linux-kernel - Re: [f2fs-dev] [PATCH 1/2] f2fs: evict inode cache for frozen fs

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Message-ID: <YircmwS2pYVutF8R@google.com>
Date:   Thu, 10 Mar 2022 21:22:35 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 1/2] f2fs: evict inode cache for frozen fs

On 03/11, Chao Yu wrote:
> Jaegeuk,
> 
> Could you please send v2 patch to mailing list? as I saw the revised
> one has been merged in dev branch.

Oops, it seems I sent a wrong patch as v2. I sent it again.

> 
> Otherwise, I've no idea where I should reply "Reviewed-by" tag to...
> 
> Thanks,
> 
> On 2022/3/10 9:53, Chao Yu wrote:
> > On 2022/3/10 5:48, Jaegeuk Kim wrote:
> > > Let's purge inode cache in order to avoid the below deadlock.
> > > 
> > > [freeze test]                         shrinkder
> > > freeze_super
> > >   - pwercpu_down_write(SB_FREEZE_FS)
> > >                                         - super_cache_scan
> > >                                           - down_read(&sb->s_umount)
> > >                                             - prune_icache_sb
> > >                                              - dispose_list
> > >                                               - evict
> > >                                                - f2fs_evict_inode
> > > thaw_super
> > >   - down_write(&sb->s_umount);
> > >                                                - __percpu_down_read(SB_FREEZE_FS)
> > 
> > Ah, finally we catch this. :)
> > 
> > > 
> > > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> > > ---
> > >   fs/f2fs/debug.c | 1 +
> > >   fs/f2fs/f2fs.h  | 1 +
> > >   fs/f2fs/inode.c | 6 ++++--
> > >   fs/f2fs/super.c | 4 ++++
> > >   4 files changed, 10 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
> > > index 9a13902c7702..cba5eab24595 100644
> > > --- a/fs/f2fs/debug.c
> > > +++ b/fs/f2fs/debug.c
> > > @@ -338,6 +338,7 @@ static char *s_flag[] = {
> > >       [SBI_QUOTA_SKIP_FLUSH]    = " quota_skip_flush",
> > >       [SBI_QUOTA_NEED_REPAIR]    = " quota_need_repair",
> > >       [SBI_IS_RESIZEFS]    = " resizefs",
> > > +    [SBI_IS_FREEZING]    = " freezefs",
> > 
> > Could you please update description of "sb_status" entry in
> > Documentation/ABI/testing/sysfs-fs-f2fs as well?
> > 
> > Thanks,
> > 
> > >   };
> > >   static int stat_show(struct seq_file *s, void *v)
> > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > > index 68d791ec8b27..da729f53daa8 100644
> > > --- a/fs/f2fs/f2fs.h
> > > +++ b/fs/f2fs/f2fs.h
> > > @@ -1293,6 +1293,7 @@ enum {
> > >       SBI_QUOTA_SKIP_FLUSH,            /* skip flushing quota in current CP */
> > >       SBI_QUOTA_NEED_REPAIR,            /* quota file may be corrupted */
> > >       SBI_IS_RESIZEFS,            /* resizefs is in process */
> > > +    SBI_IS_FREEZING,            /* freezefs is in process */
> > >   };
> > >   enum {
> > > diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> > > index ab8e0c06c78c..71f232dcf3c2 100644
> > > --- a/fs/f2fs/inode.c
> > > +++ b/fs/f2fs/inode.c
> > > @@ -778,7 +778,8 @@ void f2fs_evict_inode(struct inode *inode)
> > >       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);
> > > +    if (!is_sbi_flag_set(sbi, SBI_IS_FREEZING))
> > > +        sb_start_intwrite(inode->i_sb);
> > >       set_inode_flag(inode, FI_NO_ALLOC);
> > >       i_size_write(inode, 0);
> > >   retry:
> > > @@ -809,7 +810,8 @@ void f2fs_evict_inode(struct inode *inode)
> > >           if (dquot_initialize_needed(inode))
> > >               set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR);
> > >       }
> > > -    sb_end_intwrite(inode->i_sb);
> > > +    if (!is_sbi_flag_set(sbi, SBI_IS_FREEZING))
> > > +        sb_end_intwrite(inode->i_sb);
> > >   no_delete:
> > >       dquot_drop(inode);
> > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> > > index 8e3840973077..4b570b5c2674 100644
> > > --- a/fs/f2fs/super.c
> > > +++ b/fs/f2fs/super.c
> > > @@ -1663,11 +1663,15 @@ static int f2fs_freeze(struct super_block *sb)
> > >       /* ensure no checkpoint required */
> > >       if (!llist_empty(&F2FS_SB(sb)->cprc_info.issue_list))
> > >           return -EINVAL;
> > > +
> > > +    /* to avoid deadlock on f2fs_evict_inode->SB_FREEZE_FS */
> > > +    set_sbi_flag(F2FS_SB(sb), SBI_IS_FREEZING);
> > >       return 0;
> > >   }
> > >   static int f2fs_unfreeze(struct super_block *sb)
> > >   {
> > > +    clear_sbi_flag(F2FS_SB(sb), SBI_IS_FREEZING);
> > >       return 0;
> > >   }
> > 
> > 
> > _______________________________________________
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> > Linux-f2fs-devel@...ts.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel