312 lines
10 KiB
C
312 lines
10 KiB
C
/* $NetBSD: filecore_lookup.c,v 1.3 2003/06/29 22:31:09 fvdl Exp $ */
|
|
|
|
/*-
|
|
* Copyright (c) 1998 Andrew McMurry
|
|
* Copyright (c) 1989, 1993, 1994 The Regents of the University of California.
|
|
* All rights reserved.
|
|
*
|
|
* 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.
|
|
*
|
|
* filecore_lookup.c 1.1 1998/6/26
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__KERNEL_RCSID(0, "$NetBSD: filecore_lookup.c,v 1.3 2003/06/29 22:31:09 fvdl Exp $");
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/namei.h>
|
|
#include <sys/buf.h>
|
|
#include <sys/file.h>
|
|
#include <sys/vnode.h>
|
|
#include <sys/mount.h>
|
|
#include <sys/systm.h>
|
|
|
|
#include <fs/filecorefs/filecore.h>
|
|
#include <fs/filecorefs/filecore_extern.h>
|
|
#include <fs/filecorefs/filecore_node.h>
|
|
|
|
struct nchstats filecore_nchstats;
|
|
|
|
/*
|
|
* Convert a component of a pathname into a pointer to a locked inode.
|
|
* This is a very central and rather complicated routine.
|
|
* If the file system is not maintained in a strict tree hierarchy,
|
|
* this can result in a deadlock situation (see comments in code below).
|
|
*
|
|
* 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 and the target of the pathname
|
|
* exists, lookup returns both the target and its parent directory locked.
|
|
* When creating or renaming and LOCKPARENT is specified, the target may
|
|
* not be ".". When deleting and LOCKPARENT is specified, the target may
|
|
* be "."., but the caller must check to ensure it does an vrele and iput
|
|
* instead of two iputs.
|
|
*
|
|
* Overall outline of ufs_lookup:
|
|
*
|
|
* check accessibility of directory
|
|
* look for name in cache, if found, then if at end of path
|
|
* and deleting or creating, drop it, else return name
|
|
* search for name in directory, to found or notfound
|
|
* notfound:
|
|
* if creating, return locked directory, leaving info on available slots
|
|
* else return error
|
|
* found:
|
|
* if at end of path and deleting, return information to allow delete
|
|
* if at end of path and rewriting (RENAME and LOCKPARENT), lock target
|
|
* inode and return info to allow rewrite
|
|
* if not at end, add name to cache; if at end and neither creating
|
|
* nor deleting, add name to cache
|
|
*
|
|
* NOTE: (LOOKUP | LOCKPARENT) currently returns the parent inode unlocked.
|
|
*/
|
|
int
|
|
filecore_lookup(v)
|
|
void *v;
|
|
{
|
|
struct vop_lookup_args /* {
|
|
struct vnode *a_dvp;
|
|
struct vnode **a_vpp;
|
|
struct componentname *a_cnp;
|
|
} */ *ap = v;
|
|
struct vnode *vdp; /* vnode for directory being searched */
|
|
struct filecore_node *dp; /* inode for directory being searched */
|
|
struct filecore_mnt *fcmp; /* file system that directory is in */
|
|
struct buf *bp; /* a buffer of directory entries */
|
|
struct filecore_direntry *de;
|
|
int numdirpasses; /* strategy for directory search */
|
|
struct vnode *pdp; /* saved dp during symlink work */
|
|
struct vnode *tdp; /* returned by filecore_vget_internal */
|
|
int lockparent; /* 1 => lockparent flag is set */
|
|
int wantparent; /* 1 => wantparent or lockparent flag */
|
|
int error;
|
|
u_short namelen;
|
|
int res;
|
|
const char *name;
|
|
struct vnode **vpp = ap->a_vpp;
|
|
struct componentname *cnp = ap->a_cnp;
|
|
struct ucred *cred = cnp->cn_cred;
|
|
int flags;
|
|
int nameiop = cnp->cn_nameiop;
|
|
int i, endsearch;
|
|
|
|
cnp->cn_flags &= ~PDIRUNLOCK;
|
|
flags = cnp->cn_flags;
|
|
|
|
bp = NULL;
|
|
*vpp = NULL;
|
|
vdp = ap->a_dvp;
|
|
dp = VTOI(vdp);
|
|
fcmp = dp->i_mnt;
|
|
lockparent = flags & LOCKPARENT;
|
|
wantparent = flags & (LOCKPARENT|WANTPARENT);
|
|
|
|
/*
|
|
* Check accessiblity of directory.
