On 2023/7/10 13:02, Gao Xiang wrote:
On 2023/7/10 12:35, Chunhai Guo wrote:
On 2023/7/10 11:37, Gao Xiang wrote:
On 2023/7/10 11:32, Chunhai Guo wrote:
Hi Xiang,
On 2023/7/8 17:00, Gao Xiang wrote:
Hi Chunhai,
On 2023/7/8 14:24, Chunhai Guo wrote:
When z_erofs_read_folio() reads a page with an offset far beyond EOF, two
issues may occur:
- z_erofs_pcluster_readmore() may take a long time to loop when the offset
is big enough, which is unnecessary.
- For example, it will loop 4691368 times and take about 27 seconds
with following case.
- offset = 19217289215
- inode_size = 1442672
- z_erofs_do_read_page() may loop infinitely due to the inappropriate
truncation in the below statement. Since the offset is 64 bits and
min_t() truncates the result to 32 bits. The solution is to replace
unsigned int with another 64-bit type, such as erofs_off_t.
cur = end - min_t(unsigned int, offset + end - map->m_la, end);
- For example:
- offset = 0x400160000
- end = 0x370
- map->m_la = 0x160370
- offset + end - map->m_la = 0x400000000
- offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
Thanks for the catch!
Could you split these two into two patches?
how about using:
cur = end - min_t(erofs_off_t, offend + end - map->m_la, end)
for this?
since cur and end are all [0, PAGE_SIZE - 1] for now, and
folio_size() later.
OK. I will split the patch.
Sorry that I can not understand what is 'offend' refer to and what do you mean.
Could you please describe it more clearly?
Sorry, there is a typo here, I meant 'offset'.
`cur` and `end` both are not exceed 4096 if your page_size
is 4096.
Does
cur = end - min_t(erofs_off_t, offset + end - map->m_la, end)
fix your issue?
Yes. I think this will fix this issue. Do you mean the below change is
unncessary?
>>>> - unsigned int cur, end, spiltted;
>>>> + erofs_off_t cur, end;
>>>> + unsigned int spiltted;
Yes, please help send a fix for this!
Thanks,
Gao Xiang
Got it. I have sent the patch. Please have a check.
Thanks,
Guo Chunhai
