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[Xen-devel] [PATCH 11 of 12] blkback/blktap2: simplify address translations



# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1260981852 0
# Node ID 317cdc16a674f4aa4c57b4fdae004ca5fcc24712
# Parent  6b5c16a30bc5e7d771dec05c7cee597b71a695c2
blkback/blktap2: simplify address translations

There are quite a number of places where e.g. page->va->page
translations happen.

Besides yielding smaller code (source and binary), a second goal is to
make it easier to determine where virtual addresses of pages allocated
through alloc_empty_pages_and_pagevec() are really used (in turn in
order to determine whether using highmem pages would be possible
there).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

linux-2.6-pvops:
 * Stripped drivers/xen/gntdev/*
 * Stripped drivers/xen/netback/*

Signed-off-by: Daniel Stodden <daniel.stodden@xxxxxxxxxx>

diff -r 6b5c16a30bc5 -r 317cdc16a674 drivers/xen/blkback/blkback.c
--- a/drivers/xen/blkback/blkback.c     Fri Dec 11 08:47:19 2009 +0000
+++ b/drivers/xen/blkback/blkback.c     Wed Dec 16 16:44:12 2009 +0000
@@ -99,9 +99,11 @@
        return (req - pending_reqs) * BLKIF_MAX_SEGMENTS_PER_REQUEST + seg;
 }
 
+#define pending_page(req, seg) pending_pages[vaddr_pagenr(req, seg)]
+
 static inline unsigned long vaddr(pending_req_t *req, int seg)
 {
-       unsigned long pfn = page_to_pfn(pending_pages[vaddr_pagenr(req, seg)]);
+       unsigned long pfn = page_to_pfn(pending_page(req, seg));
        return (unsigned long)pfn_to_kaddr(pfn);
 }
 
@@ -178,7 +180,7 @@
                handle = pending_handle(req, i);
                if (handle == BLKBACK_INVALID_HANDLE)
                        continue;
-               blkback_pagemap_clear(virt_to_page(vaddr(req, i)));
+               blkback_pagemap_clear(pending_page(req, i));
                gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
                                    GNTMAP_host_map, handle);
                pending_handle(req, i) = BLKBACK_INVALID_HANDLE;
@@ -456,7 +458,7 @@
                        ret |= 1;
                } else {
                        blkback_pagemap_set(vaddr_pagenr(pending_req, i),
-                                           virt_to_page(vaddr(pending_req, i)),
+                                           pending_page(pending_req, i),
                                            blkif->domid, req->handle,
                                            req->seg[i].gref);
                }
@@ -466,8 +468,8 @@
                if (ret)
                        continue;
 
-               set_phys_to_machine(__pa(vaddr(
-                       pending_req, i)) >> PAGE_SHIFT,
+               set_phys_to_machine(
+                       page_to_pfn(pending_page(pending_req, i)),
                        FOREIGN_FRAME(map[i].dev_bus_addr >> PAGE_SHIFT));
                seg[i].buf  = map[i].dev_bus_addr |
                        (req->seg[i].first_sect << 9);
@@ -498,7 +500,7 @@
 
                while ((bio == NULL) ||
                       (bio_add_page(bio,
-                                    virt_to_page(vaddr(pending_req, i)),
+                                    pending_page(pending_req, i),
                                     seg[i].nsec << 9,
                                     seg[i].buf & ~PAGE_MASK) == 0)) {
                        if (bio) {
diff -r 6b5c16a30bc5 -r 317cdc16a674 drivers/xen/blktap/blktap.h
--- a/drivers/xen/blktap/blktap.h       Fri Dec 11 08:47:19 2009 +0000
+++ b/drivers/xen/blktap/blktap.h       Wed Dec 16 16:44:12 2009 +0000
@@ -241,6 +241,13 @@
 int blktap_request_pool_shrink(void);
 struct blktap_request *blktap_request_allocate(struct blktap *);
 void blktap_request_free(struct blktap *, struct blktap_request *);
-unsigned long request_to_kaddr(struct blktap_request *, int);
+struct page *request_to_page(struct blktap_request *, int);
+
+static inline unsigned long
+request_to_kaddr(struct blktap_request *req, int seg)
+{
+       unsigned long pfn = page_to_pfn(request_to_page(req, seg));
+       return (unsigned long)pfn_to_kaddr(pfn);
+}
 
 #endif
diff -r 6b5c16a30bc5 -r 317cdc16a674 drivers/xen/blktap/device.c
--- a/drivers/xen/blktap/device.c       Fri Dec 11 08:47:19 2009 +0000
+++ b/drivers/xen/blktap/device.c       Wed Dec 16 16:44:12 2009 +0000
@@ -315,15 +315,14 @@
        down_write(&tap->ring.vma->vm_mm->mmap_sem);
 
        for (i = 0; i < request->nr_pages; i++) {
+               kvaddr = request_to_kaddr(request, i);
                BTDBG("request: %p, seg: %d, kvaddr: 0x%08lx, khandle: %u, "
                      "uvaddr: 0x%08lx, uhandle: %u\n", request, i,
-                     request_to_kaddr(request, i),
-                     request->handles[i].kernel,
+                     kvaddr, request->handles[i].kernel,
                      MMAP_VADDR(tap->ring.user_vstart, usr_idx, i),
                      request->handles[i].user);
 
                if (request->handles[i].kernel == INVALID_GRANT_HANDLE) {
-                       kvaddr = request_to_kaddr(request, i);
                        blktap_umap_uaddr(&init_mm, kvaddr);
                        flush_tlb_kernel_page(kvaddr);
                        set_phys_to_machine(__pa(kvaddr) >> PAGE_SHIFT,
@@ -450,7 +449,7 @@
 
