diff mbox series

[1/1] f2fs: fix args passed to trace_f2fs_lookup_end

Message ID 20230524100812.80741-1-bo.wu@vivo.com
State New
Headers
Series [1/1] f2fs: fix args passed to trace_f2fs_lookup_end |

Commit Message

Wu Bo May 24, 2023, 10:08 a.m. UTC 
  The NULL return of 'd_splice_alias' dosen't mean error.

Signed-off-by: Wu Bo <bo.wu@vivo.com>
---
 fs/f2fs/namei.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Jaegeuk Kim May 26, 2023, 5:21 p.m. UTC | #1 
On 05/24, Wu Bo wrote:
> The NULL return of 'd_splice_alias' dosen't mean error.
> 
> Signed-off-by: Wu Bo <bo.wu@vivo.com>
> ---
>  fs/f2fs/namei.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> index 77a71276ecb1..e5a3e39ce90c 100644
> --- a/fs/f2fs/namei.c
> +++ b/fs/f2fs/namei.c
> @@ -577,7 +577,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
>  #endif
>  	new = d_splice_alias(inode, dentry);
>  	err = PTR_ERR_OR_ZERO(new);
> -	trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
> +	trace_f2fs_lookup_end(dir, new ? new : dentry, ino, err);

Shouldn't give an error pointer to the dentry field.

How about just giving the err?

-       err = PTR_ERR_OR_ZERO(new);
-       trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
+       trace_f2fs_lookup_end(dir, dentry, ino, PTR_ERR_OR_ZERO(new));


>  	return new;
>  out_iput:
>  	iput(inode);
> -- 
> 2.35.3
Chao Yu May 27, 2023, 1:01 a.m. UTC | #2 
On 2023/5/27 1:21, Jaegeuk Kim wrote:
> On 05/24, Wu Bo wrote:
>> The NULL return of 'd_splice_alias' dosen't mean error.
>>
>> Signed-off-by: Wu Bo <bo.wu@vivo.com>
>> ---
>>   fs/f2fs/namei.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
>> index 77a71276ecb1..e5a3e39ce90c 100644
>> --- a/fs/f2fs/namei.c
>> +++ b/fs/f2fs/namei.c
>> @@ -577,7 +577,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
>>   #endif
>>   	new = c(inode, dentry);
>>   	err = PTR_ERR_OR_ZERO(new);
>> -	trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
>> +	trace_f2fs_lookup_end(dir, new ? new : dentry, ino, err);
> 
> Shouldn't give an error pointer to the dentry field.
> 
> How about just giving the err?
> 
> -       err = PTR_ERR_OR_ZERO(new);
> -       trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
> +       trace_f2fs_lookup_end(dir, dentry, ino, PTR_ERR_OR_ZERO(new));

static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
{
	if (IS_ERR(ptr))
		return PTR_ERR(ptr);
	else
		return 0;
}

For below two cases, PTR_ERR_OR_ZERO(new) will return zero:
a) f2fs_lookup found existed dentry
b) f2fs_lookup didn't find existed dentry (-ENOENT case)

So in below commit, I passed -ENOENT to tracepoint for case b), so we can
distinguish result of f2fs_lookup in tracepoint, actually, -ENOENT is expected
value when we create a new file/directory.

Commit 84597b1f9b05 ("f2fs: fix wrong value of tracepoint parameter")

