Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block

* 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block: (43 commits)
  block: ensure that completion error gets properly traced
  blktrace: add missing probe argument to block_bio_complete
  block cfq: don't use atomic_t for cfq_group
  block cfq: don't use atomic_t for cfq_queue
  block: trace event block fix unassigned field
  block: add internal hd part table references
  block: fix accounting bug on cross partition merges
  kref: add kref_test_and_get
  bio-integrity: mark kintegrityd_wq highpri and CPU intensive
  block: make kblockd_workqueue smarter
  Revert "sd: implement sd_check_events()"
  block: Clean up exit_io_context() source code.
  Fix compile warnings due to missing removal of a 'ret' variable
  fs/block: type signature of major_to_index(int) to major_to_index(unsigned)
  block: convert !IS_ERR(p) && p to !IS_ERR_NOR_NULL(p)
  cfq-iosched: don't check cfqg in choose_service_tree()
  fs/splice: Pull buf->ops->confirm() from splice_from_pipe actors
  cdrom: export cdrom_check_events()
  sd: implement sd_check_events()
  sr: implement sr_check_events()
  ...

1 files changed, 53 insertions, 3 deletions

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index af13c62dc473..14033a36bcd0 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -1348,7 +1348,10 @@ static int cdrom_select_disc(struct cdrom_device_info *cdi, int slot)
         if (!CDROM_CAN(CDC_SELECT_DISC))
                 return -EDRIVE_CANT_DO_THIS;
 
-        (void) cdi->ops->media_changed(cdi, slot);
+        if (cdi->ops->check_events)
+                cdi->ops->check_events(cdi, 0, slot);
+        else
+                cdi->ops->media_changed(cdi, slot);
 
         if (slot == CDSL_NONE) {
                 /* set media changed bits, on both queues */
@@ -1392,6 +1395,42 @@ static int cdrom_select_disc(struct cdrom_device_info *cdi, int slot)
         return slot;
 }
 
+/*
+ * As cdrom implements an extra ioctl consumer for media changed
+ * event, it needs to buffer ->check_events() output, such that event
+ * is not lost for both the usual VFS and ioctl paths.
+ * cdi->{vfs|ioctl}_events are used to buffer pending events for each
+ * path.
+ *
+ * XXX: Locking is non-existent.  cdi->ops->check_events() can be
+ * called in parallel and buffering fields are accessed without any
+ * exclusion.  The original media_changed code had the same problem.
+ * It might be better to simply deprecate CDROM_MEDIA_CHANGED ioctl
+ * and remove this cruft altogether.  It doesn't have much usefulness
+ * at this point.
+ */
+static void cdrom_update_events(struct cdrom_device_info *cdi,
+                                unsigned int clearing)
+{
+        unsigned int events;
+
+        events = cdi->ops->check_events(cdi, clearing, CDSL_CURRENT);
+        cdi->vfs_events |= events;
+        cdi->ioctl_events |= events;
+}
+
+unsigned int cdrom_check_events(struct cdrom_device_info *cdi,
+                                unsigned int clearing)
+{
+        unsigned int events;
+
+        cdrom_update_events(cdi, clearing);
+        events = cdi->vfs_events;
+        cdi->vfs_events = 0;
+        return events;
+}
+EXPORT_SYMBOL(cdrom_check_events);
+
 /* We want to make media_changed accessible to the user through an
  * ioctl. The main problem now is that we must double-buffer the
  * low-level implementation, to assure that the VFS and the user both
@@ -1403,15 +1442,26 @@ int media_changed(struct cdrom_device_info *cdi, int queue)
 {
         unsigned int mask = (1 << (queue & 1));
         int ret = !!(cdi->mc_flags & mask);
+        bool changed;
 
         if (!CDROM_CAN(CDC_MEDIA_CHANGED))
-            return ret;
+                return ret;
+
         /* changed since last call? */
-        if (cdi->ops->media_changed(cdi, CDSL_CURRENT)) {
+        if (cdi->ops->check_events) {
+                BUG_ON(!queue); /* shouldn't be called from VFS path */
+                cdrom_update_events(cdi, DISK_EVENT_MEDIA_CHANGE);
+                changed = cdi->ioctl_events & DISK_EVENT_MEDIA_CHANGE;
+                cdi->ioctl_events = 0;
+        } else
+                changed = cdi->ops->media_changed(cdi, CDSL_CURRENT);
+
+        if (changed) {
                 cdi->mc_flags = 0x3;    /* set bit on both queues */
                 ret |= 1;
                 cdi->media_written = 0;
         }
+
         cdi->mc_flags &= ~mask;         /* clear bit */
         return ret;
 }