Re: [PATCH v14 58/64] ceph: add encryption support to writepage

[Xiubo Li <xiubli@xxxxxxxxxx>]

On 6/3/22 12:08 AM, Jeff Layton wrote:
> On Wed, 2022-04-27 at 15:13 -0400, Jeff Layton wrote:
> > Allow writepage to issue encrypted writes. Extend out the requested size
> > and offset to cover complete blocks, and then encrypt and write them to
> > the OSDs.
> >
> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > ---
> >   fs/ceph/addr.c | 34 +++++++++++++++++++++++++++-------
> >   1 file changed, 27 insertions(+), 7 deletions(-)
> >
> > diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> > index d65d431ec933..f54940fc96ee 100644
> > --- a/fs/ceph/addr.c
> > +++ b/fs/ceph/addr.c
> > @@ -586,10 +586,12 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
> >   	loff_t page_off = page_offset(page);
> >   	int err;
> >   	loff_t len = thp_size(page);
> > +	loff_t wlen;
> >   	struct ceph_writeback_ctl ceph_wbc;
> >   	struct ceph_osd_client *osdc = &fsc->client->osdc;
> >   	struct ceph_osd_request *req;
> >   	bool caching = ceph_is_cache_enabled(inode);
> > +	struct page *bounce_page = NULL;
> >   
> >   	dout("writepage %p idx %lu\n", page, page->index);
> >   
> > @@ -621,6 +623,8 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
> >   
> >   	if (ceph_wbc.i_size < page_off + len)
> >   		len = ceph_wbc.i_size - page_off;
> > +	if (IS_ENCRYPTED(inode))
> > +		wlen = round_up(len, CEPH_FSCRYPT_BLOCK_SIZE);
> >   
> The above is buggy. We're only setting "wlen" in the encrypted case. You
> would think that the compiler would catch that, but next usage of wlen
> just passes a pointer to it to another function and that cloaks the
> warning.

Nice catch !


> Fixed in the wip-fscrypt branch, but I'll hold off on re-posting the
> series in case any other new bugs turn up.
>
> >   	dout("writepage %p page %p index %lu on %llu~%llu snapc %p seq %lld\n",
> >   	     inode, page, page->index, page_off, len, snapc, snapc->seq);
> > @@ -629,24 +633,39 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
> >   	    CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb))
> >   		fsc->write_congested = true;
> >   
> > -	req = ceph_osdc_new_request(osdc, &ci->i_layout, ceph_vino(inode), page_off, &len, 0, 1,
> > -				    CEPH_OSD_OP_WRITE, CEPH_OSD_FLAG_WRITE, snapc,
> > -				    ceph_wbc.truncate_seq, ceph_wbc.truncate_size,
> > -				    true);
> > +	req = ceph_osdc_new_request(osdc, &ci->i_layout, ceph_vino(inode),
> > +				    page_off, &wlen, 0, 1, CEPH_OSD_OP_WRITE,
> > +				    CEPH_OSD_FLAG_WRITE, snapc,
> > +				    ceph_wbc.truncate_seq,
> > +				    ceph_wbc.truncate_size, true);
> >   	if (IS_ERR(req)) {
> >   		redirty_page_for_writepage(wbc, page);
> >   		return PTR_ERR(req);
> >   	}
> >   
> > +	if (wlen < len)
> > +		len = wlen;
> > +
> >   	set_page_writeback(page);
> >   	if (caching)
> >   		ceph_set_page_fscache(page);
> >   	ceph_fscache_write_to_cache(inode, page_off, len, caching);
> >   
> > +	if (IS_ENCRYPTED(inode)) {
> > +		bounce_page = fscrypt_encrypt_pagecache_blocks(page, CEPH_FSCRYPT_BLOCK_SIZE,
> > +								0, GFP_NOFS);
> > +		if (IS_ERR(bounce_page)) {
> > +			err = PTR_ERR(bounce_page);
> > +			goto out;
> > +		}
> > +	}
> >   	/* it may be a short write due to an object boundary */
> >   	WARN_ON_ONCE(len > thp_size(page));
> > -	osd_req_op_extent_osd_data_pages(req, 0, &page, len, 0, false, false);
> > -	dout("writepage %llu~%llu (%llu bytes)\n", page_off, len, len);
> > +	osd_req_op_extent_osd_data_pages(req, 0,
> > +			bounce_page ? &bounce_page : &page, wlen, 0,
> > +			false, false);
> > +	dout("writepage %llu~%llu (%llu bytes, %sencrypted)\n",
> > +	     page_off, len, wlen, IS_ENCRYPTED(inode) ? "" : "not ");
> >   
> >   	req->r_mtime = inode->i_mtime;
> >   	err = ceph_osdc_start_request(osdc, req, true);
> > @@ -655,7 +674,8 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
> >   
> >   	ceph_update_write_metrics(&fsc->mdsc->metric, req->r_start_latency,
> >   				  req->r_end_latency, len, err);
> > -
> > +	fscrypt_free_bounce_page(bounce_page);
> > +out:
> >   	ceph_osdc_put_request(req);
> >   	if (err == 0)
> >   		err = len;