freebsd-dev/sys/kern/vfs_lookup.c
John Dyson 99448ed11d Change the M_NAMEI allocations to use the zone allocator. This change
plus the previous changes to use the zone allocator decrease the useage
of malloc by half.  The Zone allocator will be upgradeable to be able
to use per CPU-pools, and has more intelligent usage of SPLs.  Additionally,
it has reasonable stats gathering capabilities, while making most calls
inline.
1997-09-21 04:24:27 +00:00

698 lines
19 KiB
C

/*
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)vfs_lookup.c 8.4 (Berkeley) 2/16/94
* $Id: vfs_lookup.c,v 1.19 1997/09/02 20:06:01 bde Exp $
*/
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/filedesc.h>
#include <sys/proc.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
/*
* Convert a pathname into a pointer to a locked inode.
*
* The FOLLOW flag is set when symbolic links are to be followed
* when they occur at the end of the name translation process.
* Symbolic links are always followed for all other pathname
* components other than the last.
*
* The segflg defines whether the name is to be copied from user
* space or kernel space.
*
* Overall outline of namei:
*
* copy in name
* get starting directory
* while (!done && !error) {
* call lookup to search path.
* if symbolic link, massage name in buffer and continue
* }
*/
int
namei(ndp)
register struct nameidata *ndp;
{
register struct filedesc *fdp; /* pointer to file descriptor state */
register char *cp; /* pointer into pathname argument */
register struct vnode *dp; /* the directory we are searching */
struct iovec aiov; /* uio for reading symbolic links */
struct uio auio;
int error, linklen;
struct componentname *cnp = &ndp->ni_cnd;
struct proc *p = cnp->cn_proc;
ndp->ni_cnd.cn_cred = ndp->ni_cnd.cn_proc->p_ucred;
#ifdef DIAGNOSTIC
if (!cnp->cn_cred || !cnp->cn_proc)
panic ("namei: bad cred/proc");
if (cnp->cn_nameiop & (~OPMASK))
panic ("namei: nameiop contaminated with flags");
if (cnp->cn_flags & OPMASK)
panic ("namei: flags contaminated with nameiops");
#endif
fdp = cnp->cn_proc->p_fd;
/*
* Get a buffer for the name to be translated, and copy the
* name into the buffer.
*/
if ((cnp->cn_flags & HASBUF) == 0)
cnp->cn_pnbuf = zalloc(namei_zone);
if (ndp->ni_segflg == UIO_SYSSPACE)
error = copystr(ndp->ni_dirp, cnp->cn_pnbuf,
MAXPATHLEN, (u_int *)&ndp->ni_pathlen);
else
error = copyinstr(ndp->ni_dirp, cnp->cn_pnbuf,
MAXPATHLEN, (u_int *)&ndp->ni_pathlen);
/*
* Don't allow empty pathnames.
*/
if (!error && *cnp->cn_pnbuf == '\0')
error = ENOENT;
if (error) {
zfree(namei_zone, cnp->cn_pnbuf);
ndp->ni_vp = NULL;
return (error);
}
ndp->ni_loopcnt = 0;
#ifdef KTRACE
if (KTRPOINT(cnp->cn_proc, KTR_NAMEI))
ktrnamei(cnp->cn_proc->p_tracep, cnp->cn_pnbuf);
#endif
/*
* Get starting point for the translation.
*/
if ((ndp->ni_rootdir = fdp->fd_rdir) == NULL)
ndp->ni_rootdir = rootvnode;
dp = fdp->fd_cdir;
VREF(dp);
for (;;) {
/*
* Check if root directory should replace current directory.
* Done at start of translation and after symbolic link.
