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Merge kern___cwd() and vn_fullpath(), which were virtually identical,
except for places where people forget to update one of them. We now collect only one set of stats for both of these routines. Other changes in this commit include: - Start acquiring Giant again in vn_fullpath(), since it is required when crossing a mount point. - Expand the scope of the cache lock to avoid dropping it and picking it up again for every pathname component. This also makes it trivial to avoid races in stats collection. - Assert that nc_dvp == v_dd for directories instead of returning an error to userland when this is not true. AFAIK, it should always be true when v_dd is non-null. - For vn_fullpath(), handle the first (non-directory) vnode separately. Glanced at by: jeff, phk
This commit is contained in:
David Schultz
parent
76e96613b2
commit
dd33f0d92f
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=144318
@ -169,6 +169,8 @@ SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD, &nchstats,
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static void cache_zap(struct namecache *ncp);
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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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static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");
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@ -700,14 +702,6 @@ static int disablecwd;
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SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0,
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"Disable the getcwd syscall");
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/* Various statistics for the getcwd syscall */
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static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls);
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static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1);
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static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2);
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static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3);
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static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4);
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static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound);
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/* Implementation of the getcwd syscall */
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int
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__getcwd(td, uap)
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@ -722,94 +716,31 @@ int
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kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen)
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{
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char *bp, *tmpbuf;
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int error, i, slash_prefixed;
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struct filedesc *fdp;
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struct namecache *ncp;
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struct vnode *vp;
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int error;
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numcwdcalls++;
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if (disablecwd)
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return (ENODEV);
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if (buflen < 2)
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return (EINVAL);
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if (buflen > MAXPATHLEN)
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buflen = MAXPATHLEN;
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mtx_lock(&Giant);
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error = 0;
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tmpbuf = bp = malloc(buflen, M_TEMP, M_WAITOK);
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bp += buflen - 1;
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*bp = '\0';
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tmpbuf = malloc(buflen, M_TEMP, M_WAITOK);
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fdp = td->td_proc->p_fd;
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slash_prefixed = 0;
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mtx_lock(&Giant);
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FILEDESC_LOCK(fdp);
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for (vp = fdp->fd_cdir; vp != fdp->fd_rdir && vp != rootvnode;) {
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if (vp->v_vflag & VV_ROOT) {
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if (vp->v_mount == NULL) { /* forced unmount */
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error = EBADF;
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goto out;
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}
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vp = vp->v_mount->mnt_vnodecovered;
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continue;
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}
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if (vp->v_dd->v_id != vp->v_ddid) {
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numcwdfail1++;
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error = ENOTDIR;
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goto out;
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}
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CACHE_LOCK();
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ncp = TAILQ_FIRST(&vp->v_cache_dst);
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if (!ncp) {
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numcwdfail2++;
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CACHE_UNLOCK();
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error = ENOENT;
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goto out;
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}
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if (ncp->nc_dvp != vp->v_dd) {
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numcwdfail3++;
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CACHE_UNLOCK();
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error = EBADF;
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goto out;
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}
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for (i = ncp->nc_nlen - 1; i >= 0; i--) {
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if (bp == tmpbuf) {
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numcwdfail4++;
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CACHE_UNLOCK();
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error = ENOMEM;
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goto out;
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}
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*--bp = ncp->nc_name[i];
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}
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if (bp == tmpbuf) {
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numcwdfail4++;
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CACHE_UNLOCK();
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error = ENOMEM;
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goto out;
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}
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*--bp = '/';
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slash_prefixed = 1;
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vp = vp->v_dd;
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CACHE_UNLOCK();
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}
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if (!slash_prefixed) {
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if (bp == tmpbuf) {
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numcwdfail4++;
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error = ENOMEM;
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goto out;
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}
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*--bp = '/';
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}
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FILEDESC_UNLOCK(fdp);
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mtx_unlock(&Giant);
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numcwdfound++;
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if (bufseg == UIO_SYSSPACE)
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bcopy(bp, buf, strlen(bp) + 1);
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else
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error = copyout(bp, buf, strlen(bp) + 1);
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free(tmpbuf, M_TEMP);
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return (error);
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out:
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error = vn_fullpath1(td, fdp->fd_cdir, fdp->fd_rdir, tmpbuf,
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&bp, buflen);
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FILEDESC_UNLOCK(fdp);
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mtx_unlock(&Giant);
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if (!error) {
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if (bufseg == UIO_SYSSPACE)
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bcopy(bp, buf, strlen(bp) + 1);
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else
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error = copyout(bp, buf, strlen(bp) + 1);
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}
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free(tmpbuf, M_TEMP);
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return (error);
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}
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@ -827,10 +758,10 @@ static int disablefullpath;
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SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0,
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"Disable the vn_fullpath function");
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/* These count for kern___getcwd(), too. */
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STATNODE(numfullpathcalls);
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STATNODE(numfullpathfail1);
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STATNODE(numfullpathfail2);
