linux/fs/freevxfs/vxfs_lookup.c
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   1/*
   2 * Copyright (c) 2000-2001 Christoph Hellwig.
   3 * All rights reserved.
   4 *
   5 * Redistribution and use in source and binary forms, with or without
   6 * modification, are permitted provided that the following conditions
   7 * are met:
   8 * 1. Redistributions of source code must retain the above copyright
   9 *    notice, this list of conditions, and the following disclaimer,
  10 *    without modification.
  11 * 2. The name of the author may not be used to endorse or promote products
  12 *    derived from this software without specific prior written permission.
  13 *
  14 * Alternatively, this software may be distributed under the terms of the
  15 * GNU General Public License ("GPL").
  16 *
  17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
  21 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27 * SUCH DAMAGE.
  28 */
  29
  30/*
  31 * Veritas filesystem driver - lookup and other directory related code.
  32 */
  33#include <linux/fs.h>
  34#include <linux/time.h>
  35#include <linux/mm.h>
  36#include <linux/highmem.h>
  37#include <linux/kernel.h>
  38#include <linux/pagemap.h>
  39
  40#include "vxfs.h"
  41#include "vxfs_dir.h"
  42#include "vxfs_inode.h"
  43#include "vxfs_extern.h"
  44
  45/*
  46 * Number of VxFS blocks per page.
  47 */
  48#define VXFS_BLOCK_PER_PAGE(sbp)  ((PAGE_CACHE_SIZE / (sbp)->s_blocksize))
  49
  50
  51static struct dentry *  vxfs_lookup(struct inode *, struct dentry *, unsigned int);
  52static int              vxfs_readdir(struct file *, void *, filldir_t);
  53
  54const struct inode_operations vxfs_dir_inode_ops = {
  55        .lookup =               vxfs_lookup,
  56};
  57
  58const struct file_operations vxfs_dir_operations = {
  59        .llseek =               generic_file_llseek,
  60        .read =                 generic_read_dir,
  61        .readdir =              vxfs_readdir,
  62};
  63
  64 
  65static inline u_long
  66dir_pages(struct inode *inode)
  67{
  68        return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
  69}
  70 
  71static inline u_long
  72dir_blocks(struct inode *ip)
  73{
  74        u_long                  bsize = ip->i_sb->s_blocksize;
  75        return (ip->i_size + bsize - 1) & ~(bsize - 1);
  76}
  77
  78/*
  79 * NOTE! unlike strncmp, vxfs_match returns 1 for success, 0 for failure.
  80 *
  81 * len <= VXFS_NAMELEN and de != NULL are guaranteed by caller.
  82 */
  83static inline int
  84vxfs_match(int len, const char * const name, struct vxfs_direct *de)
  85{
  86        if (len != de->d_namelen)
  87                return 0;
  88        if (!de->d_ino)
  89                return 0;
  90        return !memcmp(name, de->d_name, len);
  91}
  92
  93static inline struct vxfs_direct *
  94vxfs_next_entry(struct vxfs_direct *de)
  95{
  96        return ((struct vxfs_direct *)((char*)de + de->d_reclen));
  97}
  98
  99/**
 100 * vxfs_find_entry - find a mathing directory entry for a dentry
 101 * @ip:         directory inode
 102 * @dp:         dentry for which we want to find a direct
 103 * @ppp:        gets filled with the page the return value sits in
 104 *
 105 * Description:
 106 *   vxfs_find_entry finds a &struct vxfs_direct for the VFS directory
 107 *   cache entry @dp.  @ppp will be filled with the page the return
 108 *   value resides in.
 109 *
 110 * Returns:
 111 *   The wanted direct on success, else a NULL pointer.
 112 */
 113static struct vxfs_direct *
 114vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
 115{
 116        u_long                          npages, page, nblocks, pblocks, block;
 117        u_long                          bsize = ip->i_sb->s_blocksize;
 118        const char                      *name = dp->d_name.name;
 119        int                             namelen = dp->d_name.len;
 120
 121        npages = dir_pages(ip);
 122        nblocks = dir_blocks(ip);
 123        pblocks = VXFS_BLOCK_PER_PAGE(ip->i_sb);
 124        
 125        for (page = 0; page < npages; page++) {
 126                caddr_t                 kaddr;
 127                struct page             *pp;
 128
 129                pp = vxfs_get_page(ip->i_mapping, page);
 130                if (IS_ERR(pp))
 131                        continue;
 132                kaddr = (caddr_t)page_address(pp);
 133
 134                for (block = 0; block <= nblocks && block <= pblocks; block++) {
 135                        caddr_t                 baddr, limit;
 136                        struct vxfs_dirblk      *dbp;
 137                        struct vxfs_direct      *de;
 138
 139                        baddr = kaddr + (block * bsize);
 140                        limit = baddr + bsize - VXFS_DIRLEN(1);
 141                        
 142                        dbp = (struct vxfs_dirblk *)baddr;
 143                        de = (struct vxfs_direct *)(baddr + VXFS_DIRBLKOV(dbp));
 144
 145                        for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
 146                                if (!de->d_reclen)
 147                                        break;
 148                                if (!de->d_ino)
 149                                        continue;
 150                                if (vxfs_match(namelen, name, de)) {
 151                                        *ppp = pp;
 152                                        return (de);
 153                                }
 154                        }
 155                }
 156                vxfs_put_page(pp);
 157        }
 158
 159        return NULL;
 160}
 161
 162/**
 163 * vxfs_inode_by_name - find inode number for dentry
 164 * @dip:        directory to search in
 165 * @dp:         dentry we search for
 166 *
 167 * Description:
 168 *   vxfs_inode_by_name finds out the inode number of
 169 *   the path component described by @dp in @dip.
