Eliminate code duplication in vn_fullpath1() around the cache lookups
and calls to vn_vptocnp() by moving more of the common code to vn_vptocnp(). Rename vn_vptocnp() to vn_vptocnp_locked() to signify that cache is locked around the call. Do not track buffer position by both the pointer and offset, use only buflen to record the start of the free space. Export vn_vptocnp() for external consumers as a wrapper around vn_vptocnp_locked() that locks the cache and handles hold counts. Tested by: pho
This commit is contained in:
Konstantin Belousov
parent
b9131889d2
commit
0449e6e1eb
@ -206,7 +206,7 @@ SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE,
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static void cache_zap(struct namecache *ncp);
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static int vn_vptocnp(struct vnode **vp, char **bp, char *buf, u_int *buflen);
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static int vn_vptocnp_locked(struct vnode **vp, char *buf, u_int *buflen);
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static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
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char *buf, char **retbuf, u_int buflen);
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@ -1036,12 +1036,55 @@ vn_fullpath_global(struct thread *td, struct vnode *vn,
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return (error);
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}
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int
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vn_vptocnp(struct vnode **vp, char *buf, u_int *buflen)
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{
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int error;
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CACHE_RLOCK();
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error = vn_vptocnp_locked(vp, buf, buflen);
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if (error == 0) {
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/*
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* vn_vptocnp_locked() dropped hold acquired by
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* VOP_VPTOCNP immediately after locking the
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* cache. Since we are going to drop the cache rlock,
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* re-hold the result.
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*/
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vhold(*vp);
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CACHE_RUNLOCK();
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}
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return (error);
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}
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static int
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vn_vptocnp(struct vnode **vp, char **bp, char *buf, u_int *buflen)
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vn_vptocnp_locked(struct vnode **vp, char *buf, u_int *buflen)
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{
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struct vnode *dvp;
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struct namecache *ncp;
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int error, vfslocked;
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TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) {
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if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
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break;
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}
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if (ncp != NULL) {
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if (*buflen < ncp->nc_nlen) {
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CACHE_RUNLOCK();
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numfullpathfail4++;
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error = ENOMEM;
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SDT_PROBE(vfs, namecache, fullpath, return, error,
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startvp, NULL, 0, 0);
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return (error);
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}
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*buflen -= ncp->nc_nlen;
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memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen);
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SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp,
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ncp->nc_name, vp, 0, 0);
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*vp = ncp->nc_dvp;
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return (0);
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}
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SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0, 0, 0);
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vhold(*vp);
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CACHE_RUNLOCK();
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vfslocked = VFS_LOCK_GIANT((*vp)->v_mount);
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@ -1052,16 +1095,21 @@ vn_vptocnp(struct vnode **vp, char **bp, char *buf, u_int *buflen)
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VFS_UNLOCK_GIANT(vfslocked);
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if (error) {
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numfullpathfail2++;
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SDT_PROBE(vfs, namecache, fullpath, return, error, startvp,
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NULL, 0, 0);
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return (error);
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}
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*bp = buf + *buflen;
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*vp = dvp;
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CACHE_RLOCK();
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if ((*vp)->v_iflag & VI_DOOMED) {
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/* forced unmount */
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CACHE_RUNLOCK();
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vdrop(*vp);
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return (ENOENT);
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error = ENOENT;
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SDT_PROBE(vfs, namecache, fullpath, return, error, startvp,
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NULL, 0, 0);
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return (error);
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}
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vdrop(*vp);
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@ -1075,59 +1123,26 @@ static int
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vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
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char *buf, char **retbuf, u_int buflen)
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{
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char *bp;
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int error, i, slash_prefixed;
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struct namecache *ncp;
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int error, slash_prefixed;
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#ifdef KDTRACE_HOOKS
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struct vnode *startvp = vp;
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#endif
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buflen--;
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bp = buf + buflen;
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*bp = '\0';
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buf[buflen] = '\0';
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error = 0;
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slash_prefixed = 0;
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SDT_PROBE(vfs, namecache, fullpath, entry, vp, 0, 0, 0, 0);
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CACHE_RLOCK();
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numfullpathcalls++;
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CACHE_RLOCK();
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if (vp->v_type != VDIR) {
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ncp = TAILQ_FIRST(&vp->v_cache_dst);
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if (ncp != NULL) {
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buflen -= ncp->nc_nlen;
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for (i = ncp->nc_nlen - 1; i >= 0 && bp != buf; i--)
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*--bp = ncp->nc_name[i];
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if (bp == buf) {
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numfullpathfail4++;
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CACHE_RUNLOCK();
