linux-kernel - Re: [PATCH 1/3] enhanced ESTALE error handling

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Date:	Fri, 18 Jan 2008 11:45:52 -0500
From:	Peter Staubach <staubach@...hat.com>
To:	Matthew Wilcox <matthew@....cx>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-nfs@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Trond Myklebust <trond.myklebust@....uio.no>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH 1/3] enhanced ESTALE error handling

Matthew Wilcox wrote:
> On Fri, Jan 18, 2008 at 10:36:01AM -0500, Peter Staubach wrote:
>   
>> @@ -1025,12 +1027,27 @@ static int fastcall link_path_walk(const
>>  	mntget(save.mnt);
>>  
>>  	result = __link_path_walk(name, nd);
>> -	if (result == -ESTALE) {
>> +	while (result == -ESTALE) {
>> +		/*
>> +		 * If no progress was made looking up the pathname,
>> +		 * then stop and return ENOENT instead of ESTALE.
>> +		 */
>> +		if (nd->dentry == save.dentry) {
>> +			result = -ENOENT;
>> +			break;
>> +		}
>>  		*nd = save;
>>  		dget(nd->dentry);
>>  		mntget(nd->mnt);
>>  		nd->flags |= LOOKUP_REVAL;
>>  		result = __link_path_walk(name, nd);
>> +		/*
>> +		 * If no progress was made this time, then return
>> +		 * ENOENT instead of ESTALE because no recovery
>> +		 * is possible to recover the stale file handle.
>> +		 */
>> +		if (result == -ESTALE && nd->dentry == save.dentry)
>> +			result = -ENOENT;
>>  	}
>>  
>>  	dput(save.dentry);
>>     
>
> Why do you need both of these tests?  The first one should be enough,
> surely?
>
>   

Yes, good point.

>> @@ -1268,8 +1285,8 @@ int path_lookup_open(int dfd, const char
>>   * @create_mode: create intent flags
>>   */
>>  static int path_lookup_create(int dfd, const char *name,
>> -			      unsigned int lookup_flags, struct nameidata *nd,
>> -			      int open_flags, int create_mode)
>> +		unsigned int lookup_flags, struct nameidata *nd,
>> +		int open_flags, int create_mode)
>>     
>
> Gratuitous reformatting?
>
>   

Elimination of an overly long line?

>> @@ -1712,7 +1729,10 @@ int open_namei(int dfd, const char *path
>>  	int acc_mode, error;
>>  	struct path path;
>>  	struct dentry *dir;
>> -	int count = 0;
>> +	int count;
>> +
>> +top:
>> +	count = 0;
>>  
>>  	acc_mode = ACC_MODE(flag);
>>  
>> @@ -1739,7 +1759,8 @@ int open_namei(int dfd, const char *path
>>  	/*
>>  	 * Create - we need to know the parent.
>>  	 */
>> -	error = path_lookup_create(dfd,pathname,LOOKUP_PARENT,nd,flag,mode);
>> +	error = path_lookup_create(dfd, pathname, LOOKUP_PARENT, nd,
>> +				flag, mode);
>>  	if (error)
>>  		return error;
>>  
>> @@ -1812,10 +1833,17 @@ ok:
>>  	return 0;
>>  
>>  exit_dput:
>> +	if (error == -ESTALE)
>> +		d_drop(path.dentry);
>>  	dput_path(&path, nd);
>>  exit:
>>  	if (!IS_ERR(nd->intent.open.file))
>>  		release_open_intent(nd);
>> +	if (error == -ESTALE) {
>> +		d_drop(nd->dentry);
>> +		path_release(nd);
>> +		goto top;
>> +	}
>>     
>
> I wonder if a tail-call might not work better here.

"Tail-call"?

    Thanx...

       ps
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