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authorLars Ellenberg <lars@linbit.com>2014-04-28 18:43:26 +0200
committerJens Axboe <axboe@fb.com>2014-04-30 13:46:55 -0600
commit074f4afeb2277bd5ecb9fa7f91eaffa55e262126 (patch)
tree3fc09287b0094b8e2fd19c09c9b70e85135a35eb /drivers/block/drbd/drbd_worker.c
parent20c68fdea1646ed746abf19122d7699493927005 (diff)
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drbd: fix a race between start_resync and send_and_submit
In the drbd make request function, specifically in drbd_send_and_submit(), we decide whether we want to send the actual write request, or only a "set this block out of sync" information. We do so based on the current connection state, while holding the req_lock. The connection state is not supposed to change while holding the req_lock. But in drbd_start_resync, we did change that state anyways, while only holding the global_state_lock, which is enough to change sync-after dependencies (paused vs active resync), but not good enough to change the connection state. Fix: in drbd_start_resync, first grab the req_lock to serialize with drbd_send_and_submit(), before grabbing the global_state_lock to be able to evaluate the sync-after dependencies. 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>
Diffstat (limited to 'drivers/block/drbd/drbd_worker.c')
-rw-r--r--drivers/block/drbd/drbd_worker.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index 26338bedb25b..34dde10fae48 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -1686,11 +1686,15 @@ void drbd_start_resync(struct drbd_device *device, enum drbd_conns side)
}
clear_bit(B_RS_H_DONE, &device->flags);
- write_lock_irq(&global_state_lock);
+ /* req_lock: serialize with drbd_send_and_submit() and others
+ * global_state_lock: for stable sync-after dependencies */
+ spin_lock_irq(&device->resource->req_lock);
+ write_lock(&global_state_lock);
/* Did some connection breakage or IO error race with us? */
if (device->state.conn < C_CONNECTED
|| !get_ldev_if_state(device, D_NEGOTIATING)) {
- write_unlock_irq(&global_state_lock);
+ write_unlock(&global_state_lock);
+ spin_unlock_irq(&device->resource->req_lock);
mutex_unlock(device->state_mutex);
return;
}
@@ -1730,7 +1734,8 @@ void drbd_start_resync(struct drbd_device *device, enum drbd_conns side)
}
_drbd_pause_after(device);
}
- write_unlock_irq(&global_state_lock);
+ write_unlock(&global_state_lock);
+ spin_unlock_irq(&device->resource->req_lock);
if (r == SS_SUCCESS) {
/* reset rs_last_bcast when a resync or verify is started,