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

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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>
This commit is contained in:
Tejun Heo 2014-09-08 08:03:56 +09:00 committed by Jens Axboe
parent f4da80727c
commit ff9ea32381
7 changed files with 5 additions and 21 deletions
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10
block/blk-core.c
View File

@ -83,18 +83,14 @@ void blk_queue_congestion_threshold(struct request_queue *q)
* @bdev: device
*
* Locates the passed device's request queue and returns the address of its
* backing_dev_info
*
* Will return NULL if the request queue cannot be located.
* backing_dev_info. This function can only be called if @bdev is opened
* and the return value is never NULL.
*/
struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev)
{
struct backing_dev_info *ret = NULL;
struct request_queue *q = bdev_get_queue(bdev);
if (q)
ret = &q->backing_dev_info;
return ret;
return &q->backing_dev_info;
}
EXPORT_SYMBOL(blk_get_backing_dev_info);

4
block/compat_ioctl.c
View File

@ -709,8 +709,6 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
if (!arg)
return -EINVAL;
bdi = blk_get_backing_dev_info(bdev);
if (bdi == NULL)
return -ENOTTY;
return compat_put_long(arg,
(bdi->ra_pages * PAGE_CACHE_SIZE) / 512);
case BLKROGET: /* compatible */
@ -731,8 +729,6 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
bdi = blk_get_backing_dev_info(bdev);
if (bdi == NULL)
return -ENOTTY;
bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE;
return 0;
case BLKGETSIZE:

4
block/ioctl.c
View File

@ -356,8 +356,6 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
if (!arg)
return -EINVAL;
bdi = blk_get_backing_dev_info(bdev);
if (bdi == NULL)
return -ENOTTY;
return put_long(arg, (bdi->ra_pages * PAGE_CACHE_SIZE) / 512);
case BLKROGET:
return put_int(arg, bdev_read_only(bdev) != 0);
@ -386,8 +384,6 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
if(!capable(CAP_SYS_ADMIN))
return -EACCES;
bdi = blk_get_backing_dev_info(bdev);
if (bdi == NULL)
return -ENOTTY;
bdi->ra_pages = (arg * 512) / PAGE_CACHE_SIZE;
return 0;
case BLKBSZSET:

2
fs/block_dev.c
View File

@ -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);
}

2
fs/btrfs/disk-io.c
View File

@ -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;
}

2
fs/xfs/xfs_buf.c
View File

@ -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;

2
include/linux/blkdev.h
View File

@ -865,7 +865,7 @@ extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
{
return bdev->bd_disk->queue;
return bdev->bd_disk->queue; /* this is never NULL */
}
/*