linux-kernel - Re: [External] Re: [PATCH] ext4: call fallocate may cause process to hang when using fast commit

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Date:   Thu, 23 Dec 2021 11:32:49 +0800
From:   Xin Yin <yinxin.x@...edance.com>
To:     harshad shirwadkar <harshadshirwadkar@...il.com>
Cc:     "Theodore Y. Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Ext4 Developers List <linux-ext4@...r.kernel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [External] Re: [PATCH] ext4: call fallocate may cause process to
 hang when using fast commit

After applying Harshad's patch series "ext4 fast commit API cleanup" ,
this issue has been fixed.
So , please ignore this patch.

Thank,
Xin Yin

>On Thu, Dec 23, 2021 at 10:44 AM harshad shirwadkar <harshadshirwadkar@...il.com> wrote:
>
> Once the patch series "ext4 fast commit API cleanup" gets merged in
> (https://patchwork.ozlabs.org/project/linux-ext4/list/?series=277672),
> this patch won't be required anymore. So, I'll undo my review in favor
> of merging the API cleanup patch series first.
>
> - Harshad
>
> On Fri, Dec 17, 2021 at 12:17 PM harshad shirwadkar
> <harshadshirwadkar@...il.com> wrote:
> >
> > Thanks for the patch Xin, it looks good to me. I think there are a few
> > other places where we are not stopping the transaction before calling
> > commit. I'm trying to find them out.
> >
> > Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@...il.com>
> >
> > On Thu, Dec 16, 2021 at 12:04 AM Xin Yin <yinxin.x@...edance.com> wrote:
> > >
> > > If open a file with O_SYNC, and call fallocate with mode=0.when using
> > > fast commit, will cause the process to hang.
> > >
> > > During the fast_commit procedure, it will wait for inode update done.
> > > call ext4_fc_stop_update() before ext4_fc_commit() to mark inode
> > > complete update.
> > >
> > > Signed-off-by: Xin Yin <yinxin.x@...edance.com>
> > > ---
> > >  fs/ext4/extents.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > >
> > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> > > index 4108896d471b..92db33887b6c 100644
> > > --- a/fs/ext4/extents.c
> > > +++ b/fs/ext4/extents.c
> > > @@ -4707,8 +4707,12 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
> > >                 goto out;
> > >
> > >         if (file->f_flags & O_SYNC && EXT4_SB(inode->i_sb)->s_journal) {
> > > +               ext4_fc_stop_update(inode);
> > >                 ret = ext4_fc_commit(EXT4_SB(inode->i_sb)->s_journal,
> > >                                         EXT4_I(inode)->i_sync_tid);
> > > +               inode_unlock(inode);
> > > +               trace_ext4_fallocate_exit(inode, offset, max_blocks, ret);
> > > +               return ret;
> > >         }
> > >  out:
> > >         inode_unlock(inode);
> > > --
> > > 2.20.1
> > >