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Subject: Re: [PATCH] f2fs: fix to avoid accessing uninitialized field of inode
 page in is_alive()
To:     Jaegeuk Kim <jaegeuk@kernel.org>
CC:     Chao Yu <chao@kernel.org>,
        <linux-f2fs-devel@lists.sourceforge.net>,
        <linux-kernel@vger.kernel.org>
References: <20190906105426.109151-1-yuchao0@huawei.com>
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 <080e8dee-4726-8294-622a-cac26e781083@kernel.org>
 <20190909074425.GB21625@jaegeuk-macbookpro.roam.corp.google.com>
 <79228eaa-776f-da89-89f8-a9b5a90034b6@huawei.com>
 <873f4c07-5694-6554-5266-81812a6bd617@huawei.com>
 <20190909083725.GB25724@jaegeuk-macbookpro.roam.corp.google.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <05393d3c-b78d-3bb3-ff26-64d2d3939618@huawei.com>
Date:   Mon, 9 Sep 2019 17:18:47 +0800
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On 2019/9/9 16:37, Jaegeuk Kim wrote:
> On 09/09, Chao Yu wrote:
>> On 2019/9/9 15:58, Chao Yu wrote:
>>> On 2019/9/9 15:44, Jaegeuk Kim wrote:
>>>> On 09/07, Chao Yu wrote:
>>>>> On 2019-9-7 7:48, Jaegeuk Kim wrote:
>>>>>> On 09/06, Chao Yu wrote:
>>>>>>> If inode is newly created, inode page may not synchronize with inode cache,
>>>>>>> so fields like .i_inline or .i_extra_isize could be wrong, in below call
>>>>>>> path, we may access such wrong fields, result in failing to migrate valid
>>>>>>> target block.
>>>>>>
>>>>>> If data is valid, how can we get new inode page?
>>>>
>>>> Let me rephrase the question. If inode is newly created, is this data block
>>>> really valid to move in GC?
>>>
>>> I guess it's valid, let double check that.
>>
>> We can see inode page:
>>
>> - f2fs_create
>>  - f2fs_add_link
>>   - f2fs_add_dentry
>>    - f2fs_init_inode_metadata
>>     - f2fs_add_inline_entry
>>      - ipage = f2fs_new_inode_page
>>      - f2fs_put_page(ipage)   <---- after this
> 
> Can you print out how many block was assigned to this inode?

Add log like this:

		if (!test_and_set_bit(segno, SIT_I(sbi)->invalid_segmap)) {
			if (is_inode) {
				for (i = 0; i < 923 - 50; i++) {
					__le32 *base = blkaddr_in_node(node);
					unsigned ofs = offset_in_addr(inode);

					printk("i:%u, addr:%x\n", i,
						le32_to_cpu(*(base + i)));
				}
				printk("i_inline: %u\n", inode->i_inline);
			}

It shows:
...
i:10, addr:e66a
...
i:46, addr:e66c
i:47, addr:e66d
i:48, addr:e66e
i:49, addr:e66f
i:50, addr:e670
i:51, addr:e671
i:52, addr:e672
i:53, addr:e673
i:54, addr:e674
i:55, addr:e675
i:56, addr:e676
...
i:140, addr:2c35    <--- we want to migrate this block, however, without correct
.i_inline and .i_extra_isize value, we can just find i_addr[i:140-6] = NULL_ADDR
i:141, addr:2c38
i:142, addr:2c39
i:143, addr:2c3b
i:144, addr:2c3e
i:145, addr:2c40
i:146, addr:2c44
i:147, addr:2c48
i:148, addr:2c4a
i:149, addr:2c4c
i:150, addr:2c4f
i:151, addr:2c59
i:152, addr:2c5d
...
i:188, addr:e677
i:189, addr:e678
i:190, addr:e679
i:191, addr:e67a
i:192, addr:e67b
i:193, addr:e67c
i:194, addr:e67d
i:195, addr:e67e
i:196, addr:e67f
i:197, addr:e680
i:198, addr:ffffffff
i:199, addr:ffffffff
i:200, addr:ffffffff
i:201, addr:ffffffff
i:202, addr:ffffffff
i:203, addr:ffffffff
i:204, addr:ffffffff
i:205, addr:ffffffff
i:206, addr:ffffffff
i:207, addr:ffffffff
i:208, addr:ffffffff
i:209, addr:ffffffff
i:210, addr:ffffffff
i:211, addr:ffffffff
i:212, addr:ffffffff
i:213, addr:ffffffff
i:214, addr:ffffffff
i:215, addr:ffffffff
i:216, addr:ffffffff
i:217, addr:ffffffff
i:218, addr:ffffffff
i:219, addr:ffffffff
i:220, addr:ffffffff
i:221, addr:ffffffff
i:222, addr:ffffffff
i:223, addr:ffffffff
i:224, addr:ffffffff
i:225, addr:ffffffff
i:226, addr:ffffffff
i:227, addr:ffffffff
i:228, addr:ffffffff
i:229, addr:ffffffff
i:230, addr:ffffffff
i:231, addr:ffffffff
i:232, addr:ffffffff
i:233, addr:ffffffff
i:234, addr:b032
i:235, addr:b033
i:236, addr:b034
i:237, addr:b035
i:238, addr:b036
i:239, addr:b038
...
i:283, addr:e681
...
i_inline: 0

