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unionfs: lock newly-created vnodes before calling insmntque()

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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
This commit is contained in:
Jason A. Harmening 2021-09-11 22:43:57 -07:00
parent 0321a7990b
commit f9e28f9003
1 changed files with 68 additions and 18 deletions
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86
sys/fs/unionfs/union_subr.c
View File

@ -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)