Change Details

Previously, an_vnode_lock was initialized with SX_NOWITNESS to silence lock order reversals. The reversals would occur when autofs_node_vn() was called with the directory vnode lock held, then lock an_vnode_lock, then lock the vnode attached to the autofs node. It looked like: directory vnode -> an_vnode_lock -> vnode attached to autofs node The established lock order is now vnode -> an_vnode_lock Currently, we don't have to worry about losing an autofs node during the unlock/lock as autofs nodes are only removed during an unmount() after vflush(). When autofs_node_vn() is called, the mountpoint has either been busied (preventing unmount) or a directory vnode is locked which prevents vflush() from finishing until the directory vnode is unlocked. If all this looks like its going in the right direction, my next change will be to hold am_lock (the lock the protects the autofs node tree), across autofs_node_vn() - which will be step torwards getting autofs ready to handle autofs node removals

Previously, an_vnode_lock was initialized with SX_NOWITNESS to silence lock order reversals. The reversals would occur when autofs_node_vn() was called with the directory vnode lock held, then lock an_vnode_lock, then lock the vnode attached to the autofs node. It looked like: directory vnode -> an_vnode_lock -> vnode attached to autofs node The established lock order is now vnode -> an_vnode_lock Currently, we don't have to worry about losing an autofs node during the unlock/lock as autofs nodes are only removed during an unmount() after vflush(). When autofs_node_vn() is called, the mountpoint has either been busied (preventing unmount) or a directory vnode is locked which prevents vflush() from finishing until the directory vnode is unlocked. If all this looks like its going in the right direction, my next change will be to hold am_lock (the lock the protects the autofs node tree), across autofs_node_vn() - which will be step torwards getting autofs ready to handle autofs node removals

Previously, an_vnode_lock was initialized with SX_NOWITNESS to silence lock order reversals. The reversals would occur when autofs_node_vn() was called with the directory vnode lock held, then lock an_vnode_lock, then lock the vnode attached to the autofs node. It looked like: directory vnode -> an_vnode_lock -> vnode attached to autofs node The established lock order is now vnode -> an_vnode_lock Currently, we don't have to worry about losing an autofs node during the unlock/lock as autofs nodes are only removed during an unmount() after vflush(). When autofs_node_vn() is called, the mountpoint has either been busied (preventing unmount) or a directory vnode is locked which prevents vflush() from finishing until the directory vnode is unlocked. If all this looks like its going in the right direction, my next change will be to hold am_lock (the lock the protects the autofs node tree), across autofs_node_vn() - which will be step torwards getting autofs ready to handle autofs node removals