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: Christoph Hellwig <hch@xxxxxx>
---
drivers/block/brd.c | 56 -----------------------------------------------------
1 file changed, 56 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 3adc32a3153b..c15d0581531f 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -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;
@@ -357,9 +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:
bio_io_error(bio);
return BLK_QC_T_NONE;
@@ -464,11 +413,6 @@ 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
--
2.11.0
