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Commit f09a06a1 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

brd: remove discard support 



It's just a in-driver reimplementation of writing zeroes to the pages,
which fails if the discards aren't page aligned.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 19372e27

drivers/block/brd.c

+0 −54
Original line number Diff line number Diff line
@@ -134,28 +134,6 @@ static struct page *brd_insert_page(struct brd_device *brd, sector_t sector) 
	return page;

}



static void brd_free_page(struct brd_device *brd, sector_t sector)

{

	struct page *page;

	pgoff_t idx;



	spin_lock(&brd->brd_lock);

	idx = sector >> PAGE_SECTORS_SHIFT;

	page = radix_tree_delete(&brd->brd_pages, idx);

	spin_unlock(&brd->brd_lock);

	if (page)

		__free_page(page);

}



static void brd_zero_page(struct brd_device *brd, sector_t sector)

{

	struct page *page;



	page = brd_lookup_page(brd, sector);

	if (page)

		clear_highpage(page);

}



/*

 * Free all backing store pages and radix tree. This must only be called when

 * there are no other users of the device.
@@ -212,24 +190,6 @@ static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n) 
	return 0;

}



static void discard_from_brd(struct brd_device *brd,

			sector_t sector, size_t n)

{

	while (n >= PAGE_SIZE) {

		/*

		 * Don't want to actually discard pages here because

		 * re-allocating the pages can result in writeback

		 * deadlocks under heavy load.

		 */

		if (0)

			brd_free_page(brd, sector);

		else

			brd_zero_page(brd, sector);

		sector += PAGE_SIZE >> SECTOR_SHIFT;

		n -= PAGE_SIZE;

	}

}



/*

 * Copy n bytes from src to the brd starting at sector. Does not sleep.

 */
@@ -338,14 +298,6 @@ static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio) 
	if (bio_end_sector(bio) > get_capacity(bdev->bd_disk))

		goto io_error;



	if (unlikely(bio_op(bio) == REQ_OP_DISCARD)) {

		if (sector & ((PAGE_SIZE >> SECTOR_SHIFT) - 1) ||

		    bio->bi_iter.bi_size & ~PAGE_MASK)

			goto io_error;

		discard_from_brd(brd, sector, bio->bi_iter.bi_size);

		goto out;

	}



	bio_for_each_segment(bvec, bio, iter) {

		unsigned int len = bvec.bv_len;

		int err;
@@ -357,7 +309,6 @@ static blk_qc_t brd_make_request(struct request_queue *q, struct bio *bio) 
		sector += len >> SECTOR_SHIFT;

	}



out:

	bio_endio(bio);

	return BLK_QC_T_NONE;

io_error:
@@ -464,11 +415,6 @@ static struct brd_device *brd_alloc(int i) 
	 *  is harmless)

	 */

	blk_queue_physical_block_size(brd->brd_queue, PAGE_SIZE);



	brd->brd_queue->limits.discard_granularity = PAGE_SIZE;

	blk_queue_max_discard_sectors(brd->brd_queue, UINT_MAX);

	brd->brd_queue->limits.discard_zeroes_data = 1;

	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, brd->brd_queue);

#ifdef CONFIG_BLK_DEV_RAM_DAX

	queue_flag_set_unlocked(QUEUE_FLAG_DAX, brd->brd_queue);

#endif