Re: [PATCH v2] ceph: invalidate pages when doing DIO in encrypted inodes

Xiubo Li
2022-04-06T14:31:59Z

On 4/6/22 6:50 PM, Luís Henriques wrote:
> Xiubo Li <xiubli@redhat.com> writes:
>
>> On 4/1/22 9:32 PM, Luís Henriques wrote:
>>> When doing DIO on an encrypted node, we need to invalidate the page cache in
>>> the range being written to, otherwise the cache will include invalid data.
>>>
>>> Signed-off-by: Luís Henriques <lhenriques@suse.de>
>>> ---
>>> fs/ceph/file.c | 11 ++++++++++-
>>> 1 file changed, 10 insertions(+), 1 deletion(-)
>>>
>>> Changes since v1:
>>> - Replaced truncate_inode_pages_range() by invalidate_inode_pages2_range
>>> - Call fscache_invalidate with FSCACHE_INVAL_DIO_WRITE if we're doing DIO
>>>
>>> Note: I'm not really sure this last change is required, it doesn't really
>>> affect generic/647 result, but seems to be the most correct.
>>>
>>> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
>>> index 5072570c2203..b2743c342305 100644
>>> --- a/fs/ceph/file.c
>>> +++ b/fs/ceph/file.c
>>> @@ -1605,7 +1605,7 @@ ceph_sync_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos,
>>> if (ret < 0)
>>> return ret;
>>> - ceph_fscache_invalidate(inode, false);
>>> + ceph_fscache_invalidate(inode, (iocb->ki_flags & IOCB_DIRECT));
>>> ret = invalidate_inode_pages2_range(inode->i_mapping,
>>> pos >> PAGE_SHIFT,
>>> (pos + count - 1) >> PAGE_SHIFT);
>>> @@ -1895,6 +1895,15 @@ ceph_sync_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos,
>>> req->r_inode = inode;
>>> req->r_mtime = mtime;
>>> + if (IS_ENCRYPTED(inode) && (iocb->ki_flags & IOCB_DIRECT)) {
>>> + ret = invalidate_inode_pages2_range(
>>> + inode->i_mapping,
>>> + write_pos >> PAGE_SHIFT,
>>> + (write_pos + write_len - 1) >> PAGE_SHIFT);
>>> + if (ret < 0)
>>> + dout("invalidate_inode_pages2_range returned %d\n", ret);
>>> + }
>> Shouldn't we fail it if the 'invalidate_inode_pages2_range()' fails here ?
> Yeah, I'm not really sure. I'm simply following the usual pattern where
> an invalidate_inode_pages2_range() failure is logged and ignored. And
> this is not ceph-specific, other filesystems seem to do the same thing.

I think it should be they are using this to invalidate the range only,
do not depend on it to writeback the dirty pages.

Such as they may will call 'filemap_fdatawrite_range()', etc.

I saw in the beginning of the 'ceph_sync_write()', it will do
'filemap_write_and_wait_range()' too. So the dirty pages should have
already flushed.

-- Xiubo

> Cheers,