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

[Chao Yu]

Jaegeuk,

Could you please send v2 patch to mailing list? as I saw the revised
one has been merged in dev branch.

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@xxxxxxxxxx>
> > ---
> >   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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