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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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 <79228eaa-776f-da89-89f8-a9b5a90034b6@huawei.com>
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 <20190909083725.GB25724@jaegeuk-macbookpro.roam.corp.google.com>
 <05393d3c-b78d-3bb3-ff26-64d2d3939618@huawei.com>
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 <94ea2431-d4da-f1bf-d949-3c36948aeeca@huawei.com>
 <20190909143725.GC31108@jaegeuk-macbookpro.roam.corp.google.com>
From:   Chao Yu <yuchao0@huawei.com>
Message-ID: <3342f015-1c02-d388-3bfb-1bda70619e9f@huawei.com>
Date:   Tue, 10 Sep 2019 08:59:59 +0800
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On 2019/9/9 22:37, Jaegeuk Kim wrote:
> On 09/09, Chao Yu wrote:
>> On 2019/9/9 17:33, Jaegeuk Kim wrote:
>>> On 09/09, Chao Yu wrote:
>>>> 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?
> 
> Can we update inode before finally putting ipage?

Agreed.

Thanks,

> 
>>>>
>>>> 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
>>>
>>> So, the theory is the block is indeed valid and the address was updated before
>>> write_inode()?
>>
>> I guess so. :)
>>
>> Thanks,
>>
>>>
>>>> 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
>>>>>>>> .
>>>>>>>>
>>>>> .
>>>>>
>>> .
>>>
> .
>