/* $NetBSD: filecore_lookup.c,v 1.23 2024/09/08 09:36:51 rillig Exp $ */ /*- * 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. 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 */ /*- * Copyright (c) 1998 Andrew McMurry * * 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 1.23 2024/09/08 09:36:51 rillig 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> /* * 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 a 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(void *v) { struct vop_lookup_v2_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 buf *bp; /* a buffer of directory entries */ struct filecore_direntry *de; int numdirpasses; /* strategy for directory search */ int error; u_short namelen; int res; const char *name; struct vnode **vpp = ap->a_vpp; struct componentname *cnp = ap->a_cnp; kauth_cred_t cred = cnp->cn_cred; int flags; int nameiop = cnp->cn_nameiop; int i, endsearch; flags = cnp->cn_flags; bp = NULL; *vpp = NULL; vdp = ap->a_dvp; dp = VTOI(vdp); /* * Check accessibility of directory. */ if ((error = VOP_ACCESS(vdp, VEXEC, cred)) != 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 (cache_lookup(vdp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_nameiop, cnp->cn_flags, NULL, vpp)) { return *vpp == NULLVP ? ENOENT : 0; } 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; namecache_count_2passes(); } endsearch = FILECORE_MAXDIRENTS; if ((flags & ISDOTDOT) || (name[0] == '.' && namelen == 1)) goto found; error = filecore_dbread(dp, &bp); if (error) { 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, 0); } /* * Insert name into cache (as non-existent) if appropriate. */ cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags); return (nameiop == CREATE || nameiop == RENAME) ? EROFS : ENOENT; found: if (numdirpasses == 2) namecache_count_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; if (name[0] == '.' && namelen == 1) { vref(vdp); /* we want ourself, ie "." */ *vpp = vdp; } else { ino_t ino; if (flags & ISDOTDOT) { ino = filecore_getparent(dp); } else { ino = dp->i_dirent.addr | (i << FILECORE_INO_INDEX); #ifdef FILECORE_DEBUG_BR printf("brelse(%p) lo4\n", bp); #endif brelse(bp, 0); } error = vcache_get(vdp->v_mount, &ino, sizeof(ino), vpp); if (error) return error; } /* * Insert name into cache if appropriate. */ cache_enter(vdp, *vpp, cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_flags); return 0; }
