Isaku Yamahata
2009-Apr-28 03:01 UTC
[Xen-ia64-devel] [PATCH 3/4] linux/blktap: don''t use vma->vm_start to calculate offset.
blktap: don''t use vma->vm_start to calculate offset.
struct vma can be split by partial munmap(), we can''t depend on
vm_start.
Instead, use tap_blkif_t::rings_vstart.
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
diff --git a/drivers/xen/blktap/blktap.c b/drivers/xen/blktap/blktap.c
--- a/drivers/xen/blktap/blktap.c
+++ b/drivers/xen/blktap/blktap.c
@@ -317,7 +317,7 @@ static pte_t blktap_clear_pte(struct vm_
pte_t copy;
tap_blkif_t *info;
int offset, seg, usr_idx, pending_idx, mmap_idx;
- unsigned long uvstart = vma->vm_start + (RING_PAGES << PAGE_SHIFT);
+ unsigned long uvstart;
unsigned long kvaddr;
struct tap_vma_priv *priv;
struct page *pg;
@@ -329,11 +329,15 @@ static pte_t blktap_clear_pte(struct vm_
* If the address is before the start of the grant mapped region or
* if vm_file is NULL (meaning mmap failed and we have nothing to do)
*/
- if (uvaddr < uvstart || vma->vm_file == NULL)
+ if (vma->vm_file != NULL) {
+ info = vma->vm_file->private_data;
+ uvstart = info->rings_vstart + (RING_PAGES << PAGE_SHIFT);
+ } else
+ uvstart = uvaddr; /* make the following if clause true */
+ if (uvaddr < uvstart)
return ptep_get_and_clear_full(vma->vm_mm, uvaddr,
ptep, is_fullmm);
- info = vma->vm_file->private_data;
priv = vma->vm_private_data;
/* TODO Should these be changed to if statements? */
@@ -1200,8 +1204,7 @@ static int blktap_read_ufe_ring(tap_blki
pg = pfn_to_page(__pa(kvaddr) >> PAGE_SHIFT);
ClearPageReserved(pg);
- offset = (uvaddr - info->vma->vm_start)
- >> PAGE_SHIFT;
+ offset = (uvaddr - info->rings_vstart) >> PAGE_SHIFT;
priv->map[offset] = NULL;
}
fast_flush_area(pending_req, pending_idx, usr_idx, info->minor);
@@ -1492,7 +1495,7 @@ static void dispatch_rw_block_io(blkif_t
set_phys_to_machine(__pa(kvaddr) >> PAGE_SHIFT,
FOREIGN_FRAME(map[i].dev_bus_addr
>> PAGE_SHIFT));
- offset = (uvaddr - info->vma->vm_start) >> PAGE_SHIFT;
+ offset = (uvaddr - info->rings_vstart) >> PAGE_SHIFT;
pg = pfn_to_page(__pa(kvaddr) >> PAGE_SHIFT);
priv->map[offset] = pg;
}
@@ -1519,7 +1522,7 @@ static void dispatch_rw_block_io(blkif_t
if (ret)
continue;
- offset = (uvaddr - info->vma->vm_start) >> PAGE_SHIFT;
+ offset = (uvaddr - info->rings_vstart) >> PAGE_SHIFT;
pg = pfn_to_page(__pa(kvaddr) >> PAGE_SHIFT);
priv->map[offset] = pg;
}
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