Use atomic_t instead of bool as cell->cancelled

src/.gitignore

@@ -0,0 +1,8 @@
+*
+!.gitignore
+!dm-writeboost.h
+!dm-writeboost-target.[c]
+!dm-writeboost-metadata.[ch]
+!dm-writeboost-daemon.[ch]
+!dkms.conf
+!Makefile

src/dm-writeboost-target.c

@@ -752,15 +752,18 @@ static struct read_cache_cell *lookup_read_cache_cell(struct wb_device *wb, sect
 	return NULL;
 }
 
-static void read_cache_cancel_cells(struct read_cache_cells *cells, u32 n)
+/*
+ * Cancel all cells in [cursor, cursor + seqcount).
+ */
+static void read_cache_cancel_seq_cells(struct read_cache_cells *cells)
 {
 	u32 i;
 	u32 last = cells->cursor + cells->seqcount;
 	if (last > cells->size)
 		last = cells->size;
 	for (i = cells->cursor; i < last; i++) {
 		struct read_cache_cell *cell = cells->array + i;
-		cell->cancelled = true;
+		atomic_set(&cell->cancelled, 1);
 	}
 }
 
@@ -780,10 +783,10 @@ static void read_cache_cancel_foreground(struct read_cache_cells *cells,
 
 	if (cells->seqcount > cells->threshold) {
 		if (cells->over_threshold)
-			new_cell->cancelled = true;
+			atomic_set(&new_cell->cancelled, 1);
 		else {
 			cells->over_threshold = true;
-			read_cache_cancel_cells(cells, cells->seqcount);
+			read_cache_cancel_seq_cells(cells);
 		}
 	}
 	cells->last_sector = new_cell->sector;
@@ -839,7 +842,7 @@ static void might_cancel_read_cache_cell(struct wb_device *wb, struct bio *bio)
 	struct read_cache_cell *found;
 	found = lookup_read_cache_cell(wb, calc_cache_alignment(bi_sector(bio)));
 	if (found)
-		found->cancelled = true;
+		atomic_set(&found->cancelled, 1);
 }
 
 static void read_cache_cell_copy_data(struct wb_device *wb, struct bio *bio, unsigned long error)
@@ -852,13 +855,13 @@ static void read_cache_cell_copy_data(struct wb_device *wb, struct bio *bio, uns
 
 	/* Data can be broken. So don't stage. */
 	if (error)
-		cell->cancelled = true;
+		atomic_set(&cell->cancelled, 1);
 
 	/*
 	 * We can omit copying if the cell is cancelled but
 	 * copying for a non-cancelled cell isn't problematic.
 	 */
-	if (!cell->cancelled)
+	if (!atomic_read(&cell->cancelled))
 		copy_bio_payload(cell->data, bio);
 
 	if (atomic_dec_and_test(&cells->ack_count))
@@ -884,7 +887,7 @@ static void inject_read_cache(struct wb_device *wb, struct read_cache_cell *cell
 	 * if might_cancel_read_cache_cell() on the foreground
 	 * cancelled this cell, the data is now stale.
 	 */
-	if (cell->cancelled) {
+	if (atomic_read(&cell->cancelled)) {
 		mutex_unlock(&wb->io_lock);
 		return;
 	}
@@ -980,20 +983,18 @@ static void reinit_read_cache_cells(struct wb_device *wb)
 	struct read_cache_cells *cells = wb->read_cache_cells;
 	u32 i, cur_threshold;
 
-	mutex_lock(&wb->io_lock);
 	cells->rb_root = RB_ROOT;
 	cells->cursor = cells->size;
 	atomic_set(&cells->ack_count, cells->size);
 	for (i = 0; i < cells->size; i++) {
 		struct read_cache_cell *cell = cells->array + i;
-		cell->cancelled = false;
+		atomic_set(&cell->cancelled, 0);
 	}
 	cur_threshold = read_once(wb->read_cache_threshold);
 	if (cur_threshold && (cur_threshold != cells->threshold)) {
 		cells->threshold = cur_threshold;
 		cells->over_threshold = false;
 	}
-	mutex_unlock(&wb->io_lock);
 }
 
 /*
@@ -1004,7 +1005,7 @@ static void visit_and_cancel_cells(struct rb_node *first, struct rb_node *last)
 	struct rb_node *rbp = first;
 	while (rbp != last) {
 		struct read_cache_cell *cell = read_cache_cell_from_node(rbp);
-		cell->cancelled = true;
+		atomic_set(&cell->cancelled, 1);
 		rbp = rb_next(rbp);
 	}
 }
@@ -1049,7 +1050,9 @@ static void read_cache_proc(struct work_struct *work)
 		inject_read_cache(wb, cell);
 	}
 
+	mutex_lock(&wb->io_lock);
 	reinit_read_cache_cells(wb);
+	mutex_unlock(&wb->io_lock);
 }
 
 static int init_read_cache_cells(struct wb_device *wb)
@@ -1260,9 +1263,8 @@ static int process_write_wa(struct wb_device *wb, struct bio *bio)
 	if (res.found) {
 		dec_inflight_ios(wb, res.found_seg);
 		ht_del(wb, res.found_mb);
-	}
-
-	might_cancel_read_cache_cell(wb, bio);
+	} else
+		might_cancel_read_cache_cell(wb, bio);
 	mutex_unlock(&wb->io_lock);
 
 	bio_remap(bio, wb->backing_dev, bi_sector(bio));

src/dm-writeboost.h

@@ -207,7 +207,7 @@ struct writeback_segment {
 struct read_cache_cell {
 	sector_t sector;
 	void *data; /* 4KB data read */
-	bool cancelled; /* Don't include this */
+	atomic_t cancelled; /* Don't include this */
 	struct rb_node rb_node;
 };