[PATCH] SQUASHME: pnfs-obj: pg_test check for max_io_size

[Boaz Harrosh <bharrosh@panasas.com>]

This should be squashed into:
	pnfs-obj: osd raid engine read/write implementation

Implement pg_test vector to test for max IO sizes. We calculate
a max_io_size member only once, and cache it in lseg so to not
do so on every page insert.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
---
 fs/nfs/objlayout/objio_osd.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
index 0dcffc2..0dba6ec 100644
--- a/fs/nfs/objlayout/objio_osd.c
+++ b/fs/nfs/objlayout/objio_osd.c
@@ -129,6 +129,8 @@ struct objio_segment {
 	u64 group_depth;
 	unsigned group_count;
 
+	unsigned max_io_size;
+
 	unsigned comps_index;
 	unsigned num_comps;
 	/* variable length */
@@ -366,6 +368,11 @@ extern int objio_alloc_lseg(struct pnfs_layout_segment **outp,
 		objio_seg->group_count = 1;
 	}
 
+	/* Cache this calculation it will hit for every page */
+	objio_seg->max_io_size = (BIO_MAX_PAGES_KMALLOC * PAGE_SIZE -
+				  objio_seg->stripe_unit) *
+				 objio_seg->group_width;
+
 	*outp = &objio_seg->lseg;
 	return 0;
 
@@ -1000,7 +1007,12 @@ int
 objlayout_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
 		   struct nfs_page *req)
 {
-	return 1;
+	struct objio_segment *layout = OBJIO_LSEG(pgio->pg_lseg);
+
+	if ((pgio->pg_count + req->wb_bytes) > layout->max_io_size)
+		return 0;
+	else
+		return 1;
 }
 
 static struct pnfs_layoutdriver_type objlayout_type = {
-- 
1.7.2.3