*/
cnp->cn_nameptr = cnp->cn_pnbuf;
if (*(cnp->cn_nameptr) == '/') {
vrele(dp);
while (*(cnp->cn_nameptr) == '/') {
cnp->cn_nameptr++;
ndp->ni_pathlen--;
}
dp = ndp->ni_rootdir;
VREF(dp);
}
ndp->ni_startdir = dp;
error = lookup(ndp);
if (error) {
zfree(namei_zone, cnp->cn_pnbuf);
return (error);
}
/*
* Check for symbolic link
*/
if ((cnp->cn_flags & ISSYMLINK) == 0) {
if ((cnp->cn_flags & (SAVENAME | SAVESTART)) == 0)
zfree(namei_zone, cnp->cn_pnbuf);
else
cnp->cn_flags |= HASBUF;
return (0);
}
if ((cnp->cn_flags & LOCKPARENT) && ndp->ni_pathlen == 1)
VOP_UNLOCK(ndp->ni_dvp, 0, p);
if (ndp->ni_loopcnt++ >= MAXSYMLINKS) {
error = ELOOP;
break;
}
if (ndp->ni_pathlen > 1)
cp = zalloc(namei_zone);
else
cp = cnp->cn_pnbuf;
aiov.iov_base = cp;
aiov.iov_len = MAXPATHLEN;
auio.uio_iov = &aiov;
auio.uio_iovcnt = 1;
auio.uio_offset = 0;
auio.uio_rw = UIO_READ;
auio.uio_segflg = UIO_SYSSPACE;
auio.uio_procp = (struct proc *)0;
auio.uio_resid = MAXPATHLEN;
error = VOP_READLINK(ndp->ni_vp, &auio, cnp->cn_cred);
if (error) {
if (ndp->ni_pathlen > 1)
zfree(namei_zone, cp);
break;
}
linklen = MAXPATHLEN - auio.uio_resid;
if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
if (ndp->ni_pathlen > 1)
zfree(namei_zone, cp);
error = ENAMETOOLONG;
break;
}
if (ndp->ni_pathlen > 1) {
bcopy(ndp->ni_next, cp + linklen, ndp->ni_pathlen);
zfree(namei_zone, cnp->cn_pnbuf);
cnp->cn_pnbuf = cp;
} else
cnp->cn_pnbuf[linklen] = '\0';
ndp->ni_pathlen += linklen;
vput(ndp->ni_vp);
dp = ndp->ni_dvp;
}
zfree(namei_zone, cnp->cn_pnbuf);
vrele(ndp->ni_dvp);
vput(ndp->ni_vp);
ndp->ni_vp = NULL;
return (error);
}
/*
* Search a pathname.
* This is a very central and rather complicated routine.
*
* The pathname is pointed to by ni_ptr and is of length ni_pathlen.
* The starting directory is taken from ni_startdir. The pathname is
* descended until done, or a symbolic link is encountered. The variable
* ni_more is clear if the path is completed; it is set to one if a
* symbolic link needing interpretation is encountered.
*
* The flag argument is LOOKUP, CREATE, RENAME, or DELETE depending on
* whether the name is to be looked up, created, renamed, or deleted.
* When CREATE, RENAME, or DELETE is specified, information usable in
* creating, renaming, or deleting a directory entry may be calculated.
* If flag has LOCKPARENT or'ed into it, the parent directory is returned
* locked. If flag has WANTPARENT or'ed into it, the parent directory is
* returned unlocked. Otherwise the parent directory is not returned. If
* the target of the pathname exists and LOCKLEAF is or'ed into the flag
* the target is returned locked, otherwise it is returned unlocked.
* When creating or renaming and LOCKPARENT is specified, the target may not
* be ".". When deleting and LOCKPARENT is specified, the target may be ".".
*
* Overall outline of lookup:
*
* dirloop:
* identify next component of name at ndp->ni_ptr
* handle degenerate case where name is null string
* if .. and crossing mount points and on mounted filesys, find parent
* call VOP_LOOKUP routine for next component name
* directory vnode returned in ni_dvp, unlocked unless LOCKPARENT set
* component vnode returned in ni_vp (if it exists), locked.
* if result vnode is mounted on and crossing mount points,
* find mounted on vnode
* if more components of name, do next level at dirloop
* return the answer in ni_vp, locked if LOCKLEAF set
* if LOCKPARENT set, return locked parent in ni_dvp
* if WANTPARENT set, return unlocked parent in ni_dvp
*/
int
lookup(ndp)
register struct nameidata *ndp;
{
register char *cp; /* pointer into pathname argument */
register struct vnode *dp = 0; /* the directory we are searching */
struct vnode *tdp; /* saved dp */
struct mount *mp; /* mount table entry */
int docache; /* == 0 do not cache last component */
int wantparent; /* 1 => wantparent or lockparent flag */
int rdonly; /* lookup read-only flag bit */
int trailing_slash;
int error = 0;
struct componentname *cnp = &ndp->ni_cnd;
struct proc *p = cnp->cn_proc;
/*
* Setup: break out flag bits into variables.
