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Subject: Re: [PATCH][RFC] %pd - for printing dentry name
From: Joe Perches <joe@perches.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
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References: <20100201222511.GA12882@ZenIV.linux.org.uk>
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Date: Mon, 01 Feb 2010 14:45:26 -0800
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On Mon, 2010-02-01 at 22:25 +0000, Al Viro wrote:
> 	There's a lot of places doing printks with ->d_name of various
> dentries.  Unfortunately, as often as not they are b0rken due to races
> with rename().
> 
> 	I propose to add a new format - %pd.  It would print dentry name.
> However, unlike everything else in vsnprintf, it would NOT be locking-agnostic.
> It would grab and release dentry->d_lock.  And yes, I hate that as much as
> anyone.  I don't see any sane alternative.
[]
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 3b8aeec..52a09dc 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -880,6 +880,18 @@ static char *uuid_string(char *buf, char *end, const u8 *addr,
>  	return string(buf, end, uuid, spec);
>  }
>  
> +static char *dname_string(char *buf, char *end, struct dentry *d,
> +			 struct printf_spec spec)

Maybe there's value in passing fmt here to allow
printing of the various dentry fields?

"%pd<foo>"

for things like:

pr_debug("ds_read(socket %d)\n", iminor(file->f_path.dentry->d_inode));
dprintk("%s: dentry = %s/%s, cookie = %Lu\n", __func__,
			dentry->d_parent->d_name.name,
			dentry->d_name.name,



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