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Re: [PATCH v2 0/3] xfs: add O_TMPFILE support

To: Zhi Yong Wu <zwu.kernel@xxxxxxxxx>
Subject: Re: [PATCH v2 0/3] xfs: add O_TMPFILE support
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Thu, 26 Dec 2013 00:51:34 -0800
Cc: xfs@xxxxxxxxxxx, Zhi Yong Wu <wuzhy@xxxxxxxxxxxxxxxxxx>, linux-api@xxxxxxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1387326161-24530-1-git-send-email-zwu.kernel@xxxxxxxxx>
References: <1387326161-24530-1-git-send-email-zwu.kernel@xxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
Both patches looks good to me,

Reviewed-by: Christoph Hellwig <hch@xxxxxx>

But now we need to make sure we can exercise it, which will need
support for tmpfile and flink commands in xfs_io.

And tests that use those commands in xfstests.  At a minimum I'd
suggest:

 - test creating read-only/read-write/executable files
 - check how permission bits actually work for O_TMPFILE and
   enforce that (unfortunately I can't find any documentation for that)
 - check that creating non-regular files is properly rejected
 - check that flink works on O_TMPFILE files, but doesn't work on
   on other files

For an additional XFS-specific test I'd recommend:

 - creating a tmpfile, use src/godown to force the filesystem down and
   check that repair recoveres the unlinked inode list
 - creating a tmpfile, flinking it, use src/godown to force the
   filesystem down and check that repair does not have to recover
   the unlink inode list.

On Wed, Dec 18, 2013 at 08:22:38AM +0800, Zhi Yong Wu wrote:
> From: Zhi Yong Wu <wuzhy@xxxxxxxxxxxxxxxxxx>
> 
> HI, folks
> 
>   It's time to post the latest revision out, welcome to any constructive 
> comment, thanks.
> 
>   If anyone is interested in playing with it, you can get this patchset from 
> my dev git on github:
>   git://github.com/wuzhy/kernel.git xfs_tmpfile
> 
>   The patchset was tested against the code snippet from Andy Lutomirski and 
> other test cases:
>   http://lwn.net/Articles/562296/
>   If you have any other better test cases, please let me know, thanks.
> 
> #include <stdio.h>
> #include <err.h>
> #include <fcntl.h>
> #include <unistd.h>
> #include <string.h>
> 
> #define __O_TMPFILE 020000000
> #define O_DIRECTORY 0200000
> #define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)
> #define AT_EMPTY_PATH 0x1000
> 
> int main(int argc, char **argv)
> {
>    char buf[128];
> 
>    if (argc != 3)
>      errx(1, "Usage: flinktest PATH linkat|proc");
> 
>    int fd = open(".", O_TMPFILE | O_RDWR, 0600);
>    if (fd == -1)
>      err(1, "O_TMPFILE");
>    else
>      printf("fd #: %d\n", fd);
> 
>    write(fd, "test", 4);
> 
>    if (!strcmp(argv[2], "linkat")) {
>      if (linkat(fd, "", AT_FDCWD, argv[1], AT_EMPTY_PATH) != 0)
>        err(1, "linkat");
>    } else if (!strcmp(argv[2], "proc")) {
>      sprintf(buf, "/proc/self/fd/%d", fd);
>      if (linkat(AT_FDCWD, buf, AT_FDCWD, argv[1], AT_SYMLINK_FOLLOW) != 0)
>        err(1, "linkat");
>    } else {
>      errx(1, "invalid mode");
>    }
> 
>    return 0;
> }
> 
> Changelog from v1:
>  - Fixed one chunk of the comments from Christoph Hellwig and Jeff Liu.
> 
> v1:
>  - Addressed the comments from Dave Chinner and Christoph Hellwig.
> 
> Zhi Yong Wu (3):
>   xfs: factor prid related codes into xfs_get_initial_prid()
>   xfs: add O_TMPFILE support
>   xfs: allow linkat() on O_TMPFILE files
> 
>  fs/xfs/xfs_inode.c      |  123 ++++++++++++++++++++++++++++++++++++++++++++--
>  fs/xfs/xfs_inode.h      |   12 +++++
>  fs/xfs/xfs_iops.c       |   16 ++++++
>  fs/xfs/xfs_shared.h     |    4 +-
>  fs/xfs/xfs_symlink.c    |    5 +--
>  fs/xfs/xfs_trans_resv.c |   55 +++++++++++++++++++--
>  fs/xfs/xfs_trans_resv.h |    2 +
>  7 files changed, 202 insertions(+), 15 deletions(-)
> 
> -- 
> 1.7.6.5
> 
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