From: Gerd Hoffmann <kraxel@redhat.com>
Subject: [RHEL-5.1 PATCH 6/10] xen: blktap: cleanups.
Date: Fri, 15 Jun 2007 10:46:28 +0200
Bugzilla: 242122
Message-Id: <467251E4.8050303@redhat.com>
Changelog: [xen] blktap: cleanups.


  Hi,

This patch carries a bunch of cleanups, partly needed for ia64.  It also 
changes the size of the communication ring between kernel and userspace 
daemon.  Thus it is required to make the blktap driver work together 
with the updated xen tools (which contain the userspace part).

cheers,
  Gerd

rh bug 242122

# HG changeset patch
# User kfraser@localhost.localdomain
# Date 1162897295 0
# Node ID 862aca401601062aa6207a00549c19cdac054bbb
# Parent  6f3c40ee248856b84053adb9f6edfc5d31955684
[BLKTAP] Various cleanups necessary for ia64 support.
- remove magic number 8 and 64.
  page size / sector size is 8 on x86, however on ia64 page size is
  16kb.
  blkring size is 64 on x86. however it's 128 on ia64.
- replace 0xFFFF with INVALID_GRANT_HANDLE
- don't map io ring into user space with uncachable.
  kernel access the page with cacable and tapdisk uses memory barrier
  so that it isn't necessary.
- remove printk warning and inserted new line.
- remove unused variable, page.
- add one BUG()

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>

---
 drivers/xen/blktap/blktapmain.c |   27 +++++++++++++--------------
 drivers/xen/blktap/xenbus.c     |    6 +++---
 2 files changed, 16 insertions(+), 17 deletions(-)

Index: linux-2.6.18.noarch/drivers/xen/blktap/blktapmain.c
===================================================================
--- linux-2.6.18.noarch.orig/drivers/xen/blktap/blktapmain.c
+++ linux-2.6.18.noarch/drivers/xen/blktap/blktapmain.c
@@ -89,8 +89,9 @@ int setup_xen_class(void)
  * mmap_alloc is initialised to 2 and should be adjustable on the fly via
  * sysfs.
  */
-#define MAX_DYNAMIC_MEM 64
-#define MAX_PENDING_REQS 64   
+#define BLK_RING_SIZE		__RING_SIZE((blkif_sring_t *)0, PAGE_SIZE)
+#define MAX_DYNAMIC_MEM		BLK_RING_SIZE
+#define MAX_PENDING_REQS	BLK_RING_SIZE
 #define MMAP_PAGES (MAX_PENDING_REQS * BLKIF_MAX_SEGMENTS_PER_REQUEST)
 #define MMAP_VADDR(_start, _req,_seg)                                   \
         (_start +                                                       \
@@ -211,6 +212,7 @@ struct grant_handle_pair
         grant_handle_t kernel;
         grant_handle_t user;
 };
+#define INVALID_GRANT_HANDLE	0xFFFF
 
 static struct grant_handle_pair 
     pending_grant_handles[MAX_DYNAMIC_MEM][MMAP_PAGES];
@@ -289,10 +291,11 @@ static inline int GET_NEXT_REQ(unsigned 
 
 
 #define BLKTAP_INVALID_HANDLE(_g) \
-    (((_g->kernel) == 0xFFFF) && ((_g->user) == 0xFFFF))
+    (((_g->kernel) == INVALID_GRANT_HANDLE) &&  \
+     ((_g->user) == INVALID_GRANT_HANDLE))
 
 #define BLKTAP_INVALIDATE_HANDLE(_g) do {       \
-    (_g)->kernel = 0xFFFF; (_g)->user = 0xFFFF; \
+    (_g)->kernel = INVALID_GRANT_HANDLE; (_g)->user = INVALID_GRANT_HANDLE; \
     } while(0)
 
 
@@ -532,8 +535,6 @@ static int blktap_mmap(struct file *filp
 	info->user_vstart  = info->rings_vstart + (RING_PAGES << PAGE_SHIFT);
     
