 at 3:14 PM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > On Thu, 17 Sep 2009 14:59:35 +0800 > Américo Wang <xiyou.wangcong@gmail.com> wrote: > >> On Thu, Sep 17, 2009 at 10:45 AM, KAMEZAWA Hiroyuki >> <kamezawa.hiroyu@jp.fujitsu.com> wrote: >> > >> > After memory hotplug (or other events in future), kcore size >> > can be modified. >> > >> > To update inode->i_size, we have to know inode/dentry but we >> > can't get it from inside /proc directly. >> > But considerinyg memory hotplug, kcore image is updated only when >> > it's opened. Then, updating inode->i_size at open() is enough. >> > >> > Cc: WANG Cong <xiyou.wangcong@gmail.com> >> > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> >> >> >> This patch looks fine. >> >> However, I am thinking if kcore is the only file under /proc whose size >> is changed dynamically? If no, that probably means we need to change >> generic proc code. >> > I tried yesteray, and back to this ;) > > One thing which makes me confused is that there is no way to get > inode or dentry from proc_dir_entry. > > I tried to rewrite proc_getattr() for cheating "ls". But it just works for > "stat" and inode->i_size is used more widely. So, this implementation now.
Yeah, stat->size is from inode->i_size.
> > But considering practically, inode->i_size itself is not meaningful in /proc > files even if it's correct. For example, /proc/vmstat or /proc/stat, > /proc/<pid>/maps... etc...
Yes.
> > inode->i_size will be dynamically changed while reading. Now, most of users > know regular files under /proc is not a "real" file and handle them in proper > way. (programs can be used with pipe/stdin works well.) > > I wonder /proc/kcore is a special one, which gdb/objdump/readelf may access. > Above 3 programs are for "usual" files and not considering pseudo files under > /proc. So, I think adding generic i->i_size support is an overkill until > there are users depends on that.
At least I can't think out another /proc file as special as kcore. :-/
Thanks for your analysis, no problem with this patch. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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