open(): O_EVTONLY and O_NOATIME

[O'Connor, Daniel]

> On 9 Mar 2017, at 23:41, Konstantin Belousov <kostikbel at gmail.com> wrote:
>> This means that there is no way it could look at all the FDs which have this file open and see they are all noatime and then disable atime just for that one.
> 
> Well, I never claimed that the 'look at all the FDs' is needed.  I stated
> that some plumbing to pass O_NOATIME flag from file down to VOPs is needed
> if this feature is implemented.

Sorry, I didn't mean to put words in your mouth. I was just trying to explain the concept as it seemed OP was having difficulty understanding and you and he seemed to be talking past each other.

>> You are right in that if an FS can be mounted noatime it should be able to work but unfortunately there is no plumbing between the open of the file and the file system that supports that.
> 
> I fail to understand this statement.  How somebody's ability to edit /etc/fstab
> is related to potential unintended or malicious lack of metadata update due
> to the mis-use of the flags ?

That wasn't what I was trying to say.

OP said..
> If file system cant be mount with NOATIME - then it already ready to support O_NOATIME.

I took that to mean they thought that if an FS could be mounted noatime then it should be able to support O_NOATIME.

--
Daniel O'Connor
"The nice thing about standards is that there
are so many of them to choose from."
 -- Andrew Tanenbaum
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