Re: [PATCH take2] do_mpage_readpage(): remove first_logical_block parameter

[Franck Bui-Huu <vagabon.xyz@gmail.com>]

Franck Bui-Huu wrote:
> Andrew Morton wrote:
>> Unfortunately we have a conflict with the already-queued
>> do_mpage_readpage-dont-submit-lots-of-small-bios-on-boundary.patch:
>>
> 
> How about amending this on top of take #2 ?
> 

Actually the version below is better...

		Franck

---8<---

diff --git a/fs/mpage.c b/fs/mpage.c
index 74e7f83..ca33b28 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -157,6 +157,19 @@ map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block)
 }
 
 /*
+ * Since get_block() can map a range of pages, for all these pages the
+ * BH_Boundary flag will be set.  But we only need to push what I/O we
+ * have accumulated at the last block of this range.
+*/
+static int last_mapped_page(struct buffer_head *map_bh, struct page *page)
+{
+	pgoff_t map_index = map_bh->b_page->index;
+
+	return buffer_boundary(map_bh) &&
+		page->index >= map_index + (map_bh->b_size>>PAGE_CACHE_SHIFT);
+}
+
+/*
  * This is the worker routine which does all the work of mapping the disk
  * blocks and constructs largest possible bios, submits them for IO if the
  * blocks are not contiguous on the disk.
@@ -312,10 +325,7 @@ alloc_new:
 		goto alloc_new;
 	}
 
-	relative_block = block_in_file - *first_logical_block;
-	nblocks = map_bh->b_size >> blkbits;
-	if ((buffer_boundary(map_bh) && relative_block == nblocks) ||
-	    (first_hole != blocks_per_page))
+	if (last_mapped_page(map_bh, page) || first_hole != blocks_per_page)
 		bio = mpage_bio_submit(READ, bio);
 	else
 		*last_block_in_bio = blocks[blocks_per_page - 1];