fs/freevxfs/vxfs_lookup.c

   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_SIZE / (sbp)->s_blocksize))
  49
  50
  51 static struct dentry *  vxfs_lookup(struct inode *, struct dentry *, unsigned int);
  52 static int              vxfs_readdir(struct file *, struct dir_context *);
  53
  54 const struct inode_operations vxfs_dir_inode_ops = {
  55         .lookup =               vxfs_lookup,
  56 };
  57
  58 const struct file_operations vxfs_dir_operations = {
  59         .llseek =               generic_file_llseek,
  60         .read =                 generic_read_dir,
  61         .iterate_shared =       vxfs_readdir,
  62 };
  63
  64 static inline u_long
  65 dir_blocks(struct inode *ip)
  66 {
  67         u_long                  bsize = ip->i_sb->s_blocksize;
  68         return (ip->i_size + bsize - 1) & ~(bsize - 1);
  69 }
  70
  71 /*
  72  * NOTE! unlike strncmp, vxfs_match returns 1 for success, 0 for failure.
  73  *
  74  * len <= VXFS_NAMELEN and de != NULL are guaranteed by caller.
  75  */
  76 static inline int
  77 vxfs_match(struct vxfs_sb_info *sbi, int len, const char *const name,
  78                 struct vxfs_direct *de)
  79 {
  80         if (len != fs16_to_cpu(sbi, de->d_namelen))
  81                 return 0;
  82         if (!de->d_ino)
  83                 return 0;
  84         return !memcmp(name, de->d_name, len);
  85 }
  86
  87 static inline struct vxfs_direct *
  88 vxfs_next_entry(struct vxfs_sb_info *sbi, struct vxfs_direct *de)
  89 {
  90         return ((struct vxfs_direct *)
  91                 ((char *)de + fs16_to_cpu(sbi, de->d_reclen)));
  92 }
  93
  94 /**
  95  * vxfs_find_entry - find a mathing directory entry for a dentry
  96  * @ip:         directory inode
  97  * @dp:         dentry for which we want to find a direct
  98  * @ppp:        gets filled with the page the return value sits in
  99  *
 100  * Description:
 101  *   vxfs_find_entry finds a &struct vxfs_direct for the VFS directory
 102  *   cache entry @dp.  @ppp will be filled with the page the return
 103  *   value resides in.
 104  *
 105  * Returns:
 106  *   The wanted direct on success, else a NULL pointer.
 107  */
 108 static struct vxfs_direct *
 109 vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
 110 {
 111         struct vxfs_sb_info             *sbi = VXFS_SBI(ip->i_sb);
 112         u_long                          npages, page, nblocks, pblocks, block;
 113         u_long                          bsize = ip->i_sb->s_blocksize;
 114         const char                      *name = dp->d_name.name;
 115         int                             namelen = dp->d_name.len;
 116
 117         npages = dir_pages(ip);
 118         nblocks = dir_blocks(ip);
 119         pblocks = VXFS_BLOCK_PER_PAGE(ip->i_sb);
 120
 121         for (page = 0; page < npages; page++) {
 122                 caddr_t                 kaddr;
 123                 struct page             *pp;
 124
 125                 pp = vxfs_get_page(ip->i_mapping, page);
 126                 if (IS_ERR(pp))
 127                         continue;
 128                 kaddr = (caddr_t)page_address(pp);
 129
 130                 for (block = 0; block <= nblocks && block <= pblocks; block++) {
 131                         caddr_t                 baddr, limit;
 132                         struct vxfs_dirblk      *dbp;
 133                         struct vxfs_direct      *de;
 134
 135                         baddr = kaddr + (block * bsize);
 136                         limit = baddr + bsize - VXFS_DIRLEN(1);
 137
 138                         dbp = (struct vxfs_dirblk *)baddr;
 139                         de = (struct vxfs_direct *)
 140                                 (baddr + VXFS_DIRBLKOV(sbi, dbp));
 141
 142                         for (; (caddr_t)de <= limit;
 143                                         de = vxfs_next_entry(sbi, de)) {
 144                                 if (!de->d_reclen)
 145                                         break;
 146                                 if (!de->d_ino)
 147                                         continue;
 148                                 if (vxfs_match(sbi, namelen, name, de)) {
 149                                         *ppp = pp;
 150                                         return (de);
 151                                 }
 152                         }
 153                 }
 154                 vxfs_put_page(pp);
 155         }
 156
 157         return NULL;
 158 }
 159
 160 /**
 161  * vxfs_inode_by_name - find inode number for dentry
 162  * @dip:        directory to search in
 163  * @dp:         dentry we search for
 164  *
 165  * Description:
 166  *   vxfs_inode_by_name finds out the inode number of
 167  *   the path component described by @dp in @dip.
 168  *
 169  * Returns:
 170  *   The wanted inode number on success, else Zero.
