[Devel] [PATCH vz9 v2 63/65] dm-ploop: use GFP_ATOMIC instead of GFP_NOIO

[Konstantin Khorenko]

From: Alexander Atanasov <alexander.atanasov at virtuozzo.com>

GFP_NOIO can sleep so we can not use it while we
are called from block layer and device mapper in
interrupt context. It is also invalid under rcu_nesting
which happens too.
(traces in the issue)

https://virtuozzo.atlassian.net/browse/VSTOR-98291
Signed-off-by: Alexander Atanasov <alexander.atanasov 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-cmd.c |  4 ++--
 drivers/md/dm-ploop-map.c | 14 +++++++-------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/md/dm-ploop-cmd.c b/drivers/md/dm-ploop-cmd.c
index 011d37f8fe3e..e032af52b64e 100644
--- a/drivers/md/dm-ploop-cmd.c
+++ b/drivers/md/dm-ploop-cmd.c
@@ -489,13 +489,13 @@ struct pio *ploop_alloc_pio_with_pages(struct ploop *ploop)
 	u32 size;
 
 	size = sizeof(*pio) + sizeof(*pio->bi_io_vec) * nr_pages;
-	pio = kmalloc(size, GFP_NOIO);
+	pio = kmalloc(size, GFP_ATOMIC);
 	if (!pio)
 		return NULL;
 	pio->bi_io_vec = (void *)(pio + 1);
 
 	for (i = 0; i < nr_pages; i++) {
-		pio->bi_io_vec[i].bv_page = alloc_page(GFP_NOIO);
+		pio->bi_io_vec[i].bv_page = alloc_page(GFP_ATOMIC);
 		if (!pio->bi_io_vec[i].bv_page)
 			goto err;
 		pio->bi_io_vec[i].bv_offset = 0;
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 17927dd886a9..f7e7dd04773e 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -292,7 +292,7 @@ static struct pio *ploop_split_and_chain_pio(struct ploop *ploop,
 {
 	struct pio *split;
 
-	split = ploop_alloc_pio(ploop, GFP_NOIO);
+	split = ploop_alloc_pio(ploop, GFP_ATOMIC);
 	if (!split)
 		return NULL;
 
@@ -1017,13 +1017,13 @@ static int ploop_prepare_bat_update(struct ploop *ploop, struct md_page *md,
 
 	lockdep_assert_held(&ploop->bat_lock);
 
-	piwb = kmalloc(sizeof(*piwb), GFP_NOIO);
+	piwb = kmalloc(sizeof(*piwb), GFP_ATOMIC);
 	if (!piwb)
 		return -ENOMEM;
 	ploop_index_wb_init(piwb, ploop);
 
-	piwb->bat_page = page = alloc_page(GFP_NOIO);
-	piwb->pio = pio = ploop_alloc_pio(ploop, GFP_NOIO);
+	piwb->bat_page = page = alloc_page(GFP_ATOMIC);
+	piwb->pio = pio = ploop_alloc_pio(ploop, GFP_ATOMIC);
 	if (!page || !pio)
 		goto err;
 	ploop_init_pio(ploop, REQ_OP_WRITE, pio);
@@ -1558,7 +1558,7 @@ static int ploop_submit_cluster_cow(struct ploop *ploop, unsigned int level,
 
 	/* Prepare new delta read */
 	aux_pio = ploop_alloc_pio_with_pages(ploop);
-	cow = kmem_cache_alloc(cow_cache, GFP_NOIO);
+	cow = kmem_cache_alloc(cow_cache, GFP_ATOMIC);
 	if (!aux_pio || !cow)
 		goto err;
 	ploop_init_pio(ploop, REQ_OP_READ, aux_pio);
@@ -1904,7 +1904,7 @@ static struct bio_vec *ploop_create_bvec_from_rq(struct request *rq)
 		nr_bvec++;
 
 	bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
-			     GFP_NOIO);
+			     GFP_ATOMIC);
 	if (!bvec)
 		goto out;
 
@@ -2416,7 +2416,7 @@ static int ploop_prepare_flush(struct ploop *ploop, struct pio *pio)
 	unsigned long flags;
 
 	if (pio->bi_op & REQ_PREFLUSH && (pio->bi_op & REQ_OP_MASK) != REQ_OP_FLUSH) {
-		flush_pio = ploop_alloc_pio(ploop, GFP_NOIO);
+		flush_pio = ploop_alloc_pio(ploop, GFP_ATOMIC);
 		if (!flush_pio) {
 			pio->bi_status = BLK_STS_RESOURCE;
 			ploop_pio_endio(pio);
-- 
2.43.5