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error = ENOMEM;
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SDT_PROBE(vfs, namecache, fullpath, return,
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error, startvp, NULL, 0, 0);
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return (error);
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}
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SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp,
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ncp->nc_name, vp, 0, 0);
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vp = ncp->nc_dvp;
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} else {
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SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0,
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0, 0);
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error = vn_vptocnp(&vp, &bp, buf, &buflen);
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if (error) {
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SDT_PROBE(vfs, namecache, fullpath, return,
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error, startvp, NULL, 0, 0);
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return (error);
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}
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}
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if (buflen <= 0) {
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numfullpathfail4++;
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CACHE_RUNLOCK();
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error = ENOMEM;
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SDT_PROBE(vfs, namecache, fullpath, return, error,
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startvp, NULL, 0, 0);
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error = vn_vptocnp_locked(&vp, buf, &buflen);
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if (error)
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return (error);
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}
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*--bp = '/';
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buflen--;
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if (buflen == 0)
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return (ENOMEM);
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buf[--buflen] = '/';
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slash_prefixed = 1;
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}
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while (vp != rdir && vp != rootvnode) {
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@ -1141,64 +1156,39 @@ vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
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continue;
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}
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if (vp->v_type != VDIR) {
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numfullpathfail1++;
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CACHE_RUNLOCK();
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numfullpathfail1++;
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error = ENOTDIR;
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break;
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}
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TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst)
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if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
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break;
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if (ncp != NULL) {
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buflen -= ncp->nc_nlen;
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for (i = ncp->nc_nlen - 1; i >= 0 && bp != buf; i--)
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*--bp = ncp->nc_name[i];
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if (bp == buf) {
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numfullpathfail4++;
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CACHE_RUNLOCK();
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error = ENOMEM;
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break;
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}
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SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp,
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ncp->nc_name, vp, 0, 0);
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vp = ncp->nc_dvp;
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} else {
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SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0,
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0, 0);
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error = vn_vptocnp(&vp, &bp, buf, &buflen);
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if (error)
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break;
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}
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if (buflen <= 0) {
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numfullpathfail4++;
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CACHE_RUNLOCK();
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error = vn_vptocnp_locked(&vp, buf, &buflen);
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if (error)
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break;
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if (buflen == 0) {
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error = ENOMEM;
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break;
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}
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*--bp = '/';
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buflen--;
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buf[--buflen] = '/';
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slash_prefixed = 1;
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}
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if (error) {
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SDT_PROBE(vfs, namecache, fullpath, return, error, startvp,
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NULL, 0, 0);
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if (error)
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return (error);
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}
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if (!slash_prefixed) {
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if (bp == buf) {
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numfullpathfail4++;
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if (buflen == 0) {
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CACHE_RUNLOCK();
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numfullpathfail4++;
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SDT_PROBE(vfs, namecache, fullpath, return, 0,
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startvp, bp, 0, 0);
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startvp, fullpath, 0, 0);
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return (ENOMEM);
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} else
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*--bp = '/';
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}
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buf[--buflen] = '/';
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}
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numfullpathfound++;
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CACHE_RUNLOCK();
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SDT_PROBE(vfs, namecache, fullpath, return, 0, startvp, bp, 0, 0);
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*retbuf = bp;
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SDT_PROBE(vfs, namecache, fullpath, return, 0, startvp, buf + *buflen,
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0, 0);
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*retbuf = buf + buflen;
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return (0);
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}
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@ -598,6 +598,7 @@ int insmntque1(struct vnode *vp, struct mount *mp,
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int insmntque(struct vnode *vp, struct mount *mp);
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u_quad_t init_va_filerev(void);
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int speedup_syncer(void);
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int vn_vptocnp(struct vnode **vp, char *buf, u_int *buflen);
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#define textvp_fullpath(p, rb, rfb) \
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vn_fullpath(FIRST_THREAD_IN_PROC(p), (p)->p_textvp, rb, rfb)
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int vn_fullpath(struct thread *td, struct vnode *vn,
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