|
|
*/
|
|
if ((error = VOP_ACCESS(vdp, VEXEC, cred, cnp->cn_proc)) != 0)
|
|
return (error);
|
|
|
|
if ((flags & ISLASTCN) && (vdp->v_mount->mnt_flag & MNT_RDONLY) &&
|
|
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
|
|
return (EROFS);
|
|
|
|
/*
|
|
* We now have a segment name to search for, and a directory to search.
|
|
*
|
|
* Before tediously performing a linear scan of the directory,
|
|
* check the name cache to see if the directory/name pair
|
|
* we are looking for is known already.
|
|
*/
|
|
if ((error = cache_lookup(vdp, vpp, cnp)) >= 0)
|
|
return (error);
|
|
|
|
name = cnp->cn_nameptr;
|
|
namelen = cnp->cn_namelen;
|
|
|
|
/*
|
|
* If there is cached information on a previous search of
|
|
* this directory, pick up where we last left off.
|
|
* We cache only lookups as these are the most common
|
|
* and have the greatest payoff. Caching CREATE has little
|
|
* benefit as it usually must search the entire directory
|
|
* to determine that the entry does not exist. Caching the
|
|
* location of the last DELETE or RENAME has not reduced
|
|
* profiling time and hence has been removed in the interest
|
|
* of simplicity.
|
|
*/
|
|
if (nameiop != LOOKUP || dp->i_diroff == 0 ||
|
|
dp->i_diroff >= FILECORE_MAXDIRENTS) {
|
|
i = 0;
|
|
numdirpasses = 1;
|
|
} else {
|
|
i = dp->i_diroff;
|
|
numdirpasses = 2;
|
|
filecore_nchstats.ncs_2passes++;
|
|
}
|
|
endsearch = FILECORE_MAXDIRENTS;
|
|
|
|
if ((flags & ISDOTDOT) || (name[0] == '.' && namelen == 1))
|
|
goto found;
|
|
|
|
error = filecore_dbread(dp, &bp);
|
|
if (error) {
|
|
brelse(bp);
|
|
return error;
|
|
}
|
|
|
|
de = fcdirentry(bp->b_data, i);
|
|
|
|
searchloop:
|
|
while (de->name[0] != 0 && i < endsearch) {
|
|
/*
|
|
* Check for a name match.
|
|
*/
|
|
res = filecore_fncmp(de->name, name, namelen);
|
|
|
|
if (res == 0)
|
|
goto found;
|
|
if (res < 0)
|
|
goto notfound;
|
|
|
|
i++;
|
|
de++;
|
|
}
|
|
|
|
notfound:
|
|
/*
|
|
* If we started in the middle of the directory and failed
|
|
* to find our target, we must check the beginning as well.
|
|
*/
|
|
if (numdirpasses == 2) {
|
|
numdirpasses--;
|
|
i = 0;
|
|
de = fcdirentry(bp->b_data, i);
|
|
endsearch = dp->i_diroff;
|
|
goto searchloop;
|
|
}
|
|
if (bp != NULL) {
|
|
#ifdef FILECORE_DEBUG_BR
|
|
printf("brelse(%p) lo1\n", bp);
|
|
#endif
|
|
brelse(bp);
|
|
}
|
|
|
|
/*
|
|
* Insert name into cache (as non-existent) if appropriate.
