1 files changed, 50 insertions, 27 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index b48c41bf0f86..975266be67d3 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -49,23 +49,15 @@ inline struct block_device *I_BDEV(struct inode *inode)
 }
 EXPORT_SYMBOL(I_BDEV);
 
-/*
- * Move the inode from its current bdi to a new bdi.  Make sure the inode
- * is clean before moving so that it doesn't linger on the old bdi.
- */
-static void bdev_inode_switch_bdi(struct inode *inode,
-                        struct backing_dev_info *dst)
+static void bdev_write_inode(struct inode *inode)
 {
-        while (true) {
-                spin_lock(&inode->i_lock);
-                if (!(inode->i_state & I_DIRTY)) {
-                        inode->i_data.backing_dev_info = dst;
-                        spin_unlock(&inode->i_lock);
-                        return;
-                }
+        spin_lock(&inode->i_lock);
+        while (inode->i_state & I_DIRTY) {
                 spin_unlock(&inode->i_lock);
                 WARN_ON_ONCE(write_inode_now(inode, true));
+                spin_lock(&inode->i_lock);
         }
+        spin_unlock(&inode->i_lock);
 }
 
 /* Kill _all_ buffers and pagecache , dirty or not.. */
@@ -429,6 +421,46 @@ int bdev_write_page(struct block_device *bdev, sector_t sector,
 }
 EXPORT_SYMBOL_GPL(bdev_write_page);
 
+/**
+ * bdev_direct_access() - Get the address for directly-accessibly memory
+ * @bdev: The device containing the memory
+ * @sector: The offset within the device
+ * @addr: Where to put the address of the memory
+ * @pfn: The Page Frame Number for the memory
+ * @size: The number of bytes requested
+ *
+ * If a block device is made up of directly addressable memory, this function
+ * will tell the caller the PFN and the address of the memory.  The address
+ * may be directly dereferenced within the kernel without the need to call
+ * ioremap(), kmap() or similar.  The PFN is suitable for inserting into
+ * page tables.
+ *
+ * Return: negative errno if an error occurs, otherwise the number of bytes
+ * accessible at this address.
+ */
+long bdev_direct_access(struct block_device *bdev, sector_t sector,
+                        void **addr, unsigned long *pfn, long size)
+{
+        long avail;
+        const struct block_device_operations *ops = bdev->bd_disk->fops;
+
+        if (size < 0)
+                return size;
+        if (!ops->direct_access)
+                return -EOPNOTSUPP;
+        if ((sector + DIV_ROUND_UP(size, 512)) >
+                                        part_nr_sects_read(bdev->bd_part))
+                return -ERANGE;
+        sector += get_start_sect(bdev);
+        if (sector % (PAGE_SIZE / 512))
+                return -EINVAL;
+        avail = ops->direct_access(bdev, sector, addr, pfn, size);
+        if (!avail)
+                return -ERANGE;
+        return min(avail, size);
+}
+EXPORT_SYMBOL_GPL(bdev_direct_access);
+
 /*
  * pseudo-fs
  */
@@ -584,7 +616,6 @@ struct block_device *bdget(dev_t dev)
                 inode->i_bdev = bdev;
                 inode->i_data.a_ops = &def_blk_aops;
                 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
-                inode->i_data.backing_dev_info = &default_backing_dev_info;
                 spin_lock(&bdev_lock);
                 list_add(&bdev->bd_list, &all_bdevs);
                 spin_unlock(&bdev_lock);
@@ -1145,8 +1176,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                 bdev->bd_queue = disk->queue;
                 bdev->bd_contains = bdev;
                 if (!partno) {
-                        struct backing_dev_info *bdi;
-
                         ret = -ENXIO;
                         bdev->bd_part = disk_get_part(disk, partno);
                         if (!bdev->bd_part)
@@ -1172,11 +1201,8 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                                 }
                         }
 
-                        if (!ret) {
+                        if (!ret)
                                 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
-                                bdi = blk_get_backing_dev_info(bdev);
-                                bdev_inode_switch_bdi(bdev->bd_inode, bdi);
-                        }
 
                         /*
                          * If the device is invalidated, rescan partition
@@ -1203,8 +1229,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                         if (ret)
                                 goto out_clear;
                         bdev->bd_contains = whole;
-                        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) {
@@ -1244,7 +1268,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
         bdev->bd_disk = NULL;
         bdev->bd_part = NULL;
         bdev->bd_queue = NULL;
-        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;
@@ -1464,11 +1487,11 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
                 WARN_ON_ONCE(bdev->bd_holders);
                 sync_blockdev(bdev);
                 kill_bdev(bdev);
-                /* ->release can cause the old bdi to disappear,
-                 * so must switch it out first
+                /*
+                 * ->release can cause the queue to disappear, so flush all
+                 * dirty data before.
                  */
-                bdev_inode_switch_bdi(bdev->bd_inode,
-                                        &default_backing_dev_info);
+                bdev_write_inode(bdev->bd_inode);
         }
         if (bdev->bd_contains == bdev) {
                 if (disk->fops->release)