Merge branch 'for-linus' of git://git.kernel.dk/linux-block

Pull block layer updates from Jens Axboe:
 "I've got a few bits pending for 3.8 final, that I better get sent out.
  It's all been sitting for a while, I consider it safe.

  It contains:

   - Two bug fixes for mtip32xx, fixing a driver hang and a crash.

   - A few-liner protocol error fix for drbd.

   - A few fixes for the xen block front/back driver, fixing a potential
     data corruption issue.

   - A race fix for disk_clear_events(), causing spurious warnings.  Out
     of the Chrome OS base.

   - A deadlock fix for disk_clear_events(), moving it to the a
     unfreezable workqueue.  Also from the Chrome OS base."

* 'for-linus' of git://git.kernel.dk/linux-block:
  drbd: fix potential protocol error and resulting disconnect/reconnect
  mtip32xx: fix for crash when the device surprise removed during rebuild
  mtip32xx: fix for driver hang after a command timeout
  block: prevent race/cleanup
  block: remove deadlock in disk_clear_events
  xen-blkfront: handle bvecs with partial data
  llist/xen-blkfront: implement safe version of llist_for_each_entry
  xen-blkback: implement safe iterator for the list of persistent grants

8 files changed, 101 insertions, 28 deletions

diff --git a/block/genhd.c b/block/genhd.c
index 9a289d7c84bb..3993ebf4135f 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -35,6 +35,8 @@ static DEFINE_IDR(ext_devt_idr);
 
 static struct device_type disk_type;
 
+static void disk_check_events(struct disk_events *ev,
+                              unsigned int *clearing_ptr);
 static void disk_alloc_events(struct gendisk *disk);
 static void disk_add_events(struct gendisk *disk);
 static void disk_del_events(struct gendisk *disk);
@@ -1549,6 +1551,7 @@ unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
         const struct block_device_operations *bdops = disk->fops;
         struct disk_events *ev = disk->ev;
         unsigned int pending;
+        unsigned int clearing = mask;
 
         if (!ev) {
                 /* for drivers still using the old ->media_changed method */
@@ -1558,34 +1561,53 @@ unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask)
                 return 0;
         }
 
-        /* tell the workfn about the events being cleared */
+        disk_block_events(disk);
+
+        /*
+         * store the union of mask and ev->clearing on the stack so that the
+         * race with disk_flush_events does not cause ambiguity (ev->clearing
+         * can still be modified even if events are blocked).
+         */
         spin_lock_irq(&ev->lock);
-        ev->clearing |= mask;
+        clearing |= ev->clearing;
+        ev->clearing = 0;
         spin_unlock_irq(&ev->lock);
 
-        /* uncondtionally schedule event check and wait for it to finish */
-        disk_block_events(disk);
-        queue_delayed_work(system_freezable_wq, &ev->dwork, 0);
-        flush_delayed_work(&ev->dwork);
-        __disk_unblock_events(disk, false);
+        disk_check_events(ev, &clearing);
+        /*
+         * if ev->clearing is not 0, the disk_flush_events got called in the
+         * middle of this function, so we want to run the workfn without delay.
+         */
+        __disk_unblock_events(disk, ev->clearing ? true : false);
 
         /* then, fetch and clear pending events */
         spin_lock_irq(&ev->lock);
-        WARN_ON_ONCE(ev->clearing & mask);      /* cleared by workfn */
         pending = ev->pending & mask;
         ev->pending &= ~mask;
         spin_unlock_irq(&ev->lock);
+        WARN_ON_ONCE(clearing & mask);
 
         return pending;
 }
 
+/*
+ * Separate this part out so that a different pointer for clearing_ptr can be
+ * passed in for disk_clear_events.
+ */
 static void disk_events_workfn(struct work_struct *work)
 {
         struct delayed_work *dwork = to_delayed_work(work);
         struct disk_events *ev = container_of(dwork, struct disk_events, dwork);
+
+        disk_check_events(ev, &ev->clearing);
+}
+
+static void disk_check_events(struct disk_events *ev,
+                              unsigned int *clearing_ptr)
+{
         struct gendisk *disk = ev->disk;
         char *envp[ARRAY_SIZE(disk_uevents) + 1] = { };
-        unsigned int clearing = ev->clearing;
+        unsigned int clearing = *clearing_ptr;
         unsigned int events;
         unsigned long intv;
         int nr_events = 0, i;
@@ -1598,7 +1620,7 @@ static void disk_events_workfn(struct work_struct *work)
 
         events &= ~ev->pending;
         ev->pending |= events;
-        ev->clearing &= ~clearing;
+        *clearing_ptr &= ~clearing;
 
         intv = disk_events_poll_jiffies(disk);
         if (!ev->block && intv)
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index f58a4a4b4dfb..2b8303ad63c9 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -168,7 +168,7 @@ static void wake_all_senders(struct drbd_tconn *tconn) {
 }
 
