Commit 379fc7fa authored by Jeff Layton's avatar Jeff Layton Committed by Ilya Dryomov
Browse files

ceph: use attach/detach_page_private for tracking snap context 

There is some ambiguity around the use of PagePrivate. It's
generally expected in core code that if PagePrivate is set then
you have a reference to it. It's not clear that ceph always
does (and I believe it may not).

Change ceph to use attach/detach_page_private so that we keep a
reference to the page until the snap context is detached.

Link: https://lore.kernel.org/ceph-devel/2503810.1616508988@warthog.procyon.org.uk/T/#mf29e5abbb0ec8035cde0de30778690de7d956f84


Reported-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent aa60cfc3

fs/ceph/addr.c

+7 −11
Original line number Diff line number Diff line
@@ -128,8 +128,7 @@ static int ceph_set_page_dirty(struct page *page) 
	 * PagePrivate so that we get invalidatepage callback.

	 */

	BUG_ON(PagePrivate(page));

	page->private = (unsigned long)snapc;

	SetPagePrivate(page);

	attach_page_private(page, snapc);



	ret = __set_page_dirty_nobuffers(page);

	WARN_ON(!PageLocked(page));
@@ -148,7 +147,7 @@ static void ceph_invalidatepage(struct page *page, unsigned int offset, 
{

	struct inode *inode;

	struct ceph_inode_info *ci;

	struct ceph_snap_context *snapc = page_snap_context(page);

	struct ceph_snap_context *snapc;



	wait_on_page_fscache(page);
@@ -168,10 +167,9 @@ static void ceph_invalidatepage(struct page *page, unsigned int offset, 
	dout("%p invalidatepage %p idx %lu full dirty page\n",

	     inode, page, page->index);



	snapc = detach_page_private(page);

	ceph_put_wrbuffer_cap_refs(ci, 1, snapc);

	ceph_put_snap_context(snapc);

	page->private = 0;

	ClearPagePrivate(page);

}



static int ceph_releasepage(struct page *page, gfp_t gfp)
@@ -589,8 +587,8 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc) 
		dout("writepage cleaned page %p\n", page);

		err = 0;  /* vfs expects us to return 0 */

	}

	page->private = 0;

	ClearPagePrivate(page);

	oldest = detach_page_private(page);

	WARN_ON_ONCE(oldest != snapc);

	end_page_writeback(page);

	ceph_put_wrbuffer_cap_refs(ci, 1, snapc);

	ceph_put_snap_context(snapc);  /* page's reference */
@@ -682,11 +680,9 @@ static void writepages_finish(struct ceph_osd_request *req) 
				clear_bdi_congested(inode_to_bdi(inode),

						    BLK_RW_ASYNC);



			ceph_put_snap_context(page_snap_context(page));

			page->private = 0;

			ClearPagePrivate(page);

			dout("unlocking %p\n", page);

			ceph_put_snap_context(detach_page_private(page));

			end_page_writeback(page);

			dout("unlocking %p\n", page);



			if (remove_page)

				generic_error_remove_page(inode->i_mapping,