[Devel] [PATCH vz9 v2 22/65] dm-ploop: make new allocations immediately visible in BAT

[Konstantin Khorenko]

From: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>

We are planning to delay metadata writeback, so we want to
immediately apply metadata changes to BAT page.
Make all request that trigger PIWB_TYPE_ALLOC apply metadata
changes immediately.

https://virtuozzo.atlassian.net/browse/VSTOR-91817
Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>

======
Patchset description:
ploop: optimistations and scalling

Ploop processes requsts in a different threads in parallel
where possible which results in significant improvement in
performance and makes further optimistations possible.

Known bugs:
  - delayed metadata writeback is not working and is missing error handling
     - patch to disable it until fixed
  - fast path is not working - causes rcu lockups - patch to disable it

Further improvements:
  - optimize md pages lookups

Alexander Atanasov (50):
  dm-ploop: md_pages map all pages at creation time
  dm-ploop: Use READ_ONCE/WRITE_ONCE to access md page data
  dm-ploop: fsync after all pios are sent
  dm-ploop: move md status to use proper bitops
  dm-ploop: convert wait_list and wb_batch_llist to use lockless lists
  dm-ploop: convert enospc handling to use lockless lists
  dm-ploop: convert suspended_pios list to use lockless list
  dm-ploop: convert the rest of the lists to use llist variant
  dm-ploop: combine processing of pios thru prepare list and remove
    fsync worker
  dm-ploop: move from wq to kthread
  dm-ploop: move preparations of pios into the caller from worker
  dm-ploop: fast path execution for reads
  dm-ploop: do not use a wrapper for set_bit to make a page writeback
  dm-ploop: BAT use only one list for writeback
  dm-ploop: make md writeback timeout to be per page
  dm-ploop: add interface to disable bat writeback delay
  dm-ploop: convert wb_batch_list to lockless variant
  dm-ploop: convert high_prio to status
  dm-ploop: split cow processing into two functions
  dm-ploop: convert md page rw lock to spin lock
  dm-ploop: convert bat_rwlock to bat_lock spinlock
  dm-ploop: prepare bat updates under bat_lock
  dm-ploop: make ploop_bat_write_complete ready for parallel pio
    completion
  dm-ploop: make ploop_submit_metadata_writeback return number of
    requests sent
  dm-ploop: introduce pio runner threads
  dm-ploop: add pio list ids to be used when passing pios to runners
  dm-ploop: process pios via runners
  dm-ploop: disable metadata writeback delay
  dm-ploop: disable fast path
  dm-ploop: use lockless lists for chained cow updates list
  dm-ploop: use lockless lists for data ready pios
  dm-ploop: give runner threads better name
  dm-ploop: resize operation - add holes bitmap locking
  dm-ploop: remove unnecessary operations
  dm-ploop: use filp per thread
  dm-ploop: catch if we try to advance pio past bio end
  dm-ploop: support REQ_FUA for data pios
  dm-ploop: proplerly access nr_bat_entries
  dm-ploop: fix locking and improve error handling when submitting pios
  dm-ploop: fix how ENOTBLK is handled
  dm-ploop: sync when suspended or stopping
  dm-ploop: rework bat completion logic
  dm-ploop: rework logic in pio processing
  dm-ploop: end fsync pios in parallel
  dm-ploop: make filespace preallocations async
  dm-ploop: resubmit enospc pios from dispatcher thread
  dm-ploop: dm-ploop: simplify discard completion
  dm-ploop: use GFP_ATOMIC instead of GFP_NOIO
  dm-ploop: fix locks used in mixed context
  dm-ploop: fix how current flags are managed inside threads

Andrey Zhadchenko (13):
  dm-ploop: do not flush after metadata writes
  dm-ploop: set IOCB_DSYNC on all FUA requests
  dm-ploop: remove extra ploop_cluster_is_in_top_delta()
  dm-ploop: introduce per-md page locking
  dm-ploop: reduce BAT accesses on discard completion
  dm-ploop: simplify llseek
  dm-ploop: speed up ploop_prepare_bat_update()
  dm-ploop: make new allocations immediately visible in BAT
  dm-ploop: drop ploop_cluster_is_in_top_delta()
  dm-ploop: do not wait for BAT update for non-FUA requests
  dm-ploop: add delay for metadata writeback
  dm-ploop: submit all postponed metadata on REQ_OP_FLUSH
  dm-ploop: handle REQ_PREFLUSH

