linux-ext4 - Re: [PATCH] ext2: optimize ext2_xattr

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Date:   Fri, 24 May 2019 10:07:40 +0200
From:   Jan Kara <jack@...e.cz>
To:     "cgxu519@...o.com.cn" <cgxu519@...o.com.cn>
Cc:     Jan Kara <jack@...e.cz>, jack@...e.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext2: optimize ext2_xattr_get()

On Fri 24-05-19 10:07:05, cgxu519@...o.com.cn wrote:
> On Thu, 2019-05-23 at 16:46 +0200, Jan Kara wrote:
> > On Tue 21-05-19 16:21:39, Chengguang Xu wrote:
> > > Since xattr entry names are sorted, we don't have
> > > to continue when current entry name is greater than
> > > target.
> > > 
> > > Signed-off-by: Chengguang Xu <cgxu519@...o.com.cn>
> > 
> > Thanks for the patch! If we are going to do these comparisons in multiple
> > places, then please create a helper function to do the comparison (so that
> > we have the same comparison in every place). Something like:
> > 
> > int ext2_xattr_cmp(int name_index, size_t name_len, const char *name,
> > 		   struct ext2_xattr_entry *entry)
> > 
> 
> Hi Jan,
> 
> Thanks for the review and advice. 
> 
> You are right we should introduce a helper to handle this part of work
> and personally I think maybe implementing a helper to find target entry
> will be more useful, do you think it makes sense?

It makes sense but ext2_xattr_set() also computes min_offs and last during
the search so using the search function in that case won't be a readbility
win I guess. So I'm not sure the search function pays off in the end.

								Honza

> 
> 
> Thanks,
> Chengguang
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR