Date: Tue, 4 Aug 2020 19:54:11 +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: r363856 - in head/sys: kern sys Message-ID: <202008041954.074JsBEP009762@repo.freebsd.org>
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Author: mjg Date: Tue Aug 4 19:54:10 2020 New Revision: 363856 URL: https://svnweb.freebsd.org/changeset/base/363856 Log: vfs: add vfs_op_thread_enter/exit _crit variants and employ them in the namecache. Eliminates all spurious checks for preemption. Modified: head/sys/kern/vfs_cache.c head/sys/sys/mount.h Modified: head/sys/kern/vfs_cache.c ============================================================================== --- head/sys/kern/vfs_cache.c Tue Aug 4 19:52:52 2020 (r363855) +++ head/sys/kern/vfs_cache.c Tue Aug 4 19:54:10 2020 (r363856) @@ -3484,29 +3484,29 @@ cache_fplookup_climb_mount(struct cache_fpl *fpl) prev_mp = NULL; for (;;) { - if (!vfs_op_thread_enter(mp)) { + if (!vfs_op_thread_enter_crit(mp)) { if (prev_mp != NULL) - vfs_op_thread_exit(prev_mp); + vfs_op_thread_exit_crit(prev_mp); return (cache_fpl_partial(fpl)); } if (prev_mp != NULL) - vfs_op_thread_exit(prev_mp); + vfs_op_thread_exit_crit(prev_mp); if (!vn_seqc_consistent(vp, vp_seqc)) { - vfs_op_thread_exit(mp); + vfs_op_thread_exit_crit(mp); return (cache_fpl_partial(fpl)); } if (!cache_fplookup_mp_supported(mp)) { - vfs_op_thread_exit(mp); + vfs_op_thread_exit_crit(mp); return (cache_fpl_partial(fpl)); } vp = atomic_load_ptr(&mp->mnt_rootvnode); if (vp == NULL || VN_IS_DOOMED(vp)) { - vfs_op_thread_exit(mp); + vfs_op_thread_exit_crit(mp); return (cache_fpl_partial(fpl)); } vp_seqc = vn_seqc_read_any(vp); if (seqc_in_modify(vp_seqc)) { - vfs_op_thread_exit(mp); + vfs_op_thread_exit_crit(mp); return (cache_fpl_partial(fpl)); } prev_mp = mp; @@ -3515,7 +3515,7 @@ cache_fplookup_climb_mount(struct cache_fpl *fpl) break; } - vfs_op_thread_exit(prev_mp); + vfs_op_thread_exit_crit(prev_mp); fpl->tvp = vp; fpl->tvp_seqc = vp_seqc; return (0); Modified: head/sys/sys/mount.h ============================================================================== --- head/sys/sys/mount.h Tue Aug 4 19:52:52 2020 (r363855) +++ head/sys/sys/mount.h Tue Aug 4 19:54:10 2020 (r363856) @@ -1023,23 +1023,36 @@ int vfs_mount_fetch_counter(struct mount *, enum mount *zpcpu_get(mp->mnt_thread_in_ops_pcpu) == 1; \ }) -#define vfs_op_thread_enter(mp) ({ \ - bool _retval = true; \ - critical_enter(); \ +#define vfs_op_thread_enter_crit(mp) ({ \ + bool _retval_crit = true; \ + MPASS(curthread->td_critnest > 0); \ MPASS(!vfs_op_thread_entered(mp)); \ zpcpu_set_protected(mp->mnt_thread_in_ops_pcpu, 1); \ __compiler_membar(); \ if (__predict_false(mp->mnt_vfs_ops > 0)) { \ - vfs_op_thread_exit(mp); \ - _retval = false; \ + vfs_op_thread_exit_crit(mp); \ + _retval_crit = false; \ } \ + _retval_crit; \ +}) + +#define vfs_op_thread_enter(mp) ({ \ + bool _retval; \ + critical_enter(); \ + _retval = vfs_op_thread_enter_crit(mp); \ + if (__predict_false(!_retval)) \ + critical_exit(); \ _retval; \ }) -#define vfs_op_thread_exit(mp) do { \ +#define vfs_op_thread_exit_crit(mp) do { \ MPASS(vfs_op_thread_entered(mp)); \ __compiler_membar(); \ zpcpu_set_protected(mp->mnt_thread_in_ops_pcpu, 0); \ +} while (0) + +#define vfs_op_thread_exit(mp) do { \ + vfs_op_thread_exit_crit(mp); \ critical_exit(); \ } while (0)
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