cache: stop manipulating pathlen
It is a copy-pasto from regular lookup. Add debug to ensure the result is the same.
This commit is contained in:
Mateusz Guzik
parent
20fb2ea2c7
commit
0f1fc3a31f
@ -3616,13 +3616,22 @@ SYSCTL_PROC(_vfs, OID_AUTO, cache_fast_lookup, CTLTYPE_INT|CTLFLAG_RW|CTLFLAG_MP
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*/
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struct nameidata_saved {
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char *cn_nameptr;
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#ifdef INVARIANTS
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size_t ni_pathlen;
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#endif
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int cn_flags;
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};
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#ifdef INVARIANTS
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struct cache_fpl_debug {
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size_t ni_pathlen;
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};
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#endif
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struct cache_fpl {
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struct nameidata *ndp;
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struct componentname *cnp;
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char *nulchar;
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struct pwd **pwd;
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struct vnode *dvp;
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struct vnode *tvp;
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@ -3635,12 +3644,18 @@ struct cache_fpl {
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bool in_smr;
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bool fsearch;
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bool savename;
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#ifdef INVARIANTS
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struct cache_fpl_debug debug;
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#endif
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};
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static bool cache_fplookup_is_mp(struct cache_fpl *fpl);
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static int cache_fplookup_cross_mount(struct cache_fpl *fpl);
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static int cache_fplookup_partial_setup(struct cache_fpl *fpl);
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static int cache_fplookup_skip_slashes(struct cache_fpl *fpl);
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static void cache_fpl_pathlen_dec(struct cache_fpl *fpl);
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static void cache_fpl_pathlen_inc(struct cache_fpl *fpl);
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static void cache_fpl_pathlen_sub(struct cache_fpl *fpl, size_t n);
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static void
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cache_fpl_cleanup_cnp(struct componentname *cnp)
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@ -3664,12 +3679,12 @@ cache_fpl_handle_root(struct cache_fpl *fpl)
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MPASS(*(cnp->cn_nameptr) == '/');
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cnp->cn_nameptr++;
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ndp->ni_pathlen--;
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cache_fpl_pathlen_dec(fpl);
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if (__predict_false(*(cnp->cn_nameptr) == '/')) {
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do {
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cnp->cn_nameptr++;
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ndp->ni_pathlen--;
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cache_fpl_pathlen_dec(fpl);
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} while (*(cnp->cn_nameptr) == '/');
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}
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@ -3682,7 +3697,9 @@ cache_fpl_checkpoint(struct cache_fpl *fpl, struct nameidata_saved *snd)
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snd->cn_flags = fpl->ndp->ni_cnd.cn_flags;
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snd->cn_nameptr = fpl->ndp->ni_cnd.cn_nameptr;
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snd->ni_pathlen = fpl->ndp->ni_pathlen;
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#ifdef INVARIANTS
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snd->ni_pathlen = fpl->debug.ni_pathlen;
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#endif
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}
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static void
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@ -3691,7 +3708,9 @@ cache_fpl_restore_partial(struct cache_fpl *fpl, struct nameidata_saved *snd)
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fpl->ndp->ni_cnd.cn_flags = snd->cn_flags;
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fpl->ndp->ni_cnd.cn_nameptr = snd->cn_nameptr;
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fpl->ndp->ni_pathlen = snd->ni_pathlen;
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#ifdef INVARIANTS
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fpl->debug.ni_pathlen = snd->ni_pathlen;
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#endif
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}
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static void
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@ -4014,10 +4033,18 @@ cache_fplookup_partial_setup(struct cache_fpl *fpl)
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if (__predict_false(*(cnp->cn_nameptr) == '/')) {
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do {
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cnp->cn_nameptr++;
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ndp->ni_pathlen--;
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cache_fpl_pathlen_dec(fpl);
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} while (*(cnp->cn_nameptr) == '/');
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}
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ndp->ni_pathlen = fpl->nulchar - cnp->cn_nameptr + 1;
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#ifdef INVARIANTS
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if (ndp->ni_pathlen != fpl->debug.ni_pathlen) {
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panic("%s: mismatch (%zu != %zu) nulchar %p nameptr %p [%s] ; full string [%s]\n",
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__func__, ndp->ni_pathlen, fpl->debug.ni_pathlen, fpl->nulchar,
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cnp->cn_nameptr, cnp->cn_nameptr, cnp->cn_pnbuf);
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}
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#endif
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return (0);
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}
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@ -4876,6 +4903,50 @@ cache_fplookup_is_mp(struct cache_fpl *fpl)
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* must take into account that in case off fallback the resulting
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* nameidata state has to be compatible with the original.
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*/
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/*
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* Debug ni_pathlen tracking.
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*/
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#ifdef INVARIANTS
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static void
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cache_fpl_pathlen_dec(struct cache_fpl *fpl)
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{
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cache_fpl_pathlen_sub(fpl, 1);
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}
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static void
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cache_fpl_pathlen_inc(struct cache_fpl *fpl)
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{
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fpl->debug.ni_pathlen++;
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}
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static void
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cache_fpl_pathlen_sub(struct cache_fpl *fpl, size_t n)
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{
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fpl->debug.ni_pathlen -= n;
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KASSERT(fpl->debug.ni_pathlen <= PATH_MAX,
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("%s: pathlen underflow to %zd\n", __func__, fpl->debug.ni_pathlen));
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}
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#else
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static void __always_inline
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cache_fpl_pathlen_dec(struct cache_fpl *fpl)
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{
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}
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static void __always_inline
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cache_fpl_pathlen_inc(struct cache_fpl *fpl)
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{
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}
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static void
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cache_fpl_pathlen_sub(struct cache_fpl *fpl, size_t n)
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{
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}
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#endif
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static int
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cache_fplookup_preparse(struct cache_fpl *fpl)
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{
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@ -4893,10 +4964,13 @@ cache_fplookup_preparse(struct cache_fpl *fpl)
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* By this point the shortest possible pathname is one character + nul
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* terminator, hence 2.
