xen-blkback: move free persistent grants code

Move the code that frees persistent grants from the red-black tree
to a function. This will make it easier for other consumers to move
this to a common place.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 37 insertions, 31 deletions

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index a05961683efa..74374fb762aa 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -212,6 +212,39 @@ static struct persistent_gnt *get_persistent_gnt(struct rb_root *root,
         return NULL;
 }
 
+static void free_persistent_gnts(struct rb_root *root, unsigned int num)
+{
+        struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+        struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
+        struct persistent_gnt *persistent_gnt;
+        int ret = 0;
+        int segs_to_unmap = 0;
+
+        foreach_grant(persistent_gnt, root, node) {
+                BUG_ON(persistent_gnt->handle ==
+                        BLKBACK_INVALID_HANDLE);
+                gnttab_set_unmap_op(&unmap[segs_to_unmap],
+                        (unsigned long) pfn_to_kaddr(page_to_pfn(
+                                persistent_gnt->page)),
+                        GNTMAP_host_map,
+                        persistent_gnt->handle);
+
+                pages[segs_to_unmap] = persistent_gnt->page;
+                rb_erase(&persistent_gnt->node, root);
+                kfree(persistent_gnt);
+                num--;
+
+                if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
+                        !rb_next(&persistent_gnt->node)) {
+                        ret = gnttab_unmap_refs(unmap, NULL, pages,
+                                segs_to_unmap);
+                        BUG_ON(ret);
+                        segs_to_unmap = 0;
+                }
+        }
+        BUG_ON(num != 0);
+}
+
 /*
  * Retrieve from the 'pending_reqs' a free pending_req structure to be used.
  */
@@ -358,11 +391,6 @@ int xen_blkif_schedule(void *arg)
 {
         struct xen_blkif *blkif = arg;
         struct xen_vbd *vbd = &blkif->vbd;
-        struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
-        struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
-        struct persistent_gnt *persistent_gnt;
-        int ret = 0;
-        int segs_to_unmap = 0;
 
         xen_blkif_get(blkif);
 
@@ -391,34 +419,12 @@ int xen_blkif_schedule(void *arg)
         }
 
         /* Free all persistent grant pages */
-        if (!RB_EMPTY_ROOT(&blkif->persistent_gnts)) {
-                foreach_grant(persistent_gnt, &blkif->persistent_gnts, node) {
-                        BUG_ON(persistent_gnt->handle ==
-                                BLKBACK_INVALID_HANDLE);
-                        gnttab_set_unmap_op(&unmap[segs_to_unmap],
-                            (unsigned long) pfn_to_kaddr(page_to_pfn(
-                                persistent_gnt->page)),
-                            GNTMAP_host_map,
-                            persistent_gnt->handle);
-
-                        pages[segs_to_unmap] = persistent_gnt->page;
-                        rb_erase(&persistent_gnt->node,
-                                &blkif->persistent_gnts);
-                        kfree(persistent_gnt);
-                        blkif->persistent_gnt_c--;
-
-                        if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
-                                !rb_next(&persistent_gnt->node)) {
-                                ret = gnttab_unmap_refs(unmap, NULL, pages,
-                                                        segs_to_unmap);
-                                BUG_ON(ret);
-                                segs_to_unmap = 0;
-                        }
-                }
-        }
+        if (!RB_EMPTY_ROOT(&blkif->persistent_gnts))
+                free_persistent_gnts(&blkif->persistent_gnts,
+                        blkif->persistent_gnt_c);
 
-        BUG_ON(blkif->persistent_gnt_c != 0);
         BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
+        blkif->persistent_gnt_c = 0;
 
         if (log_stats)
                 print_stats(blkif);