Date: Thu, 5 Dec 2019 13:41:22 +0000 (UTC) From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r355415 - head/sys/fs/nullfs Message-ID: <201912051341.xB5DfMdc087836@repo.freebsd.org>
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Author: mjg Date: Thu Dec 5 13:41:22 2019 New Revision: 355415 URL: https://svnweb.freebsd.org/changeset/base/355415 Log: nullfs: locklessly check for entries in null_hashget During random sampling over poudriere -j 104 over 10% of calls returned NULL. Modified: head/sys/fs/nullfs/null_subr.c Modified: head/sys/fs/nullfs/null_subr.c ============================================================================== --- head/sys/fs/nullfs/null_subr.c Thu Dec 5 13:40:10 2019 (r355414) +++ head/sys/fs/nullfs/null_subr.c Thu Dec 5 13:41:22 2019 (r355415) @@ -113,6 +113,8 @@ null_hashget(mp, lowervp) * reference count (but NOT the lower vnode's VREF counter). */ hd = NULL_NHASH(lowervp); + if (LIST_EMPTY(hd)) + return (NULLVP); rw_rlock(&null_hash_lock); LIST_FOREACH(a, hd, null_hash) { if (a->null_lowervp == lowervp && NULLTOV(a)->v_mount == mp) {
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