CC'd Jens.
Andi Kleen <andi@xxxxxxxxxxxxxx> writes:
> From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
>
> This makes it possible to get from the inode to the request_queue
> with one less cache miss. Used in followon optimization.
>
> The livetime of the pointer is the same as the gendisk.
>
> This assumes that the queue will always stay the same in the
> gendisk while it's visible to block_devices. I think that's safe correct?
>
> Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> ---
> fs/block_dev.c | 3 +++
> include/linux/fs.h | 2 ++
> 2 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index f55aad4..5e07536 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -1110,6 +1110,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
> mutex_lock_nested(&bdev->bd_mutex, for_part);
> if (!bdev->bd_openers) {
> bdev->bd_disk = disk;
> + bdev->bd_queue = disk->queue;
> bdev->bd_contains = bdev;
> if (!partno) {
> struct backing_dev_info *bdi;
> @@ -1130,6 +1131,7 @@ static int __blkdev_get(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_queue = NULL;
> mutex_unlock(&bdev->bd_mutex);
> disk_unblock_events(disk);
> module_put(disk->fops->owner);
> @@ -1203,6 +1205,7 @@ 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_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);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index f23bcb7..ea5cb4d 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -657,6 +657,7 @@ struct address_space {
> * must be enforced here for CRIS, to let the least significant bit
> * of struct page's "mapping" pointer be used for PAGE_MAPPING_ANON.
> */
> +struct request_queue;
>
> struct block_device {
> dev_t bd_dev; /* not a kdev_t - it's a search key */
> @@ -679,6 +680,7 @@ struct block_device {
> unsigned bd_part_count;
> int bd_invalidated;
> struct gendisk * bd_disk;
> + struct request_queue * bd_queue;
> struct list_head bd_list;
> /*
> * Private data. You must have bd_claim'ed the block_device
--
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