Hi:
On 2021/1/18 15:59, Muchun Song wrote:
> On Sat, Jan 16, 2021 at 5:11 PM Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote:
>>
>> When we reach here with inode = NULL, we should have crashed as inode has
>> already been dereferenced via hstate_inode. In order to make BUG_ON(!inode)
>> takes effect, we should defer initializing hstate until we really need it.
>> Also do this for hugetlbfs_inode_info as it's only used when ia_valid is
>> verified with ATTR_SIZE.
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
>> ---
>> fs/hugetlbfs/inode.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
>> index 740693d7f255..9b221b87fbea 100644
>> --- a/fs/hugetlbfs/inode.c
>> +++ b/fs/hugetlbfs/inode.c
>> @@ -755,10 +755,8 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
>> static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
>> {
>> struct inode *inode = d_inode(dentry);
>> - struct hstate *h = hstate_inode(inode);
>
> If inode == NULL, it will panic here when we access inode->i_sb.
> I have seen many other file system implementations about setattr,
> they all think that d_inode() will return a non-NULL pointer. So
> I prefer to just remove the BUG_ON().
>
Sounds reasonable. Will do it in v2. Many thanks.
> Thanks.
>
>
>> int error;
>> unsigned int ia_valid = attr->ia_valid;
>> - struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
>>
>> BUG_ON(!inode);
>>
>> @@ -767,6 +765,8 @@ static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
>> return error;
>>
>> if (ia_valid & ATTR_SIZE) {
>> + struct hstate *h = hstate_inode(inode);
>> + struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
>> loff_t oldsize = inode->i_size;
>> loff_t newsize = attr->ia_size;
>>
>> --
>> 2.19.1
>>
> .
>
