ceph: implement writeback livelock avoidance using page tagging

While the mapped IOs continue if we try to flush a file's buffer
we can see that the fsync() won't complete until the IOs finish.

This is analogous to Jan Kara's commit (f446daaea9d4 mm: implement
writeback livelock avoidance using page tagging), we will try to
avoid livelocks of writeback when some steadily creates dirty pages
in a mapping we are writing out.

Signed-off-by: Xiubo Li <[e-mail]>
Reviewed-by: Ilya Dryomov <[e-mail]>
Signed-off-by: Ilya Dryomov <[e-mail]>

fs/ceph/addr.c

···
 	bool should_loop, range_whole = false;
 	bool done = false;
 	bool caching = ceph_is_cache_enabled(inode);
+	xa_mark_t tag;
 
 	if (wbc->sync_mode == WB_SYNC_NONE &&
 	    fsc->write_congested)
···
 	start_index = wbc->range_cyclic ? mapping->writeback_index : 0;
 	index = start_index;
 
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages) {
+		tag = PAGECACHE_TAG_TOWRITE;
+	} else {
+		tag = PAGECACHE_TAG_DIRTY;
+	}
 retry:
 	/* find oldest snap context with dirty data */
 	snapc = get_oldest_context(inode, &ceph_wbc, NULL);
···
 		dout(" non-head snapc, range whole\n");
 	}
 
+	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+		tag_pages_for_writeback(mapping, index, end);
+
 	ceph_put_snap_context(last_snapc);
 	last_snapc = snapc;
 
···
 
 get_more_pages:
 		nr_folios = filemap_get_folios_tag(mapping, &index,
-				end, PAGECACHE_TAG_DIRTY, &fbatch);
+						   end, tag, &fbatch);
 		dout("pagevec_lookup_range_tag got %d\n", nr_folios);
 		if (!nr_folios && !locked_pages)
 			break;