*/
wantparent = cnp->cn_flags & (LOCKPARENT | WANTPARENT);
docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
if (cnp->cn_nameiop == DELETE ||
(wantparent && cnp->cn_nameiop != CREATE &&
cnp->cn_nameiop != LOOKUP))
docache = 0;
rdonly = cnp->cn_flags & RDONLY;
ndp->ni_dvp = NULL;
cnp->cn_flags &= ~ISSYMLINK;
dp = ndp->ni_startdir;
ndp->ni_startdir = NULLVP;
vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p);
dirloop:
/*
* Search a new directory.
*
* The cn_hash value is for use by vfs_cache.
* The last component of the filename is left accessible via
* cnp->cn_nameptr for callers that need the name. Callers needing
* the name set the SAVENAME flag. When done, they assume
* responsibility for freeing the pathname buffer.
*/
cnp->cn_consume = 0;
cnp->cn_hash = 0;
for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
cnp->cn_hash += (unsigned char)*cp;
cnp->cn_namelen = cp - cnp->cn_nameptr;
if (cnp->cn_namelen > NAME_MAX) {
error = ENAMETOOLONG;
goto bad;
}
#ifdef NAMEI_DIAGNOSTIC
{ char c = *cp;
*cp = '\0';
printf("{%s}: ", cnp->cn_nameptr);
*cp = c; }
#endif
ndp->ni_pathlen -= cnp->cn_namelen;
ndp->ni_next = cp;
/*
* Replace multiple slashes by a single slash and trailing slashes
* by a null. This must be done before VOP_LOOKUP() because some
* fs's don't know about trailing slashes. Remember if there were
* trailing slashes to handle symlinks, existing non-directories
* and non-existing files that won't be directories specially later.
*/
trailing_slash = 0;
while (*cp == '/' && (cp[1] == '/' || cp[1] == '\0')) {
cp++;
ndp->ni_pathlen--;
if (*cp == '\0') {
trailing_slash = 1;
*ndp->ni_next = '\0'; /* XXX for direnter() ... */
}
}
ndp->ni_next = cp;
cnp->cn_flags |= MAKEENTRY;
if (*cp == '\0' && docache == 0)
cnp->cn_flags &= ~MAKEENTRY;
if (cnp->cn_namelen == 2 &&
cnp->cn_nameptr[1] == '.' && cnp->cn_nameptr[0] == '.')
cnp->cn_flags |= ISDOTDOT;
else
cnp->cn_flags &= ~ISDOTDOT;
if (*ndp->ni_next == 0)
cnp->cn_flags |= ISLASTCN;
else
cnp->cn_flags &= ~ISLASTCN;
/*
* Check for degenerate name (e.g. / or "")
* which is a way of talking about a directory,
* e.g. like "/." or ".".
*/
if (cnp->cn_nameptr[0] == '\0') {
if (dp->v_type != VDIR) {
error = ENOTDIR;
goto bad;
}
if (cnp->cn_nameiop != LOOKUP) {
error = EISDIR;
goto bad;
}
if (wantparent) {
ndp->ni_dvp = dp;
VREF(dp);
}
ndp->ni_vp = dp;
if (!(cnp->cn_flags & (LOCKPARENT | LOCKLEAF)))
VOP_UNLOCK(dp, 0, p);
if (cnp->cn_flags & SAVESTART)
panic("lookup: SAVESTART");
return (0);
}
/*
* Handle "..": two special cases.
* 1. If at root directory (e.g. after chroot)
* or at absolute root directory
* then ignore it so can't get out.
* 2. If this vnode is the root of a mounted
* filesystem, then replace it with the
* vnode which was mounted on so we take the
* .. in the other file system.
*/
if (cnp->cn_flags & ISDOTDOT) {
for (;;) {
if (dp == ndp->ni_rootdir || dp == rootvnode) {
ndp->ni_dvp = dp;
ndp->ni_vp = dp;
VREF(dp);
goto nextname;
}
if ((dp->v_flag & VROOT) == 0 ||
(cnp->cn_flags & NOCROSSMOUNT))
break;
tdp = dp;
dp = dp->v_mount->mnt_vnodecovered;
vput(tdp);
VREF(dp);
vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p);
}
}
/*
* We now have a segment name to search for, and a directory to search.
