[PATCH 2/2] block: pass a phys_addr_t to get_max_segment_size

Christoph Hellwig
2024-07-05T12:32:45Z

Work on a single address to simplify the logic, and prepare the callers
from using better helpers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
block/blk-merge.c | 27 ++++++++++++---------------
1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index cff20bcc0252a7..b1e1b7a6933511 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -207,25 +207,24 @@ static inline unsigned get_max_io_size(struct bio *bio,
}

/**
- * get_max_segment_size() - maximum number of bytes to add as a single segment
+ * get_max_segment_size() - maximum number of bytes to add to a single segment
* @lim: Request queue limits.
- * @start_page: See below.
- * @offset: Offset from @start_page where to add a segment.
+ * @paddr: address of the range to add
+ * @max_len: maximum length available to add at @paddr
*
- * Returns the maximum number of bytes that can be added as a single segment.
+ * Returns the maximum number of bytes of the range starting at @paddr that can
+ * be added to a single segment.
*/
static inline unsigned get_max_segment_size(const struct queue_limits *lim,
- struct page *start_page, unsigned long offset)
+ phys_addr_t paddr, unsigned int len)
{
- unsigned long mask = lim->seg_boundary_mask;
-
- offset = mask & (page_to_phys(start_page) + offset);
-
/*
* Prevent an overflow if mask = ULONG_MAX and offset = 0 by adding 1
* after having calculated the minimum.
*/
- return min(mask - offset, (unsigned long)lim->max_segment_size - 1) + 1;
+ return min_t(unsigned long, len,
+ min(lim->seg_boundary_mask - (lim->seg_boundary_mask & paddr),
+ (unsigned long)lim->max_segment_size - 1) + 1);
}

/**
@@ -258,9 +257,7 @@ static bool bvec_split_segs(const struct queue_limits *lim,
unsigned seg_size = 0;

while (len && *nsegs < max_segs) {
- seg_size = get_max_segment_size(lim, bv->bv_page,
- bv->bv_offset + total_len);
- seg_size = min(seg_size, len);
+ seg_size = get_max_segment_size(lim, bvec_phys(bv) + total_len, len);

(*nsegs)++;
total_len += seg_size;
@@ -494,8 +491,8 @@ static unsigned blk_bvec_map_sg(struct request_queue *q,

while (nbytes > 0) {
unsigned offset = bvec->bv_offset + total;
- unsigned len = min(get_max_segment_size(&q->limits,
- bvec->bv_page, offset), nbytes);
+ unsigned len = get_max_segment_size(&q->limits, bvec_phys(bvec),
+ nbytes);
struct page *page = bvec->bv_page;

/*
--
2.43.0