Existing VOP_VPTOCNP() interface has a fatal flow that is critical for
nullfs. The problem is that resulting vnode is only required to be held on return from the successfull call to vop, instead of being referenced. Nullfs VOP_INACTIVE() method reclaims the vnode, which in combination with the VOP_VPTOCNP() interface means that the directory vnode returned from VOP_VPTOCNP() is reclaimed in advance, causing vn_fullpath() to error with EBADF or like. Change the interface for VOP_VPTOCNP(), now the dvp must be referenced. Convert all in-tree implementations of VOP_VPTOCNP(), which is trivial, because vhold(9) and vref(9) are similar in the locking prerequisites. Out-of-tree fs implementation of VOP_VPTOCNP(), if any, should have no trouble with the fix. Tested by: pho Reviewed by: mckusick MFC after: 3 weeks (subject of re approval)
This commit is contained in:
parent
f82ee01c1c
commit
f82360acf2
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=227697
@ -1594,7 +1594,7 @@ zfsctl_snapshot_vptocnp(struct vop_vptocnp_args *ap)
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*ap->a_buflen -= len;
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bcopy(sep->se_name, ap->a_buf + *ap->a_buflen, len);
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mutex_exit(&sdp->sd_lock);
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vhold(dvp);
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vref(dvp);
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*ap->a_vpp = dvp;
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}
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VN_RELE(dvp);
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@ -261,7 +261,7 @@ devfs_vptocnp(struct vop_vptocnp_args *ap)
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} else if (vp->v_type == VDIR) {
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if (dd == dmp->dm_rootdir) {
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*dvp = vp;
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vhold(*dvp);
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vref(*dvp);
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goto finished;
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}
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i -= dd->de_dirent->d_namlen;
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@ -289,6 +289,8 @@ devfs_vptocnp(struct vop_vptocnp_args *ap)
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mtx_unlock(&devfs_de_interlock);
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vholdl(*dvp);
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VI_UNLOCK(*dvp);
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vref(*dvp);
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vdrop(*dvp);
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} else {
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mtx_unlock(&devfs_de_interlock);
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error = ENOENT;
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@ -784,6 +784,7 @@ null_vptocnp(struct vop_vptocnp_args *ap)
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vhold(lvp);
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VOP_UNLOCK(vp, 0); /* vp is held by vn_vptocnp_locked that called us */
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ldvp = lvp;
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vref(lvp);
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error = vn_vptocnp(&ldvp, cred, ap->a_buf, ap->a_buflen);
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vdrop(lvp);
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if (error != 0) {
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@ -797,19 +798,17 @@ null_vptocnp(struct vop_vptocnp_args *ap)
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*/
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error = vn_lock(ldvp, LK_EXCLUSIVE);
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if (error != 0) {
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vrele(ldvp);
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vn_lock(vp, locked | LK_RETRY);
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vdrop(ldvp);
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return (ENOENT);
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}
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vref(ldvp);
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vdrop(ldvp);
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error = null_nodeget(vp->v_mount, ldvp, dvp);
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if (error == 0) {
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#ifdef DIAGNOSTIC
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NULLVPTOLOWERVP(*dvp);
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#endif
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vhold(*dvp);
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vput(*dvp);
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VOP_UNLOCK(*dvp, 0); /* keep reference on *dvp */
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} else
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vput(ldvp);
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@ -410,8 +410,7 @@ pfs_vptocnp(struct vop_vptocnp_args *ap)
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}
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*buflen = i;
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vhold(*dvp);
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vput(*dvp);
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VOP_UNLOCK(*dvp, 0);
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vn_lock(vp, locked | LK_RETRY);
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vfs_unbusy(mp);
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@ -1068,16 +1068,8 @@ vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen)
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CACHE_RLOCK();
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error = vn_vptocnp_locked(vp, cred, 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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if (error == 0)
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CACHE_RUNLOCK();
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}
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return (error);
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}
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@ -1096,6 +1088,9 @@ vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf,
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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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vfslocked = VFS_LOCK_GIANT((*vp)->v_mount);
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vrele(*vp);
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VFS_UNLOCK_GIANT(vfslocked);
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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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@ -1106,18 +1101,23 @@ vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf,
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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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dvp = *vp;
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*vp = ncp->nc_dvp;
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vref(*vp);
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CACHE_RUNLOCK();
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vfslocked = VFS_LOCK_GIANT(dvp->v_mount);
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vrele(dvp);
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VFS_UNLOCK_GIANT(vfslocked);
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CACHE_RLOCK();
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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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vn_lock(*vp, LK_SHARED | LK_RETRY);
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error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen);
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VOP_UNLOCK(*vp, 0);
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vdrop(*vp);
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vput(*vp);
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VFS_UNLOCK_GIANT(vfslocked);
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if (error) {
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numfullpathfail2++;
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@ -1128,16 +1128,20 @@ vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf,
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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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if (dvp->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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vfslocked = VFS_LOCK_GIANT(dvp->v_mount);
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vrele(dvp);
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VFS_UNLOCK_GIANT(vfslocked);
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error = ENOENT;
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SDT_PROBE(vfs, namecache, fullpath, return, error, vp,
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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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/*
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* *vp has its use count incremented still.
