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authorKeith Busch <kbusch@kernel.org>2020-05-12 17:55:47 +0900
committerJens Axboe <axboe@kernel.dk>2020-05-12 20:36:28 -0600
commit0512a75b98f847c2e9a4b664013424e603e202f7 (patch)
tree06cfd06a4bc26fb345a3afb40fa0fa58ba54062c /block/bio.c
parente4581105771b3523ced88f781eb2672195d217aa (diff)
block: Introduce REQ_OP_ZONE_APPEND
Define REQ_OP_ZONE_APPEND to append-write sectors to a zone of a zoned block device. This is a no-merge write operation. A zone append write BIO must: * Target a zoned block device * Have a sector position indicating the start sector of the target zone * The target zone must be a sequential write zone * The BIO must not cross a zone boundary * The BIO size must not be split to ensure that a single range of LBAs is written with a single command. Implement these checks in generic_make_request_checks() using the helper function blk_check_zone_append(). To avoid write append BIO splitting, introduce the new max_zone_append_sectors queue limit attribute and ensure that a BIO size is always lower than this limit. Export this new limit through sysfs and check these limits in bio_full(). Also when a LLDD can't dispatch a request to a specific zone, it will return BLK_STS_ZONE_RESOURCE indicating this request needs to be delayed, e.g. because the zone it will be dispatched to is still write-locked. If this happens set the request aside in a local list to continue trying dispatching requests such as READ requests or a WRITE/ZONE_APPEND requests targetting other zones. This way we can still keep a high queue depth without starving other requests even if one request can't be served due to zone write-locking. Finally, make sure that the bio sector position indicates the actual write position as indicated by the device on completion. Signed-off-by: Keith Busch <kbusch@kernel.org> [ jth: added zone-append specific add_page and merge_page helpers ] Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bio.c')
-rw-r--r--block/bio.c62
1 files changed, 58 insertions, 4 deletions
diff --git a/block/bio.c b/block/bio.c
index aad0a6dad4f9..3aa3c4ce2e5e 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1025,6 +1025,50 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
return 0;
}
+static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
+{
+ unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt;
+ unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt;
+ struct request_queue *q = bio->bi_disk->queue;
+ unsigned int max_append_sectors = queue_max_zone_append_sectors(q);
+ struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt;
+ struct page **pages = (struct page **)bv;
+ ssize_t size, left;
+ unsigned len, i;
+ size_t offset;
+
+ if (WARN_ON_ONCE(!max_append_sectors))
+ return 0;
+
+ /*
+ * Move page array up in the allocated memory for the bio vecs as far as
+ * possible so that we can start filling biovecs from the beginning
+ * without overwriting the temporary page array.
+ */
+ BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2);
+ pages += entries_left * (PAGE_PTRS_PER_BVEC - 1);
+
+ size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset);
+ if (unlikely(size <= 0))
+ return size ? size : -EFAULT;
+
+ for (left = size, i = 0; left > 0; left -= len, i++) {
+ struct page *page = pages[i];
+ bool same_page = false;
+
+ len = min_t(size_t, PAGE_SIZE - offset, left);
+ if (bio_add_hw_page(q, bio, page, len, offset,
+ max_append_sectors, &same_page) != len)
+ return -EINVAL;
+ if (same_page)
+ put_page(page);
+ offset = 0;
+ }
+
+ iov_iter_advance(iter, size);
+ return 0;
+}
+
/**
* bio_iov_iter_get_pages - add user or kernel pages to a bio
* @bio: bio to add pages to
@@ -1054,10 +1098,16 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
return -EINVAL;
do {
- if (is_bvec)
- ret = __bio_iov_bvec_add_pages(bio, iter);
- else
- ret = __bio_iov_iter_get_pages(bio, iter);
+ if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
+ if (WARN_ON_ONCE(is_bvec))
+ return -EINVAL;
+ ret = __bio_iov_append_get_pages(bio, iter);
+ } else {
+ if (is_bvec)
+ ret = __bio_iov_bvec_add_pages(bio, iter);
+ else
+ ret = __bio_iov_iter_get_pages(bio, iter);
+ }
} while (!ret && iov_iter_count(iter) && !bio_full(bio, 0));
if (is_bvec)
@@ -1460,6 +1510,10 @@ struct bio *bio_split(struct bio *bio, int sectors,
BUG_ON(sectors <= 0);
BUG_ON(sectors >= bio_sectors(bio));
+ /* Zone append commands cannot be split */
+ if (WARN_ON_ONCE(bio_op(bio) == REQ_OP_ZONE_APPEND))
+ return NULL;
+
split = bio_clone_fast(bio, gfp, bs);
if (!split)
return NULL;