> 
> 
>>   	return new;
>>   out_iput:
>>   	iput(inode);
>> -- 
>> 2.35.3
Wu Bo May 29, 2023, 4:13 a.m. UTC | #3 
On Sat, May 27, 2023 at 09:01:41AM +0800, Chao Yu wrote:
> On 2023/5/27 1:21, Jaegeuk Kim wrote:
> > On 05/24, Wu Bo wrote:
> > > The NULL return of 'd_splice_alias' dosen't mean error.
> > > 
> > > Signed-off-by: Wu Bo <bo.wu@vivo.com>
> > > ---
> > >   fs/f2fs/namei.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> > > index 77a71276ecb1..e5a3e39ce90c 100644
> > > --- a/fs/f2fs/namei.c
> > > +++ b/fs/f2fs/namei.c
> > > @@ -577,7 +577,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
> > >   #endif
> > >   	new = c(inode, dentry);
> > >   	err = PTR_ERR_OR_ZERO(new);
> > > -	trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
> > > +	trace_f2fs_lookup_end(dir, new ? new : dentry, ino, err);
> > 
> > Shouldn't give an error pointer to the dentry field.
> > 
> > How about just giving the err?
> > 
> > -       err = PTR_ERR_OR_ZERO(new);
> > -       trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
> > +       trace_f2fs_lookup_end(dir, dentry, ino, PTR_ERR_OR_ZERO(new));
> 
> static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
> {
> 	if (IS_ERR(ptr))
> 		return PTR_ERR(ptr);
> 	else
> 		return 0;
> }
> 
> For below two cases, PTR_ERR_OR_ZERO(new) will return zero:
> a) f2fs_lookup found existed dentry
> b) f2fs_lookup didn't find existed dentry (-ENOENT case)
> 
> So in below commit, I passed -ENOENT to tracepoint for case b), so we can
> distinguish result of f2fs_lookup in tracepoint, actually, -ENOENT is expected
> value when we create a new file/directory.
> 
> Commit 84597b1f9b05 ("f2fs: fix wrong value of tracepoint parameter")
I can see this commit is try to distinguish the dentry not existed case.
But a normal case which dentry is exactly found will also go through
'd_splice_alias', and its return is also NULL. This makes the tracepoint always
print 'err:-2' like the following:
      ls-11676   [004] .... 329281.943118: f2fs_lookup_end: dev = (254,39), pino = 4451, name:Alarms, ino:7093, err:-2
      ls-11676   [004] .... 329281.943145: f2fs_lookup_end: dev = (254,39), pino = 4451, name:Notifications, ino:7094, err:-2
      ls-11676   [004] .... 329281.943172: f2fs_lookup_end: dev = (254,39), pino = 4451, name:Pictures, ino:7095, err:-2
Even these lookup are acctually successful, this is a bit strange.
> 
> > 
> > 
> > >   	return new;
> > >   out_iput:
> > >   	iput(inode);
> > > -- 
> > > 2.35.3
> 
> 
> _______________________________________________
> Linux-f2fs-devel mailing list
> Linux-f2fs-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
Chao Yu May 29, 2023, 10:18 a.m. UTC | #4 
On 2023/5/29 12:13, Wu Bo wrote:
> On Sat, May 27, 2023 at 09:01:41AM +0800, Chao Yu wrote:
>> On 2023/5/27 1:21, Jaegeuk Kim wrote:
>>> On 05/24, Wu Bo wrote:
>>>> The NULL return of 'd_splice_alias' dosen't mean error.
>>>>
>>>> Signed-off-by: Wu Bo <bo.wu@vivo.com>
>>>> ---
>>>>    fs/f2fs/namei.c | 2 +-
>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
>>>> index 77a71276ecb1..e5a3e39ce90c 100644
>>>> --- a/fs/f2fs/namei.c
>>>> +++ b/fs/f2fs/namei.c
>>>> @@ -577,7 +577,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
>>>>    #endif
>>>>    	new = c(inode, dentry);
>>>>    	err = PTR_ERR_OR_ZERO(new);
>>>> -	trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
>>>> +	trace_f2fs_lookup_end(dir, new ? new : dentry, ino, err);
>>>
>>> Shouldn't give an error pointer to the dentry field.
>>>
>>> How about just giving the err?
>>>
>>> -       err = PTR_ERR_OR_ZERO(new);
>>> -       trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
>>> +       trace_f2fs_lookup_end(dir, dentry, ino, PTR_ERR_OR_ZERO(new));
>>
>> static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
>> {
>> 	if (IS_ERR(ptr))
>> 		return PTR_ERR(ptr);
>> 	else
>> 		return 0;
>> }
>>
>> For below two cases, PTR_ERR_OR_ZERO(new) will return zero:
>> a) f2fs_lookup found existed dentry
>> b) f2fs_lookup didn't find existed dentry (-ENOENT case)
>>
>> So in below commit, I passed -ENOENT to tracepoint for case b), so we can
>> distinguish result of f2fs_lookup in tracepoint, actually, -ENOENT is expected
>> value when we create a new file/directory.
>>
>> Commit 84597b1f9b05 ("f2fs: fix wrong value of tracepoint parameter")
> I can see this commit is try to distinguish the dentry not existed case.
> But a normal case which dentry is exactly found will also go through
> 'd_splice_alias', and its return is also NULL. This makes the tracepoint always
> print 'err:-2' like the following:
>        ls-11676   [004] .... 329281.943118: f2fs_lookup_end: dev = (254,39), pino = 4451, name:Alarms, ino:7093, err:-2
>        ls-11676   [004] .... 329281.943145: f2fs_lookup_end: dev = (254,39), pino = 4451, name:Notifications, ino:7094, err:-2
>        ls-11676   [004] .... 329281.943172: f2fs_lookup_end: dev = (254,39), pino = 4451, name:Pictures, ino:7095, err:-2
> Even these lookup are acctually successful, this is a bit strange.

Ah, I misunderstand return value's meaning of .lookup.

