linux-kernel - Re: [PATCH v2] f2fs: support zero sized file truncate for device aliasing files

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Message-ID: <CACOAw_wLBW1p0z8yNRfwX0GPUtvcoFVYVm_TbJBWe=yzVvwKsQ@mail.gmail.com>
Date: Mon, 24 Mar 2025 09:56:30 -0700
From: Daeho Jeong <daeho43@...il.com>
To: Jaegeuk Kim <jaegeuk@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net, 
	kernel-team@...roid.com, Daeho Jeong <daehojeong@...gle.com>
Subject: Re: [PATCH v2] f2fs: support zero sized file truncate for device
 aliasing files

On Mon, Mar 24, 2025 at 9:28 AM Jaegeuk Kim <jaegeuk@...nel.org> wrote:
>
> Do we still need this patch?

Yes, in many circumstances, we cannot remove the aliasing file because
of SELinux.

>
> On 03/21, Daeho Jeong wrote:
> > From: Daeho Jeong <daehojeong@...gle.com>
> >
> > support a file truncation to zero size for device aliasing files.
> >
> > Signed-off-by: Daeho Jeong <daehojeong@...gle.com>
> > ---
> > v2: make the extent length zero
> > ---
> >  fs/f2fs/file.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index f92a9fba9991..69952f208086 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -775,6 +775,11 @@ int f2fs_do_truncate_blocks(struct inode *inode, u64 from, bool lock)
> >               f2fs_update_time(sbi, REQ_TIME);
> >
> >               f2fs_put_page(ipage, 1);
> > +
> > +             write_lock(&et->lock);
> > +             et->largest.len = 0;
> > +             write_unlock(&et->lock);
> > +
> >               goto out;
> >       }
> >
> > @@ -1036,7 +1041,7 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
> >
> >       if ((attr->ia_valid & ATTR_SIZE)) {
> >               if (!f2fs_is_compress_backend_ready(inode) ||
> > -                             IS_DEVICE_ALIASING(inode))
> > +                             (IS_DEVICE_ALIASING(inode) && attr->ia_size))
> >                       return -EOPNOTSUPP;
> >               if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED) &&
> >                       !IS_ALIGNED(attr->ia_size,
> > --
> > 2.49.0.395.g12beb8f557-goog
> >