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Date:   Wed, 8 Jul 2020 22:39:43 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     Daeho Jeong <daeho43@gmail.com>, linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com,
        Daeho Jeong <daehojeong@google.com>
Subject: Re: [f2fs-dev] [PATCH] f2fs: ignore when len of range in
 f2fs_sec_trim_file is zero
Message-ID: <20200709053943.GA352648@google.com>
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 <619af72b-2f8a-4a84-f73e-ac49989ba79f@huawei.com>
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On 07/09, Chao Yu wrote:
> On 2020/7/9 9:57, Daeho Jeong wrote:
> > From: Daeho Jeong <daehojeong@google.com>
> > 
> > When end_addr comes to zero, it'll trigger different behaviour.
> > To prevent this, we need to ignore the case of that range.len is
> > zero in the function.
> > 
> > Signed-off-by: Daeho Jeong <daehojeong@google.com>
> > ---
> >  fs/f2fs/file.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> > 
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 368c80f8e2a1..98b0a8dbf669 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -3813,15 +3813,14 @@ static int f2fs_sec_trim_file(struct file *filp, unsigned long arg)
> >  	file_start_write(filp);
> >  	inode_lock(inode);
> >  
> > -	if (f2fs_is_atomic_file(inode) || f2fs_compressed_file(inode)) {
> > +	if (f2fs_is_atomic_file(inode) || f2fs_compressed_file(inode) ||
> > +			range.start >= inode->i_size) {
> >  		ret = -EINVAL;
> >  		goto err;
> >  	}
> >  
> > -	if (range.start >= inode->i_size) {
> > -		ret = -EINVAL;
> > +	if (range.len == 0)
> >  		goto err;
> > -	}
> >  
> >  	if (inode->i_size - range.start < range.len) {
> >  		ret = -E2BIG;
> 
> How about the case trimming last partial written block?
> 
> i_size = 8000
> range.start = 4096
> range.len = 4096
> 
> Do we need to roundup(isize, PAGE_SIZE) before comparison?

If we want to trim whole file, do we need to give the exact i_size?
Wouldn't it be better to give trim(0, -1)?

> 
> Thanks,
> 
> > 
> 
> 
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