linux-kernel - Re: [PATCH v2 3/4] f2fs: atomic: fix to truncate pagecache before on-disk metadata truncation

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Message-ID: <ZqkUJAMJzW_4ANhY@google.com>
Date: Tue, 30 Jul 2024 16:26:12 +0000
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] f2fs: atomic: fix to truncate pagecache before
 on-disk metadata truncation

On 07/30, Chao Yu wrote:
> On 2024/7/30 0:26, Jaegeuk Kim wrote:
> > On 07/26, Chao Yu wrote:
> > > We should always truncate pagecache while truncating on-disk data.
> > > 
> > > Fixes: a46bebd502fe ("f2fs: synchronize atomic write aborts")
> > > Signed-off-by: Chao Yu <chao@...nel.org>
> > > ---
> > > v2:
> > > - fix to use cow_inode instead of inode
> > >   fs/f2fs/file.c | 1 +
> > >   1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > index 6c62f76474d1..54886ddcb8ab 100644
> > > --- a/fs/f2fs/file.c
> > > +++ b/fs/f2fs/file.c
> > > @@ -2202,6 +2202,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
> > >   		F2FS_I(fi->cow_inode)->atomic_inode = inode;
> > >   	} else {
> > >   		/* Reuse the already created COW inode */
> > > +		truncate_setsize(fi->cow_inode, 0);
> > 
> > What if the below truncation failed?
> 
> What about just dropping page cache and do not set isize to 0?

Can we also check if there's any dirty page before truncating it?

> 
> Thanks,
> 
> > 
> > >   		ret = f2fs_do_truncate_blocks(fi->cow_inode, 0, true);
> > >   		if (ret) {
> > >   			f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
> > > -- 
> > > 2.40.1