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Date:   Sat, 19 Jun 2021 15:27:07 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Al Viro <viro@zeniv.linux.org.uk>
Cc:     Arthur Williams <taaparthur@gmail.com>,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] fs: Allow open with O_CREAT to succeed if existing dir
 is specified
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 <YM3mJjDovNHUxZ8v@zeniv-ca.linux.org.uk>
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On Sat, Jun 19, 2021 at 12:42:14PM +0000, Al Viro wrote:
> On Sat, Jun 19, 2021 at 06:01:48AM -0500, Arthur Williams wrote:
> > Make opening a file with the O_CREAT flag a no-op if the specified file
> > exists even if it exists as a directory. Allows userspace commands, like
> > flock, to open a file and create it if it doesn't exist instead of
> > having to parse errno.
> 
> Not going to happen.  It's a user-visible behaviour, consistent between
> all kinds of Unices, consistent with POSIX and it does make sense.
> 
> NAK.

Agreed.  POSIX states:

[EISDIR]
    The named file is a directory and oflag includes O_WRONLY or O_RDWR, or includes O_CREAT without O_DIRECTORY.

so I would say the POSIX committee considered this situation and
explicitly did not want it to succeed.