[Devel] [PATCH vz9 v2 38/65] dm-ploop: make ploop_bat_write_complete ready for parallel pio completion
Konstantin Khorenko
khorenko at virtuozzo.com
Wed Feb 12 12:33:31 MSK 2025
From: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
There are some requirements listed in the comment inside
ploop_bat_write_complete:
* Success: now update local BAT copy. We could do this
* from our delayed work, but we want to publish new
* mapping in the fastest way. This must be done before
* data bios completion, since right after we complete
* a bio, subsequent read wants to see written data
* (ploop_map() wants to see not zero bat_entries[.])
Currently it assumes sequential pio completion but with threads
it must be ready to have them in any order.
To meet that only ploop_advance_local_after_bat_wb when if it is
the last call to ploop_bat_write_complete.
Complete ready data and cow pios - protect lists with piwb->lock
and deferred_lock - as per other users do.
Code assumes that no one can touch the lists since it is assumed to
be complete which is not valid when pios are processed in parallel.
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-map.c | 47 +++++++++++++++++++++++++--------------
1 file changed, 30 insertions(+), 17 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 50d974245519..6923e0bad794 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -895,35 +895,47 @@ static void ploop_bat_write_complete(struct pio *pio, void *piwb_ptr,
struct ploop_cow *cow;
struct pio *data_pio;
unsigned long flags;
-
- if (!bi_status) {
- /*
- * Success: now update local BAT copy. We could do this
- * from our delayed work, but we want to publish new
- * mapping in the fastest way. This must be done before
- * data bios completion, since right after we complete
- * a bio, subsequent read wants to see written data
- * (ploop_map() wants to see not zero bat_entries[.]).
- */
- ploop_advance_local_after_bat_wb(ploop, piwb, true);
+ LIST_HEAD(lready_pios);
+ LIST_HEAD(lcow_pios);
+ int completed = atomic_read(&piwb->count) == 1;
+
+ if (completed) {
+ /* We are the last count so it is safe to advance bat */
+ if (!bi_status) {
+ /*
+ * Success: now update local BAT copy. We could do this
+ * from our delayed work, but we want to publish new
+ * mapping in the fastest way. This must be done before
+ * data bios completion, since right after we complete
+ * a bio, subsequent read wants to see written data
+ * (ploop_map() wants to see not zero bat_entries[.]).
+ */
+ ploop_advance_local_after_bat_wb(ploop, piwb, true);
+ }
}
spin_lock_irqsave(&piwb->lock, flags);
- piwb->completed = true;
+ if (completed)
+ piwb->completed = completed;
piwb->bi_status = bi_status;
+ list_splice_init(&piwb->ready_data_pios, &lready_pios);
spin_unlock_irqrestore(&piwb->lock, flags);
+ spin_lock_irqsave(&ploop->deferred_lock, flags);
+ list_splice_init(&piwb->cow_list, &lcow_pios);
+ spin_unlock_irqrestore(&ploop->deferred_lock, flags);
+
/*
- * End pending data bios. Unlocked, as nobody can
- * add a new element after piwc->completed is true.
+ * End pending data bios.
*/
- while ((data_pio = ploop_pio_list_pop(&piwb->ready_data_pios)) != NULL) {
+
+ while ((data_pio = ploop_pio_list_pop(&lready_pios)) != NULL) {
if (bi_status)
data_pio->bi_status = bi_status;
ploop_pio_endio(data_pio);
}
- while ((aux_pio = ploop_pio_list_pop(&piwb->cow_list))) {
+ while ((aux_pio = ploop_pio_list_pop(&lcow_pios))) {
cow = aux_pio->endio_cb_data;
ploop_complete_cow(cow, bi_status);
}
@@ -1899,7 +1911,6 @@ static void ploop_submit_metadata_writeback(struct ploop *ploop)
*/
llist_for_each_safe(pos, t, ll_wb_batch) {
md = list_entry((struct list_head *)pos, typeof(*md), wb_link);
- INIT_LIST_HEAD(&md->wb_link);
if (!llist_empty(&md->wait_llist) ||
test_bit(MD_HIGHPRIO, &md->status) ||
time_before(md->dirty_timeout, timeout) ||
@@ -1911,7 +1922,9 @@ static void ploop_submit_metadata_writeback(struct ploop *ploop)
clear_bit(MD_DIRTY, &md->status);
clear_bit(MD_HIGHPRIO, &md->status);
ploop_index_wb_submit(ploop, md->piwb);
+ ret++;
} else {
+ INIT_LIST_HEAD(&md->wb_link);
llist_add((struct llist_node *)&md->wb_link, &ploop->wb_batch_llist);
}
}
--
2.43.5
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