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

[Xiubo Li]

On 4/6/22 6:50 PM, Luís Henriques wrote:
> Xiubo Li <xiubli@xxxxxxxxxx> 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@xxxxxxx>
> > > ---
> > >    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,