Revert "cache: modification and last entry filling support in lockless lookup"
This reverts commit 6dbb07ed68.
Some ports unreliably fail to build with rmdir getting ENOTEMPTY.
This commit is contained in:
Mateusz Guzik
parent
581ade97d5
commit
a1fc1f10c6
@ -3724,13 +3724,6 @@ cache_fpl_handled_impl(struct cache_fpl *fpl, int error, int line)
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#define cache_fpl_handled(x, e) cache_fpl_handled_impl((x), (e), __LINE__)
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static bool
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cache_fpl_terminated(struct cache_fpl *fpl)
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{
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return (fpl->status != CACHE_FPL_STATUS_UNSET);
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}
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#define CACHE_FPL_SUPPORTED_CN_FLAGS \
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(NC_NOMAKEENTRY | NC_KEEPPOSENTRY | LOCKLEAF | LOCKPARENT | WANTPARENT | \
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FOLLOW | LOCKSHARED | SAVENAME | SAVESTART | WILLBEDIR | ISOPEN | \
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@ -3742,8 +3735,6 @@ cache_fpl_terminated(struct cache_fpl *fpl)
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_Static_assert((CACHE_FPL_SUPPORTED_CN_FLAGS & CACHE_FPL_INTERNAL_CN_FLAGS) == 0,
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"supported and internal flags overlap");
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static bool cache_fplookup_need_climb_mount(struct cache_fpl *fpl);
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static bool
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cache_fpl_islastcn(struct nameidata *ndp)
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{
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@ -3866,16 +3857,6 @@ cache_fplookup_partial_setup(struct cache_fpl *fpl)
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return (cache_fpl_aborted(fpl));
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}
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/*
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* Note that seqc is checked before the vnode is locked, so by
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* the time regular lookup gets to it it may have moved.
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*
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* Ultimately this does not affect correctness, any lookup errors
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* are userspace racing with itself. It is guaranteed that any
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* path which ultimatley gets found could also have been found
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* by regular lookup going all the way in absence of concurrent
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* modifications.
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*/
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dvs = vget_prep_smr(dvp);
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cache_fpl_smr_exit(fpl);
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if (__predict_false(dvs == VGET_NONE)) {
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@ -3893,7 +3874,6 @@ cache_fplookup_partial_setup(struct cache_fpl *fpl)
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cache_fpl_restore_partial(fpl, &fpl->snd);
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ndp->ni_startdir = dvp;
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MPASS((cnp->cn_flags & MAKEENTRY) == 0);
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cnp->cn_flags |= MAKEENTRY;
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if (cache_fpl_islastcn(ndp))
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cnp->cn_flags |= ISLASTCN;
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@ -3940,159 +3920,18 @@ cache_fplookup_final_child(struct cache_fpl *fpl, enum vgetstate tvs)
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/*
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* They want to possibly modify the state of the namecache.
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*
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* Don't try to match the API contract, just leave.
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* TODO: this leaves scalability on the table
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*/
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static int __noinline
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static int
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cache_fplookup_final_modifying(struct cache_fpl *fpl)
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{
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struct nameidata *ndp;
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struct componentname *cnp;
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enum vgetstate dvs;
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struct vnode *dvp, *tvp;
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struct mount *mp;
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seqc_t dvp_seqc;
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int error;
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bool docache;
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ndp = fpl->ndp;
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cnp = fpl->cnp;
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dvp = fpl->dvp;
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dvp_seqc = fpl->dvp_seqc;
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MPASS(cache_fpl_islastcn(ndp));
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if ((cnp->cn_flags & LOCKPARENT) == 0)
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MPASS((cnp->cn_flags & WANTPARENT) != 0);
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MPASS((cnp->cn_flags & TRAILINGSLASH) == 0);
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MPASS(cnp->cn_nameiop == CREATE || cnp->cn_nameiop == DELETE ||
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cnp->cn_nameiop == RENAME);
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docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
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if (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)
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docache = false;
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mp = atomic_load_ptr(&dvp->v_mount);
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if (__predict_false(mp == NULL)) {
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return (cache_fpl_aborted(fpl));
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}
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if (__predict_false(mp->mnt_flag & MNT_RDONLY)) {
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cache_fpl_smr_exit(fpl);
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/*
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* Original code keeps not checking for CREATE which
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* might be a bug. For now let the old lookup decide.
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*/
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if (cnp->cn_nameiop == CREATE) {
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return (cache_fpl_aborted(fpl));
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}
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return (cache_fpl_handled(fpl, EROFS));
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}
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/*
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* Secure access to dvp; check cache_fplookup_partial_setup for
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* reasoning.
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*
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* XXX At least UFS requires its lookup routine to be called for
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* the last path component, which leads to some level of complicaton
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* and inefficiency:
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* - the target routine always locks the target vnode, but our caller
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* may not need it locked
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* - some of the VOP machinery asserts that the parent is locked, which
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* once more may be not required
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*
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* TODO: add a flag for filesystems which don't need this.
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*/
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dvs = vget_prep_smr(dvp);
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cache_fpl_smr_exit(fpl);
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if (__predict_false(dvs == VGET_NONE)) {
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return (cache_fpl_aborted(fpl));
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}
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vget_finish_ref(dvp, dvs);
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if (!vn_seqc_consistent(dvp, dvp_seqc)) {
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vrele(dvp);
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return (cache_fpl_aborted(fpl));
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}
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error = vn_lock(dvp, LK_EXCLUSIVE);
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if (__predict_false(error != 0)) {
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vrele(dvp);
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return (cache_fpl_aborted(fpl));
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}
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tvp = NULL;
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MPASS((cnp->cn_flags & MAKEENTRY) == 0);
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if (docache)
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cnp->cn_flags |= MAKEENTRY;
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cnp->cn_flags |= ISLASTCN;
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cnp->cn_lkflags = LK_EXCLUSIVE;
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error = VOP_LOOKUP(dvp, &tvp, cnp);
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switch (error) {
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case EJUSTRETURN:
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case 0:
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break;
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case ENOTDIR:
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case ENOENT:
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vput(dvp);
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return (cache_fpl_handled(fpl, error));
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default:
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vput(dvp);
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return (cache_fpl_aborted(fpl));
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}
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fpl->tvp = tvp;
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if (tvp == NULL) {
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if ((cnp->cn_flags & SAVESTART) != 0) {
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ndp->ni_startdir = dvp;
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vrefact(ndp->ni_startdir);
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cnp->cn_flags |= SAVENAME;
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}
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MPASS(error == EJUSTRETURN);
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if ((cnp->cn_flags & LOCKPARENT) == 0) {
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VOP_UNLOCK(dvp);
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}
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return (cache_fpl_handled(fpl, 0));
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}
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/*
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* Check if the target is either a symlink or a mount point.
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* Since we expect this to be the terminal vnode it should
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* almost never be true.
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*/
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if (__predict_false(!cache_fplookup_vnode_supported(tvp) ||
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cache_fplookup_need_climb_mount(fpl))) {
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vput(dvp);
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vput(tvp);
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return (cache_fpl_aborted(fpl));
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}
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if ((cnp->cn_flags & LOCKLEAF) == 0) {
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VOP_UNLOCK(tvp);
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}
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if ((cnp->cn_flags & LOCKPARENT) == 0) {
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VOP_UNLOCK(dvp);
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}
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if ((cnp->cn_flags & SAVESTART) != 0) {
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ndp->ni_startdir = dvp;
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vrefact(ndp->ni_startdir);
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cnp->cn_flags |= SAVENAME;
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}
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return (cache_fpl_handled(fpl, 0));
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}
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static int __noinline
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cache_fplookup_modifying(struct cache_fpl *fpl)
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{
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struct nameidata *ndp;
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ndp = fpl->ndp;
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if (!cache_fpl_islastcn(ndp)) {
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return (cache_fpl_partial(fpl));
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}
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return (cache_fplookup_final_modifying(fpl));
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MPASS(cnp->cn_nameiop != LOOKUP);
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return (cache_fpl_partial(fpl));
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}
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static int __noinline
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@ -4173,6 +4012,8 @@ cache_fplookup_final(struct cache_fpl *fpl)
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dvp_seqc = fpl->dvp_seqc;
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tvp = fpl->tvp;
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VNPASS(cache_fplookup_vnode_supported(dvp), dvp);
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if (cnp->cn_nameiop != LOOKUP) {
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return (cache_fplookup_final_modifying(fpl));
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}
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@ -4195,117 +4036,6 @@ cache_fplookup_final(struct cache_fpl *fpl)
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return (cache_fplookup_final_child(fpl, tvs));
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}
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static int __noinline
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cache_fplookup_noentry(struct cache_fpl *fpl)
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{
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struct nameidata *ndp;
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struct componentname *cnp;
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enum vgetstate dvs;
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struct vnode *dvp, *tvp;
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seqc_t dvp_seqc;
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int error;
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bool docache;
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ndp = fpl->ndp;
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cnp = fpl->cnp;
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dvp = fpl->dvp;
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dvp_seqc = fpl->dvp_seqc;
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if (cnp->cn_nameiop != LOOKUP) {
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return (cache_fplookup_modifying(fpl));
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}
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MPASS((cnp->cn_flags & SAVESTART) == 0);
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/*
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* Only try to fill in the component if it is the last one,
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* otherwise not only there may be several to handle but the
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* walk may be complicated.
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*/
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if (!cache_fpl_islastcn(ndp)) {
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return (cache_fpl_partial(fpl));
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}
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/*
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* Secure access to dvp; check cache_fplookup_partial_setup for
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* reasoning.
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*/
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dvs = vget_prep_smr(dvp);
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cache_fpl_smr_exit(fpl);
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if (__predict_false(dvs == VGET_NONE)) {
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return (cache_fpl_aborted(fpl));
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}
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vget_finish_ref(dvp, dvs);
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if (!vn_seqc_consistent(dvp, dvp_seqc)) {
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vrele(dvp);
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return (cache_fpl_aborted(fpl));
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}
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error = vn_lock(dvp, LK_SHARED);
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if (__predict_false(error != 0)) {
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vrele(dvp);
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return (cache_fpl_aborted(fpl));
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}
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tvp = NULL;
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/*
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* TODO: provide variants which don't require locking either vnode.
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*/
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docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
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MPASS((cnp->cn_flags & MAKEENTRY) == 0);
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if (docache)
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cnp->cn_flags |= MAKEENTRY;
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cnp->cn_flags |= ISLASTCN;
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cnp->cn_lkflags = LK_SHARED;
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if ((cnp->cn_flags & LOCKSHARED) == 0) {
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cnp->cn_lkflags = LK_EXCLUSIVE;
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}
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error = VOP_LOOKUP(dvp, &tvp, cnp);
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switch (error) {
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case EJUSTRETURN:
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case 0:
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break;
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case ENOTDIR:
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case ENOENT:
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vput(dvp);
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return (cache_fpl_handled(fpl, error));
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default:
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vput(dvp);
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return (cache_fpl_aborted(fpl));
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}
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fpl->tvp = tvp;
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if (tvp == NULL) {
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MPASS(error == EJUSTRETURN);
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if ((cnp->cn_flags & (WANTPARENT | LOCKPARENT)) == 0) {
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vput(dvp);
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} else if ((cnp->cn_flags & LOCKPARENT) == 0) {
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VOP_UNLOCK(dvp);
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}
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return (cache_fpl_handled(fpl, 0));
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}
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if (__predict_false(!cache_fplookup_vnode_supported(tvp) ||
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cache_fplookup_need_climb_mount(fpl))) {
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vput(dvp);
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vput(tvp);
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return (cache_fpl_aborted(fpl));
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}
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if ((cnp->cn_flags & LOCKLEAF) == 0) {
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VOP_UNLOCK(tvp);
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}
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if ((cnp->cn_flags & (WANTPARENT | LOCKPARENT)) == 0) {
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vput(dvp);
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} else if ((cnp->cn_flags & LOCKPARENT) == 0) {
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VOP_UNLOCK(dvp);
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}
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return (cache_fpl_handled(fpl, 0));
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}
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static int __noinline
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cache_fplookup_dot(struct cache_fpl *fpl)
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{
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@ -4454,8 +4184,13 @@ cache_fplookup_next(struct cache_fpl *fpl)
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break;
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}
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/*
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* If there is no entry we have to punt to the slow path to perform
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* actual lookup. Should there be nothing with this name a negative
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* entry will be created.
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*/
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if (__predict_false(ncp == NULL)) {
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return (cache_fplookup_noentry(fpl));
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return (cache_fpl_partial(fpl));
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}
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tvp = atomic_load_ptr(&ncp->nc_vp);
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@ -4804,12 +4539,12 @@ cache_fplookup_impl(struct vnode *dvp, struct cache_fpl *fpl)
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if (__predict_false(cache_fpl_isdotdot(cnp))) {
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error = cache_fplookup_dotdot(fpl);
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if (__predict_false(cache_fpl_terminated(fpl))) {
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if (__predict_false(error != 0)) {
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break;
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}
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} else {
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error = cache_fplookup_next(fpl);
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if (__predict_false(cache_fpl_terminated(fpl))) {
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if (__predict_false(error != 0)) {
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break;
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}
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