linux-kernel - Re: POSIX violation by writeback error

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Message-ID: <20180925173510.273hshp4iapd6dcd@angband.pl>
Date:   Tue, 25 Sep 2018 19:35:11 +0200
From:   Adam Borowski <kilobyte@...band.pl>
To:     "Theodore Y. Ts'o" <tytso@....edu>,
        Jeff Layton <jlayton@...hat.com>,
        Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        焦晓冬 <milestonejxd@...il.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Rogier Wolff <R.E.Wolff@...Wizard.nl>
Subject: Re: POSIX violation by writeback error

On Tue, Sep 25, 2018 at 11:46:27AM -0400, Theodore Y. Ts'o wrote:
> P.S.  One thought: it might be cool if there was some way for
> userspace applications to mark files with "nuke if not closed" flag,
> such that if the system crashes, the file systems would automatically
> unlink the file after a reboot or if the process was killed or exits
> without an explicit close(2).  For networked/remote file systems that
> supported this flag, after the client comes back up after a reboot, it
> could notify the server that all files created previously from that
> client should be unlinked.
> 
> Unlike O_TMPFILE, this would require file system changes to support,
> so maybe it's not worth having something which automatically cleans up
> files that were in the middle of being written at the time of a system
> crash.

Isn't this what the snippet for O_TMPFILE in "man 2 open" does?:

                  char path[PATH_MAX];
                  fd = open("/path/to/dir", O_TMPFILE | O_RDWR,
                                          S_IRUSR | S_IWUSR);

                  /* File I/O on 'fd'... */

                  snprintf(path, PATH_MAX,  "/proc/self/fd/%d", fd);
                  linkat(AT_FDCWD, path, AT_FDCWD, "/path/for/file",
                                          AT_SYMLINK_FOLLOW);


Meow!
-- 
⢀⣴⠾⠻⢶⣦⠀ 10 people enter a bar:
⣾⠁⢰⠒⠀⣿⡁ • 1 who understands binary,
⢿⡄⠘⠷⠚⠋⠀ • 1 who doesn't,
⠈⠳⣄⠀⠀⠀⠀ • and E who prefer to write it as hex.