linux-kernel - Re: [PATCH 1/1] f2fs: allocate trace path buffer from names

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Date:   Tue, 18 Apr 2023 09:07:01 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     Wu Bo <bo.wu@...o.com>, linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, wubo.oduw@...il.com
Subject: Re: [PATCH 1/1] f2fs: allocate trace path buffer from names_cache

On 04/18, Chao Yu wrote:
> On 2023/4/14 18:43, Wu Bo wrote:
> > It would be better to use the dedicated slab to store path.
> > 
> > Signed-off-by: Wu Bo <bo.wu@...o.com>
> > ---
> >   fs/f2fs/file.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 15dabeac4690..27137873958f 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -4361,7 +4361,7 @@ static void f2fs_trace_rw_file_path(struct kiocb *iocb, size_t count, int rw)
> >   	struct inode *inode = file_inode(iocb->ki_filp);
> >   	char *buf, *path;
> > -	buf = f2fs_kmalloc(F2FS_I_SB(inode), PATH_MAX, GFP_KERNEL);
> > +	buf = __getname();
> 
> How about:
> 
> buf = f2fs_kmem_cache_alloc(names_cachep, GFP_KERNEL, NULL, F2FS_I_SB(inode));

This looks like a hack using names_cachep?

> 
> >   	if (!buf)
> >   		return;
> >   	path = dentry_path_raw(file_dentry(iocb->ki_filp), buf, PATH_MAX);
> > @@ -4374,7 +4374,7 @@ static void f2fs_trace_rw_file_path(struct kiocb *iocb, size_t count, int rw)
> >   		trace_f2fs_dataread_start(inode, iocb->ki_pos, count,
> >   				current->pid, path, current->comm);
> >   free_buf:
> > -	kfree(buf);
> > +	__putname(buf);
> 
> kmem_cache_free(names_cachep, buf);
> 
> Thanks,
> 
> >   }
> >   static ssize_t f2fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)