 171  */
 172 static ino_t
 173 vxfs_inode_by_name(struct inode *dip, struct dentry *dp)
 174 {
 175         struct vxfs_direct              *de;
 176         struct page                     *pp;
 177         ino_t                           ino = 0;
 178
 179         de = vxfs_find_entry(dip, dp, &pp);
 180         if (de) {
 181                 ino = fs32_to_cpu(VXFS_SBI(dip->i_sb), de->d_ino);
 182                 kunmap(pp);
 183                 put_page(pp);
 184         }
 185
 186         return (ino);
 187 }
 188
 189 /**
 190  * vxfs_lookup - lookup pathname component
 191  * @dip:        dir in which we lookup
 192  * @dp:         dentry we lookup
 193  * @flags:      lookup flags
 194  *
 195  * Description:
 196  *   vxfs_lookup tries to lookup the pathname component described
 197  *   by @dp in @dip.
 198  *
 199  * Returns:
 200  *   A NULL-pointer on success, else a negative error code encoded
 201  *   in the return pointer.
 202  */
 203 static struct dentry *
 204 vxfs_lookup(struct inode *dip, struct dentry *dp, unsigned int flags)
 205 {
 206         struct inode            *ip = NULL;
 207         ino_t                   ino;
 208
 209         if (dp->d_name.len > VXFS_NAMELEN)
 210                 return ERR_PTR(-ENAMETOOLONG);
 211
 212         ino = vxfs_inode_by_name(dip, dp);
 213         if (ino) {
 214                 ip = vxfs_iget(dip->i_sb, ino);
 215                 if (IS_ERR(ip))
 216                         return ERR_CAST(ip);
 217         }
 218         d_add(dp, ip);
 219         return NULL;
 220 }
 221
 222 /**
 223  * vxfs_readdir - read a directory
 224  * @fp:         the directory to read
 225  * @retp:       return buffer
 226  * @filler:     filldir callback
 227  *
 228  * Description:
 229  *   vxfs_readdir fills @retp with directory entries from @fp
 230  *   using the VFS supplied callback @filler.
 231  *
 232  * Returns:
 233  *   Zero.
 234  */
 235 static int
 236 vxfs_readdir(struct file *fp, struct dir_context *ctx)
 237 {
 238         struct inode            *ip = file_inode(fp);
 239         struct super_block      *sbp = ip->i_sb;
 240         struct vxfs_sb_info     *sbi = VXFS_SBI(sbp);
 241         u_long                  bsize = sbp->s_blocksize;
 242         u_long                  page, npages, block, pblocks, nblocks, offset;
 243         loff_t                  pos;
 244
 245
 246         if (ctx->pos == 0) {
 247                 if (!dir_emit_dot(fp, ctx))
 248                         return 0;
 249                 ctx->pos = 1;
 250         }
 251         if (ctx->pos == 1) {
 252                 if (!dir_emit(ctx, "..", 2, VXFS_INO(ip)->vii_dotdot, DT_DIR))
 253                         return 0;
 254                 ctx->pos = 2;
 255         }
 256         pos = ctx->pos - 2;
 257
 258         if (pos > VXFS_DIRROUND(ip->i_size))
 259                 return 0;
 260
 261         npages = dir_pages(ip);
 262         nblocks = dir_blocks(ip);
 263         pblocks = VXFS_BLOCK_PER_PAGE(sbp);
 264
 265         page = pos >> PAGE_SHIFT;
 266         offset = pos & ~PAGE_MASK;
 267         block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;
 268
 269         for (; page < npages; page++, block = 0) {
 270                 char                    *kaddr;
 271                 struct page             *pp;
 272
 273                 pp = vxfs_get_page(ip->i_mapping, page);
 274                 if (IS_ERR(pp))
 275                         continue;
 276                 kaddr = (char *)page_address(pp);
 277
 278                 for (; block <= nblocks && block <= pblocks; block++) {
 279                         char                    *baddr, *limit;
 280                         struct vxfs_dirblk      *dbp;
 281                         struct vxfs_direct      *de;
 282
 283                         baddr = kaddr + (block * bsize);
 284                         limit = baddr + bsize - VXFS_DIRLEN(1);
 285
 286                         dbp = (struct vxfs_dirblk *)baddr;
 287                         de = (struct vxfs_direct *)
 288                                 (offset ?
 289                                  (kaddr + offset) :
 290                                  (baddr + VXFS_DIRBLKOV(sbi, dbp)));
 291
 292                         for (; (char *)de <= limit;
 293                                         de = vxfs_next_entry(sbi, de)) {
 294                                 if (!de->d_reclen)
 295                                         break;
 296                                 if (!de->d_ino)
 297                                         continue;
 298
 299                                 offset = (char *)de - kaddr;
 300                                 ctx->pos = ((page << PAGE_SHIFT) | offset) + 2;
 301                                 if (!dir_emit(ctx, de->d_name,
 302                                                 fs16_to_cpu(sbi, de->d_namelen),
 303                                                 fs32_to_cpu(sbi, de->d_ino),
 304                                                 DT_UNKNOWN)) {
 305                                         vxfs_put_page(pp);
 306                                         return 0;
 307                                 }
 308                         }
 309                         offset = 0;
 310                 }
 311                 vxfs_put_page(pp);
 312                 offset = 0;
 313         }
 314         ctx->pos = ((page << PAGE_SHIFT) | offset) + 2;
 315         return 0;
 316 }