block: Get rid of blk_get_backing_dev_info()

BugLink: http://bugs.launchpad.net/bugs/1659111

blk_get_backing_dev_info() is now a simple dereference. Remove that
function and simplify some code around that.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
(back ported from commit efa7c9f9)

Conflicts:
	block/compat_ioctl.c
	block/ioctl.c
	fs/btrfs/volumes.c
	include/linux/blkdev.h
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

block/blk-core.c

@@ -103,20 +103,6 @@ void blk_queue_congestion_threshold(struct request_queue *q)
 	q->nr_congestion_off = nr;
 }
 
-/**
- * blk_get_backing_dev_info - get the address of a queue's backing_dev_info
- * @bdev:	device
- *
- * Locates the passed device's request queue and returns the address of its
- * backing_dev_info. The return value is never NULL however we may return
- * &noop_backing_dev_info if the bdev is not currently open.
- */
-struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
-{
-	return bdev->bd_bdi;
-}
-EXPORT_SYMBOL(blk_get_backing_dev_info);
-
 void blk_rq_init(struct request_queue *q, struct request *rq)
 {
 	memset(rq, 0, sizeof(*rq));

block/compat_ioctl.c

@@ -661,7 +661,6 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 	struct block_device *bdev = inode->i_bdev;
 	struct gendisk *disk = bdev->bd_disk;
 	fmode_t mode = file->f_mode;
-	struct backing_dev_info *bdi;
 	loff_t size;
 	unsigned int max_sectors;
 
@@ -708,9 +707,8 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 	case BLKFRAGET:
 		if (!arg)
 			return -EINVAL;
-		bdi = blk_get_backing_dev_info(bdev);
 		return compat_put_long(arg,
-				       (bdi->ra_pages * PAGE_CACHE_SIZE) / 512);
+			       (bdev->bd_bdi->ra_pages * PAGE_CACHE_SIZE) / 512);
 	case BLKROGET: /* compatible */
 		return compat_put_int(arg, bdev_read_only(bdev) != 0);
 	case BLKBSZGET_32: /* get the logical block size (cf. BLKSSZGET) */
@@ -728,8 +726,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 	case BLKFRASET:
 		if (!capable(CAP_SYS_ADMIN))
 			return -EACCES;
-		bdi = blk_get_backing_dev_info(bdev);
-		bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE;
+		bdev->bd_bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE;
 		return 0;
 	case BLKGETSIZE:
 		size = i_size_read(bdev->bd_inode);

block/ioctl.c

@@ -496,7 +496,6 @@ static int blkdev_bszset(struct block_device *bdev, fmode_t mode,
 int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
 			unsigned long arg)
 {
-	struct backing_dev_info *bdi;
 	void __user *argp = (void __user *)arg;
 	loff_t size;
 	unsigned int max_sectors;
@@ -519,8 +518,7 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
 	case BLKFRAGET:
 		if (!arg)
 			return -EINVAL;
-		bdi = blk_get_backing_dev_info(bdev);
-		return put_long(arg, (bdi->ra_pages * PAGE_CACHE_SIZE) / 512);
+		return put_long(arg, (bdev->bd_bdi->ra_pages*PAGE_CACHE_SIZE) / 512);
 	case BLKROGET:
 		return put_int(arg, bdev_read_only(bdev) != 0);
 	case BLKBSZGET: /* get block device soft block size (cf. BLKSSZGET) */
@@ -547,8 +545,7 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
 	case BLKFRASET:
 		if(!capable(CAP_SYS_ADMIN))
 			return -EACCES;
-		bdi = blk_get_backing_dev_info(bdev);
-		bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE;
+		bdev->bd_bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE;
 		return 0;
 	case BLKBSZSET:
 		return blkdev_bszset(bdev, mode, argp);

fs/btrfs/disk-io.c

@@ -1727,7 +1727,7 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits)
 	list_for_each_entry_rcu(device, &info->fs_devices->devices, dev_list) {
 		if (!device->bdev)
 			continue;
-		bdi = blk_get_backing_dev_info(device->bdev);
+		bdi = device->bdev->bd_bdi;
 		if (bdi_congested(bdi, bdi_bits)) {
 			ret = 1;
 			break;

fs/btrfs/volumes.c

@@ -351,7 +351,7 @@ static noinline void run_scheduled_bios(struct btrfs_device *device)
 	 */
 	blk_start_plug(&plug);
 
-	bdi = blk_get_backing_dev_info(device->bdev);
+	bdi = device->bdev->bd_bdi;
 	fs_info = device->dev_root->fs_info;
 	limit = btrfs_async_submit_limit(fs_info);
 	limit = limit * 2 / 3;

fs/xfs/xfs_buf.c

@@ -682,7 +682,7 @@ xfs_buf_readahead_map(
 	int			nmaps,
 	const struct xfs_buf_ops *ops)
 {
-	if (bdi_read_congested(target->bt_bdi))
+	if (bdi_read_congested(target->bt_bdev->bd_bdi))
 		return;
 
 	xfs_buf_read_map(target, map, nmaps,
@@ -1692,7 +1692,6 @@ xfs_alloc_buftarg(
 	btp->bt_mount = mp;
 	btp->bt_dev =  bdev->bd_dev;
 	btp->bt_bdev = bdev;
-	btp->bt_bdi = blk_get_backing_dev_info(bdev);
 
 	if (xfs_setsize_buftarg_early(btp, bdev))
 		goto error;

fs/xfs/xfs_buf.h

@@ -105,7 +105,6 @@ typedef unsigned int xfs_buf_flags_t;
 typedef struct xfs_buftarg {
 	dev_t			bt_dev;
 	struct block_device	*bt_bdev;
-	struct backing_dev_info	*bt_bdi;
 	struct xfs_mount	*bt_mount;
 	unsigned int		bt_meta_sectorsize;
 	size_t			bt_meta_sectormask;

include/linux/backing-dev.h

@@ -191,7 +191,7 @@ static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
 	sb = inode->i_sb;
 #ifdef CONFIG_BLOCK
 	if (sb_is_blkdev_sb(sb))
-		return blk_get_backing_dev_info(I_BDEV(inode));
+		return I_BDEV(inode)->bd_bdi;
 #endif
 	return sb->s_bdi;
 }

include/linux/blkdev.h

@@ -1004,7 +1004,6 @@ extern void blk_queue_rq_timed_out(struct request_queue *, rq_timed_out_fn *);
 extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
 extern void blk_queue_flush(struct request_queue *q, unsigned int flush);
 extern void blk_queue_flush_queueable(struct request_queue *q, bool queueable);
-extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
 
 extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *);
 extern void blk_dump_rq_flags(struct request *, char *);