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?
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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