linux-kernel - Re: [PATCH v5 0/4] make '%pD' print the full path of file

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Date:   Tue, 22 Jun 2021 17:43:23 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Jia He <justin.he@....com>
Cc:     Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Jonathan Corbet <corbet@....net>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Eric Biggers <ebiggers@...gle.com>,
        "Ahmed S. Darwish" <a.darwish@...utronix.de>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        Matthew Wilcox <willy@...radead.org>,
        Christoph Hellwig <hch@...radead.org>, nd@....com
Subject: Re: [PATCH v5 0/4] make '%pD' print the full path of file

On Tue, Jun 22, 2021 at 10:06:30PM +0800, Jia He wrote:
> Background
> ==========
> Linus suggested printing the full path of file instead of printing
> the components as '%pd'.
> 
> Typically, there is no need for printk specifiers to take any real locks
> (ie mount_lock or rename_lock). So I introduce a new helper d_path_fast
> which is similar to d_path except it doesn't take any seqlock/spinlock.
> 
> This series is based on Al Viro's d_path cleanup patches [1] which
> lifted the inner lockless loop into a new helper. 
> 
> Link: https://lkml.org/lkml/2021/5/18/1260 [1]
> 
> Test
> ====
> The cases I tested:
> 1. print '%pD' with full path of ext4 file
> 2. mount a ext4 filesystem upon a ext4 filesystem, and print the file
>    with '%pD'
> 3. all test_print selftests, including the new '%14pD' '%-14pD'

> 4. kasnprintf

I believe you are talking about kasprintf().


> Changelog
> =========
> v5:
> - remove the RFC tag

JFYI, when we drop RFC we usually start the series from v1.

> - refine the commit msg/comments(by Petr, Andy)
> - make using_scratch_space a new parameter of the test case 

Thanks for the update, I have found few minor things, please address them and
feel free to add
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

> v4:
> - don't support spec.precision anymore for '%pD'
> - add Rasmus's patch into this series
>  
> v3:
> - implement new d_path_unsafe to use [buf, end] instead of stack space for
>   filling bytes (by Matthew)
> - add new test cases for '%pD'
> - drop patch "hmcdrv: remove the redundant directory path" before removing rfc.
> 
> v2: 
> - implement new d_path_fast based on Al Viro's patches
> - add check_pointer check (by Petr)
> - change the max full path size to 256 in stack space
> 
> v1: https://lkml.org/lkml/2021/5/8/122
> 
> 
> Jia He (3):
>   fs: introduce helper d_path_unsafe()
>   lib/vsprintf.c: make '%pD' print the full path of file
>   lib/test_printf.c: add test cases for '%pD'
> 
> Rasmus Villemoes (1):
>   lib/test_printf.c: split write-beyond-buffer check in two
> 
>  Documentation/core-api/printk-formats.rst |   5 +-
>  fs/d_path.c                               | 104 +++++++++++++++++++++-
>  include/linux/dcache.h                    |   1 +
>  lib/test_printf.c                         |  54 ++++++++---
>  lib/vsprintf.c                            |  40 ++++++++-
>  5 files changed, 184 insertions(+), 20 deletions(-)
> 
> -- 
> 2.17.1
> 

-- 
With Best Regards,
Andy Shevchenko