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rbd: prevent busy loop when requesting exclusive lock

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commit 9d01e07fd1 upstream.

Due to rbd_try_acquire_lock() effectively swallowing all but
EBLOCKLISTED error from rbd_try_lock() ("request lock anyway") and
rbd_request_lock() returning ETIMEDOUT error not only for an actual
notify timeout but also when the lock owner doesn't respond, a busy
loop inside of rbd_acquire_lock() between rbd_try_acquire_lock() and
rbd_request_lock() is possible.

Requesting the lock on EBUSY error (returned by get_lock_owner_info()
if an incompatible lock or invalid lock owner is detected) makes very
little sense.  The same goes for ETIMEDOUT error (might pop up pretty
much anywhere if osd_request_timeout option is set) and many others.

Just fail I/O requests on rbd_dev->acquiring_list immediately on any
error from rbd_try_lock().

Cc: stable@vger.kernel.org # 588159009d: rbd: retrieve and check lock owner twice before blocklisting
Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ilya Dryomov 2023-08-01 19:14:24 +02:00 • committed by Justin Hammond
parent 3cb2060049
commit c2ae3f7e0b
1 changed files with 15 additions and 13 deletions
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28
drivers/block/rbd.c
View file

@ -3677,7 +3677,7 @@ static int rbd_lock(struct rbd_device *rbd_dev)
ret = ceph_cls_lock(osdc, &rbd_dev->header_oid, &rbd_dev->header_oloc,
RBD_LOCK_NAME, CEPH_CLS_LOCK_EXCLUSIVE, cookie,
RBD_LOCK_TAG, "", 0);
if (ret)
if (ret && ret != -EEXIST)
return ret;
__rbd_lock(rbd_dev, cookie);
@ -3880,7 +3880,7 @@ static struct ceph_locker *get_lock_owner_info(struct rbd_device *rbd_dev)
&rbd_dev->header_oloc, RBD_LOCK_NAME,
&lock_type, &lock_tag, &lockers, &num_lockers);
if (ret) {
rbd_warn(rbd_dev, "failed to retrieve lockers: %d", ret);
rbd_warn(rbd_dev, "failed to get header lockers: %d", ret);
return ERR_PTR(ret);
}
@ -3942,8 +3942,10 @@ static int find_watcher(struct rbd_device *rbd_dev,
ret = ceph_osdc_list_watchers(osdc, &rbd_dev->header_oid,
&rbd_dev->header_oloc, &watchers,
&num_watchers);
if (ret)
if (ret) {
rbd_warn(rbd_dev, "failed to get watchers: %d", ret);
return ret;
}
sscanf(locker->id.cookie, RBD_LOCK_COOKIE_PREFIX " %llu", &cookie);
for (i = 0; i < num_watchers; i++) {
@ -3987,8 +3989,12 @@ static int rbd_try_lock(struct rbd_device *rbd_dev)
locker = refreshed_locker = NULL;
ret = rbd_lock(rbd_dev);
if (ret != -EBUSY)
if (!ret)
goto out;
if (ret != -EBUSY) {
rbd_warn(rbd_dev, "failed to lock header: %d", ret);
goto out;
}
/* determine if the current lock holder is still alive */
locker = get_lock_owner_info(rbd_dev);
@ -4091,11 +4097,8 @@ static int rbd_try_acquire_lock(struct rbd_device *rbd_dev)
ret = rbd_try_lock(rbd_dev);
if (ret < 0) {
rbd_warn(rbd_dev, "failed to lock header: %d", ret);
if (ret == -EBLOCKLISTED)
goto out;
ret = 1; /* request lock anyway */
rbd_warn(rbd_dev, "failed to acquire lock: %d", ret);
goto out;
}
if (ret > 0) {
up_write(&rbd_dev->lock_rwsem);
@ -6631,12 +6634,11 @@ static int rbd_add_acquire_lock(struct rbd_device *rbd_dev)
cancel_delayed_work_sync(&rbd_dev->lock_dwork);
if (!ret)
ret = -ETIMEDOUT;
}
if (ret) {
rbd_warn(rbd_dev, "failed to acquire exclusive lock: %ld", ret);
return ret;
rbd_warn(rbd_dev, "failed to acquire lock: %ld", ret);
}
if (ret)
return ret;
/*
* The lock may have been released by now, unless automatic lock