*/
unionlookup:
ndp->ni_dvp = dp;
ndp->ni_vp = NULL;
ASSERT_VOP_LOCKED(dp, "lookup");
if (error = VOP_LOOKUP(dp, &ndp->ni_vp, cnp)) {
#ifdef DIAGNOSTIC
if (ndp->ni_vp != NULL)
panic("leaf should be empty");
#endif
#ifdef NAMEI_DIAGNOSTIC
printf("not found\n");
#endif
if ((error == ENOENT) &&
(dp->v_flag & VROOT) &&
(dp->v_mount->mnt_flag & MNT_UNION)) {
tdp = dp;
dp = dp->v_mount->mnt_vnodecovered;
vput(tdp);
VREF(dp);
vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p);
goto unionlookup;
}
if (error != EJUSTRETURN)
goto bad;
/*
* If creating and at end of pathname, then can consider
* allowing file to be created.
*/
if (rdonly) {
error = EROFS;
goto bad;
}
if (*cp == '\0' && trailing_slash &&
!(cnp->cn_flags & WILLBEDIR)) {
error = ENOENT;
goto bad;
}
/*
* We return with ni_vp NULL to indicate that the entry
* doesn't currently exist, leaving a pointer to the
* (possibly locked) directory inode in ndp->ni_dvp.
*/
if (cnp->cn_flags & SAVESTART) {
ndp->ni_startdir = ndp->ni_dvp;
VREF(ndp->ni_startdir);
}
return (0);
}
#ifdef NAMEI_DIAGNOSTIC
printf("found\n");
#endif
ASSERT_VOP_LOCKED(ndp->ni_vp, "lookup");
/*
* Take into account any additional components consumed by
* the underlying filesystem.
*/
if (cnp->cn_consume > 0) {
cnp->cn_nameptr += cnp->cn_consume;
ndp->ni_next += cnp->cn_consume;
ndp->ni_pathlen -= cnp->cn_consume;
cnp->cn_consume = 0;
}
dp = ndp->ni_vp;
/*
* Check to see if the vnode has been mounted on;
* if so find the root of the mounted file system.
*/
while (dp->v_type == VDIR && (mp = dp->v_mountedhere) &&
(cnp->cn_flags & NOCROSSMOUNT) == 0) {
if (vfs_busy(mp, 0, 0, p))
continue;
error = VFS_ROOT(mp, &tdp);
vfs_unbusy(mp, p);
if (error)
goto bad2;
vput(dp);
ndp->ni_vp = dp = tdp;
}
/*
* Check for symbolic link
*/
if ((dp->v_type == VLNK) &&
((cnp->cn_flags & FOLLOW) || trailing_slash ||
*ndp->ni_next == '/')) {
cnp->cn_flags |= ISSYMLINK;
return (0);
}
/*
* Check for bogus trailing slashes.
*/
if (trailing_slash && dp->v_type != VDIR) {
error = ENOTDIR;
goto bad2;
}
nextname:
/*
* Not a symbolic link. If more pathname,
* continue at next component, else return.
*/
if (*ndp->ni_next == '/') {
cnp->cn_nameptr = ndp->ni_next;
while (*cnp->cn_nameptr == '/') {
cnp->cn_nameptr++;
ndp->ni_pathlen--;
}
if (ndp->ni_dvp != ndp->ni_vp) {
ASSERT_VOP_UNLOCKED(ndp->ni_dvp, "lookup");
}
vrele(ndp->ni_dvp);
goto dirloop;
}
/*
* Disallow directory write attempts on read-only file systems.
*/
if (rdonly &&
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
error = EROFS;
goto bad2;
}
if (cnp->cn_flags & SAVESTART) {
ndp->ni_startdir = ndp->ni_dvp;
VREF(ndp->ni_startdir);
}
if (!wantparent)
vrele(ndp->ni_dvp);
if ((cnp->cn_flags & LOCKLEAF) == 0)
VOP_UNLOCK(dp, 0, p);
return (0);
bad2:
if ((cnp->cn_flags & LOCKPARENT) && *ndp->ni_next == '\0')
VOP_UNLOCK(ndp->ni_dvp, 0, p);
vrele(ndp->ni_dvp);
bad:
vput(dp);
ndp->ni_vp = NULL;
return (error);
}
/*
* relookup - lookup a path name component
* Used by lookup to re-aquire things.
