Tested-by: Yiqun Leng <yqleng@linux.alibaba.com>

Please get more test details in this link: 
https://tone.openanolis.cn/ws/nrh4nnio/test_result/106066

Thanks and Regards,
Yiqun Leng


On 2024/1/3 04:37, Gao Xiang wrote:
>
>
> On 2024/1/3 01:11, David Howells wrote:
>> Gao Xiang <hsiangkao@linux.alibaba.com> wrote:
>>
>>>>        down = start - round_down(start, PAGE_SIZE);
>>>>        *_start = start - down;
>>>>        *_len = round_up(down + len, PAGE_SIZE);
>>>> +    if (down < start || *_len > upper_len)
>>>> +        return -ENOBUFS;
>>>
>>> Sorry for bothering. We just found some strange when testing
>>> today-next EROFS over fscache.
>>>
>>> I'm not sure the meaning of
>>>      if (down < start
>>>
>>> For example, if start is page-aligned, down == 0.
>>>
>>> so as long as start > 0 and page-aligned, it will return
>>> -ENOBUFS.  Does it an intended behavior?
>>
>> Yeah, I think that's wrong.
>>
>> Does the attached help?
>
> (+cc more people for testing)
>
> Will test and feedback later.
>
> Thanks,
> Gao Xiang
>
>>
>> David
>> ---
>>
>> diff --git a/fs/cachefiles/io.c b/fs/cachefiles/io.c
>> index bffffedce4a9..7529b40bc95a 100644
>> --- a/fs/cachefiles/io.c
>> +++ b/fs/cachefiles/io.c
>> @@ -522,16 +522,22 @@ int __cachefiles_prepare_write(struct 
>> cachefiles_object *object,
>>                      bool no_space_allocated_yet)
>>   {
>>       struct cachefiles_cache *cache = object->volume->cache;
>> -    loff_t start = *_start, pos;
>> -    size_t len = *_len, down;
>> +    unsigned long long start = *_start, pos;
>> +    size_t len = *_len;
>>       int ret;
>>         /* Round to DIO size */
>> -    down = start - round_down(start, PAGE_SIZE);
>> -    *_start = start - down;
>> -    *_len = round_up(down + len, PAGE_SIZE);
>> -    if (down < start || *_len > upper_len)
>> +    start = round_down(*_start, PAGE_SIZE);
>> +    if (start != *_start) {
>> +        kleave(" = -ENOBUFS [down]");
>> +        return -ENOBUFS;
>> +    }
>> +    if (*_len > upper_len) {
>> +        kleave(" = -ENOBUFS [up]");
>>           return -ENOBUFS;
>> +    }
>> +
>> +    *_len = round_up(len, PAGE_SIZE);
>>         /* We need to work out whether there's sufficient disk space 
>> to perform
>>        * the write - but we can skip that check if we have space already
>> @@ -542,7 +548,7 @@ int __cachefiles_prepare_write(struct 
>> cachefiles_object *object,
>>         pos = cachefiles_inject_read_error();
>>       if (pos == 0)
>> -        pos = vfs_llseek(file, *_start, SEEK_DATA);
>> +        pos = vfs_llseek(file, start, SEEK_DATA);
>>       if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
>>           if (pos == -ENXIO)
>>               goto check_space; /* Unallocated tail */
>> @@ -550,7 +556,7 @@ int __cachefiles_prepare_write(struct 
>> cachefiles_object *object,
>>                         cachefiles_trace_seek_error);
>>           return pos;
>>       }
>> -    if ((u64)pos >= (u64)*_start + *_len)
>> +    if (pos >= start + *_len)
>>           goto check_space; /* Unallocated region */
>>         /* We have a block that's at least partially filled - if 
>> we're low on
>> @@ -563,13 +569,13 @@ int __cachefiles_prepare_write(struct 
>> cachefiles_object *object,
>>         pos = cachefiles_inject_read_error();
>>       if (pos == 0)
>> -        pos = vfs_llseek(file, *_start, SEEK_HOLE);
>> +        pos = vfs_llseek(file, start, SEEK_HOLE);
>>       if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
>>           trace_cachefiles_io_error(object, file_inode(file), pos,
>>                         cachefiles_trace_seek_error);
>>           return pos;
>>       }
>> -    if ((u64)pos >= (u64)*_start + *_len)
>> +    if (pos >= start + *_len)
>>           return 0; /* Fully allocated */
>>         /* Partially allocated, but insufficient space: cull. */
>> @@ -577,7 +583,7 @@ int __cachefiles_prepare_write(struct 
>> cachefiles_object *object,
>>       ret = cachefiles_inject_remove_error();
>>       if (ret == 0)
>>           ret = vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE | 
>> FALLOC_FL_KEEP_SIZE,
>> -                    *_start, *_len);
>> +                    start, *_len);
>>       if (ret < 0) {
>>           trace_cachefiles_io_error(object, file_inode(file), ret,
>>                         cachefiles_trace_fallocate_error);
>>
>