linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: remove circular locking between sb_internal and fs

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Message-ID: <CACOAw_wjhr8j=-qEDHP_H+_7cTh_ep7Wix4=JC+5x5zp-zpUFA@mail.gmail.com>
Date:   Mon, 25 Oct 2021 09:22:13 -0700
From:   Daeho Jeong <daeho43@...il.com>
To:     Chao Yu <chao@...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: [f2fs-dev] [PATCH] f2fs: remove circular locking between
 sb_internal and fs_reclaim

On Fri, Oct 22, 2021 at 8:32 AM Chao Yu <chao@...nel.org> wrote:
>
> On 2021/10/22 0:44, Daeho Jeong wrote:
> > There is a deadlock between sb_internal lock (sb_start_intwrite()) and
> > dquot related lock.
> > It's because we call f2fs_truncate(), which eventually calls
> > dquot_initialize(), while holding sb_internal lock.
> > So, I called dquot_initialize() in advance to make the 2nd calling of
> > it in f2fs_truncate() ineffective.
> > This is similar with the thing in f2fs_evict_inode() in inode.c
>
> Well, if dquot_initialize() fails in f2fs_drop_inode(), will we still run
> into deadlock?
>

Do you think the same issue is in f2fs_evict_inode() in inode.c?
In fact, I picked up the idea from here.

        err = dquot_initialize(inode);
        if (err) {
                err = 0;
                set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR);
        }

        f2fs_remove_ino_entry(sbi, inode->i_ino, APPEND_INO);
        f2fs_remove_ino_entry(sbi, inode->i_ino, UPDATE_INO);
        f2fs_remove_ino_entry(sbi, inode->i_ino, FLUSH_INO);

        sb_start_intwrite(inode->i_sb);
        set_inode_flag(inode, FI_NO_ALLOC);
        i_size_write(inode, 0);
retry:
        if (F2FS_HAS_BLOCKS(inode))
                err = f2fs_truncate(inode);