 /* must hold resource->req_lock */
-static void start_new_tl_epoch(struct drbd_tconn *tconn)
+void start_new_tl_epoch(struct drbd_tconn *tconn)
 {
         /* no point closing an epoch, if it is empty, anyways. */
         if (tconn->current_tle_writes == 0)
diff --git a/drivers/block/drbd/drbd_req.h b/drivers/block/drbd/drbd_req.h
index 016de6b8bb57..c08d22964d06 100644
--- a/drivers/block/drbd/drbd_req.h
+++ b/drivers/block/drbd/drbd_req.h
@@ -267,6 +267,7 @@ struct bio_and_error {
         int error;
 };
 
+extern void start_new_tl_epoch(struct drbd_tconn *tconn);
 extern void drbd_req_destroy(struct kref *kref);
 extern void _req_may_be_done(struct drbd_request *req,
                 struct bio_and_error *m);
diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c
index 53bf6182bac4..0fe220cfb9e9 100644
--- a/drivers/block/drbd/drbd_state.c
+++ b/drivers/block/drbd/drbd_state.c
@@ -931,6 +931,7 @@ __drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
         enum drbd_state_rv rv = SS_SUCCESS;
         enum sanitize_state_warnings ssw;
         struct after_state_chg_work *ascw;
+        bool did_remote, should_do_remote;
 
         os = drbd_read_state(mdev);
 
@@ -981,11 +982,17 @@ __drbd_set_state(struct drbd_conf *mdev, union drbd_state ns,
             (os.disk != D_DISKLESS && ns.disk == D_DISKLESS))
                 atomic_inc(&mdev->local_cnt);
 
+        did_remote = drbd_should_do_remote(mdev->state);
         mdev->state.i = ns.i;
+        should_do_remote = drbd_should_do_remote(mdev->state);
         mdev->tconn->susp = ns.susp;
         mdev->tconn->susp_nod = ns.susp_nod;
         mdev->tconn->susp_fen = ns.susp_fen;
 
+        /* put replicated vs not-replicated requests in seperate epochs */
+        if (did_remote != should_do_remote)
+                start_new_tl_epoch(mdev->tconn);
+
         if (os.disk == D_ATTACHING && ns.disk >= D_NEGOTIATING)
                 drbd_print_uuids(mdev, "attached to UUIDs");
 
diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index 9694dd99bbbc..3fd100990453 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -626,12 +626,13 @@ static void mtip_timeout_function(unsigned long int data)
                 }
         }
 
-        if (cmdto_cnt && !test_bit(MTIP_PF_IC_ACTIVE_BIT, &port->flags)) {
+        if (cmdto_cnt) {
                 print_tags(port->dd, "timed out", tagaccum, cmdto_cnt);
-
-                mtip_restart_port(port);
+                if (!test_bit(MTIP_PF_IC_ACTIVE_BIT, &port->flags)) {
+                        mtip_restart_port(port);
+                        wake_up_interruptible(&port->svc_wait);
+                }
                 clear_bit(MTIP_PF_EH_ACTIVE_BIT, &port->flags);
-                wake_up_interruptible(&port->svc_wait);
         }
 
         if (port->ic_pause_timer) {
@@ -3887,7 +3888,12 @@ static int mtip_block_remove(struct driver_data *dd)
          * Delete our gendisk structure. This also removes the device
          * from /dev
          */
-        del_gendisk(dd->disk);
+        if (dd->disk) {
+                if (dd->disk->queue)
+                        del_gendisk(dd->disk);
+                else
+                        put_disk(dd->disk);
+        }
 
         spin_lock(&rssd_index_lock);
         ida_remove(&rssd_index_ida, dd->index);
@@ -3921,7 +3927,13 @@ static int mtip_block_shutdown(struct driver_data *dd)
                 "Shutting down %s ...\n", dd->disk->disk_name);
 
         /* Delete our gendisk structure, and cleanup the blk queue. */
-        del_gendisk(dd->disk);
+        if (dd->disk) {
+                if (dd->disk->queue)
+                        del_gendisk(dd->disk);
+                else
+                        put_disk(dd->disk);
+        }
+
 
         spin_lock(&rssd_index_lock);
         ida_remove(&rssd_index_ida, dd->index);
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 74374fb762aa..5ac841ff6cc7 100644
--- 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 96e9b00db081..11043c18ac5a 100644
--- 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 a5199f6d0e82..d0ab98f73d38 100644
--- a/include/linux/llist.h
+++ b/include/linux/llist.h
@@ -125,6 +125,31 @@ static inline void init_llist_head(struct llist_head *list)
              (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
  *