 170 *
 171 * Returns:
 172 *   The wanted inode number on success, else Zero.
 173 */
 174static ino_t
 175vxfs_inode_by_name(struct inode *dip, struct dentry *dp)
 176{
 177        struct vxfs_direct              *de;
 178        struct page                     *pp;
 179        ino_t                           ino = 0;
 180
 181        de = vxfs_find_entry(dip, dp, &pp);
 182        if (de) {
 183                ino = de->d_ino;
 184                kunmap(pp);
 185                page_cache_release(pp);
 186        }
 187        
 188        return (ino);
 189}
 190
 191/**
 192 * vxfs_lookup - lookup pathname component
 193 * @dip:        dir in which we lookup
 194 * @dp:         dentry we lookup
 195 * @nd:         lookup nameidata
 196 *
 197 * Description:
 198 *   vxfs_lookup tries to lookup the pathname component described
 199 *   by @dp in @dip.
 200 *
 201 * Returns:
 202 *   A NULL-pointer on success, else an negative error code encoded
 203 *   in the return pointer.
 204 */
 205static struct dentry *
 206vxfs_lookup(struct inode *dip, struct dentry *dp, unsigned int flags)
 207{
 208        struct inode            *ip = NULL;
 209        ino_t                   ino;
 210                         
 211        if (dp->d_name.len > VXFS_NAMELEN)
 212                return ERR_PTR(-ENAMETOOLONG);
 213                                 
 214        ino = vxfs_inode_by_name(dip, dp);
 215        if (ino) {
 216                ip = vxfs_iget(dip->i_sb, ino);
 217                if (IS_ERR(ip))
 218                        return ERR_CAST(ip);
 219        }
 220        d_add(dp, ip);
 221        return NULL;
 222}
 223
 224/**
 225 * vxfs_readdir - read a directory
 226 * @fp:         the directory to read
 227 * @retp:       return buffer
 228 * @filler:     filldir callback
 229 *
 230 * Description:
 231 *   vxfs_readdir fills @retp with directory entries from @fp
 232 *   using the VFS supplied callback @filler.
 233 *
 234 * Returns:
 235 *   Zero.
 236 */
 237static int
 238vxfs_readdir(struct file *fp, void *retp, filldir_t filler)
 239{
 240        struct inode            *ip = fp->f_path.dentry->d_inode;
 241        struct super_block      *sbp = ip->i_sb;
 242        u_long                  bsize = sbp->s_blocksize;
 243        u_long                  page, npages, block, pblocks, nblocks, offset;
 244        loff_t                  pos;
 245
 246        switch ((long)fp->f_pos) {
 247        case 0:
 248                if (filler(retp, ".", 1, fp->f_pos, ip->i_ino, DT_DIR) < 0)
 249                        goto out;
 250                fp->f_pos++;
 251                /* fallthrough */
 252        case 1:
 253                if (filler(retp, "..", 2, fp->f_pos, VXFS_INO(ip)->vii_dotdot, DT_DIR) < 0)
 254                        goto out;
 255                fp->f_pos++;
 256                /* fallthrough */
 257        }
 258
 259        pos = fp->f_pos - 2;
 260        
 261        if (pos > VXFS_DIRROUND(ip->i_size))
 262                return 0;
 263
 264        npages = dir_pages(ip);
 265        nblocks = dir_blocks(ip);
 266        pblocks = VXFS_BLOCK_PER_PAGE(sbp);
 267
 268        page = pos >> PAGE_CACHE_SHIFT;
 269        offset = pos & ~PAGE_CACHE_MASK;
 270        block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;
 271
 272        for (; page < npages; page++, block = 0) {
 273                caddr_t                 kaddr;
 274                struct page             *pp;
 275
 276                pp = vxfs_get_page(ip->i_mapping, page);
 277                if (IS_ERR(pp))
 278                        continue;
 279                kaddr = (caddr_t)page_address(pp);
 280
 281                for (; block <= nblocks && block <= pblocks; block++) {
 282                        caddr_t                 baddr, limit;
 283                        struct vxfs_dirblk      *dbp;
 284                        struct vxfs_direct      *de;
 285
 286                        baddr = kaddr + (block * bsize);
 287                        limit = baddr + bsize - VXFS_DIRLEN(1);
 288        
 289                        dbp = (struct vxfs_dirblk *)baddr;
 290                        de = (struct vxfs_direct *)
 291                                (offset ?
 292                                 (kaddr + offset) :
 293                                 (baddr + VXFS_DIRBLKOV(dbp)));
 294
 295                        for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
 296                                int     over;
 297
 298                                if (!de->d_reclen)
 299                                        break;
 300                                if (!de->d_ino)
 301                                        continue;
 302
 303                                offset = (caddr_t)de - kaddr;
 304                                over = filler(retp, de->d_name, de->d_namelen,
 305                                        ((page << PAGE_CACHE_SHIFT) | offset) + 2,
 306                                        de->d_ino, DT_UNKNOWN);
 307                                if (over) {
 308                                        vxfs_put_page(pp);
 309                                        goto done;
 310                                }
 311                        }
 312                        offset = 0;
 313                }
 314                vxfs_put_page(pp);
 315                offset = 0;
 316        }
 317
 318done:
 319        fp->f_pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
 320out:
 321        return 0;
 322}
 323
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