On 2018/3/1 10:50, Jaegeuk Kim wrote:
> On 02/28, Chao Yu wrote:
>> Hi Jaegeuk,
>>
>> On 2018/2/28 13:48, Jaegeuk Kim wrote:
>>> Hi Yunlong,
>>>
>>> As Eric pointed out, how do you think using nohighmem for directory likewise
>>
>> I'd like to ask, at the beginning, why we choose to use highmem for dentry
>> page?
>> any history reason there?
>
> There was no huge preference on it based on performance. I just wanted not to
> abuse lowmem.
Got you, thanks for explanation.
Thanks,
>
> Thanks,
>
>>
>>> ext4, which looks like more efficient? Actually, we don't need to do this in
>>> most of recent kernels, right?
>>
>> It's OK to me to keep a line with ext4.
>>
>> Thanks,
>>
>>>
>>> Thanks,
>>>
>>> On 02/28, Yunlong Song wrote:
>>>> This reverts commit e06f86e61d7a67fe6e826010f57aa39c674f4b1b.
>>>>
>>>> Conflicts:
>>>> fs/f2fs/dir.c
>>>>
>>>> In some platforms (such as arm), high memory is used, then the
>>>> decrypting filename will cause panic, the reason see commit
>>>> 569cf1876a32e574ba8a7fb825cd91bafd003882 ("f2fs crypto: allocate buffer
>>>> for decrypting filename"):
>>>>
>>>> We got dentry pages from high_mem, and its address space directly goes
>>>> into the
>>>> decryption path via f2fs_fname_disk_to_usr.
>>>> But, sg_init_one assumes the address is not from high_mem, so we can get
>>>> this
>>>> panic since it doesn't call kmap_high but kunmap_high is triggered at the
>>>> end.
>>>>
>>>> kernel BUG at ../../../../../../kernel/mm/highmem.c:290!
>>>> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
>>>> ...
>>>> (kunmap_high+0xb0/0xb8) from [<c0114534>] (__kunmap_atomic+0xa0/0xa4)
>>>> (__kunmap_atomic+0xa0/0xa4) from [<c035f028>]
>>>> (blkcipher_walk_done+0x128/0x1ec)
>>>> (blkcipher_walk_done+0x128/0x1ec) from [<c0366c24>]
>>>> (crypto_cbc_decrypt+0xc0/0x170)
>>>> (crypto_cbc_decrypt+0xc0/0x170) from [<c0367148>]
>>>> (crypto_cts_decrypt+0xc0/0x114)
>>>> (crypto_cts_decrypt+0xc0/0x114) from [<c035ea98>]
>>>> (async_decrypt+0x40/0x48)
>>>> (async_decrypt+0x40/0x48) from [<c032ca34>]
>>>> (f2fs_fname_disk_to_usr+0x124/0x304)
>>>> (f2fs_fname_disk_to_usr+0x124/0x304) from [<c03056fc>]
>>>> (f2fs_fill_dentries+0xac/0x188)
>>>> (f2fs_fill_dentries+0xac/0x188) from [<c03059c8>]
>>>> (f2fs_readdir+0x1f0/0x300)
>>>> (f2fs_readdir+0x1f0/0x300) from [<c0218054>] (vfs_readdir+0x90/0xb4)
>>>> (vfs_readdir+0x90/0xb4) from [<c0218418>] (SyS_getdents64+0x64/0xcc)
>>>> (SyS_getdents64+0x64/0xcc) from [<c0105ba0>] (ret_fast_syscall+0x0/0x30)
>>>>
>>>> Howerver, later patch:
>>>> commit e06f86e61d7a ("f2fs crypto: avoid unneeded memory allocation in
>>>> ->readdir")
>>>> reverts the codes, which causes panic again in arm, so fix it back to the
>>>> old version.
>>>>
>>>> Signed-off-by: Yunlong Song <yunlong.s...@huawei.com>
>>>> Reviewed-by: Chao Yu <yuch...@huawei.com>
>>>> ---
>>>> fs/f2fs/dir.c | 7 +++++++
>>>> 1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
>>>> index f00b5ed..de2e295 100644
>>>> --- a/fs/f2fs/dir.c
>>>> +++ b/fs/f2fs/dir.c
>>>> @@ -825,9 +825,16 @@ int f2fs_fill_dentries(struct dir_context *ctx,
>>>> struct f2fs_dentry_ptr *d,
>>>> int save_len = fstr->len;
>>>> int err;
>>>>
>>>> + de_name.name = f2fs_kmalloc(sbi, de_name.len, GFP_NOFS);
>>>> + if (!de_name.name)
>>>> + return -ENOMEM;
>>>> +
>>>> + memcpy(de_name.name, d->filename[bit_pos], de_name.len);
>>>> +
>>>> err = fscrypt_fname_disk_to_usr(d->inode,
>>>> (u32)de->hash_code, 0,
>>>> &de_name, fstr);
>>>> + kfree(de_name.name);
>>>> if (err)
>>>> return err;
>>>>
>>>> --
>>>> 1.8.5.2
>>>
>>> .
>>>
>
> .
>
