[Devel] [PATCH RHEL9 COMMIT] dm-ploop: resize operation - add holes bitmap locking

[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 540abebd83c61c8414a4a11088b36fdd48f9d4bd
Author: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
Date:   Fri Jan 24 17:36:20 2025 +0200

    dm-ploop: resize operation - add holes bitmap locking
    
    lock bitmap in grow update header and disable delayed writeback
    
    https://virtuozzo.atlassian.net/browse/VSTOR-91821
    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 | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/md/dm-ploop-cmd.c b/drivers/md/dm-ploop-cmd.c
index 84e965855698..88af310ee52d 100644
--- a/drivers/md/dm-ploop-cmd.c
+++ b/drivers/md/dm-ploop-cmd.c
@@ -294,19 +294,24 @@ static int ploop_grow_relocate_cluster(struct ploop *ploop,
 
 	dst_clu = cmd->resize.dst_clu;
 
+	spin_lock_irq(&ploop->bat_lock);
+
 	/* Relocate clu and update index */
 	clu = ploop_find_bat_entry(ploop, dst_clu, &is_locked);
 	if (clu == UINT_MAX || is_locked) {
 		/* dst_clu in top delta is not occupied? */
 		if (!test_bit(dst_clu, ploop->holes_bitmap) || is_locked) {
 			WARN_ON_ONCE(1);
+			spin_unlock_irq(&ploop->bat_lock);
 			ret = -EIO;
 			goto out;
 		}
 		/* Cluster is free, occupy it. Skip relocaton */
 		ploop_hole_clear_bit(dst_clu, ploop);
+		spin_unlock_irq(&ploop->bat_lock);
 		goto not_occupied;
 	}
+	spin_unlock_irq(&ploop->bat_lock);
 
 	/* Read full clu sync */
 	ret = ploop_read_cluster_sync(ploop, pio, dst_clu);
@@ -441,6 +446,7 @@ static int ploop_process_resize_cmd(struct ploop *ploop, struct ploop_cmd *cmd)
 	u32 dst_clu;
 	int ret = 0;
 
+	ploop_disable_writeback_delay(ploop);
 	/* Update memory arrays and hb_nr, but do not update nr_bat_entries. */
 	ploop_advance_holes_bitmap(ploop, cmd);
 
@@ -469,6 +475,8 @@ static int ploop_process_resize_cmd(struct ploop *ploop, struct ploop_cmd *cmd)
 	}
 	spin_unlock_irq(&ploop->bat_lock);
 
+	ploop_enable_writeback_delay(ploop);
+
 	return ret;
 }
 ALLOW_ERROR_INJECTION(ploop_process_resize_cmd, ERRNO);