Re: [f2fs-dev] [PATCH] f2fs: fix to avoid potential deadloop in f2fs_fsync_node_pages()

[Zhiguo Niu]

Chao Yu <chao@xxxxxxxxxx> 于2026年9月9日周三 10:03写道：
>
> On 9/9/26 09:12, Zhiguo Niu wrote:
> > Chao Yu via Linux-f2fs-devel <linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx>
> > 于2026年8月24日周一 21:19写道：
> >>
> >> There is potential deadloop in race condition:
> >>
> >> Thread A                                Thread B
> >> - fsync
> >>  - f2fs_do_sync_file
> >>   - f2fs_fsync_node_pages
> >>    - last_fsync_dnode
> >>     - folio_get(last_folio)
> >>                                         - f2fs_setattr
> >>                                          - f2fs_truncate
> >>                                           - f2fs_truncate_blocks
> >>                                            - f2fs_do_truncate_blocks
> >>                                             - f2fs_truncate_inode_blocks
> >>                                              - truncate_dnode
> >>                                               - truncate_node
> >>                                                - invalidate_mapping_pages
> >>                                                 - folio->mapping = NULL
> >>    - is_node_folio alwasy return false
> >>    - atomic && !marked is always true,
> >>      then goto retry
> >>
> >> Cc: stable@xxxxxxxxxx
> >> Fixes: 608514deba38 ("f2fs: set fsync mark only for the last dnode")
> >> Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
> >> ---
> >>  fs/f2fs/node.c | 5 +++++
> >>  1 file changed, 5 insertions(+)
> >>
> >> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> >> index 968e5ed38816..86c2e67e43b6 100644
> >> --- a/fs/f2fs/node.c
> >> +++ b/fs/f2fs/node.c
> >> @@ -2016,6 +2016,11 @@ int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
> >>                 f2fs_debug(sbi, "Retry to write fsync mark: ino=%u, idx=%lx",
> >>                            ino, last_folio->index);
> >>                 folio_lock(last_folio);
> >> +               if (unlikely(!is_node_folio(last_folio))) {
> > Hi Chao,
> > is_node_folio->NODE_MAPPING(F2FS_F_SB(folio))->F2FS_M_SB(folio->mappping)->F2FS_I_SB(mapping->host)
> > if mapping==NULL, panic will occur here?
> > just like  commit msg in  mai: "f2fs: parameterize node helpers and macros"
>
> Hi Zhiguo,
>
> Ah, seems we need to revert ("f2fs: introduce is_{meta,node}_folio") which
> introduce this bug? IIUC.
Hi Chao,
seems yes,  we can use sbi directly.
thanks！
>
> Thanks,
>
> > thanks！
> >
> >> +                       f2fs_folio_put(last_folio, true);
> >> +                       ret = -EAGAIN;
> >> +                       goto out;
> >> +               }
> >>                 f2fs_folio_wait_writeback(last_folio, NODE, true, true);
> >>                 folio_mark_dirty(last_folio);
> >>                 folio_unlock(last_folio);
> >> --
> >> 2.49.0
> >>
> >>
> >>
> >> _______________________________________________
> >> Linux-f2fs-devel mailing list
> >> Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>