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Add a default implementation for VOP_VPTOCNP(9) which scans the parent
directory of a vnode to find a dirent with a matching file number. The name from that dirent is then used to provide the component name. Note: if the initial vnode argument is not a directory itself, then the default VOP_VPTOCNP(9) implementation still returns ENOENT. Reviewed by: kib Approved by: kib Tested by: pho
This commit is contained in:
Joe Marcus Clarke
parent
01cd0a978f
commit
f8ecc40737
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=189539
@ -48,8 +48,11 @@ __FBSDID("$FreeBSD$");
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#include <sys/malloc.h>
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#include <sys/mount.h>
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#include <sys/mutex.h>
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#include <sys/namei.h>
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#include <sys/fcntl.h>
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#include <sys/unistd.h>
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#include <sys/vnode.h>
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#include <sys/dirent.h>
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#include <sys/poll.h>
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#include <vm/vm.h>
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@ -63,6 +66,14 @@ __FBSDID("$FreeBSD$");
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static int vop_nolookup(struct vop_lookup_args *);
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static int vop_nostrategy(struct vop_strategy_args *);
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static int get_next_dirent(struct vnode *vp, struct dirent **dpp,
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char *dirbuf, int dirbuflen, off_t *off,
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char **cpos, int *len, int *eofflag,
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struct thread *td);
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static int dirent_exists(struct vnode *vp, const char *dirname,
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struct thread *td);
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#define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4)
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/*
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* This vnode table stores what we want to do if the filesystem doesn't
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@ -98,7 +109,7 @@ struct vop_vector default_vnodeops = {
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.vop_revoke = VOP_PANIC,
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.vop_strategy = vop_nostrategy,
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.vop_unlock = vop_stdunlock,
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.vop_vptocnp = VOP_ENOENT,
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.vop_vptocnp = vop_stdvptocnp,
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.vop_vptofh = vop_stdvptofh,
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};
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@ -210,6 +221,108 @@ vop_nostrategy (struct vop_strategy_args *ap)
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return (EOPNOTSUPP);
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}
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static int
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get_next_dirent(struct vnode *vp, struct dirent **dpp, char *dirbuf,
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int dirbuflen, off_t *off, char **cpos, int *len,
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int *eofflag, struct thread *td)
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{
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int error, reclen;
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struct uio uio;
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struct iovec iov;
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struct dirent *dp;
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KASSERT(VOP_ISLOCKED(vp), ("vp %p is not locked", vp));
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KASSERT(vp->v_type == VDIR, ("vp %p is not a directory", vp));
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if (*len == 0) {
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iov.iov_base = dirbuf;
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iov.iov_len = dirbuflen;
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uio.uio_iov = &iov;
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uio.uio_iovcnt = 1;
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uio.uio_offset = *off;
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uio.uio_resid = dirbuflen;
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uio.uio_segflg = UIO_SYSSPACE;
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uio.uio_rw = UIO_READ;
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uio.uio_td = td;
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*eofflag = 0;
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#ifdef MAC
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error = mac_vnode_check_readdir(td->td_ucred, vp);
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if (error == 0)
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#endif
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error = VOP_READDIR(vp, &uio, td->td_ucred, eofflag,
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NULL, NULL);
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if (error)
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return (error);
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*off = uio.uio_offset;
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*cpos = dirbuf;
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*len = (dirbuflen - uio.uio_resid);
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}
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dp = (struct dirent *)(*cpos);
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reclen = dp->d_reclen;
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*dpp = dp;
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/* check for malformed directory.. */
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if (reclen < DIRENT_MINSIZE)
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return (EINVAL);
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*cpos += reclen;
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*len -= reclen;
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return (0);
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}
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/*
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* Check if a named file exists in a given directory vnode.
