Author: mjg
Date: Tue May 16 19:35:25 2017
New Revision: 318367
URL: https://svnweb.freebsd.org/changeset/base/318367

Log:
  MFC r317784:
  
  cache: stop holding the ncneg_hot lock across purging
  
  Only non-hot entries are purged so the lock is not needed in the first place.
  This saves one lock/unlock pair.

Modified:
  stable/11/sys/kern/vfs_cache.c

Modified: stable/11/sys/kern/vfs_cache.c
==============================================================================
--- stable/11/sys/kern/vfs_cache.c      Tue May 16 19:03:26 2017        
(r318366)
+++ stable/11/sys/kern/vfs_cache.c      Tue May 16 19:35:25 2017        
(r318367)
@@ -735,13 +735,12 @@ cache_negative_remove(struct namecache *
                        list_locked = true;
                        mtx_lock(&neglist->nl_lock);
                }
-       } else {
-               mtx_assert(&neglist->nl_lock, MA_OWNED);
-               mtx_assert(&ncneg_hot.nl_lock, MA_OWNED);
        }
        if (ncp->nc_flag & NCF_HOTNEGATIVE) {
+               mtx_assert(&ncneg_hot.nl_lock, MA_OWNED);
                TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst);
        } else {
+               mtx_assert(&neglist->nl_lock, MA_OWNED);
                TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst);
        }
        if (list_locked)
@@ -816,7 +815,6 @@ cache_negative_zap_one(void)
        mtx_unlock(&ncneg_hot.nl_lock);
        mtx_lock(dvlp);
        rw_wlock(blp);
-       mtx_lock(&ncneg_hot.nl_lock);
        mtx_lock(&neglist->nl_lock);
        ncp2 = TAILQ_FIRST(&neglist->nl_list);
        if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) ||
@@ -830,7 +828,6 @@ cache_negative_zap_one(void)
        cache_zap_locked(ncp, true);
 out_unlock_all:
        mtx_unlock(&neglist->nl_lock);
-       mtx_unlock(&ncneg_hot.nl_lock);
        rw_wunlock(blp);
        mtx_unlock(dvlp);
 out:
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