[Devel] [PATCH RHEL9 COMMIT] dm-ploop: fix how current flags are managed inside threads
Konstantin Khorenko
khorenko at virtuozzo.com
Mon Jan 27 16:12:56 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 82040b9a30ca738170689738aa53ab617ccb6169
Author: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
Date: Fri Jan 24 17:36:37 2025 +0200
dm-ploop: fix how current flags are managed inside threads
currently threads do
old_flags = current->flags;
current->flags |= ploop flags;
...
current->flags = old_flags;
this can break process flags
To fix this use current_restore_flags(..) macro which only removes
our flags and it preserves any other flags.
https://virtuozzo.atlassian.net/browse/VSTOR-98626
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 | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index c6c46b49bccf..7efbaedd69e0 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -2150,6 +2150,7 @@ void ploop_resubmit_enospc_pios(struct ploop *ploop)
ploop_submit_embedded_pios(ploop, llist_reverse_order(enospc_pending));
}
+#define PLOOP_PFLAGS (PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO)
void do_ploop_run_work(struct ploop *ploop)
{
LLIST_HEAD(deferred_pios);
@@ -2163,7 +2164,7 @@ void do_ploop_run_work(struct ploop *ploop)
int npios;
int force_md_update;
- current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
+ current->flags |= PLOOP_PFLAGS;
if (ploop->submit_enospc) {
ploop->submit_enospc = false;
@@ -2201,10 +2202,10 @@ void do_ploop_run_work(struct ploop *ploop)
* put stick in the wheel - wait for all pios to be executed before doing metadata
* we could gain a bit more iops if we can skip this wait but for now we can not
*/
- current->flags = old_flags;
+ current_restore_flags(old_flags, PLOOP_PFLAGS);
wait_event_interruptible(ploop->dispatcher_wq_data,
(!ploop_runners_have_pending(ploop)));
- current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
+ current->flags |= PLOOP_PFLAGS;
/* if we have a flush we must sync md data too */
force_md_update = !!llflush_pios | ploop->force_md_writeback;
@@ -2212,25 +2213,25 @@ void do_ploop_run_work(struct ploop *ploop)
if (npios) {
/* wait for metadata writeback to complete */
- current->flags = old_flags;
+ current_restore_flags(old_flags, PLOOP_PFLAGS);
/* First wait all pios to be processed */
wait_event_interruptible(ploop->dispatcher_wq_data,
(!ploop_runners_have_pending(ploop)));
- current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
+ current->flags |= PLOOP_PFLAGS;
}
if (llflush_pios || npios) {
/* Now process fsync pios after we have done all other */
npios = process_ploop_fsync_work(ploop, llflush_pios);
/* Since dispatcher is single thread no other work can be queued */
if (npios) {
- current->flags = old_flags;
+ current_restore_flags(old_flags, PLOOP_PFLAGS);
wait_event_interruptible(ploop->dispatcher_wq_fsync,
!atomic_read(&ploop->kt_worker->fsync_pios));
- current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
+ current->flags |= PLOOP_PFLAGS;
}
}
- current->flags = old_flags;
+ current_restore_flags(old_flags, PLOOP_PFLAGS);
}
void do_ploop_work(struct work_struct *ws)
@@ -2253,7 +2254,7 @@ int ploop_allocator(void *data)
if (ploop->prealloc_size) {
__set_current_state(TASK_RUNNING);
file = ploop_top_delta(ploop)->file;
- current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
+ current->flags |= PLOOP_PFLAGS;
ret = ploop_preallocate_cluster(ploop, file);
if (ret) {
/*
@@ -2266,7 +2267,7 @@ int ploop_allocator(void *data)
ploop_device_name(ploop), ret);
}
wake_up_interruptible(&ploop->dispatcher_wq_prealloc);
- current->flags = old_flags;
+ current_restore_flags(old_flags, PLOOP_PFLAGS);
}
if (kthread_should_stop()) {
__set_current_state(TASK_RUNNING);
@@ -2291,7 +2292,7 @@ int ploop_pio_runner(void *data)
int did_process_fsync = 0;
for (;;) {
- current->flags = old_flags;
+ current_restore_flags(old_flags, PLOOP_PFLAGS);
set_current_state(TASK_INTERRUPTIBLE);
check_for_more:
@@ -2314,8 +2315,7 @@ int ploop_pio_runner(void *data)
continue;
}
__set_current_state(TASK_RUNNING);
- old_flags = current->flags;
- current->flags |= PF_IO_THREAD|PF_LOCAL_THROTTLE|PF_MEMALLOC_NOIO;
+ current->flags |= PLOOP_PFLAGS;
llist_for_each_safe(pos, t, llwork) {
pio = list_entry((struct list_head *)pos, typeof(*pio), list);
More information about the Devel
mailing list