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*/
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KASSERT(ndp->ni_pathlen >= 2, ("%s: ni_pathlen %zu\n", __func__,
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ndp->ni_pathlen));
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if (__predict_false(cnp->cn_nameptr[ndp->ni_pathlen - 2] == '/')) {
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KASSERT(fpl->debug.ni_pathlen >= 2, ("%s: pathlen %zu\n", __func__,
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fpl->debug.ni_pathlen));
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KASSERT(&cnp->cn_nameptr[fpl->debug.ni_pathlen - 2] == fpl->nulchar - 1,
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("%s: mismatch on string (%p != %p) [%s]\n", __func__,
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&cnp->cn_nameptr[fpl->debug.ni_pathlen - 2], fpl->nulchar - 1,
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cnp->cn_pnbuf));
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if (__predict_false(*(fpl->nulchar - 1) == '/')) {
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/*
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* TODO
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* Regular lookup performs the following:
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@ -4931,22 +5005,24 @@ cache_fplookup_parse(struct cache_fpl *fpl)
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* to test for. Pathnames tend to be short so this should not be
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* resulting in cache misses.
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*/
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KASSERT(cnp->cn_nameptr[ndp->ni_pathlen - 1] == '\0',
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("%s: expected nul at %p + %zu; string [%s]\n", __func__,
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cnp->cn_nameptr, ndp->ni_pathlen - 1, cnp->cn_nameptr));
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cnp->cn_nameptr[ndp->ni_pathlen - 1] = '/';
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KASSERT(&cnp->cn_nameptr[fpl->debug.ni_pathlen - 1] == fpl->nulchar,
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("%s: mismatch between pathlen (%zu) and nulchar (%p != %p), string [%s]\n",
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__func__, fpl->debug.ni_pathlen, &cnp->cn_nameptr[fpl->debug.ni_pathlen - 1],
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fpl->nulchar, cnp->cn_pnbuf));
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KASSERT(*fpl->nulchar == '\0',
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("%s: expected nul at %p; string [%s]\n", __func__, fpl->nulchar,
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cnp->cn_pnbuf));
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*fpl->nulchar = '/';
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for (cp = cnp->cn_nameptr; *cp != '/'; cp++) {
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KASSERT(*cp != '\0',
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("%s: encountered unexpected nul; string [%s]\n", __func__,
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cnp->cn_nameptr));
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continue;
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}
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cnp->cn_nameptr[ndp->ni_pathlen - 1] = '\0';
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*fpl->nulchar = '\0';
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cnp->cn_namelen = cp - cnp->cn_nameptr;
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ndp->ni_pathlen -= cnp->cn_namelen;
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KASSERT(ndp->ni_pathlen <= PATH_MAX,
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("%s: ni_pathlen underflow to %zd\n", __func__, ndp->ni_pathlen));
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cache_fpl_pathlen_sub(fpl, cnp->cn_namelen);
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/*
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* Hack: we have to check if the found path component's length exceeds
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* NAME_MAX. However, the condition is very rarely true and check can
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@ -4992,7 +5068,7 @@ cache_fplookup_parse_advance(struct cache_fpl *fpl)
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("%s: should have seen slash at %p ; buf %p [%s]\n", __func__,
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cnp->cn_nameptr, cnp->cn_pnbuf, cnp->cn_pnbuf));
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cnp->cn_nameptr++;
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ndp->ni_pathlen--;
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cache_fpl_pathlen_dec(fpl);
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}
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/*
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@ -5016,7 +5092,7 @@ cache_fplookup_skip_slashes(struct cache_fpl *fpl)
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MPASS(*(cnp->cn_nameptr) == '/');
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do {
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cnp->cn_nameptr++;
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ndp->ni_pathlen--;
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cache_fpl_pathlen_dec(fpl);
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} while (*(cnp->cn_nameptr) == '/');
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/*
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@ -5024,7 +5100,7 @@ cache_fplookup_skip_slashes(struct cache_fpl *fpl)
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* something to skip.
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*/
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cnp->cn_nameptr--;
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ndp->ni_pathlen++;
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cache_fpl_pathlen_inc(fpl);
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/*
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* cache_fplookup_parse_advance starts from ndp->ni_next
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@ -5309,6 +5385,10 @@ cache_fplookup(struct nameidata *ndp, enum cache_fpl_status *status,
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cache_fpl_checkpoint(&fpl, &fpl.snd_orig);
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cache_fpl_smr_enter_initial(&fpl);
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#ifdef INVARIANTS
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fpl.debug.ni_pathlen = ndp->ni_pathlen;
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#endif
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fpl.nulchar = &cnp->cn_nameptr[ndp->ni_pathlen - 1];
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fpl.fsearch = false;
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fpl.savename = (cnp->cn_flags & SAVENAME) != 0;
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fpl.pwd = pwdp;
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