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Message-ID: <7fb3ffcb-4513-45da-8f83-eebe8f5e008b@kernel.org>
Date: Wed, 26 Feb 2025 11:49:41 +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 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:
---
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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