Feature: dm-ploop: ploop target driver
---
 drivers/md/dm-ploop-map.c | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index e34bc4aafc79..350bfef189e0 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -777,6 +777,10 @@ static void ploop_advance_local_after_bat_wb(struct ploop *ploop,
 		i = PLOOP_MAP_OFFSET;
 
 	dst_clu = kmap_local_page(piwb->bat_page);
+
+	if (piwb->type == PIWB_TYPE_ALLOC)
+		goto skip_apply;
+
 	for (; i < last; i++) {
 		if (piwb->type == PIWB_TYPE_DISCARD) {
 			ploop_piwb_discard_completed(ploop, success, i + off, dst_clu[i]);
@@ -786,12 +790,6 @@ static void ploop_advance_local_after_bat_wb(struct ploop *ploop,
 		if (!dst_clu[i])
 			continue;
 
-		if (ploop_cluster_is_in_top_delta(ploop, i + off)
-						&& piwb->type == PIWB_TYPE_ALLOC) {
-			WARN_ON(bat_entries[i] != dst_clu[i]);
-			continue;
-		}
-
 		if (success) {
 			WRITE_ONCE(bat_entries[i], READ_ONCE(dst_clu[i]));
 			WRITE_ONCE(md->bat_levels[i], ploop_top_level(ploop));
@@ -799,11 +797,12 @@ static void ploop_advance_local_after_bat_wb(struct ploop *ploop,
 			ploop_hole_set_bit(i + off, ploop);
 		}
 	}
+skip_apply:
 
 	WARN_ON_ONCE(!test_bit(MD_WRITEBACK, &md->status));
+	/* protect piwb */
 	spin_lock_irqsave(&md->md_lock, flags); /* write */
 	clear_bit(MD_WRITEBACK, &md->status);
-	/* protect piwb */
 	md->piwb = NULL;
 	spin_unlock_irqrestore(&md->md_lock, flags);
 	kunmap_local(dst_clu);
@@ -930,7 +929,7 @@ static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
 	piwb->page_id = page_id;
 	to = kmap_local_page(page);
 
-	read_lock_irq(&md->lock);
+	spin_lock_irq(&md->md_lock);
 	memcpy((void *)to, bat_entries, PAGE_SIZE);
 
 	/* Absolute number of first index in page (negative for page#0) */
@@ -955,7 +954,7 @@ static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
 		if (clu == BAT_ENTRY_NONE || level < ploop_top_level(ploop))
 			to[i] = 0;
 	}
-	read_unlock_irq(&md->lock);
+	spin_unlock_irq(&md->md_lock);
 
 	if (is_last_page) {
 	/* Fill tail of page with 0 */
@@ -1103,6 +1102,7 @@ static int ploop_alloc_cluster(struct ploop *ploop, struct ploop_index_wb *piwb,
 	map_index_t *to;
 	int ret = 0;
 	u32 tmp_clu;
+	unsigned long flags;
 
 	/* Cluster index related to the page[page_id] start */
 	clu -= piwb->page_id * PAGE_SIZE / sizeof(map_index_t) - PLOOP_MAP_OFFSET;
@@ -1124,8 +1124,13 @@ static int ploop_alloc_cluster(struct ploop *ploop, struct ploop_index_wb *piwb,
 		goto out;
 
 	to = kmap_local_page(piwb->bat_page);
+	spin_lock_irqsave(&piwb->md->md_lock, flags);
 	WRITE_ONCE(to[clu], *dst_clu);
+	WRITE_ONCE(piwb->md->bat_levels[clu], ploop_top_level(ploop));
+	spin_unlock_irqrestore(&piwb->md->md_lock, flags);
 	kunmap_local(to);
+	to = piwb->md->kmpage;
+	WRITE_ONCE(to[clu], *dst_clu);
 out:
 	return ret;
 }
@@ -1384,6 +1389,7 @@ static void ploop_submit_cow_index_wb(struct ploop_cow *cow)
 	u32 page_id, clu = cow_pio->clu;
 	struct ploop_index_wb *piwb;
 	struct md_page *md;
+	unsigned long flags;
 	map_index_t *to;
 
 	WARN_ON_ONCE(cow->aux_pio->queue_list_id != PLOOP_LIST_COW);
@@ -1409,6 +1415,12 @@ static void ploop_submit_cow_index_wb(struct ploop_cow *cow)
 	WRITE_ONCE(to[clu], cow->dst_clu);
 	kunmap_local(to);
 
+	spin_lock_irqsave(&md->md_lock, flags);
+	to = md->kmpage;
+	WRITE_ONCE(to[clu], cow->dst_clu);
+	WRITE_ONCE(md->bat_levels[clu], ploop_top_level(ploop));
+	spin_unlock_irqrestore(&md->md_lock, flags);
+
 	/* Prevent double clearing of holes_bitmap bit on complete_cow() */
 	cow->dst_clu = BAT_ENTRY_NONE;
 	spin_lock_irq(&ploop->deferred_lock);
-- 
2.43.5