Merge branch 'stable/for-jens-3.8' of git://git.kernel.org/pub/scm/linux/kernel/git...

Konrad writes:

Please git pull the following branch:

 git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git stable/for-jens-3.8

which has a bug-fix to the xen-blkfront and xen-blkback driver
when using the persistent mode. An issue was discovered where LVM
disks could not be read correctly and this fixes it. There
is also a change in llist.h which has been blessed by akpm.

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 74374fb762aa5bcf835e73a7390f12b7403525ee..5ac841ff6cc73acd59c7439722ab799a27fac93b 100644 (file)
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -161,10 +161,12 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
 static void make_response(struct xen_blkif *blkif, u64 id,
                          unsigned short op, int st);
 
-#define foreach_grant(pos, rbtree, node) \
-       for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node); \
+#define foreach_grant_safe(pos, n, rbtree, node) \
+       for ((pos) = container_of(rb_first((rbtree)), typeof(*(pos)), node), \
+            (n) = rb_next(&(pos)->node); \
             &(pos)->node != NULL; \
-            (pos) = container_of(rb_next(&(pos)->node), typeof(*(pos)), node))
+            (pos) = container_of(n, typeof(*(pos)), node), \
+            (n) = (&(pos)->node != NULL) ? rb_next(&(pos)->node) : NULL)
 
 
 static void add_persistent_gnt(struct rb_root *root,
@@ -217,10 +219,11 @@ 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;
+       struct rb_node *n;
        int ret = 0;
        int segs_to_unmap = 0;
 
-       foreach_grant(persistent_gnt, root, node) {
+       foreach_grant_safe(persistent_gnt, n, root, node) {
                BUG_ON(persistent_gnt->handle ==
                        BLKBACK_INVALID_HANDLE);
                gnttab_set_unmap_op(&unmap[segs_to_unmap],
@@ -230,9 +233,6 @@ static void free_persistent_gnts(struct rb_root *root, unsigned int num)
                        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)) {
@@ -241,6 +241,10 @@ static void free_persistent_gnts(struct rb_root *root, unsigned int num)
                        BUG_ON(ret);
                        segs_to_unmap = 0;
                }
+
+               rb_erase(&persistent_gnt->node, root);
+               kfree(persistent_gnt);
+               num--;
        }
        BUG_ON(num != 0);
 }

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 96e9b00db08118a164d03845df86139169e78f71..11043c18ac5ab01fcfd2e492fff70a87260143fd 100644 (file)
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -792,6 +792,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 {
        struct llist_node *all_gnts;
        struct grant *persistent_gnt;
+       struct llist_node *n;
 
        /* Prevent new requests being issued until we fix things up. */
        spin_lock_irq(&info->io_lock);
@@ -804,7 +805,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
        /* Remove all persistent grants */
        if (info->persistent_gnts_c) {
                all_gnts = llist_del_all(&info->persistent_gnts);
-               llist_for_each_entry(persistent_gnt, all_gnts, node) {
+               llist_for_each_entry_safe(persistent_gnt, n, all_gnts, node) {
                        gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
                        __free_page(pfn_to_page(persistent_gnt->pfn));
                        kfree(persistent_gnt);
@@ -835,7 +836,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
                             struct blkif_response *bret)
 {
-       int i;
+       int i = 0;
        struct bio_vec *bvec;
        struct req_iterator iter;
        unsigned long flags;
@@ -852,7 +853,8 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
                 */
                rq_for_each_segment(bvec, s->request, iter) {
                        BUG_ON((bvec->bv_offset + bvec->bv_len) > PAGE_SIZE);
-                       i = offset >> PAGE_SHIFT;
+                       if (bvec->bv_offset < offset)
+                               i++;
                        BUG_ON(i >= s->req.u.rw.nr_segments);
                        shared_data = kmap_atomic(
                                pfn_to_page(s->grants_used[i]->pfn));
@@ -861,7 +863,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
                                bvec->bv_len);
                        bvec_kunmap_irq(bvec_data, &flags);
                        kunmap_atomic(shared_data);
-                       offset += bvec->bv_len;
+                       offset = bvec->bv_offset + bvec->bv_len;
                }
        }
        /* Add the persistent grant into the list of free grants */

diff --git a/include/linux/llist.h b/include/linux/llist.h
index a5199f6d0e82592dde0e4ba7908b1d1b70323483..d0ab98f73d380c67f2572a0b9536719e17325ca9 100644 (file)
--- a/include/linux/llist.h
+++ b/include/linux/llist.h
@@ -124,6 +124,31 @@ static inline void init_llist_head(struct llist_head *list)
             &(pos)->member != NULL;                                    \
             (pos) = llist_entry((pos)->member.next, typeof(*(pos)), member))
 
+/**
+ * llist_for_each_entry_safe - iterate safely against remove over some entries
+ * of lock-less list of given type.
+ * @pos:       the type * to use as a loop cursor.
+ * @n:         another type * to use as a temporary storage.
+ * @node:      the fist entry of deleted list entries.
+ * @member:    the name of the llist_node with the struct.
+ *
+ * In general, some entries of the lock-less list can be traversed
+ * safely only after being removed from list, so start with an entry
+ * instead of list head. This variant allows removal of entries
+ * as we iterate.
+ *
+ * If being used on entries deleted from lock-less list directly, the
+ * traverse order is from the newest to the oldest added entry.  If
+ * you want to traverse from the oldest to the newest, you must
+ * reverse the order by yourself before traversing.
+ */
+#define llist_for_each_entry_safe(pos, n, node, member)                \
+       for ((pos) = llist_entry((node), typeof(*(pos)), member),       \
+            (n) = (pos)->member.next;                                  \
+            &(pos)->member != NULL;                                    \
+            (pos) = llist_entry(n, typeof(*(pos)), member),            \
+            (n) = (&(pos)->member != NULL) ? (pos)->member.next : NULL)
+
 /**
  * llist_empty - tests whether a lock-less list is empty
  * @head:      the list to test