 #ifdef BLKTAP_CHAINED_BLKTAP
        /* enable chained tap devices */
-       tap_page = pfn_to_page(__pa(kvaddr) >> PAGE_SHIFT);
+       tap_page = request_to_page(request, seg);
        set_page_private(tap_page, page_private(page));
        SetPageBlkback(tap_page);
 #endif
@@ -480,7 +479,7 @@
        struct page *page;
        int i, grant, err, usr_idx;
        struct blktap_ring *ring;
-       unsigned long uvaddr, kvaddr, foreign_mfn;
+       unsigned long uvaddr, foreign_mfn;
 
        if (!table->cnt)
                return 0;
@@ -498,7 +497,6 @@
                        continue;
 
                uvaddr = MMAP_VADDR(ring->user_vstart, usr_idx, i);
-               kvaddr = request_to_kaddr(request, i);
 
                if (unlikely(table->grants[grant].status)) {
                        BTERR("invalid kernel buffer: could not remap it\n");
@@ -526,18 +524,19 @@
                if (err)
                        continue;
 
-               page = pfn_to_page(__pa(kvaddr) >> PAGE_SHIFT);
+               page = request_to_page(request, i);
 
                if (!xen_feature(XENFEAT_auto_translated_physmap))
-                       set_phys_to_machine(__pa(kvaddr) >> PAGE_SHIFT,
+                       set_phys_to_machine(page_to_pfn(page),
                                            FOREIGN_FRAME(foreign_mfn));
                else if (vm_insert_page(ring->vma, uvaddr, page))
                        err |= 1;
 
                BTDBG("pending_req: %p, seg: %d, page: %p, "
-                     "kvaddr: 0x%08lx, khandle: %u, uvaddr: 0x%08lx, "
+                     "kvaddr: 0x%p, khandle: %u, uvaddr: 0x%08lx, "
                      "uhandle: %u\n", request, i, page,
-                     kvaddr, request->handles[i].kernel,                      
+                     pfn_to_kaddr(page_to_pfn(page)),
+                     request->handles[i].kernel,
                      uvaddr, request->handles[i].user);
        }
 
@@ -585,7 +584,7 @@
        struct scatterlist *sg;
        struct blktap_grant_table table;
        unsigned int fsect, lsect, nr_sects;
-       unsigned long offset, uvaddr, kvaddr;
+       unsigned long offset, uvaddr;
        struct blkif_request blkif_req, *target;
 
        err = -1;
@@ -641,18 +640,17 @@
                        }
 
                        uvaddr = MMAP_VADDR(ring->user_vstart, usr_idx, i);
-                       kvaddr = request_to_kaddr(request, i);
                        offset = (uvaddr - ring->vma->vm_start) >> PAGE_SHIFT;
-                       page   = pfn_to_page(__pa(kvaddr) >> PAGE_SHIFT);
+                       page   = request_to_page(request, i);
                        ring->foreign_map.map[offset] = page;
                        SetPageReserved(page);
 
                        BTDBG("mapped uaddr %08lx to page %p pfn 0x%lx\n",
-                             uvaddr, page, __pa(kvaddr) >> PAGE_SHIFT);
+                             uvaddr, page, page_to_pfn(page));
                        BTDBG("offset: 0x%08lx, pending_req: %p, seg: %d, "
-                             "page: %p, kvaddr: 0x%08lx, uvaddr: 0x%08lx\n",
+                             "page: %p, kvaddr: %p, uvaddr: 0x%08lx\n",
                              offset, request, i,
-                             page, kvaddr, uvaddr);
+                             page, pfn_to_kaddr(page_to_pfn(page)), uvaddr);
 
                        request->nr_pages++;
        }
diff -r 6b5c16a30bc5 -r 317cdc16a674 drivers/xen/blktap/request.c
--- a/drivers/xen/blktap/request.c      Fri Dec 11 08:47:19 2009 +0000
+++ b/drivers/xen/blktap/request.c      Wed Dec 16 16:44:12 2009 +0000
@@ -124,13 +124,12 @@
        kfree(bucket);
 }
 
-unsigned long
-request_to_kaddr(struct blktap_request *req, int seg)
+struct page *
+request_to_page(struct blktap_request *req, int seg)
 {
        struct blktap_request_handle *handle = blktap_request_to_handle(req);
        int idx = handle->slot * BLKIF_MAX_SEGMENTS_PER_REQUEST + seg;
-       unsigned long pfn = page_to_pfn(handle->bucket->foreign_pages[idx]);
-       return (unsigned long)pfn_to_kaddr(pfn);
+       return handle->bucket->foreign_pages[idx];
 }
 
 int

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