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SubjectRe: [PATCH] f2fs: fix to avoid accessing uninitialized field of inode page in is_alive()
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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.

>
>>
>> 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);
> }
>
>>
>> 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.".

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
> .
>

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