Merge branch 'for-2.6.38/event-handling' into for-2.6.38/core

1 files changed, 34 insertions, 7 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index c1c1b8c3fb99..6017389711ee 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -948,10 +948,11 @@ int check_disk_change(struct block_device *bdev)
 {
         struct gendisk *disk = bdev->bd_disk;
         const struct block_device_operations *bdops = disk->fops;
+        unsigned int events;
 
-        if (!bdops->media_changed)
-                return 0;
-        if (!bdops->media_changed(bdev->bd_disk))
+        events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
+                                   DISK_EVENT_EJECT_REQUEST);
+        if (!(events & DISK_EVENT_MEDIA_CHANGE))
                 return 0;
 
         flush_disk(bdev);
@@ -1158,9 +1159,10 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
 
         if (whole) {
                 /* finish claiming */
+                mutex_lock(&bdev->bd_mutex);
                 spin_lock(&bdev_lock);
 
-                if (res == 0) {
+                if (!res) {
                         BUG_ON(!bd_may_claim(bdev, whole, holder));
                         /*
                          * Note that for a whole device bd_holders
@@ -1180,6 +1182,20 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
                 wake_up_bit(&whole->bd_claiming, 0);
 
                 spin_unlock(&bdev_lock);
+
+                /*
+                 * Block event polling for write claims.  Any write
+                 * holder makes the write_holder state stick until all
+                 * are released.  This is good enough and tracking
+                 * individual writeable reference is too fragile given
+                 * the way @mode is used in blkdev_get/put().
+                 */
+                if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder) {
+                        bdev->bd_write_holder = true;
+                        disk_block_events(bdev->bd_disk);
+                }
+
+                mutex_unlock(&bdev->bd_mutex);
                 bdput(whole);
         }
 
@@ -1353,12 +1369,23 @@ int blkdev_put(struct block_device *bdev, fmode_t mode)
 
                 spin_unlock(&bdev_lock);
 
-                /* if this was the last claim, holder link should go too */
-                if (bdev_free)
+                /*
+                 * If this was the last claim, remove holder link and
+                 * unblock evpoll if it was a write holder.
+                 */
+                if (bdev_free) {
                         bd_unlink_disk_holder(bdev);
+                        if (bdev->bd_write_holder) {
+                                disk_unblock_events(bdev->bd_disk);
+                                bdev->bd_write_holder = false;
+                        } else
+                                disk_check_events(bdev->bd_disk);
+                }
 
                 mutex_unlock(&bdev->bd_mutex);
-        }
+        } else
+                disk_check_events(bdev->bd_disk);
+
         return __blkdev_put(bdev, mode, 0);
 }
 EXPORT_SYMBOL(blkdev_put);