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authorJennifer Herbert <jennifer.herbert@citrix.com>2015-01-05 15:07:46 +0000
committerDavid Vrabel <david.vrabel@citrix.com>2015-01-28 14:03:15 +0000
commit745282256c754ac5ed3dbe2fbef6471dc1373417 (patch)
tree9dbec8c554c05a2dde6dad9c040dba740486c077 /drivers/xen
parent1401c00e59ea021c575f74612fe2dbba36d6a4ee (diff)
downloadop-kernel-dev-745282256c754ac5ed3dbe2fbef6471dc1373417.zip
op-kernel-dev-745282256c754ac5ed3dbe2fbef6471dc1373417.tar.gz
xen/gntdev: safely unmap grants in case they are still in use
Use gnttab_unmap_refs_async() to wait until the mapped pages are no longer in use before unmapping them. This allows userspace programs to safely use Direct I/O and AIO to a network filesystem which may retain refs to pages in queued skbs after the filesystem I/O has completed. Signed-off-by: Jennifer Herbert <jennifer.herbert@citrix.com> Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/gntdev.c36
1 files changed, 31 insertions, 5 deletions
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 3c25344..bccc54a 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -309,9 +309,30 @@ static int map_grant_pages(struct grant_map *map)
return err;
}
+struct unmap_grant_pages_callback_data
+{
+ struct completion completion;
+ int result;
+};
+
+static void unmap_grant_callback(int result,
+ struct gntab_unmap_queue_data *data)
+{
+ struct unmap_grant_pages_callback_data* d = data->data;
+
+ d->result = result;
+ complete(&d->completion);
+}
+
static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
{
int i, err = 0;
+ struct gntab_unmap_queue_data unmap_data;
+ struct unmap_grant_pages_callback_data data;
+
+ init_completion(&data.completion);
+ unmap_data.data = &data;
+ unmap_data.done= &unmap_grant_callback;
if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
int pgno = (map->notify.addr >> PAGE_SHIFT);
@@ -323,11 +344,16 @@ static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
}
}
- err = gnttab_unmap_refs(map->unmap_ops + offset,
- use_ptemod ? map->kunmap_ops + offset : NULL, map->pages + offset,
- pages);
- if (err)
- return err;
+ unmap_data.unmap_ops = map->unmap_ops + offset;
+ unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL;
+ unmap_data.pages = map->pages + offset;
+ unmap_data.count = pages;
+
+ gnttab_unmap_refs_async(&unmap_data);
+
+ wait_for_completion(&data.completion);
+ if (data.result)
+ return data.result;
for (i = 0; i < pages; i++) {
if (map->unmap_ops[offset+i].status)
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