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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Tue, 15 Jun 2021 23:42:22 +0300
Message-ID: <CAHp75Vc+QkpuCAXba=Q2Nbv4zKmk_YqW1qTiLVd80BHM_uTV=Q@mail.gmail.com>
Subject: Re: [PATCH RFCv4 0/4] make '%pD' print full path for file
To:     Jia He <justin.he@arm.com>
Cc:     Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Jonathan Corbet <corbet@lwn.net>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Eric Biggers <ebiggers@google.com>,
        "Ahmed S. Darwish" <a.darwish@linutronix.de>,
        Linux Documentation List <linux-doc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux FS Devel <linux-fsdevel@vger.kernel.org>,
        Matthew Wilcox <willy@infradead.org>
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On Tue, Jun 15, 2021 at 6:54 PM Jia He <justin.he@arm.com> wrote:
>
> Background
> ==========
> Linus suggested printing full path for file instead of printing

the full
the file

> 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.
>
> [1] https://lkml.org/lkml/2021/5/18/1260
>
> 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

kasprintf()

After commenting on patch 1, I suggest you to always build with `make W=1 ...`

> Changelog
> =========
> 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 (4):
>   fs: introduce helper d_path_unsafe()
>   lib/vsprintf.c: make '%pD' print full path for file
>   lib/test_printf.c: split write-beyond-buffer check in two
>   lib/test_printf.c: add test cases for '%pD'
>
>  Documentation/core-api/printk-formats.rst |  5 +-
>  fs/d_path.c                               | 83 ++++++++++++++++++++++-
>  include/linux/dcache.h                    |  1 +
>  lib/test_printf.c                         | 31 ++++++++-
>  lib/vsprintf.c                            | 37 ++++++++--
>  5 files changed, 148 insertions(+), 9 deletions(-)
>
> --
> 2.17.1
>


-- 
With Best Regards,
Andy Shevchenko