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>
This commit is contained in:
Keith Busch 2020-05-12 17:55:47 +09:00 committed by Jens Axboe
parent e458110577
commit 0512a75b98
8 changed files with 207 additions and 4 deletions

View File

@ -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 (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;

View File

@ -135,6 +135,7 @@ static const char *const blk_op_name[] = {
REQ_OP_NAME(ZONE_OPEN),
REQ_OP_NAME(ZONE_CLOSE),
REQ_OP_NAME(ZONE_FINISH),
REQ_OP_NAME(ZONE_APPEND),
REQ_OP_NAME(WRITE_SAME),
REQ_OP_NAME(WRITE_ZEROES),
REQ_OP_NAME(SCSI_IN),
@ -240,6 +241,17 @@ static void req_bio_endio(struct request *rq, struct bio *bio,
bio_advance(bio, nbytes);
if (req_op(rq) == REQ_OP_ZONE_APPEND && error == BLK_STS_OK) {
/*
* Partial zone append completions cannot be supported as the
* BIO fragments may end up not being written sequentially.
*/
if (bio->bi_iter.bi_size)
bio->bi_status = BLK_STS_IOERR;
else
bio->bi_iter.bi_sector = rq->__sector;
}
/* don't actually finish bio if it's part of flush sequence */
if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ))
bio_endio(bio);
@ -887,6 +899,41 @@ out:
return ret;
}
/*
* Check write append to a zoned block device.
*/
static inline blk_status_t blk_check_zone_append(struct request_queue *q,
struct bio *bio)
{
sector_t pos = bio->bi_iter.bi_sector;
int nr_sectors = bio_sectors(bio);
/* Only applicable to zoned block devices */
if (!blk_queue_is_zoned(q))
return BLK_STS_NOTSUPP;
/* The bio sector must point to the start of a sequential zone */
if (pos & (blk_queue_zone_sectors(q) - 1) ||
!blk_queue_zone_is_seq(q, pos))
return BLK_STS_IOERR;
/*
* Not allowed to cross zone boundaries. Otherwise, the BIO will be
* split and could result in non-contiguous sectors being written in
* different zones.
*/
if (nr_sectors > q->limits.chunk_sectors)
return BLK_STS_IOERR;
/* Make sure the BIO is small enough and will not get split */
if (nr_sectors > q->limits.max_zone_append_sectors)
return BLK_STS_IOERR;
bio->bi_opf |= REQ_NOMERGE;
return BLK_STS_OK;
}
static noinline_for_stack bool
generic_make_request_checks(struct bio *bio)
{
@ -959,6 +1006,11 @@ generic_make_request_checks(struct bio *bio)
if (!q->limits.max_write_same_sectors)
goto not_supported;
break;
case REQ_OP_ZONE_APPEND:
status = blk_check_zone_append(q, bio);
if (status != BLK_STS_OK)
goto end_io;
break;
case REQ_OP_ZONE_RESET:
case REQ_OP_ZONE_OPEN:
case REQ_OP_ZONE_CLOSE:

View File

@ -1183,6 +1183,19 @@ static void blk_mq_handle_dev_resource(struct request *rq,
__blk_mq_requeue_request(rq);
}
static void blk_mq_handle_zone_resource(struct request *rq,
struct list_head *zone_list)
{
/*
* If we end up here it is because we cannot dispatch a request to a
* specific zone due to LLD level zone-write locking or other zone
* related resource not being available. In this case, set the request
* aside in zone_list for retrying it later.
*/
list_add(&rq->queuelist, zone_list);
__blk_mq_requeue_request(rq);
}
/*
* Returns true if we did some work AND can potentially do more.
*/
@ -1195,6 +1208,7 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
int errors, queued;
blk_status_t ret = BLK_STS_OK;
bool no_budget_avail = false;
LIST_HEAD(zone_list);
if (list_empty(list))
return false;
@ -1256,6 +1270,16 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
blk_mq_handle_dev_resource(rq, list);
break;
} else if (ret == BLK_STS_ZONE_RESOURCE) {
/*
* Move the request to zone_list and keep going through
* the dispatch list to find more requests the drive can
* accept.
*/
blk_mq_handle_zone_resource(rq, &zone_list);
if (list_empty(list))
break;
continue;
}
if (unlikely(ret != BLK_STS_OK)) {
@ -1267,6 +1291,9 @@ bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
queued++;
} while (!list_empty(list));
if (!list_empty(&zone_list))
list_splice_tail_init(&zone_list, list);
hctx->dispatched[queued_to_index(queued)]++;
/*

View File

@ -48,6 +48,7 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->chunk_sectors = 0;
lim->max_write_same_sectors = 0;
lim->max_write_zeroes_sectors = 0;
lim->max_zone_append_sectors = 0;
lim->max_discard_sectors = 0;
lim->max_hw_discard_sectors = 0;
lim->discard_granularity = 0;
@ -83,6 +84,7 @@ void blk_set_stacking_limits(struct queue_limits *lim)
lim->max_dev_sectors = UINT_MAX;
lim->max_write_same_sectors = UINT_MAX;
lim->max_write_zeroes_sectors = UINT_MAX;
lim->max_zone_append_sectors = UINT_MAX;
}
EXPORT_SYMBOL(blk_set_stacking_limits);
@ -221,6 +223,33 @@ void blk_queue_max_write_zeroes_sectors(struct request_queue *q,
}
EXPORT_SYMBOL(blk_queue_max_write_zeroes_sectors);
/**
* blk_queue_max_zone_append_sectors - set max sectors for a single zone append
* @q: the request queue for the device
* @max_zone_append_sectors: maximum number of sectors to write per command
**/
void blk_queue_max_zone_append_sectors(struct request_queue *q,
unsigned int max_zone_append_sectors)
{
unsigned int max_sectors;
if (WARN_ON(!blk_queue_is_zoned(q)))
return;
max_sectors = min(q->limits.max_hw_sectors, max_zone_append_sectors);
max_sectors = min(q->limits.chunk_sectors, max_sectors);
/*
* Signal eventual driver bugs resulting in the max_zone_append sectors limit
* being 0 due to a 0 argument, the chunk_sectors limit (zone size) not set,
* or the max_hw_sectors limit not set.
*/
WARN_ON(!max_sectors);
q->limits.max_zone_append_sectors = max_sectors;
}
EXPORT_SYMBOL_GPL(blk_queue_max_zone_append_sectors);
/**
* blk_queue_max_segments - set max hw segments for a request for this queue
* @q: the request queue for the device
@ -470,6 +499,8 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
b->max_write_same_sectors);
t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors,
b->max_write_zeroes_sectors);
t->max_zone_append_sectors = min(t->max_zone_append_sectors,
b->max_zone_append_sectors);
t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);
t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,

