linux-kernel - Re: [PATCH] f2fs: protect new segment allocation in expand_inode

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Date:   Wed, 3 Jun 2020 16:06:15 +0900
From:   Daeho Jeong <daeho43@...il.com>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net, kernel-team@...roid.com,
        Daeho Jeong <daehojeong@...gle.com>
Subject: Re: [PATCH] f2fs: protect new segment allocation in expand_inode_data

Oh, thanks for notification!

2020년 6월 3일 (수) 오후 3:59, Chao Yu <yuchao0@...wei.com>님이 작성:
>
> On 2020/6/1 11:03, Daeho Jeong wrote:
> > From: Daeho Jeong <daehojeong@...gle.com>
> >
> > Found a new segemnt allocation without f2fs_lock_op() in
> > expand_inode_data(). So, when we do fallocate() for a pinned file
> > and trigger checkpoint very frequently and simultaneously. F2FS gets
> > stuck in the below code of do_checkpoint() forever.
> >
> >   f2fs_sync_meta_pages(sbi, META, LONG_MAX, FS_CP_META_IO);
> >   /* Wait for all dirty meta pages to be submitted for IO */
> >                                                 <= if fallocate() here,
> >   f2fs_wait_on_all_pages(sbi, F2FS_DIRTY_META); <= it'll wait forever.
> >
> > Signed-off-by: Daeho Jeong <daehojeong@...gle.com>
> > Reviewed-by: Chao Yu <yuchao0@...wei.com>
>
> Daeho,
>
> I guess Jaegeuk could add the tag when merging this patch, we don't have
> to resend the patch if there is no updates on code and message.
>
> Thanks,
>
> > ---
> >  fs/f2fs/file.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index f7de2a1da528..14ace885baa9 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -1660,7 +1660,11 @@ static int expand_inode_data(struct inode *inode, loff_t offset,
> >
> >               down_write(&sbi->pin_sem);
> >               map.m_seg_type = CURSEG_COLD_DATA_PINNED;
> > +
> > +             f2fs_lock_op(sbi);
> >               f2fs_allocate_new_segments(sbi, CURSEG_COLD_DATA);
> > +             f2fs_unlock_op(sbi);
> > +
> >               err = f2fs_map_blocks(inode, &map, 1, F2FS_GET_BLOCK_PRE_DIO);
> >               up_write(&sbi->pin_sem);
> >
> >