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STATNODE(numfullpathfail3);
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STATNODE(numfullpathfail4);
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STATNODE(numfullpathfound);
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@ -841,90 +772,116 @@ STATNODE(numfullpathfound);
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int
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vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf)
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{
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char *bp, *buf;
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int i, slash_prefixed;
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char *buf;
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struct filedesc *fdp;
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struct namecache *ncp;
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struct vnode *vp;
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int error;
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numfullpathcalls++;
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if (disablefullpath)
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return (ENODEV);
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if (vn == NULL)
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return (EINVAL);
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buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
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bp = buf + MAXPATHLEN - 1;
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*bp = '\0';
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fdp = td->td_proc->p_fd;
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slash_prefixed = 0;
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ASSERT_VOP_LOCKED(vn, "vn_fullpath");
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mtx_lock(&Giant);
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FILEDESC_LOCK(fdp);
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for (vp = vn; vp != fdp->fd_rdir && vp != rootvnode;) {
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if (vp->v_vflag & VV_ROOT) {
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if (vp->v_mount == NULL) { /* forced unmount */
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FILEDESC_UNLOCK(fdp);
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free(buf, M_TEMP);
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return (EBADF);
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}
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vp = vp->v_mount->mnt_vnodecovered;
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continue;
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}
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if (vp != vn && vp->v_dd->v_id != vp->v_ddid) {
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FILEDESC_UNLOCK(fdp);
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free(buf, M_TEMP);
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numfullpathfail1++;
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return (ENOTDIR);
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}
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CACHE_LOCK();
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error = vn_fullpath1(td, vn, fdp->fd_rdir, buf, retbuf, MAXPATHLEN);
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FILEDESC_UNLOCK(fdp);
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mtx_unlock(&Giant);
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if (!error)
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*freebuf = buf;
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else
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free(buf, M_TEMP);
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return (error);
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}
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/*
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* The magic behind kern___getcwd() and vn_fullpath().
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*/
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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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mtx_assert(&Giant, MA_OWNED);
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bp = buf + buflen - 1;
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*bp = '\0';
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error = 0;
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slash_prefixed = 0;
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CACHE_LOCK();
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numfullpathcalls++;
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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) {
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numfullpathfail2++;
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CACHE_UNLOCK();
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FILEDESC_UNLOCK(fdp);
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free(buf, M_TEMP);
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return (ENOENT);
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}
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if (vp != vn && ncp->nc_dvp != vp->v_dd) {
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numfullpathfail3++;
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CACHE_UNLOCK();
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FILEDESC_UNLOCK(fdp);
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free(buf, M_TEMP);
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return (EBADF);
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}
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for (i = ncp->nc_nlen - 1; i >= 0; i--) {
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if (bp == buf) {
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numfullpathfail4++;
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CACHE_UNLOCK();
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FILEDESC_UNLOCK(fdp);
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free(buf, M_TEMP);
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return (ENOMEM);
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}
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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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}
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if (bp == buf) {
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numfullpathfail4++;
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CACHE_UNLOCK();
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FILEDESC_UNLOCK(fdp);
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free(buf, M_TEMP);
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return (ENOMEM);
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}
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*--bp = '/';
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slash_prefixed = 1;
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vp = ncp->nc_dvp;
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}
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while (vp != rdir && vp != rootvnode) {
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if (vp->v_vflag & VV_ROOT) {
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if (vp->v_mount == NULL) { /* forced unmount */
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error = EBADF;
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break;
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}
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vp = vp->v_mount->mnt_vnodecovered;
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continue;
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}
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if (vp->v_dd->v_id != vp->v_ddid) {
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numfullpathfail1++;
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error = ENOTDIR;
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break;
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}
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ncp = TAILQ_FIRST(&vp->v_cache_dst);
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if (!ncp) {
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numfullpathfail2++;
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error = ENOENT;
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break;
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}
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MPASS(ncp->nc_dvp == vp->v_dd);
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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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error = ENOMEM;
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break;
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}
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*--bp = '/';
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slash_prefixed = 1;
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vp = ncp->nc_dvp;
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}
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if (error) {
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CACHE_UNLOCK();
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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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FILEDESC_UNLOCK(fdp);
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free(buf, M_TEMP);
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CACHE_UNLOCK();
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return (ENOMEM);
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} else {
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*--bp = '/';
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}
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*--bp = '/';
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}
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FILEDESC_UNLOCK(fdp);
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numfullpathfound++;
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CACHE_UNLOCK();
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*retbuf = bp;
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*freebuf = buf;
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return (0);
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}
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