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authorMateusz Guzik <mjg@FreeBSD.org>2021-04-15 07:54:18 +0000
committerMateusz Guzik <mjg@FreeBSD.org>2021-04-21 15:25:32 +0000
commit9c651561a2a31fcb08390d37947afc27ec03d87b (patch)
tree9a74783d28170864cb2a3c904a64103cd95b08ec
parent54f98c4dbf9b1203a4e3e1b13fd0738441226991 (diff)
downloadsrc-9c651561a2a31fcb08390d37947afc27ec03d87b.tar.gz
src-9c651561a2a31fcb08390d37947afc27ec03d87b.zip
zfs: damage control racing .. lookups in face of mkdir/rmdir
Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D29769
-rw-r--r--sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
index 8172916c4329..a1e9c359b893 100644
--- a/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
+++ b/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c
@@ -781,6 +781,7 @@ zfs_lookup(vnode_t *dvp, const char *nm, vnode_t **vpp,
znode_t *zdp = VTOZ(dvp);
znode_t *zp;
zfsvfs_t *zfsvfs = zdp->z_zfsvfs;
+ seqc_t dvp_seqc;
int error = 0;
/*
@@ -806,6 +807,8 @@ zfs_lookup(vnode_t *dvp, const char *nm, vnode_t **vpp,
ZFS_ENTER(zfsvfs);
ZFS_VERIFY_ZP(zdp);
+ dvp_seqc = vn_seqc_read_any(dvp);
+
*vpp = NULL;
if (flags & LOOKUP_XATTR) {
@@ -975,6 +978,24 @@ zfs_lookup(vnode_t *dvp, const char *nm, vnode_t **vpp,
}
}
+ if ((cnp->cn_flags & ISDOTDOT) != 0) {
+ /*
+ * FIXME: zfs_lookup_lock relocks vnodes and does nothing to
+ * handle races. In particular different callers may end up
+ * with different vnodes and will try to add conflicting
+ * entries to the namecache.
+ *
+ * While finding different result may be acceptable in face
+ * of concurrent modification, adding conflicting entries
+ * trips over an assert in the namecache.
+ *
+ * Ultimately let an entry through once everything settles.
+ */
+ if (!vn_seqc_consistent(dvp, dvp_seqc)) {
+ cnp->cn_flags &= ~MAKEENTRY;
+ }
+ }
+
/* Insert name into cache (as non-existent) if appropriate. */
if (zfsvfs->z_use_namecache && !zfsvfs->z_replay &&
error == ENOENT && (cnp->cn_flags & MAKEENTRY) != 0)