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authorPhilipp Reisner <philipp.reisner@linbit.com>2013-02-28 10:30:19 +0100
committerJens Axboe <axboe@fb.com>2015-11-25 09:22:03 -0700
commit7dbb4386b90a13a7b0cab12aae184e5e04c536c3 (patch)
tree6a2d4915247505c314e8b3cceb2e1eeb45980cba
parentf85d9f2d02cdcd1b79e00fccd667b37b251ba3ac (diff)
drbd: make suspend_io() / resume_io() must be thread and recursion safe
Avoid to prematurely resume application IO: don't set/clear a single bit, but inc/dec an atomic counter. Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com> Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com> Signed-off-by: Jens Axboe <axboe@fb.com>
-rw-r--r--drivers/block/drbd/drbd_int.h4
-rw-r--r--drivers/block/drbd/drbd_nl.c8
-rw-r--r--drivers/block/drbd/drbd_state.c2
3 files changed, 8 insertions, 6 deletions
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index a26265375e1e..df3d89d5777a 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -500,7 +500,6 @@ enum {
MD_NO_FUA, /* Users wants us to not use FUA/FLUSH on meta data dev */
- SUSPEND_IO, /* suspend application io */
BITMAP_IO, /* suspend application io;
once no more io in flight, start bitmap io */
BITMAP_IO_QUEUED, /* Started bitmap IO */
@@ -880,6 +879,7 @@ struct drbd_device {
atomic_t rs_pending_cnt; /* RS request/data packets on the wire */
atomic_t unacked_cnt; /* Need to send replies for */
atomic_t local_cnt; /* Waiting for local completion */
+ atomic_t suspend_cnt;
/* Interval tree of pending local requests */
struct rb_root read_requests;
@@ -2263,7 +2263,7 @@ static inline bool may_inc_ap_bio(struct drbd_device *device)
if (drbd_suspended(device))
return false;
- if (test_bit(SUSPEND_IO, &device->flags))
+ if (atomic_read(&device->suspend_cnt))
return false;
/* to avoid potential deadlock or bitmap corruption,
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 613778994b23..c7cd3df8107e 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -865,9 +865,11 @@ char *ppsize(char *buf, unsigned long long size)
* and can be long lived.
* This changes an device->flag, is triggered by drbd internals,
* and should be short-lived. */
+/* It needs to be a counter, since multiple threads might
+ independently suspend and resume IO. */
void drbd_suspend_io(struct drbd_device *device)
{
- set_bit(SUSPEND_IO, &device->flags);
+ atomic_inc(&device->suspend_cnt);
if (drbd_suspended(device))
return;
wait_event(device->misc_wait, !atomic_read(&device->ap_bio_cnt));
@@ -875,8 +877,8 @@ void drbd_suspend_io(struct drbd_device *device)
void drbd_resume_io(struct drbd_device *device)
{
- clear_bit(SUSPEND_IO, &device->flags);
- wake_up(&device->misc_wait);
+ if (atomic_dec_and_test(&device->suspend_cnt))
+ wake_up(&device->misc_wait);
}
/**
diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c
index f022e99f9855..5a7ef7873b67 100644
--- a/drivers/block/drbd/drbd_state.c
+++ b/drivers/block/drbd/drbd_state.c
@@ -1484,7 +1484,7 @@ int drbd_bitmap_io_from_worker(struct drbd_device *device,
D_ASSERT(device, current == first_peer_device(device)->connection->worker.task);
/* open coded non-blocking drbd_suspend_io(device); */
- set_bit(SUSPEND_IO, &device->flags);
+ atomic_inc(&device->suspend_cnt);
drbd_bm_lock(device, why, flags);
rv = io_fn(device);