 	/* Map the ring pages to the start of the region and reserve it. */
-	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-
 	if (remap_pfn_range(vma, vma->vm_start, 
 			    __pa(info->ufe_ring.sring) >> PAGE_SHIFT, 
 			    PAGE_SIZE, vma->vm_page_prot)) {
@@ -845,14 +846,14 @@ static void fast_flush_area(pending_req_
 
 		khandle = &pending_handle(mmap_idx, k_idx, i);
 
-		if (khandle->kernel != 0xFFFF) {
+		if (khandle->kernel != INVALID_GRANT_HANDLE) {
 			gnttab_set_unmap_op(&unmap[invcount],
 				    idx_to_kaddr(mmap_idx, k_idx, i), 
 				    GNTMAP_host_map, khandle->kernel);
 			invcount++;
 		}
 
-		if (khandle->user != 0xFFFF) {
+		if (khandle->user != INVALID_GRANT_HANDLE) {
 			if (create_lookup_pte_addr(
 		    		info->vma->vm_mm,
 		    		MMAP_VADDR(info->user_vstart, u_idx, i),
@@ -1165,14 +1166,12 @@ static void dispatch_rw_block_io(blkif_t
 		unsigned long uvaddr;
 		unsigned long kvaddr;
 		uint64_t ptep;
-		struct page *page;
 		uint32_t flags;
 
 		uvaddr = MMAP_VADDR(info->user_vstart, usr_idx, i);
 		kvaddr = idx_to_kaddr(mmap_idx, pending_idx, i);
-		page = virt_to_page(kvaddr);
 
-		sector = req->sector_number + (8*i);
+		sector = req->sector_number + ((PAGE_SIZE / 512) * i);
 		if( (blkif->sectors > 0) && (sector >= blkif->sectors) ) {
 			WPRINTK("BLKTAP: Sector request greater" 
 			       "than size\n");
@@ -1182,7 +1181,7 @@ static void dispatch_rw_block_io(blkif_t
 				BLKIF_OP_WRITE ? "WRITE" : "READ"),
 				(long long unsigned) sector,
 				(long long unsigned) sector>>9,
-				blkif->sectors);
+				(long long unsigned) blkif->sectors);
 		}
 
 		flags = GNTMAP_host_map;
@@ -1227,14 +1226,14 @@ static void dispatch_rw_block_io(blkif_t
 			WPRINTK("invalid kernel buffer -- "
 				"could not remap it\n");
 			ret |= 1;
-			map[i].handle = 0xFFFF;
+			map[i].handle = INVALID_GRANT_HANDLE;
 		}
 
 		if (unlikely(map[i+1].status != 0)) {
 			WPRINTK("invalid user buffer -- "
 				"could not remap it\n");
 			ret |= 1;
-			map[i+1].handle = 0xFFFF;
+			map[i+1].handle = INVALID_GRANT_HANDLE;
 		}
 
 		pending_handle(mmap_idx, pending_idx, i/2).kernel 
Index: linux-2.6.18.noarch/drivers/xen/blktap/xenbus.c
===================================================================
--- linux-2.6.18.noarch.orig/drivers/xen/blktap/xenbus.c
+++ linux-2.6.18.noarch/drivers/xen/blktap/xenbus.c
@@ -189,7 +189,7 @@ static int blktap_probe(struct xenbus_de
 	return 0;
 
 fail:
-	DPRINTK("blktap probe failed");
+	DPRINTK("blktap probe failed\n");
 	blktap_remove(dev);
 	return err;
 }
@@ -243,7 +243,7 @@ static void tap_frontend_changed(struct 
 	struct backend_info *be = dev->dev.driver_data;
 	int err;
 
-	DPRINTK("");
+	DPRINTK("\n");
 
 	switch (frontend_state) {
 	case XenbusStateInitialising:
@@ -318,7 +318,7 @@ static int connect_ring(struct backend_i
 	unsigned int evtchn;
 	int err;
 
-	DPRINTK("%s", dev->otherend);
+	DPRINTK("%s\n", dev->otherend);
 
 	err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu", 
 			    &ring_ref, "event-channel", "%u", &evtchn, NULL);