git: 0ef41997b3c7 - stable/13 - cache: remove incomplete lockless lockout support during resize

[Mateusz Guzik]

The branch stable/13 has been updated by mjg:

URL: https://cgit.FreeBSD.org/src/commit/?id=0ef41997b3c740dc5369b1dfac82ac107fe7d707

commit 0ef41997b3c740dc5369b1dfac82ac107fe7d707
Author:     Mateusz Guzik <mjg at FreeBSD.org>
AuthorDate: 2021-04-10 17:20:28 +0000
Commit:     Mateusz Guzik <mjg at FreeBSD.org>
CommitDate: 2021-05-22 18:21:39 +0000

    cache: remove incomplete lockless lockout support during resize
    
    This is already properly handled thanks to 2 step hash replacement.
    
    (cherry picked from commit 074abaccfaadef0da6e2695225ce537cb53bb8de)
---
 sys/kern/vfs_cache.c | 32 --------------------------------
 1 file changed, 32 deletions(-)

diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c
index ec5bb0c39c99..2def9900096f 100644
--- a/sys/kern/vfs_cache.c
+++ b/sys/kern/vfs_cache.c
@@ -580,9 +580,6 @@ static long cache_lock_vnodes_cel_3_failures;
 DEBUGNODE_ULONG(vnodes_cel_3_failures, cache_lock_vnodes_cel_3_failures,
     "Number of times 3-way vnode locking failed");
 
-static void cache_fplookup_lockout(void);
-static void cache_fplookup_restore(void);
-
 static void cache_zap_locked(struct namecache *ncp);
 static int vn_fullpath_hardlink(struct nameidata *ndp, char **retbuf,
     char **freebuf, size_t *buflen);
@@ -2771,7 +2768,6 @@ cache_changesize(u_long newmaxvnodes)
 	 * None of the namecache entries in the table can be removed
 	 * because to do so, they have to be removed from the hash table.
 	 */
-	cache_fplookup_lockout();
 	cache_lock_all_vnodes();
 	cache_lock_all_buckets();
 	old_nchashtbl = nchashtbl;
@@ -2790,7 +2786,6 @@ cache_changesize(u_long newmaxvnodes)
 	cache_changesize_set_new(new_nchashtbl, new_nchash);
 	cache_unlock_all_buckets();
 	cache_unlock_all_vnodes();
-	cache_fplookup_restore();
 	ncfreetbl(old_nchashtbl);
 	ncfreetbl(temptbl);
 }
@@ -3865,33 +3860,6 @@ syscal_vfs_cache_fast_lookup(SYSCTL_HANDLER_ARGS)
 SYSCTL_PROC(_vfs, OID_AUTO, cache_fast_lookup, CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MPSAFE,
     &cache_fast_lookup, 0, syscal_vfs_cache_fast_lookup, "IU", "");
 
-/*
- * Disable lockless lookup and observe all CPUs not executing it.
- *
- * Used when resizing the hash table.
- *
- * TODO: no provisions are made to handle tweaking of the knob at the same time
- */
-static void
-cache_fplookup_lockout(void)
-{
-	bool on;
-
-	on = atomic_load_char(&cache_fast_lookup_enabled);
-	if (on) {
-		atomic_store_char(&cache_fast_lookup_enabled, false);
-		atomic_thread_fence_rel();
-		vfs_smr_synchronize();
-	}
-}
-
-static void
-cache_fplookup_restore(void)
-{
-
-	cache_fast_lookup_enabled_recalc();
-}
-
 /*
  * Components of nameidata (or objects it can point to) which may
  * need restoring in case fast path lookup fails.