File 0018-drbd-rework-autopromote.patch of Package drbd.36406
From e3ef0e229a6ae88346164d1507697ae1b397cdf9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Moritz=20=22WanzenBug=22=20Wanzenb=C3=B6ck?=
<moritz.wanzenboeck@linbit.com>
Date: Tue, 12 Sep 2023 10:17:08 +0200
Subject: [PATCH 18/20] drbd: rework autopromote
With upstream commit ae220766d87c we lost the ability to keep separate
counts for RW and RO openers. Instead, we keep track of openers using a
single count, and a flag indicating if the device was opened RW once.
Once a device was opened RW, it will stay "writable" for DRBD, until all
openers are gone. This should offer a good compromise between keeping
the old auto-promote behaviour, and the changed device interface.
---
drbd/drbd_int.h | 3 ++-
drbd/drbd_main.c | 38 +++++++++++++++++++++-----------------
drbd/drbd_nl.c | 9 +++++----
drbd/drbd_state.c | 7 ++++---
4 files changed, 32 insertions(+), 25 deletions(-)
diff --git a/drbd/drbd_int.h b/drbd/drbd_int.h
index b705f26e71a4..cf593c09cda1 100644
--- a/drbd/drbd_int.h
+++ b/drbd/drbd_int.h
@@ -1399,7 +1399,8 @@ struct drbd_device {
struct drbd_bitmap *bitmap;
- int open_rw_cnt, open_ro_cnt;
+ int open_cnt;
+ bool writable;
/* FIXME clean comments, restructure so it is more obvious which
* members are protected by what */
diff --git a/drbd/drbd_main.c b/drbd/drbd_main.c
index 4b0b967c2c97..bb05b2215dfb 100644
--- a/drbd/drbd_main.c
+++ b/drbd/drbd_main.c
@@ -2579,10 +2579,9 @@ static enum ioc_rv inc_open_count(struct drbd_device *device, fmode_t mode)
r = IOC_ABORT;
else if (!resource->remote_state_change) {
r = IOC_OK;
+ device->open_cnt++;
if (mode & FMODE_WRITE)
- device->open_rw_cnt++;
- else
- device->open_ro_cnt++;
+ device->writable = true;
}
read_unlock_irq(&resource->state_rwlock);
@@ -2756,8 +2755,10 @@ void drbd_open_counts(struct drbd_resource *resource, int *rw_count_ptr, int *ro
rcu_read_lock();
idr_for_each_entry(&resource->devices, device, vnr) {
- rw_count += device->open_rw_cnt;
- ro_count += device->open_ro_cnt;
+ if (device->writable)
+ rw_count += device->open_cnt;
+ else
+ ro_count += device->open_cnt;
}
rcu_read_unlock();
*rw_count_ptr = rw_count;
@@ -2825,33 +2826,35 @@ static void drbd_release(struct gendisk *gd, fmode_t mode)
{
struct drbd_device *device = gd->private_data;
struct drbd_resource *resource = device->resource;
+ bool was_writable = device->writable;
int open_rw_cnt, open_ro_cnt;
mutex_lock(&resource->open_release);
- if (mode & FMODE_WRITE)
- device->open_rw_cnt--;
- else
- device->open_ro_cnt--;
+ device->open_cnt--;
drbd_open_counts(resource, &open_rw_cnt, &open_ro_cnt);
- /* last one to close will be responsible for write-out of all dirty pages */
- if (mode & FMODE_WRITE && device->open_rw_cnt == 0)
+ /* last one to close will be responsible for write-out of all dirty pages.
+ * We also reset the writable flag for this device here: later code may
+ * check if the device is still opened for writes to determine things
+ * like auto-demote.