So, how about this? it only update err if d_splice_alias() returns a negative
value?

if (IS_ERR(new))
	err = PTR_ERR(new);
trace_f2fs_lookup_end(dir, new ? new : dentry, ino, err);

Thanks,

>>
>>>
>>>
>>>>    	return new;
>>>>    out_iput:
>>>>    	iput(inode);
>>>> -- 
>>>> 2.35.3
>>
>>
>> _______________________________________________
>> Linux-f2fs-devel mailing list
>> Linux-f2fs-devel@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
Wu Bo May 29, 2023, 12:41 p.m. UTC | #5 
On 2023/5/29 18:18, Chao Yu wrote:
> On 2023/5/29 12:13, Wu Bo wrote:
>> On Sat, May 27, 2023 at 09:01:41AM +0800, Chao Yu wrote:
>>> On 2023/5/27 1:21, Jaegeuk Kim wrote:
>>>> On 05/24, Wu Bo wrote:
>>>>> The NULL return of 'd_splice_alias' dosen't mean error.
>>>>>
>>>>> Signed-off-by: Wu Bo <bo.wu@vivo.com>
>>>>> ---
>>>>>    fs/f2fs/namei.c | 2 +-
>>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
>>>>> index 77a71276ecb1..e5a3e39ce90c 100644
>>>>> --- a/fs/f2fs/namei.c
>>>>> +++ b/fs/f2fs/namei.c
>>>>> @@ -577,7 +577,7 @@ static struct dentry *f2fs_lookup(struct inode 
>>>>> *dir, struct dentry *dentry,
>>>>>    #endif
>>>>>        new = c(inode, dentry);
>>>>>        err = PTR_ERR_OR_ZERO(new);
>>>>> -    trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
>>>>> +    trace_f2fs_lookup_end(dir, new ? new : dentry, ino, err);
>>>>
>>>> Shouldn't give an error pointer to the dentry field.
>>>>
>>>> How about just giving the err?
>>>>
>>>> -       err = PTR_ERR_OR_ZERO(new);
>>>> -       trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
>>>> +       trace_f2fs_lookup_end(dir, dentry, ino, PTR_ERR_OR_ZERO(new));
>>>
>>> static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
>>> {
>>>     if (IS_ERR(ptr))
>>>         return PTR_ERR(ptr);
>>>     else
>>>         return 0;
>>> }
>>>
>>> For below two cases, PTR_ERR_OR_ZERO(new) will return zero:
>>> a) f2fs_lookup found existed dentry
>>> b) f2fs_lookup didn't find existed dentry (-ENOENT case)
>>>
>>> So in below commit, I passed -ENOENT to tracepoint for case b), so 
>>> we can
>>> distinguish result of f2fs_lookup in tracepoint, actually, -ENOENT 
>>> is expected
>>> value when we create a new file/directory.
>>>
>>> Commit 84597b1f9b05 ("f2fs: fix wrong value of tracepoint parameter")
>> I can see this commit is try to distinguish the dentry not existed case.
>> But a normal case which dentry is exactly found will also go through
>> 'd_splice_alias', and its return is also NULL. This makes the 
>> tracepoint always
>> print 'err:-2' like the following:
>>        ls-11676   [004] .... 329281.943118: f2fs_lookup_end: dev = 
>> (254,39), pino = 4451, name:Alarms, ino:7093, err:-2
>>        ls-11676   [004] .... 329281.943145: f2fs_lookup_end: dev = 
>> (254,39), pino = 4451, name:Notifications, ino:7094, err:-2
>>        ls-11676   [004] .... 329281.943172: f2fs_lookup_end: dev = 
>> (254,39), pino = 4451, name:Pictures, ino:7095, err:-2
>> Even these lookup are acctually successful, this is a bit strange.
>
> Ah, I misunderstand return value's meaning of .lookup.
>
> So, how about this? it only update err if d_splice_alias() returns a 
> negative
> value?
>
> if (IS_ERR(new))
>     err = PTR_ERR(new);
> trace_f2fs_lookup_end(dir, new ? new : dentry, ino, err);
>
> Thanks,
>
Yes, this will be better.

>>>
>>>>
>>>>
>>>>>        return new;
>>>>>    out_iput:
>>>>>        iput(inode);
>>>>> -- 
>>>>> 2.35.3
>>>
>>>
>>> _______________________________________________
>>> Linux-f2fs-devel mailing list
>>> Linux-f2fs-devel@lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
diff mbox series

Patch

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 77a71276ecb1..e5a3e39ce90c 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -577,7 +577,7 @@  static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
 #endif
 	new = d_splice_alias(inode, dentry);
 	err = PTR_ERR_OR_ZERO(new);
-	trace_f2fs_lookup_end(dir, dentry, ino, !new ? -ENOENT : err);
+	trace_f2fs_lookup_end(dir, new ? new : dentry, ino, err);
 	return new;
 out_iput:
 	iput(inode);