*/
int
relookup(dvp, vpp, cnp)
struct vnode *dvp, **vpp;
struct componentname *cnp;
{
struct proc *p = cnp->cn_proc;
struct vnode *dp = 0; /* the directory we are searching */
int docache; /* == 0 do not cache last component */
int wantparent; /* 1 => wantparent or lockparent flag */
int rdonly; /* lookup read-only flag bit */
int error = 0;
#ifdef NAMEI_DIAGNOSTIC
int newhash; /* DEBUG: check name hash */
char *cp; /* DEBUG: check name ptr/len */
#endif
/*
* Setup: break out flag bits into variables.
*/
wantparent = cnp->cn_flags & (LOCKPARENT|WANTPARENT);
docache = (cnp->cn_flags & NOCACHE) ^ NOCACHE;
if (cnp->cn_nameiop == DELETE ||
(wantparent && cnp->cn_nameiop != CREATE))
docache = 0;
rdonly = cnp->cn_flags & RDONLY;
cnp->cn_flags &= ~ISSYMLINK;
dp = dvp;
vn_lock(dp, LK_EXCLUSIVE | LK_RETRY, p);
/* dirloop: */
/*
* Search a new directory.
*
* The cn_hash value is for use by vfs_cache.
* The last component of the filename is left accessible via
* cnp->cn_nameptr for callers that need the name. Callers needing
* the name set the SAVENAME flag. When done, they assume
* responsibility for freeing the pathname buffer.
*/
#ifdef NAMEI_DIAGNOSTIC
for (newhash = 0, cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
newhash += (unsigned char)*cp;
if (newhash != cnp->cn_hash)
panic("relookup: bad hash");
if (cnp->cn_namelen != cp - cnp->cn_nameptr)
panic ("relookup: bad len");
if (*cp != 0)
panic("relookup: not last component");
printf("{%s}: ", cnp->cn_nameptr);
#endif
/*
* Check for degenerate name (e.g. / or "")
* which is a way of talking about a directory,
* e.g. like "/." or ".".
*/
if (cnp->cn_nameptr[0] == '\0') {
if (cnp->cn_nameiop != LOOKUP || wantparent) {
error = EISDIR;
goto bad;
}
if (dp->v_type != VDIR) {
error = ENOTDIR;
goto bad;
}
if (!(cnp->cn_flags & LOCKLEAF))
VOP_UNLOCK(dp, 0, p);
*vpp = dp;
if (cnp->cn_flags & SAVESTART)
panic("lookup: SAVESTART");
return (0);
}
if (cnp->cn_flags & ISDOTDOT)
panic ("relookup: lookup on dot-dot");
/*
* We now have a segment name to search for, and a directory to search.
*/
if (error = VOP_LOOKUP(dp, vpp, cnp)) {
#ifdef DIAGNOSTIC
if (*vpp != NULL)
panic("leaf should be empty");
#endif
if (error != EJUSTRETURN)
goto bad;
/*
* If creating and at end of pathname, then can consider
* allowing file to be created.
*/
if (rdonly) {
error = EROFS;
goto bad;
}
/* ASSERT(dvp == ndp->ni_startdir) */
if (cnp->cn_flags & SAVESTART)
VREF(dvp);
/*
* We return with ni_vp NULL to indicate that the entry
* doesn't currently exist, leaving a pointer to the
* (possibly locked) directory inode in ndp->ni_dvp.
*/
return (0);
}
dp = *vpp;
#ifdef DIAGNOSTIC
/*
* Check for symbolic link
*/
if (dp->v_type == VLNK && (cnp->cn_flags & FOLLOW))
panic ("relookup: symlink found.\n");
#endif
/*
* Disallow directory write attempts on read-only file systems.
*/
if (rdonly &&
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
error = EROFS;
goto bad2;
}
/* ASSERT(dvp == ndp->ni_startdir) */
if (cnp->cn_flags & SAVESTART)
VREF(dvp);
if (!wantparent)
vrele(dvp);
if ((cnp->cn_flags & LOCKLEAF) == 0)
VOP_UNLOCK(dp, 0, p);
return (0);
bad2:
if ((cnp->cn_flags & LOCKPARENT) && (cnp->cn_flags & ISLASTCN))
VOP_UNLOCK(dvp, 0, p);
vrele(dvp);
bad:
vput(dp);
*vpp = NULL;
return (error);
}