1 files changed, 39 insertions, 23 deletions

diff --git a/block/blk-settings.c b/block/blk-settings.c
index e0cc7a1fe4ac..91449147bae9 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -221,6 +221,8 @@ static void blk_atomic_writes_update_limits(struct queue_limits *lim)
 static void blk_validate_atomic_write_limits(struct queue_limits *lim)
 {
 	unsigned int boundary_sectors;
+	unsigned int atomic_write_hw_max_sectors =
+			lim->atomic_write_hw_max >> SECTOR_SHIFT;
 
 	if (!(lim->features & BLK_FEAT_ATOMIC_WRITES))
 		goto unsupported;
@@ -242,6 +244,10 @@ static void blk_validate_atomic_write_limits(struct queue_limits *lim)
 			 lim->atomic_write_hw_max))
 		goto unsupported;
 
+	if (WARN_ON_ONCE(lim->chunk_sectors &&
+			atomic_write_hw_max_sectors > lim->chunk_sectors))
+		goto unsupported;
+
 	boundary_sectors = lim->atomic_write_hw_boundary >> SECTOR_SHIFT;
 
 	if (boundary_sectors) {
@@ -636,41 +642,50 @@ static bool blk_stack_atomic_writes_boundary_head(struct queue_limits *t,
 	return true;
 }
 
-
-/* Check stacking of first bottom device */
-static bool blk_stack_atomic_writes_head(struct queue_limits *t,
-				struct queue_limits *b)
+static void blk_stack_atomic_writes_chunk_sectors(struct queue_limits *t)
 {
-	if (b->atomic_write_hw_boundary &&
-	    !blk_stack_atomic_writes_boundary_head(t, b))
-		return false;
+	unsigned int chunk_bytes;
 
-	if (t->io_min <= SECTOR_SIZE) {
-		/* No chunk sectors, so use bottom device values directly */
-		t->atomic_write_hw_unit_max = b->atomic_write_hw_unit_max;
-		t->atomic_write_hw_unit_min = b->atomic_write_hw_unit_min;
-		t->atomic_write_hw_max = b->atomic_write_hw_max;
-		return true;
-	}
+	if (!t->chunk_sectors)
+		return;
+
+	/*
+	 * If chunk sectors is so large that its value in bytes overflows
+	 * UINT_MAX, then just shift it down so it definitely will fit.
+	 * We don't support atomic writes of such a large size anyway.
+	 */
+	if (check_shl_overflow(t->chunk_sectors, SECTOR_SHIFT, &chunk_bytes))
+		chunk_bytes = t->chunk_sectors;
 
 	/*
 	 * Find values for limits which work for chunk size.
 	 * b->atomic_write_hw_unit_{min, max} may not be aligned with chunk
-	 * size (t->io_min), as chunk size is not restricted to a power-of-2.
+	 * size, as the chunk size is not restricted to a power-of-2.
 	 * So we need to find highest power-of-2 which works for the chunk
 	 * size.
-	 * As an example scenario, we could have b->unit_max = 16K and
-	 * t->io_min = 24K. For this case, reduce t->unit_max to a value
-	 * aligned with both limits, i.e. 8K in this example.
+	 * As an example scenario, we could have t->unit_max = 16K and
+	 * t->chunk_sectors = 24KB. For this case, reduce t->unit_max to a
+	 * value aligned with both limits, i.e. 8K in this example.
 	 */
-	t->atomic_write_hw_unit_max = b->atomic_write_hw_unit_max;
-	while (t->io_min % t->atomic_write_hw_unit_max)
-		t->atomic_write_hw_unit_max /= 2;
+	t->atomic_write_hw_unit_max = min(t->atomic_write_hw_unit_max,
+					max_pow_of_two_factor(chunk_bytes));
 
-	t->atomic_write_hw_unit_min = min(b->atomic_write_hw_unit_min,
+	t->atomic_write_hw_unit_min = min(t->atomic_write_hw_unit_min,
 					  t->atomic_write_hw_unit_max);
-	t->atomic_write_hw_max = min(b->atomic_write_hw_max, t->io_min);
+	t->atomic_write_hw_max = min(t->atomic_write_hw_max, chunk_bytes);
+}
 
+/* Check stacking of first bottom device */
+static bool blk_stack_atomic_writes_head(struct queue_limits *t,
+				struct queue_limits *b)
+{
+	if (b->atomic_write_hw_boundary &&
+	    !blk_stack_atomic_writes_boundary_head(t, b))
+		return false;
+
+	t->atomic_write_hw_unit_max = b->atomic_write_hw_unit_max;
+	t->atomic_write_hw_unit_min = b->atomic_write_hw_unit_min;
+	t->atomic_write_hw_max = b->atomic_write_hw_max;
 	return true;
 }
 
@@ -698,6 +713,7 @@ static void blk_stack_atomic_writes_limits(struct queue_limits *t,
 
 	if (!blk_stack_atomic_writes_head(t, b))
 		goto unsupported;
+	blk_stack_atomic_writes_chunk_sectors(t);
 	return;
 
 unsupported: