[Devel] [PATCH RHEL9 COMMIT] dm-ploop: do not flush after metadata writes

[Konstantin Khorenko]

The commit is pushed to "branch-rh9-5.14.0-427.44.1.vz9.80.x-ovz" and will appear at git at bitbucket.org:openvz/vzkernel.git
after rh9-5.14.0-427.44.1.vz9.80.6
------>
commit 199014891c29c2be4acd17527df6884aa23de1a8
Author: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>
Date:   Fri Jan 24 17:35:47 2025 +0200

    dm-ploop: do not flush after metadata writes
    
    Flushed should be explicitly called by the writer if he really
    wants it.
    Drop ploop_md_write_endio() and ploop_md_fsync_endio().
    
    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 | 31 +++----------------------------
 1 file changed, 3 insertions(+), 28 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 8e1d4bf6438a..c83b93f0590a 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -848,9 +848,10 @@ static void ploop_put_piwb(struct ploop_index_wb *piwb)
 }
 
 /* This handler is called after BAT is updated. */
-static void ploop_bat_write_complete(struct ploop_index_wb *piwb,
+static void ploop_bat_write_complete(struct pio *pio, void *piwb_ptr,
 				     blk_status_t bi_status)
 {
+	struct ploop_index_wb *piwb = piwb_ptr;
 	struct ploop *ploop = piwb->ploop;
 	struct pio *aux_pio;
 	struct ploop_cow *cow;
@@ -1572,32 +1573,6 @@ static int ploop_process_one_deferred_bio(struct ploop *ploop, struct pio *pio)
 	return 0;
 }
 
-static void ploop_md_fsync_endio(struct pio *pio, void *piwb_ptr,
-				 blk_status_t bi_status)
-{
-	struct ploop_index_wb *piwb = piwb_ptr;
-
-	ploop_bat_write_complete(piwb, bi_status);
-}
-
-static void ploop_md_write_endio(struct pio *pio, void *piwb_ptr,
-				 blk_status_t bi_status)
-{
-	struct ploop_index_wb *piwb = piwb_ptr;
-	struct ploop *ploop = piwb->ploop;
-
-	if (bi_status) {
-		ploop_md_fsync_endio(pio, piwb, bi_status);
-	} else {
-		ploop_init_pio(ploop, REQ_OP_FLUSH, pio);
-		pio->endio_cb = ploop_md_fsync_endio;
-		pio->endio_cb_data = piwb;
-
-		pio->queue_list_id = PLOOP_LIST_FLUSH;
-		ploop_dispatch_pios(ploop, pio, NULL);
-	}
-}
-
 void ploop_index_wb_submit(struct ploop *ploop, struct ploop_index_wb *piwb)
 {
 	loff_t pos = (loff_t)piwb->page_id << PAGE_SHIFT;
@@ -1614,7 +1589,7 @@ void ploop_index_wb_submit(struct ploop *ploop, struct ploop_index_wb *piwb)
 	pio->bi_iter.bi_bvec_done = 0;
 	pio->bi_io_vec = bvec;
 	pio->level = ploop_top_level(ploop);
-	pio->endio_cb = ploop_md_write_endio;
+	pio->endio_cb = ploop_bat_write_complete;
 	pio->endio_cb_data = piwb;
 
 	ploop_submit_rw_mapped(ploop, pio);