[Devel] [PATCH RHEL9 COMMIT] dm-ploop: resubmit enospc pios from dispatcher thread
Konstantin Khorenko
khorenko at virtuozzo.com
Mon Jan 27 16:12:55 MSK 2025
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 71831d9c59b6d7622dec38dc7219564baeb480cc
Author: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
Date: Fri Jan 24 17:36:33 2025 +0200
dm-ploop: resubmit enospc pios from dispatcher thread
When running out of space pios are delayed and retried
from a timer. This timer is the only thing that runs in
interrupt context and brings requirement to use _irqsave
variants, since a complete request processing can be started
from the timer. To avoid this set a flag from the timer
and process delayed pios from the dispatcher thread.
Follow up patches will cleanup flags saving.
https://virtuozzo.atlassian.net/browse/VSTOR-98016
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 | 31 ++++++++++++++++++-------------
drivers/md/dm-ploop-target.c | 2 +-
drivers/md/dm-ploop.h | 2 ++
3 files changed, 21 insertions(+), 14 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 00929455fcf5..98297fb46bb6 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -151,12 +151,7 @@ static void ploop_init_prq_and_embedded_pio(struct ploop *ploop,
void ploop_enospc_timer(struct timer_list *timer)
{
struct ploop *ploop = from_timer(ploop, timer, enospc_timer);
- struct llist_node *enospc_pending = llist_del_all(&ploop->enospc_pios);
-
- if (enospc_pending) {
- enospc_pending = llist_reverse_order(enospc_pending);
- ploop_submit_embedded_pios(ploop, enospc_pending);
- }
+ ploop->submit_enospc = true;
}
void do_ploop_event_work(struct work_struct *ws)
@@ -169,12 +164,11 @@ void do_ploop_event_work(struct work_struct *ws)
static bool ploop_try_delay_enospc(struct ploop_rq *prq, struct pio *pio)
{
struct ploop *ploop = pio->ploop;
- bool delayed = true;
unsigned long flags;
if (unlikely(ploop->wants_suspend)) {
- delayed = false;
- goto unlock;
+ PL_WARN("dropping pio enospc\n");
+ return false;
}
ploop_init_prq_and_embedded_pio(ploop, prq->rq, prq, pio);
@@ -185,13 +179,11 @@ static bool ploop_try_delay_enospc(struct ploop_rq *prq, struct pio *pio)
ploop->event_enospc = true;
spin_unlock_irqrestore(&ploop->deferred_lock, flags);
llist_add((struct llist_node *)(&pio->list), &ploop->enospc_pios);
-unlock:
- if (delayed)
- mod_timer(&ploop->enospc_timer, jiffies + PLOOP_ENOSPC_TIMEOUT);
+ mod_timer(&ploop->enospc_timer, jiffies + PLOOP_ENOSPC_TIMEOUT);
schedule_work(&ploop->event_work);
- return delayed;
+ return true;
}
static void ploop_prq_endio(struct pio *pio, void *prq_ptr,
@@ -2165,6 +2157,14 @@ static inline int ploop_runners_add_work_list(struct ploop *ploop, struct llist_
return 0;
}
+void ploop_resubmit_enospc_pios(struct ploop *ploop)
+{
+ struct llist_node *enospc_pending = llist_del_all(&ploop->enospc_pios);
+
+ if (enospc_pending)
+ ploop_submit_embedded_pios(ploop, llist_reverse_order(enospc_pending));
+}
+
void do_ploop_run_work(struct ploop *ploop)
{
LLIST_HEAD(deferred_pios);
@@ -2180,6 +2180,11 @@ void do_ploop_run_work(struct ploop *ploop)
current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
+ if (ploop->submit_enospc) {
+ ploop->submit_enospc = false;
+ ploop_resubmit_enospc_pios(ploop);
+ }
+
llembedded_pios = llist_del_all(&ploop->pios[PLOOP_LIST_PREPARE]);
lldeferred_pios = llist_del_all(&ploop->pios[PLOOP_LIST_DEFERRED]);
diff --git a/drivers/md/dm-ploop-target.c b/drivers/md/dm-ploop-target.c
index 641950031fe3..f306f0c85ee5 100644
--- a/drivers/md/dm-ploop-target.c
+++ b/drivers/md/dm-ploop-target.c
@@ -695,7 +695,7 @@ static void ploop_presuspend(struct dm_target *ti)
wait_event_interruptible(ploop->dispatcher_wq_data,
(!atomic_read(&ploop->kt_worker->inflight_pios)));
vfs_fsync(ploop_top_delta(ploop)->file, 0);
- ploop_enospc_timer(&ploop->enospc_timer);
+ ploop_resubmit_enospc_pios(ploop);
}
static void ploop_presuspend_undo(struct dm_target *ti)
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index edf9b1448887..43e65e841e4a 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -259,6 +259,7 @@ struct ploop {
bool nokblkcg;
struct timer_list enospc_timer;
+ bool submit_enospc; /* timer expired run pios from dispatcher */
bool event_enospc;
loff_t prealloc_size;
@@ -637,5 +638,6 @@ extern void ploop_disable_writeback_delay(struct ploop *ploop);
extern void ploop_enable_writeback_delay(struct ploop *ploop);
extern void ploop_should_prealloc(struct ploop *ploop, struct file *file);
+extern void ploop_resubmit_enospc_pios(struct ploop *ploop);
#endif /* __DM_PLOOP_H */
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