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*/
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return (0);
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}
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@ -1149,10 +1153,11 @@ 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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int error, slash_prefixed;
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int error, slash_prefixed, vfslocked;
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#ifdef KDTRACE_HOOKS
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struct vnode *startvp = vp;
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#endif
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struct vnode *vp1;
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buflen--;
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buf[buflen] = '\0';
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@ -1161,6 +1166,7 @@ vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
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SDT_PROBE(vfs, namecache, fullpath, entry, vp, 0, 0, 0, 0);
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numfullpathcalls++;
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vref(vp);
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CACHE_RLOCK();
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if (vp->v_type != VDIR) {
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error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen);
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@ -1168,6 +1174,9 @@ vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
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return (error);
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if (buflen == 0) {
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CACHE_RUNLOCK();
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vfslocked = VFS_LOCK_GIANT(vp->v_mount);
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vrele(vp);
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VFS_UNLOCK_GIANT(vfslocked);
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return (ENOMEM);
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}
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buf[--buflen] = '/';
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@ -1177,16 +1186,29 @@ vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
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if (vp->v_vflag & VV_ROOT) {
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if (vp->v_iflag & VI_DOOMED) { /* forced unmount */
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CACHE_RUNLOCK();
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vfslocked = VFS_LOCK_GIANT(vp->v_mount);
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vrele(vp);
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VFS_UNLOCK_GIANT(vfslocked);
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error = ENOENT;
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SDT_PROBE(vfs, namecache, fullpath, return,
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error, vp, NULL, 0, 0);
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break;
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}
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vp = vp->v_mount->mnt_vnodecovered;
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vp1 = vp->v_mount->mnt_vnodecovered;
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vref(vp1);
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CACHE_RUNLOCK();
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vfslocked = VFS_LOCK_GIANT(vp->v_mount);
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vrele(vp);
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VFS_UNLOCK_GIANT(vfslocked);
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vp = vp1;
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CACHE_RLOCK();
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continue;
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}
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if (vp->v_type != VDIR) {
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CACHE_RUNLOCK();
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vfslocked = VFS_LOCK_GIANT(vp->v_mount);
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vrele(vp);
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VFS_UNLOCK_GIANT(vfslocked);
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numfullpathfail1++;
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error = ENOTDIR;
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SDT_PROBE(vfs, namecache, fullpath, return,
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@ -1198,6 +1220,9 @@ vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
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break;
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if (buflen == 0) {
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CACHE_RUNLOCK();
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vfslocked = VFS_LOCK_GIANT(vp->v_mount);
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vrele(vp);
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VFS_UNLOCK_GIANT(vfslocked);
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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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@ -1211,6 +1236,9 @@ vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
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if (!slash_prefixed) {
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if (buflen == 0) {
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CACHE_RUNLOCK();
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vfslocked = VFS_LOCK_GIANT(vp->v_mount);
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vrele(vp);
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VFS_UNLOCK_GIANT(vfslocked);
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numfullpathfail4++;
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SDT_PROBE(vfs, namecache, fullpath, return, ENOMEM,
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startvp, NULL, 0, 0);
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@ -1220,6 +1248,9 @@ vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
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}
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numfullpathfound++;
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CACHE_RUNLOCK();
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vfslocked = VFS_LOCK_GIANT(vp->v_mount);
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vrele(vp);
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VFS_UNLOCK_GIANT(vfslocked);
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SDT_PROBE(vfs, namecache, fullpath, return, 0, startvp, buf + buflen,
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0, 0);
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@ -844,7 +844,7 @@ vop_stdvptocnp(struct vop_vptocnp_args *ap)
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free(dirbuf, M_TEMP);
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if (!error) {
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*buflen = i;
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vhold(*dvp);
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vref(*dvp);
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}
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if (covered) {
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vput(*dvp);
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