+ */
+ if (was_writable && device->open_cnt == 0) {
drbd_fsync_device(device);
+ device->writable = false;
+ }
if (open_ro_cnt == 0)
wake_up_all(&resource->state_wait);
- if (test_bit(UNREGISTERED, &device->flags) &&
- device->open_rw_cnt == 0 && device->open_ro_cnt == 0 &&
+ if (test_bit(UNREGISTERED, &device->flags) && device->open_cnt == 0 &&
!test_and_set_bit(DESTROYING_DEV, &device->flags))
call_rcu(&device->rcu, drbd_reclaim_device);
if (resource->res_opts.auto_promote) {
enum drbd_state_rv rv;
- if (mode & FMODE_WRITE &&
- open_rw_cnt == 0 &&
+ if (was_writable && open_rw_cnt == 0 &&
resource->role[NOW] == R_PRIMARY &&
!test_bit(EXPLICIT_PRIMARY, &resource->flags)) {
rv = drbd_set_role(resource, R_SECONDARY, false, "auto-demote", NULL);
@@ -2869,9 +2872,10 @@ static void drbd_release(struct gendisk *gd, fmode_t mode)
end_state_change(resource, &irq_flags, "release");
}
- /* if the open counts are 0, we free the whole list, otherwise we remove the specific pid */
+ /* if the open count is 0, we free the whole list, otherwise we remove the specific pid */
prune_or_free_openers(device,
- (open_ro_cnt == 0 && open_rw_cnt == 0) ? 0 : task_pid_nr(current));
+ (open_ro_cnt == 0 && open_rw_cnt == 0) ?
+ 0 : task_pid_nr(current));
mutex_unlock(&resource->open_release);
diff --git a/drbd/drbd_nl.c b/drbd/drbd_nl.c
index b0a1e6fa46f1..71ed4272614e 100644
--- a/drbd/drbd_nl.c
+++ b/drbd/drbd_nl.c
@@ -4541,8 +4541,10 @@ int drbd_open_ro_count(struct drbd_resource *resource)
int vnr, open_ro_cnt = 0;
read_lock_irq(&resource->state_rwlock);
- idr_for_each_entry(&resource->devices, device, vnr)
- open_ro_cnt += device->open_ro_cnt;
+ idr_for_each_entry(&resource->devices, device, vnr) {
+ if (!device->writable)
+ open_ro_cnt += device->open_cnt;
+ }
read_unlock_irq(&resource->state_rwlock);
return open_ro_cnt;
@@ -6394,8 +6396,7 @@ static enum drbd_ret_code adm_del_minor(struct drbd_device *device)
notify_device_state(NULL, 0, device, NULL, NOTIFY_DESTROY);
mutex_unlock(¬ification_mutex);
- if (device->open_ro_cnt == 0 && device->open_rw_cnt == 0 &&
- !test_and_set_bit(DESTROYING_DEV, &device->flags))
+ if (device->open_cnt == 0 && !test_and_set_bit(DESTROYING_DEV, &device->flags))
call_rcu(&device->rcu, drbd_reclaim_device);
return ret;
diff --git a/drbd/drbd_state.c b/drbd/drbd_state.c
index 22cd134be962..fa70507df425 100644
--- a/drbd/drbd_state.c
+++ b/drbd/drbd_state.c
@@ -1634,7 +1634,7 @@ handshake_found:
return SS_TWO_PRIMARIES;
if (!fail_io[NEW]) {
idr_for_each_entry(&resource->devices, device, vnr) {
- if (device->open_ro_cnt)
+ if (!device->writable && device->open_cnt)
return SS_PRIMARY_READER;
/*
* One might be tempted to add "|| open_rw_cont" here.
@@ -1661,7 +1661,7 @@ handshake_found:
(disk_state[OLD] > D_DETACHING && disk_state[NEW] == D_DETACHING)))
return SS_IN_TRANSIENT_STATE;
- if (role[OLD] == R_PRIMARY && role[NEW] == R_SECONDARY && device->open_rw_cnt &&
+ if (role[OLD] == R_PRIMARY && role[NEW] == R_SECONDARY && device->writable &&
!(resource->state_change_flags & CS_FS_IGN_OPENERS))
return SS_DEVICE_IN_USE;
@@ -1693,7 +1693,8 @@ handshake_found:
return SS_NO_UP_TO_DATE_DISK;
/* Prevent detach or disconnect while held open read only */
- if (device->open_ro_cnt && any_disk_up_to_date[OLD] && !any_disk_up_to_date[NEW])
+ if (!device->writable && device->open_cnt &&
+ any_disk_up_to_date[OLD] && !any_disk_up_to_date[NEW])
return SS_NO_UP_TO_DATE_DISK;
if (disk_state[NEW] == D_NEGOTIATING)
--
2.35.3
