The branch stable/13 has been updated by mjg:
URL:
https://cgit.FreeBSD.org/src/commit/?id=b3e8bfd771b4b172a4f3619da25b79459e46ba41
commit b3e8bfd771b4b172a4f3619da25b79459e46ba41
Author: Mateusz Guzik <m...@freebsd.org>
AuthorDate: 2021-05-11 03:48:08 +0000
Commit: Mateusz Guzik <m...@freebsd.org>
CommitDate: 2021-05-19 15:53:34 +0000
cache: fix lockless absolute symlink traversal to non-fp mounts
Said lookups would incorrectly fail with EOPNOTSUP.
Reported by: kib
(cherry picked from commit 12288bd999ca3a493b8dc4cba109e5a8fa838c45)
---
sys/kern/vfs_cache.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c
index 8819ef483af5..31d6668a3565 100644
--- a/sys/kern/vfs_cache.c
+++ b/sys/kern/vfs_cache.c
@@ -3936,6 +3936,7 @@ struct cache_fpl {
#endif
};
+static bool cache_fplookup_mp_supported(struct mount *mp);
static bool cache_fplookup_is_mp(struct cache_fpl *fpl);
static int cache_fplookup_cross_mount(struct cache_fpl *fpl);
static int cache_fplookup_partial_setup(struct cache_fpl *fpl);
@@ -5174,6 +5175,19 @@ cache_fplookup_symlink(struct cache_fpl *fpl)
if (seqc_in_modify(fpl->dvp_seqc)) {
return (cache_fpl_aborted(fpl));
}
+ /*
+ * The main loop assumes that ->dvp points to a vnode belonging
+ * to a filesystem which can do lockless lookup, but the
absolute
+ * symlink can be wandering off to one which does not.
+ */
+ mp = atomic_load_ptr(&fpl->dvp->v_mount);
+ if (__predict_false(mp == NULL)) {
+ return (cache_fpl_aborted(fpl));
+ }
+ if (!cache_fplookup_mp_supported(mp)) {
+ cache_fpl_checkpoint(fpl);
+ return (cache_fpl_partial(fpl));
+ }
}
return (0);
}
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