|
|
*/
|
|
if (cnp->cn_flags & MAKEENTRY)
|
|
cache_enter(vdp, *vpp, cnp);
|
|
if (nameiop == CREATE || nameiop == RENAME)
|
|
return (EROFS);
|
|
return (ENOENT);
|
|
|
|
found:
|
|
if (numdirpasses == 2)
|
|
filecore_nchstats.ncs_pass2++;
|
|
|
|
/*
|
|
* Found component in pathname.
|
|
* If the final component of path name, save information
|
|
* in the cache as to where the entry was found.
|
|
*/
|
|
if ((flags & ISLASTCN) && nameiop == LOOKUP)
|
|
dp->i_diroff = i;
|
|
|
|
/*
|
|
* Step through the translation in the name. We do not `iput' the
|
|
* directory because we may need it again if a symbolic link
|
|
* is relative to the current directory. Instead we save it
|
|
* unlocked as "pdp". We must get the target inode before unlocking
|
|
* the directory to insure that the inode will not be removed
|
|
* before we get it. We prevent deadlock by always fetching
|
|
* inodes from the root, moving down the directory tree. Thus
|
|
* when following backward pointers ".." we must unlock the
|
|
* parent directory before getting the requested directory.
|
|
* There is a potential race condition here if both the current
|
|
* and parent directories are removed before the `iget' for the
|
|
* inode associated with ".." returns. We hope that this occurs
|
|
* infrequently since we cannot avoid this race condition without
|
|
* implementing a sophisticated deadlock detection algorithm.
|
|
* Note also that this simple deadlock detection scheme will not
|
|
* work if the file system has any hard links other than ".."
|
|
* that point backwards in the directory structure.
|
|
*/
|
|
pdp = vdp;
|
|
/*
|
|
* If ino is different from dp->i_ino,
|
|
* it's a relocated directory.
|
|
*/
|
|
if (flags & ISDOTDOT) {
|
|
ino_t pin = filecore_getparent(dp);
|
|
VOP_UNLOCK(pdp, 0); /* race to get the inode */
|
|
cnp->cn_flags |= PDIRUNLOCK;
|
|
error = VFS_VGET(vdp->v_mount, pin, &tdp);
|
|
if (error) {
|
|
if (vn_lock(pdp, LK_EXCLUSIVE | LK_RETRY) == 0)
|
|
cnp->cn_flags &= ~PDIRUNLOCK;
|
|
return (error);
|
|
}
|
|
if (lockparent && (flags & ISLASTCN)) {
|
|
if ((error = vn_lock(pdp, LK_EXCLUSIVE))) {
|
|
vput(tdp);
|
|
return (error);
|
|
}
|
|
cnp->cn_flags &= ~PDIRUNLOCK;
|
|
}
|
|
*vpp = tdp;
|
|
} else if (name[0] == '.' && namelen == 1) {
|
|
VREF(vdp); /* we want ourself, ie "." */
|
|
*vpp = vdp;
|
|
} else {
|
|
#ifdef FILECORE_DEBUG_BR
|
|
printf("brelse(%p) lo4\n", bp);
|
|
#endif
|
|
brelse(bp);
|
|
error = VFS_VGET(vdp->v_mount, dp->i_dirent.addr |
|
|
(i << FILECORE_INO_INDEX), &tdp);
|
|
if (error)
|
|
return (error);
|
|
if (!lockparent || !(flags & ISLASTCN)) {
|
|
VOP_UNLOCK(pdp, 0);
|
|
cnp->cn_flags |= PDIRUNLOCK;
|
|
}
|
|
*vpp = tdp;
|
|
}
|
|
|
|
/*
|
|
* Insert name into cache if appropriate.
|
|
*/
|
|
if (cnp->cn_flags & MAKEENTRY)
|
|
cache_enter(vdp, *vpp, cnp);
|
|
return (0);
|
|
}
|