Re: [PATCH v2 1/1] f2fs: fix args passed to trace_f2fs_lookup_end

[Chao Yu]

On 2023/5/31 7:32, Jaegeuk Kim wrote:
> On 05/30, Wu Bo wrote:
> > The NULL return of 'd_splice_alias' dosen't mean error. Thus the
> > successful case will also return NULL, which makes the tracepoint always
> > print 'err=-ENOENT'.
> >
> > Signed-off-by: Wu Bo <bo.wu@xxxxxxxx>
> > ---
> >   fs/f2fs/namei.c | 5 +++--
> >   1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> > index 77a71276ecb1..0c5e4c424eab 100644
> > --- a/fs/f2fs/namei.c
> > +++ b/fs/f2fs/namei.c
> > @@ -576,8 +576,9 @@ 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);
> > +	if (IS_ERR(new))
> > +		err = PTR_ERR(new);
> > +	trace_f2fs_lookup_end(dir, new ? new : dentry, ino, err);
>
> Again, new can be an error pointer, and the previous err was supposed to be
> zero or -ENOENT.
>
> case 1) dentry exists: err (0) with new (NULL) --> dentry, err=0
> case 2) dentry exists: err (0) with new (VALID) --> new, err=0
> case 3) dentry exists: err (0) with new (ERR) --> dentry, err=ERR
> case 4) no dentry exists: err (-ENOENT) with new (NULL) --> dentry, err=-ENOENT
> case 4) no dentry exists: err (-ENOENT) with new (VALID) --> new, err=-ENOENT
> case 5) no dentry exists: err (-ENOENT) with new (ERR) --> dentry, err=ERR
>
> 	trace_f2fs_lookup_end(dir, !IS_ERR_OR_NULL(new) ? new : dentry,
> 				ino, IS_ERR(new) ? PTR_ERR(new) : err);

Agreed, could you please add above description in commit message?

Thanks,

> >   	return new;
> >   out_iput:
> >   	iput(inode);
> > --
> > 2.35.3