Author: mjg
Date: Fri Oct 9 19:10:00 2020
New Revision: 366582
URL: https://svnweb.freebsd.org/changeset/base/366582
Log:
cache: fix vexec panic when racing against vgone
Use of dead_vnodeops would result in a panic instead of returning the intended
EOPNOTSUPP error.
While here make sure to abort, not just try to return a partial result.
The former allows the regular lookup to restart from scratch, while the latter
makes it stuck with an unusable vnode.
Reported by: kevans
Modified:
head/sys/fs/deadfs/dead_vnops.c
head/sys/kern/vfs_cache.c
Modified: head/sys/fs/deadfs/dead_vnops.c
==============================================================================
--- head/sys/fs/deadfs/dead_vnops.c Fri Oct 9 18:30:49 2020
(r366581)
+++ head/sys/fs/deadfs/dead_vnops.c Fri Oct 9 19:10:00 2020
(r366582)
@@ -79,6 +79,7 @@ struct vop_vector dead_vnodeops = {
.vop_vptocnp = VOP_EBADF,
.vop_unset_text = dead_unset_text,
.vop_write = dead_write,
+ .vop_fplookup_vexec = VOP_EOPNOTSUPP,
};
VFS_VOP_VECTOR_REGISTER(dead_vnodeops);
Modified: head/sys/kern/vfs_cache.c
==============================================================================
--- head/sys/kern/vfs_cache.c Fri Oct 9 18:30:49 2020 (r366581)
+++ head/sys/kern/vfs_cache.c Fri Oct 9 19:10:00 2020 (r366582)
@@ -4040,32 +4040,46 @@ cache_fplookup_parse_advance(struct cache_fpl *fpl)
}
}
+/*
+ * See the API contract for VOP_FPLOOKUP_VEXEC.
+ */
static int __noinline
cache_fplookup_failed_vexec(struct cache_fpl *fpl, int error)
{
+ struct vnode *dvp;
+ seqc_t dvp_seqc;
+ dvp = fpl->dvp;
+ dvp_seqc = fpl->dvp_seqc;
+
/*
* Hack: they may be looking up foo/bar, where foo is a
* regular file. In such a case we need to turn ENOTDIR,
* but we may happen to get here with a different error.
*/
- if (fpl->dvp->v_type != VDIR) {
+ if (dvp->v_type != VDIR) {
+ /*
+ * The check here is predominantly to catch
+ * EOPNOTSUPP from dead_vnodeops. If the vnode
+ * gets doomed past this point it is going to
+ * fail seqc verification.
+ */
+ if (VN_IS_DOOMED(dvp)) {
+ return (cache_fpl_aborted(fpl));
+ }
error = ENOTDIR;
}
switch (error) {
case EAGAIN:
- /*
- * Can happen when racing against vgone.
- * */
- case EOPNOTSUPP:
- cache_fpl_partial(fpl);
+ if (!vn_seqc_consistent(dvp, dvp_seqc)) {
+ error = cache_fpl_aborted(fpl);
+ } else {
+ cache_fpl_partial(fpl);
+ }
break;
default:
- /*
- * See the API contract for VOP_FPLOOKUP_VEXEC.
- */
- if (!vn_seqc_consistent(fpl->dvp, fpl->dvp_seqc)) {
+ if (!vn_seqc_consistent(dvp, dvp_seqc)) {
error = cache_fpl_aborted(fpl);
} else {
cache_fpl_smr_exit(fpl);
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