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Message-ID: <fced113e-885d-4be7-87c2-1e14b9d64357@kernel.org>
Date: Fri, 28 Feb 2025 09:49:55 +0800
From: Chao Yu <chao@...nel.org>
To: Jaegeuk Kim <jaegeuk@...nel.org>
Cc: chao@...nel.org, linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, Leo Stone <leocstone@...il.com>,
syzbot+b01a36acd7007e273a83@...kaller.appspotmail.com
Subject: Re: [PATCH v4] f2fs: add check for deleted inode
On 2025/2/27 1:15, Jaegeuk Kim wrote:
> On 02/26, Chao Yu wrote:
>> On 2/26/25 11:28, Jaegeuk Kim wrote:
>>> On 02/24, Chao Yu wrote:
>>>> On 2/14/25 09:44, Chao Yu wrote:
>>>>> On 2/14/25 01:38, Jaegeuk Kim wrote:
>>>>>> On 02/13, Chao Yu wrote:
>>>>>>> On 2/13/25 00:47, Jaegeuk Kim wrote:
>>>>>>>> On 02/12, Chao Yu wrote:
>>>>>>>>> From: Leo Stone <leocstone@...il.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+b01a36acd7007e273a83@...kaller.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 <leocstone@...il.com>
>>>>>>>>> Signed-off-by: Chao Yu <chao@...nel.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?
>>>>>
>>>>> Sure, we need to cover f2fs_rename() as well, please check this:
>>>>>
>>>>> https://lore.kernel.org/all/67450f9a.050a0220.21d33d.0003.GAE@google.com
>>>>
>>>> Hi Jaegeuk,
>>>>
>>>> I'm testing this, seems there is a problem, once we opened an inode that
>>>> has zeroed nlink, in f2fs_evict_inode(), the inode and all its data will be
>>>> deleted, then leaving its stale dir entry in parent directory.
>>>>
>>>> What do you think using v4? so that we may has chance to repair it w/ fsck
>>>> rather than just deleting it?
>>>
>>> Do you mean v4 as the below change?
>>
>> I mean this v4 patch:
>
> What about checking i_nlink right after f2fs_iget in f2fs_lookup?
Fine to me, I've updated in v5.
Thanks,
>
>>
>> ---
>> 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);
>> +
>> 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;
>> }
>>
>> Thanks,
>>
>>>
>>>>
>>>> ---
>>>> fs/f2fs/namei.c | 19 +++++++++++++++++++
>>>> 1 file changed, 19 insertions(+)
>>>>
>>>> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
>>>> index a278c7da8177..949621bc0d07 100644
>>>> --- a/fs/f2fs/namei.c
>>>> +++ b/fs/f2fs/namei.c
>>>> @@ -547,6 +547,16 @@ static int f2fs_unlink(struct inode *dir, struct dentry *dentry)
>>>> goto fail;
>>>> }
>>>>
>>>> + if (unlikely(S_ISDIR(inode->i_mode) ?
>>>> + inode->i_nlink <= 1 : inode->i_nlink == 0)) {
>>>> + f2fs_err_ratelimited(sbi, "%s: inode (ino=%lx) has inconsistent nlink: %u, isdir: %d",
>>>> + __func__, inode->i_ino, inode->i_nlink,
>>>> + S_ISDIR(inode->i_mode));
>>>> + err = -EFSCORRUPTED;
>>>> + set_sbi_flag(sbi, SBI_NEED_FSCK);
>>>> + goto fail;
>>>> + }
>>>> +
>>>> err = f2fs_dquot_initialize(dir);
>>>> if (err)
>>>> goto fail;
>>>> @@ -968,6 +978,15 @@ static int f2fs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
>>>> }
>>>>
>>>> if (new_inode) {
>>>> + if (unlikely(old_is_dir ?
>>>> + new_inode->i_nlink <= 1 : new_inode->i_nlink == 0)) {
>>>> + f2fs_err_ratelimited(sbi, "%s: inode (ino=%lx) has inconsistent nlink: %u, isdir: %d",
>>>> + __func__, new_inode->i_ino, new_inode->i_nlink,
>>>> + S_ISDIR(new_inode->i_mode));
>>>> + err = -EFSCORRUPTED;
>>>> + set_sbi_flag(sbi, SBI_NEED_FSCK);
>>>> + goto out_dir;
>>>> + }
>>>>
>>>> err = -ENOTEMPTY;
>>>> if (old_is_dir && !f2fs_empty_dir(new_inode))
>>>> --
>>>> 2.48.1.601.g30ceb7b040-goog
>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>>>
>>>>>>>
>>>>>>> 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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