On Fri, May 14, 2021 at 09:15:54AM +0800, Chao Yu wrote:
> On 2021/5/14 5:17, Eric Biggers wrote:
> > On Wed, May 12, 2021 at 09:52:19AM +0800, Chao Yu wrote:
> > > On 2021/5/12 5:50, Jaegeuk Kim wrote:
> > > > On 05/11, changfeng...@vivo.com wrote:
> > > > > Hi Jaegeuk:
> > > > >
> > > > > If there're existing clusters beyond i_size, may cause data
> > > > > corruption, but
> > > > > will this happen in normal? maybe some error can cause this, if
> > > > > i_size is
> > > > > error the data beyond size still can't handle properly. Is there
> > > > > normal
> > > > > case can casue existing clusters beyond i_size?
> > > >
> > > > We don't have a rule to sync between i_size and i_blocks.
> > >
> > > I can't image a case that compressed cluster may cross filesize, it looks
> > > it's
> > > a bug if that happened, but I'm not sure I have considered all cases. So,
> > > I
> > > prefer to add a check condition as below, then testing w/
> > > xfstest/por_fsstress
> > > for a while.
> > >
> > > Subject: [PATCH] f2fs: compress: compressed cluster should not cross
> > > i_size
> > >
> > > ---
> > > fs/f2fs/data.c | 2 ++
> > > 1 file changed, 2 insertions(+)
> > >
> > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > > index 06d1e58d3882..9acca358d578 100644
> > > --- a/fs/f2fs/data.c
> > > +++ b/fs/f2fs/data.c
> > > @@ -3325,6 +3325,8 @@ static int f2fs_write_begin(struct file *file,
> > > struct address_space *mapping,
> > > err = ret;
> > > goto fail;
> > > } else if (ret) {
> > > + f2fs_bug_on(sbi, index >=
> > > + DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
> > > return 0;
> > > }
> > > }
> >
> > If a file has both fs-verity and compression enabled, it can have compressed
> > clusters past i_size.
>
> Correct, any other case we missed for a writable file? let us know.
>
> Thanks,
>
Well, files become read-only once fs-verity is enabled on them, but that happens
after the blocks past i_size are written in the first place. That part still
uses ->write_begin(), ->write_end(), ->writepages(), etc.
- Eric
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