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*/
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static int
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dirent_exists(struct vnode *vp, const char *dirname, struct thread *td)
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{
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char *dirbuf, *cpos;
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int error, eofflag, dirbuflen, len, found;
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off_t off;
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struct dirent *dp;
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struct vattr va;
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KASSERT(VOP_ISLOCKED(vp), ("vp %p is not locked", vp));
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KASSERT(vp->v_type == VDIR, ("vp %p is not a directory", vp));
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found = 0;
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error = VOP_GETATTR(vp, &va, td->td_ucred);
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if (error)
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return (found);
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dirbuflen = DEV_BSIZE;
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if (dirbuflen < va.va_blocksize)
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dirbuflen = va.va_blocksize;
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dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);
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off = 0;
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len = 0;
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do {
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error = get_next_dirent(vp, &dp, dirbuf, dirbuflen, &off,
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&cpos, &len, &eofflag, td);
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if (error)
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goto out;
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if ((dp->d_type != DT_WHT) &&
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!strcmp(dp->d_name, dirname)) {
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found = 1;
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goto out;
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}
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} while (len > 0 || !eofflag);
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out:
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free(dirbuf, M_TEMP);
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return (found);
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}
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/*
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* Advisory record locking support
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*/
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@ -557,6 +670,127 @@ vop_stdvptofh(struct vop_vptofh_args *ap)
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return (EOPNOTSUPP);
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}
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int
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vop_stdvptocnp(struct vop_vptocnp_args *ap)
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{
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struct vnode *vp = ap->a_vp;
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struct vnode **dvp = ap->a_vpp;
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char *buf = ap->a_buf;
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int *buflen = ap->a_buflen;
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char *dirbuf, *cpos;
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int i, error, eofflag, dirbuflen, flags, locked, len, covered;
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off_t off;
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ino_t fileno;
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struct vattr va;
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struct nameidata nd;
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struct thread *td;
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struct dirent *dp;
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struct vnode *mvp;
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i = *buflen;
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error = 0;
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covered = 0;
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td = curthread;
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if (vp->v_type != VDIR)
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return (ENOENT);
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error = VOP_GETATTR(vp, &va, td->td_ucred);
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if (error)
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return (error);
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VREF(vp);
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locked = VOP_ISLOCKED(vp);
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VOP_UNLOCK(vp, 0);
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NDINIT_ATVP(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
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"..", vp, td);
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flags = FREAD;
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error = vn_open(&nd, &flags, 0, NULL);
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if (error) {
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vn_lock(vp, locked | LK_RETRY);
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return (error);
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}
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NDFREE(&nd, NDF_ONLY_PNBUF);
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mvp = *dvp = nd.ni_vp;
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if (vp->v_mount != (*dvp)->v_mount &&
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((*dvp)->v_vflag & VV_ROOT) &&
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((*dvp)->v_mount->mnt_flag & MNT_UNION)) {
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*dvp = (*dvp)->v_mount->mnt_vnodecovered;
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VREF(mvp);
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VOP_UNLOCK(mvp, 0);
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vn_close(mvp, FREAD, td->td_ucred, td);
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VREF(*dvp);
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vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
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covered = 1;
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}
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fileno = va.va_fileid;
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dirbuflen = DEV_BSIZE;
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if (dirbuflen < va.va_blocksize)
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dirbuflen = va.va_blocksize;
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dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);
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if ((*dvp)->v_type != VDIR) {
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error = ENOENT;
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goto out;
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}
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off = 0;
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len = 0;
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do {
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/* call VOP_READDIR of parent */
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error = get_next_dirent(*dvp, &dp, dirbuf, dirbuflen, &off,
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&cpos, &len, &eofflag, td);
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if (error)
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goto out;
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if ((dp->d_type != DT_WHT) &&
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(dp->d_fileno == fileno)) {
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if (covered) {
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VOP_UNLOCK(*dvp, 0);
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vn_lock(mvp, LK_EXCLUSIVE | LK_RETRY);
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if (dirent_exists(mvp, dp->d_name, td)) {
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error = ENOENT;
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VOP_UNLOCK(mvp, 0);
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vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
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goto out;
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}
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VOP_UNLOCK(mvp, 0);
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vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
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}
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i -= dp->d_namlen;
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if (i < 0) {
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error = ENOMEM;
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goto out;
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}
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bcopy(dp->d_name, buf + i, dp->d_namlen);
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error = 0;
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goto out;
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}
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} while (len > 0 || !eofflag);
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error = ENOENT;
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out:
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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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}
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if (covered) {
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vput(*dvp);
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vrele(mvp);
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} else {
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VOP_UNLOCK(mvp, 0);
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vn_close(mvp, FREAD, td->td_ucred, td);
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}
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vn_lock(vp, locked | LK_RETRY);
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return (error);
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}
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/*
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* vfs default ops
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* used to fill the vfs function table to get reasonable default return values.
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