[PATCH v2 3/5] block: Remove a DMA segment boundary mask check

[Bart Van Assche <bvanassche@acm.org>]

Commit d690cb8ae14b ("block: add an API to atomically update queue limits")
introduced the following code:

       /*
        * By default there is no limit on the segment boundary alignment,
        * but if there is one it can't be smaller than the page size as
        * that would break all the normal I/O patterns.
        */
       if (!lim->seg_boundary_mask)
               lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
       if (WARN_ON_ONCE(lim->seg_boundary_mask < PAGE_SIZE - 1))
               return -EINVAL;

The comment about "breaking normal I/O patterns" is incorrect - block
layer code like get_max_segment_size() supports arbitrary boundary mask
values as long as the boundary mask is not zero. Remove the comment and
the check because both are confusing.

This patch prepares for reducing the value of BLK_MIN_SEGMENT_SIZE.

Fixes: d690cb8ae14b ("block: add an API to atomically update queue limits")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 block/blk-settings.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 13f5457f9f4e..8538e50afe2c 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -447,15 +447,9 @@ int blk_validate_limits(struct queue_limits *lim)
 	if (!lim->max_discard_segments)
 		lim->max_discard_segments = 1;
 
-	/*
-	 * By default there is no limit on the segment boundary alignment,
-	 * but if there is one it can't be smaller than the page size as
-	 * that would break all the normal I/O patterns.
-	 */
+	/* By default there is no limit on the segment boundary alignment. */
 	if (!lim->seg_boundary_mask)
 		lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
-	if (WARN_ON_ONCE(lim->seg_boundary_mask < BLK_MIN_SEGMENT_SIZE - 1))
-		return -EINVAL;
 
 	/*
 	 * Stacking device may have both virtual boundary and max segment