The branch main has been updated by jah:
URL:
https://cgit.FreeBSD.org/src/commit/?id=f9e28f900353ca8681fa1815afaebaca16ef254b
commit f9e28f900353ca8681fa1815afaebaca16ef254b
Author: Jason A. Harmening <j...@freebsd.org>
AuthorDate: 2021-09-12 05:43:57 +0000
Commit: Jason A. Harmening <j...@freebsd.org>
CommitDate: 2021-09-24 02:20:30 +0000
unionfs: lock newly-created vnodes before calling insmntque()
This fixes an insta-panic when attempting to use unionfs with
DEBUG_VFS_LOCKS. Note that unionfs still has a long way to
go before it's generally stable or usable.
Reviewed by: kib (prior version), markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D31917
---
sys/fs/unionfs/union_subr.c | 86 +++++++++++++++++++++++++++++++++++----------
1 file changed, 68 insertions(+), 18 deletions(-)
diff --git a/sys/fs/unionfs/union_subr.c b/sys/fs/unionfs/union_subr.c
index 5cb27dc94d55..dcdb41e55258 100644
--- a/sys/fs/unionfs/union_subr.c
+++ b/sys/fs/unionfs/union_subr.c
@@ -243,6 +243,49 @@ unionfs_rem_cached_vnode(struct unionfs_node *unp, struct
vnode *dvp)
VI_UNLOCK(dvp);
}
+/*
+ * Common cleanup handling for unionfs_nodeget
+ * Upper, lower, and parent directory vnodes are expected to be referenced by
+ * the caller. Upper and lower vnodes, if non-NULL, are also expected to be
+ * exclusively locked by the caller.
+ * This function will return with the caller's locks and references undone.
+ */
+static void
+unionfs_nodeget_cleanup(struct vnode *vp, void *arg)
+{
+ struct unionfs_node *unp;
+
+ /*
+ * Lock and reset the default vnode lock; vgone() expects a locked
+ * vnode, and we're going to reset the vnode ops.
+ */
+ lockmgr(&vp->v_lock, LK_EXCLUSIVE, NULL);
+
+ /*
+ * Clear out private data and reset the vnode ops to avoid use of
+ * unionfs vnode ops on a partially constructed vnode.
+ */
+ VI_LOCK(vp);
+ vp->v_data = NULL;
+ vp->v_vnlock = &vp->v_lock;
+ vp->v_op = &dead_vnodeops;
+ VI_UNLOCK(vp);
+ vgone(vp);
+ vput(vp);
+
+ unp = arg;
+ if (unp->un_dvp != NULLVP)
+ vrele(unp->un_dvp);
+ if (unp->un_uppervp != NULLVP)
+ vput(unp->un_uppervp);
+ if (unp->un_lowervp != NULLVP)
+ vput(unp->un_lowervp);
+ if (unp->un_hashtbl != NULL)
+ hashdestroy(unp->un_hashtbl, M_UNIONFSHASH, unp->un_hashmask);
+ free(unp->un_path, M_UNIONFSPATH);
+ free(unp, M_UNIONFSNODE);
+}
+
/*
* Make a new or get existing unionfs node.
*
@@ -263,6 +306,7 @@ unionfs_nodeget(struct mount *mp, struct vnode *uppervp,
int lkflags;
enum vtype vt;
+ error = 0;
ump = MOUNTTOUNIONFSMOUNT(mp);
lkflags = (cnp ? cnp->cn_lkflags : 0);
path = (cnp ? cnp->cn_nameptr : NULL);
@@ -301,11 +345,6 @@ unionfs_nodeget(struct mount *mp, struct vnode *uppervp,
free(unp, M_UNIONFSNODE);
return (error);
}
- error = insmntque(vp, mp); /* XXX: Too early for mpsafe fs */
- if (error != 0) {
- free(unp, M_UNIONFSNODE);
- return (error);
- }
if (dvp != NULLVP)
vref(dvp);
if (uppervp != NULLVP)
@@ -340,24 +379,35 @@ unionfs_nodeget(struct mount *mp, struct vnode *uppervp,
(lowervp != NULLVP && ump->um_lowervp == lowervp))
vp->v_vflag |= VV_ROOT;
+ vn_lock_pair(lowervp, false, uppervp, false);
+ error = insmntque1(vp, mp, unionfs_nodeget_cleanup, unp);
+ if (error != 0)
+ return (error);
+ if (lowervp != NULL && VN_IS_DOOMED(lowervp)) {
+ vput(lowervp);
+ unp->un_lowervp = NULL;
+ }
+ if (uppervp != NULL && VN_IS_DOOMED(uppervp)) {
+ vput(uppervp);
+ unp->un_uppervp = NULL;
+ }
+ if (unp->un_lowervp == NULL && unp->un_uppervp == NULL) {
+ unionfs_nodeget_cleanup(vp, unp);
+ return (ENOENT);
+ }
if (path != NULL && dvp != NULLVP && vt == VDIR)
*vpp = unionfs_ins_cached_vnode(unp, dvp, path);
- if ((*vpp) != NULLVP) {
- if (dvp != NULLVP)
- vrele(dvp);
- if (uppervp != NULLVP)
- vrele(uppervp);
- if (lowervp != NULLVP)
- vrele(lowervp);
-
- unp->un_uppervp = NULLVP;
- unp->un_lowervp = NULLVP;
- unp->un_dvp = NULLVP;
- vrele(vp);
+ if (*vpp != NULLVP) {
+ unionfs_nodeget_cleanup(vp, unp);
vp = *vpp;
vref(vp);
- } else
+ } else {
+ if (uppervp != NULL)
+ VOP_UNLOCK(uppervp);
+ if (lowervp != NULL)
+ VOP_UNLOCK(lowervp);
*vpp = vp;
+ }
unionfs_nodeget_out:
if (lkflags & LK_TYPE_MASK)
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