block, bdi: an active gendisk always has a request_queue associated with it

bdev_get_queue() returns the request_queue associated with the
specified block_device.  blk_get_backing_dev_info() makes use of
bdev_get_queue() to determine the associated bdi given a block_device.

All the callers of bdev_get_queue() including
blk_get_backing_dev_info() assume that bdev_get_queue() may return
NULL and implement NULL handling; however, bdev_get_queue() requires
the passed in block_device is opened and attached to its gendisk.
Because an active gendisk always has a valid request_queue associated
with it, bdev_get_queue() can never return NULL and neither can
blk_get_backing_dev_info().

Make it clear that neither of the two functions can return NULL and
remove NULL handling from all the callers.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

3 files changed, 1 insertions, 5 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 6d7274619bf9..d3251eca6429 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1173,8 +1173,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
                         if (!ret) {
                                 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
                                 bdi = blk_get_backing_dev_info(bdev);
-                                if (bdi == NULL)
-                                        bdi = &default_backing_dev_info;
                                 bdev_inode_switch_bdi(bdev->bd_inode, bdi);
                         }
 
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index d0ed9e664f7d..39ff591ae1b4 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1694,7 +1694,7 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits)
                 if (!device->bdev)
                         continue;
                 bdi = blk_get_backing_dev_info(device->bdev);
-                if (bdi && bdi_congested(bdi, bdi_bits)) {
+                if (bdi_congested(bdi, bdi_bits)) {
                         ret = 1;
                         break;
                 }
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index cd7b8ca9b064..497fcde381d7 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1678,8 +1678,6 @@ xfs_alloc_buftarg(
         btp->bt_dev =  bdev->bd_dev;
         btp->bt_bdev = bdev;
         btp->bt_bdi = blk_get_backing_dev_info(bdev);
-        if (!btp->bt_bdi)
-                goto error;
 
         if (xfs_setsize_buftarg_early(btp, bdev))
                 goto error;