View File

@ -218,6 +218,13 @@ static ssize_t queue_write_zeroes_max_show(struct request_queue *q, char *page)
(unsigned long long)q->limits.max_write_zeroes_sectors << 9);
}
static ssize_t queue_zone_append_max_show(struct request_queue *q, char *page)
{
unsigned long long max_sectors = q->limits.max_zone_append_sectors;
return sprintf(page, "%llu\n", max_sectors << SECTOR_SHIFT);
}
static ssize_t
queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
{
@ -639,6 +646,11 @@ static struct queue_sysfs_entry queue_write_zeroes_max_entry = {
.show = queue_write_zeroes_max_show,
};
static struct queue_sysfs_entry queue_zone_append_max_entry = {
.attr = {.name = "zone_append_max_bytes", .mode = 0444 },
.show = queue_zone_append_max_show,
};
static struct queue_sysfs_entry queue_nonrot_entry = {
.attr = {.name = "rotational", .mode = 0644 },
.show = queue_show_nonrot,
@ -749,6 +761,7 @@ static struct attribute *queue_attrs[] = {
&queue_discard_zeroes_data_entry.attr,
&queue_write_same_max_entry.attr,
&queue_write_zeroes_max_entry.attr,
&queue_zone_append_max_entry.attr,
&queue_nonrot_entry.attr,
&queue_zoned_entry.attr,
&queue_nr_zones_entry.attr,

View File

@ -1706,6 +1706,7 @@ out_put_budget:
case BLK_STS_OK:
break;
case BLK_STS_RESOURCE:
case BLK_STS_ZONE_RESOURCE:
if (atomic_read(&sdev->device_busy) ||
scsi_device_blocked(sdev))
ret = BLK_STS_DEV_RESOURCE;

View File

@ -63,6 +63,18 @@ typedef u8 __bitwise blk_status_t;
*/
#define BLK_STS_DEV_RESOURCE ((__force blk_status_t)13)
/*
* BLK_STS_ZONE_RESOURCE is returned from the driver to the block layer if zone
* related resources are unavailable, but the driver can guarantee the queue
* will be rerun in the future once the resources become available again.
*
* This is different from BLK_STS_DEV_RESOURCE in that it explicitly references
* a zone specific resource and IO to a different zone on the same device could
* still be served. Examples of that are zones that are write-locked, but a read
* to the same zone could be served.
*/
#define BLK_STS_ZONE_RESOURCE ((__force blk_status_t)14)
/**
* blk_path_error - returns true if error may be path related
* @error: status the request was completed with
@ -296,6 +308,8 @@ enum req_opf {
REQ_OP_ZONE_CLOSE = 11,
/* Transition a zone to full */
REQ_OP_ZONE_FINISH = 12,
/* write data at the current zone write pointer */
REQ_OP_ZONE_APPEND = 13,
/* SCSI passthrough using struct scsi_request */
REQ_OP_SCSI_IN = 32,

View File

@ -332,6 +332,7 @@ struct queue_limits {
unsigned int max_hw_discard_sectors;
unsigned int max_write_same_sectors;
unsigned int max_write_zeroes_sectors;
unsigned int max_zone_append_sectors;
unsigned int discard_granularity;
unsigned int discard_alignment;
@ -750,6 +751,9 @@ static inline bool rq_mergeable(struct request *rq)
if (req_op(rq) == REQ_OP_WRITE_ZEROES)
return false;
if (req_op(rq) == REQ_OP_ZONE_APPEND)
return false;
if (rq->cmd_flags & REQ_NOMERGE_FLAGS)
return false;
if (rq->rq_flags & RQF_NOMERGE_FLAGS)
@ -1084,6 +1088,8 @@ extern void blk_queue_max_write_same_sectors(struct request_queue *q,
extern void blk_queue_max_write_zeroes_sectors(struct request_queue *q,
unsigned int max_write_same_sectors);
extern void blk_queue_logical_block_size(struct request_queue *, unsigned int);
extern void blk_queue_max_zone_append_sectors(struct request_queue *q,
unsigned int max_zone_append_sectors);
extern void blk_queue_physical_block_size(struct request_queue *, unsigned int);
extern void blk_queue_alignment_offset(struct request_queue *q,
unsigned int alignment);
@ -1301,6 +1307,11 @@ static inline unsigned int queue_max_segment_size(const struct request_queue *q)
return q->limits.max_segment_size;
}
static inline unsigned int queue_max_zone_append_sectors(const struct request_queue *q)
{
return q->limits.max_zone_append_sectors;
}
static inline unsigned queue_logical_block_size(const struct request_queue *q)
{
int retval = 512;