On 02/13, Chao Yu wrote:
> On 2/13/25 00:47, Jaegeuk Kim wrote:
> > On 02/12, Chao Yu wrote:
> >> From: Leo Stone <leocst...@gmail.com>
> >>
> >> The syzbot reproducer mounts a f2fs image, then tries to unlink an
> >> existing file. However, the unlinked file already has a link count of 0
> >> when it is read for the first time in do_read_inode().
> >>
> >> Add a check to sanity_check_inode() for i_nlink == 0.
> >>
> >> [Chao Yu: rebase the code and fix orphan inode recovery issue]
> >> Reported-by: syzbot+b01a36acd7007e273...@syzkaller.appspotmail.com
> >> Closes: https://syzkaller.appspot.com/bug?extid=b01a36acd7007e273a83
> >> Fixes: 39a53e0ce0df ("f2fs: add superblock and major in-memory structure")
> >> Signed-off-by: Leo Stone <leocst...@gmail.com>
> >> Signed-off-by: Chao Yu <c...@kernel.org>
> >> ---
> >> fs/f2fs/checkpoint.c | 4 ++++
> >> fs/f2fs/f2fs.h | 1 +
> >> fs/f2fs/inode.c | 6 ++++++
> >> 3 files changed, 11 insertions(+)
> >>
> >> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> >> index bd890738b94d..ada2c548645c 100644
> >> --- a/fs/f2fs/checkpoint.c
> >> +++ b/fs/f2fs/checkpoint.c
> >> @@ -751,6 +751,8 @@ int f2fs_recover_orphan_inodes(struct f2fs_sb_info
> >> *sbi)
> >> if (is_sbi_flag_set(sbi, SBI_IS_WRITABLE))
> >> f2fs_info(sbi, "orphan cleanup on readonly fs");
> >>
> >> + set_sbi_flag(sbi, SBI_ORPHAN_RECOVERY);
> >
> > What about using SBI_POR_DOING?
>
> SBI_POR_DOING will cover most flow of f2fs_fill_super(), I think we can add a
> separated flag just covering f2fs_recover_orphan_inodes(), so that we can
> allow
> iget() of root_inode and all inodes during roll-forward recovery to do sanity
> check nlink w/ zero. What do you think?
Can we do this sanity check after f2fs_iget in the f2fs_unlink() only?
>
> Thanks,
>
> >
> >> +
> >> start_blk = __start_cp_addr(sbi) + 1 + __cp_payload(sbi);
> >> orphan_blocks = __start_sum_addr(sbi) - 1 - __cp_payload(sbi);
> >>
> >> @@ -778,9 +780,11 @@ int f2fs_recover_orphan_inodes(struct f2fs_sb_info
> >> *sbi)
> >> }
> >> f2fs_put_page(page, 1);
> >> }
> >> +
> >> /* clear Orphan Flag */
> >> clear_ckpt_flags(sbi, CP_ORPHAN_PRESENT_FLAG);
> >> out:
> >> + clear_sbi_flag(sbi, SBI_ORPHAN_RECOVERY);
> >> set_sbi_flag(sbi, SBI_IS_RECOVERED);
> >>
> >> return err;
> >> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> >> index 05879c6dc4d6..1c75081c0c14 100644
> >> --- a/fs/f2fs/f2fs.h
> >> +++ b/fs/f2fs/f2fs.h
> >> @@ -1322,6 +1322,7 @@ enum {
> >> SBI_IS_CLOSE, /* specify unmounting */
> >> SBI_NEED_FSCK, /* need fsck.f2fs to fix */
> >> SBI_POR_DOING, /* recovery is doing or not */
> >> + SBI_ORPHAN_RECOVERY, /* orphan inodes recovery is
> >> doing */
> >> SBI_NEED_SB_WRITE, /* need to recover superblock */
> >> SBI_NEED_CP, /* need to checkpoint */
> >> SBI_IS_SHUTDOWN, /* shutdown by ioctl */
> >> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> >> index d6ad7810df69..02f1b69d03d8 100644
> >> --- a/fs/f2fs/inode.c
> >> +++ b/fs/f2fs/inode.c
> >> @@ -386,6 +386,12 @@ static bool sanity_check_inode(struct inode *inode,
> >> struct page *node_page)
> >> }
> >> }
> >>
> >> + if (inode->i_nlink == 0 && !is_sbi_flag_set(sbi, SBI_ORPHAN_RECOVERY)) {
> >> + f2fs_warn(sbi, "%s: inode (ino=%lx) has a link count of 0",
> >> + __func__, inode->i_ino);
> >> + return false;
> >> + }
> >> +
> >> return true;
> >> }
> >>
> >> --
> >> 2.48.1.502.g6dc24dfdaf-goog
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