Re: [PATCH] xfs: Add check for unsupported xflags

Xiao Yang
2020-09-03T02:58:16Z

On 2020/9/3 1:45, Darrick J. Wong wrote:
> On Wed, Sep 02, 2020 at 10:38:28AM -0700, Ira Weiny wrote:
>> On Wed, Sep 02, 2020 at 10:03:26AM -0700, Darrick J. Wong wrote:
>>> On Wed, Sep 02, 2020 at 01:11:00PM +0800, Xiao Yang wrote:
>>>> Hi Darrick,
>>>>
>>>> It is reasonable for your concern to add a check in VFS, but checking all
>>>> defined xflags is too rough in VFS if one filesystem only supports few
>>>> xflags. :-)
>>> I was advocating for two levels of flags checks: one in the VFS for
>>> undefined flags, and a second check in each filesystem for whichever
>>> flag it wants to recognize. I was not implying that the VFS checks
>>> would be sufficient on their own.
>>>
>> I've not really followed this thread completely but wouldn't this proposed
>> check in the VFS layer be redundant because the set of flags the filesystem
>> accepts should always be a strict subset of the VFS flags?
Hi,

I also think this check in the VFS is redundant. :-)

> Yes. It's 100% CYA. I wouldn't be that bent out of shape if the vfs
> part never happens, but as we already have a vfs argument checker
> function in addition to the per-fs validation I don't see why we would
> leave a gap... ;)

After looking at vfs_ioc_fssetxattr_check(), why do we need to move the
check of extent
size hint to vfs? It seems a xfs-specific flag, right?
btw:
It is fine to move DAX and project id to vfs because they are supported
by more than one
filesystem(e.g. ext4 and xfs).

Best Regards,
Xiao Yang
> --D
>
>> Ira
>
> .
>