On 2021/3/18 上午10:22, Sidong Yang wrote:
On Wed, Mar 17, 2021 at 07:36:47PM +0100, David Sterba wrote:
On Tue, Mar 16, 2021 at 01:27:46PM +0000, Sidong Yang wrote:
When user assign qgroup with qgroup id that is too big to exceeds
range and invade level value, and it works without any error. but
this action would be make undefined error. this code make sure that
qgroup id doesn't exceed range(0 ~ 2^48-1).
Should the level be also validate? The function parse_qgroupid does not
do full validation, so eg 0//0 would be parsed as a path and not as a
typo, level larger than 64K will be silently clamped.
I agree. 0//0 would be parsed as path but it failed in
btrfs_util_is_subvolume() and goes to err. I understand that upper 16
bits of qgroupid is for level. so, The valid llevel range is [0~2^16-1].
But I can't get it that level larger than 64K will be clampled.
one more question about that, I see that the ioctl calls just store the
qgroupid without any opeartion with level. is the level meaningless in
kernel?
No, kernel uses the qgroup level, but it's deep in qgroup code.
In fact, kernel treats qgroupid just as an u64, and sometimes checks the
qgroup level for relationship, but under most cases, it's just a u64,
level/id doesn't really matter that much.
Thanks,
Qu
