1 files changed, 25 insertions, 9 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index b737451e2e9d..dea3b628a6ce 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -48,6 +48,21 @@ inline struct block_device *I_BDEV(struct inode *inode)
 
 EXPORT_SYMBOL(I_BDEV);
 
+/*
+ * move the inode from it's current bdi to the a new bdi. if the inode is dirty
+ * we need to move it onto the dirty list of @dst so that the inode is always
+ * on the right list.
+ */
+static void bdev_inode_switch_bdi(struct inode *inode,
+                        struct backing_dev_info *dst)
+{
+        spin_lock(&inode_lock);
+        inode->i_data.backing_dev_info = dst;
+        if (inode->i_state & I_DIRTY)
+                list_move(&inode->i_wb_list, &dst->wb.b_dirty);
+        spin_unlock(&inode_lock);
+}
+
 static sector_t max_block(struct block_device *bdev)
 {
         sector_t retval = ~((sector_t)0);
@@ -550,7 +565,7 @@ EXPORT_SYMBOL(bdget);
  */
 struct block_device *bdgrab(struct block_device *bdev)
 {
-        atomic_inc(&bdev->bd_inode->i_count);
+        ihold(bdev->bd_inode);
         return bdev;
 }
 
@@ -580,7 +595,7 @@ static struct block_device *bd_acquire(struct inode *inode)
         spin_lock(&bdev_lock);
         bdev = inode->i_bdev;
         if (bdev) {
-                atomic_inc(&bdev->bd_inode->i_count);
+                ihold(bdev->bd_inode);
                 spin_unlock(&bdev_lock);
                 return bdev;
         }
@@ -591,12 +606,12 @@ static struct block_device *bd_acquire(struct inode *inode)
                 spin_lock(&bdev_lock);
                 if (!inode->i_bdev) {
                         /*
-                         * We take an additional bd_inode->i_count for inode,
+                         * We take an additional reference to bd_inode,
                          * and it's released in clear_inode() of inode.
                          * So, we can access it via ->i_mapping always
                          * without igrab().
                          */
-                        atomic_inc(&bdev->bd_inode->i_count);
+                        ihold(bdev->bd_inode);
                         inode->i_bdev = bdev;
                         inode->i_mapping = bdev->bd_inode->i_mapping;
                         list_add(&inode->i_devices, &bdev->bd_inodes);
@@ -1390,7 +1405,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                                 bdi = blk_get_backing_dev_info(bdev);
                                 if (bdi == NULL)
                                         bdi = &default_backing_dev_info;
-                                bdev->bd_inode->i_data.backing_dev_info = bdi;
+                                bdev_inode_switch_bdi(bdev->bd_inode, bdi);
                         }
                         if (bdev->bd_invalidated)
                                 rescan_partitions(disk, bdev);
@@ -1405,8 +1420,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                         if (ret)
                                 goto out_clear;
                         bdev->bd_contains = whole;
-                        bdev->bd_inode->i_data.backing_dev_info =
-                           whole->bd_inode->i_data.backing_dev_info;
+                        bdev_inode_switch_bdi(bdev->bd_inode,
+                                whole->bd_inode->i_data.backing_dev_info);
                         bdev->bd_part = disk_get_part(disk, partno);
                         if (!(disk->flags & GENHD_FL_UP) ||
                             !bdev->bd_part || !bdev->bd_part->nr_sects) {
@@ -1439,7 +1454,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
         disk_put_part(bdev->bd_part);
         bdev->bd_disk = NULL;
         bdev->bd_part = NULL;
-        bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
+        bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info);
         if (bdev != bdev->bd_contains)
                 __blkdev_put(bdev->bd_contains, mode, 1);
         bdev->bd_contains = NULL;
@@ -1533,7 +1548,8 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
                 disk_put_part(bdev->bd_part);
                 bdev->bd_part = NULL;
                 bdev->bd_disk = NULL;
-                bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info;
+                bdev_inode_switch_bdi(bdev->bd_inode,
+                                        &default_backing_dev_info);
                 if (bdev != bdev->bd_contains)
                         victim = bdev->bd_contains;
                 bdev->bd_contains = NULL;