zvol: Fix suspend lock leaks (openzfs#16270)

In several functions, we use a flag variable to track whether zv_suspend_lock is held. This flag was not getting reset in a particular case where we need to retry the underlying operation, resulting in a lock leak. Make sure to update the flag where necessary. Signed-off-by: Mark Johnston <[email protected]> Reviewed-by: Allan Jude <[email protected]> Reviewed-by: Alexander Motin <[email protected]> Reviewed-by: Tino Reichardt <[email protected]> Reviewed-by: Tony Hutter <[email protected]>
geppi · Jul 10, 2024 · 4367312 · 4367312
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commit 4367312
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diff --git a/module/os/freebsd/zfs/zvol_os.c b/module/os/freebsd/zfs/zvol_os.c
@@ -292,6 +292,7 @@ zvol_geom_open(struct g_provider *pp, int flag, int count)
 			if (!mutex_tryenter(&spa_namespace_lock)) {
 				mutex_exit(&zv->zv_state_lock);
 				rw_exit(&zv->zv_suspend_lock);
+				drop_suspend = B_FALSE;
 				kern_yield(PRI_USER);
 				goto retry;
 			} else {
@@ -983,6 +984,7 @@ zvol_cdev_open(struct cdev *dev, int flags, int fmt, struct thread *td)
 			if (!mutex_tryenter(&spa_namespace_lock)) {
 				mutex_exit(&zv->zv_state_lock);
 				rw_exit(&zv->zv_suspend_lock);
+				drop_suspend = B_FALSE;
 				kern_yield(PRI_USER);
 				goto retry;
 			} else {

diff --git a/module/os/linux/zfs/zvol_os.c b/module/os/linux/zfs/zvol_os.c
@@ -791,6 +791,7 @@ zvol_open(struct block_device *bdev, fmode_t flag)
 			if (!mutex_tryenter(&spa_namespace_lock)) {
 				mutex_exit(&zv->zv_state_lock);
 				rw_exit(&zv->zv_suspend_lock);
+				drop_suspend = B_FALSE;
 
 #ifdef HAVE_BLKDEV_GET_ERESTARTSYS
 				schedule();