F2FS-fs (zram1): summary nid: 360, ofs: 134, ver: 0
F2FS-fs (zram1): blkaddr 2c35 (blkaddr in node 0) <-blkaddr in node is NULL_ADDR
F2FS-fs (zram1): expect: seg 14, ofs_in_seg: 53
F2FS-fs (zram1): real: seg 4294967295, ofs_in_seg: 0
F2FS-fs (zram1): ofs: 53, 0
F2FS-fs (zram1): node info ino:360, nid:360, nofs:0
F2FS-fs (zram1): ofs_in_addr: 0
F2FS-fs (zram1): end ========

> 
>>
>>>
>>>>
>>>>>
>>>>> is_alive()
>>>>> {
>>>>> ...
>>>>> 	node_page = f2fs_get_node_page(sbi, nid);  <--- inode page
>>>>
>>>> Aren't we seeing the below version warnings?
>>>>
>>>> if (sum->version != dni->version) {
>>>> 	f2fs_warn(sbi, "%s: valid data with mismatched node version.",
>>>>                            __func__);
>>>>         set_sbi_flag(sbi, SBI_NEED_FSCK);
>>>> }
>>
>> The version of summary and dni are all zero.
> 
> Then, this node was allocated and removed without being flushed.
> 
>>
>> summary nid: 613, ofs: 111, ver: 0
>> blkaddr 2436 (blkaddr in node 0)
>> expect: seg 10, ofs_in_seg: 54
>> real: seg 4294967295, ofs_in_seg: 0
>> ofs: 54, 0
>> node info ino:613, nid:613, nofs:0
>> ofs_in_addr: 0
>>
>> Thanks,
>>
>>>>
>>>>>
>>>>> 	source_blkaddr = datablock_addr(NULL, node_page, ofs_in_node);
>>>>
>>>> So, we're getting this? Does this incur infinite loop in GC?
>>>>
>>>> if (!test_and_set_bit(segno, SIT_I(sbi)->invalid_segmap)) {
>>>> 	f2fs_err(sbi, "mismatched blkaddr %u (source_blkaddr %u) in seg %u\n",
>>>> 	f2fs_bug_on(sbi, 1);
>>>> }
>>>
>>> Yes, I only get this with generic/269, rather than "valid data with mismatched
>>> node version.".
> 
> Was this block moved as valid? In either way, is_alive() returns false, no?
> How about checking i_blocks to detect the page is initialized in is_alive()?
> 
>>>
>>> With this patch, generic/269 won't panic again.
>>>
>>> Thanks,
>>>
>>>>
>>>>> ...
>>>>> }
>>>>>
>>>>> datablock_addr()
>>>>> {
>>>>> ...
>>>>> 	base = offset_in_addr(&raw_node->i);  <--- the base could be wrong here due to
>>>>> accessing uninitialized .i_inline of raw_node->i.
>>>>> ...
>>>>> }
>>>>>
>>>>> Thanks,
>>>>>
>>>>>>
>>>>>>>
>>>>>>> - gc_data_segment
>>>>>>>  - is_alive
>>>>>>>   - datablock_addr
>>>>>>>    - offset_in_addr
>>>>>>>
>>>>>>> Fixes: 7a2af766af15 ("f2fs: enhance on-disk inode structure scalability")
>>>>>>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>>>>>>> ---
>>>>>>>  fs/f2fs/dir.c | 3 +++
>>>>>>>  1 file changed, 3 insertions(+)
>>>>>>>
>>>>>>> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
>>>>>>> index 765f13354d3f..b1840852967e 100644
>>>>>>> --- a/fs/f2fs/dir.c
>>>>>>> +++ b/fs/f2fs/dir.c
>>>>>>> @@ -479,6 +479,9 @@ struct page *f2fs_init_inode_metadata(struct inode *inode, struct inode *dir,
>>>>>>>  		if (IS_ERR(page))
>>>>>>>  			return page;
>>>>>>>  
>>>>>>> +		/* synchronize inode page's data from inode cache */
>>>>>>> +		f2fs_update_inode(inode, page);
>>>>>>> +
>>>>>>>  		if (S_ISDIR(inode->i_mode)) {
>>>>>>>  			/* in order to handle error case */
>>>>>>>  			get_page(page);
>>>>>>> -- 
>>>>>>> 2.18.0.rc1
>>>> .
>>>>
> .
>