From: Lars Ellenberg <lars.ellenb...@linbit.com>
A D_FAILED disk transitions as quickly as possible to
D_DISKLESS. But in the "unresponsive local disk" case,
there remains a time window where a administrative detach command could
find the disk already failed, but some internal meta data IO against the
unresponsive local disk still pending.
In that case, drbd_md_get_buffer() will return NULL.
Don't unconditionally call drbd_md_put_buffer(), or it will cause
refcount imbalance, and prevent any further re-attach on this volume
(until it is deleted and re-created).
Signed-off-by: Philipp Reisner <philipp.reis...@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenb...@linbit.com>
---
drivers/block/drbd/drbd_nl.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 7229d8e..4c8d8e7 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1915,6 +1915,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info
*info)
static int adm_detach(struct drbd_device *device, int force)
{
enum drbd_state_rv retcode;
+ void *buffer;
int ret;
if (force) {
@@ -1925,9 +1926,12 @@ static int adm_detach(struct drbd_device *device, int
force)
}
drbd_suspend_io(device); /* so no-one is stuck in drbd_al_begin_io */
- drbd_md_get_buffer(device, __func__); /* make sure there is no
in-flight meta-data IO */
- retcode = drbd_request_state(device, NS(disk, D_FAILED));
- drbd_md_put_buffer(device);
+ buffer = drbd_md_get_buffer(device, __func__); /* make sure there is no
in-flight meta-data IO */
+ if (buffer) {
+ retcode = drbd_request_state(device, NS(disk, D_FAILED));
+ drbd_md_put_buffer(device);
+ } else /* already <= D_FAILED */
+ retcode = SS_NOTHING_TO_DO;
/* D_FAILED will transition to DISKLESS. */
drbd_resume_io(device);
ret = wait_event_interruptible(device->misc_wait,
--
1.9.1
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