[Devel] [PATCH vz9 v1 63/63] dm-ploop: fix how current flags are managed inside threads

[Alexander Atanasov]

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>
---
 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);
-- 
2.43.0