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 #include <linux/smp_lock.h>
  40
  41 #include "vxfs.h"
  42 #include "vxfs_dir.h"
  43 #include "vxfs_inode.h"
  44 #include "vxfs_extern.h"
  45
  46 /*
  47  * Number of VxFS blocks per page.
  48  */
  49 #define VXFS_BLOCK_PER_PAGE(sbp)  ((PAGE_CACHE_SIZE / (sbp)->s_blocksize))
  50
  51
  52 static struct dentry *  vxfs_lookup(struct inode *, struct dentry *, struct nameidata *);
  53 static int              vxfs_readdir(struct file *, void *, filldir_t);
  54
  55 const struct inode_operations vxfs_dir_inode_ops = {
  56         .lookup =               vxfs_lookup,
  57 };
  58
  59 const struct file_operations vxfs_dir_operations = {
  60         .readdir =              vxfs_readdir,
  61 };
  62
  63
  64 static inline u_long
  65 dir_pages(struct inode *inode)
  66 {
  67         return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
  68 }
  69
  70 static inline u_long
  71 dir_blocks(struct inode *ip)
  72 {
  73         u_long                  bsize = ip->i_sb->s_blocksize;
  74         return (ip->i_size + bsize - 1) & ~(bsize - 1);
  75 }
  76
  77 /*
  78  * NOTE! unlike strncmp, vxfs_match returns 1 for success, 0 for failure.
  79  *
  80  * len <= VXFS_NAMELEN and de != NULL are guaranteed by caller.
  81  */
  82 static inline int
  83 vxfs_match(int len, const char * const name, struct vxfs_direct *de)
  84 {
  85         if (len != de->d_namelen)
  86                 return 0;
  87         if (!de->d_ino)
  88                 return 0;
  89         return !memcmp(name, de->d_name, len);
  90 }
  91
  92 static inline struct vxfs_direct *
  93 vxfs_next_entry(struct vxfs_direct *de)
  94 {
  95         return ((struct vxfs_direct *)((char*)de + de->d_reclen));
  96 }
  97
  98 /**
  99  * vxfs_find_entry - find a mathing directory entry for a dentry
 100  * @ip:         directory inode
 101  * @dp:         dentry for which we want to find a direct
 102  * @ppp:        gets filled with the page the return value sits in
 103  *
 104  * Description:
 105  *   vxfs_find_entry finds a &struct vxfs_direct for the VFS directory
 106  *   cache entry @dp.  @ppp will be filled with the page the return
 107  *   value resides in.
 108  *
 109  * Returns:
 110  *   The wanted direct on success, else a NULL pointer.
 111  */
 112 static struct vxfs_direct *
 113 vxfs_find_entry(struct inode *ip, struct dentry *dp, struct page **ppp)
 114 {
 115         u_long                          npages, page, nblocks, pblocks, block;
 116         u_long                          bsize = ip->i_sb->s_blocksize;
 117         const char                      *name = dp->d_name.name;
 118         int                             namelen = dp->d_name.len;
 119
 120         npages = dir_pages(ip);
 121         nblocks = dir_blocks(ip);
 122         pblocks = VXFS_BLOCK_PER_PAGE(ip->i_sb);
 123
 124         for (page = 0; page < npages; page++) {
 125                 caddr_t                 kaddr;
 126                 struct page             *pp;
 127
 128                 pp = vxfs_get_page(ip->i_mapping, page);
 129                 if (IS_ERR(pp))
 130                         continue;
 131                 kaddr = (caddr_t)page_address(pp);
 132
 133                 for (block = 0; block <= nblocks && block <= pblocks; block++) {
 134                         caddr_t                 baddr, limit;
 135                         struct vxfs_dirblk      *dbp;
 136                         struct vxfs_direct      *de;
 137
 138                         baddr = kaddr + (block * bsize);
 139                         limit = baddr + bsize - VXFS_DIRLEN(1);
 140
 141                         dbp = (struct vxfs_dirblk *)baddr;
 142                         de = (struct vxfs_direct *)(baddr + VXFS_DIRBLKOV(dbp));
 143
 144                         for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
 145                                 if (!de->d_reclen)
 146                                         break;
 147                                 if (!de->d_ino)
 148                                         continue;
 149                                 if (vxfs_match(namelen, name, de)) {
 150                                         *ppp = pp;
 151                                         return (de);
 152                                 }
 153                         }
 154                 }
 155                 vxfs_put_page(pp);
 156         }
 157
 158         return NULL;
 159 }
 160
 161 /**
 162  * vxfs_inode_by_name - find inode number for dentry
 163  * @dip:        directory to search in
 164  * @dp:         dentry we seach for
 165  *
 166  * Description:
 167  *   vxfs_inode_by_name finds out the inode number of
 168  *   the path component described by @dp in @dip.
 169  *
 170  * Returns:
 171  *   The wanted inode number on success, else Zero.
 172  */
 173 static ino_t
 174 vxfs_inode_by_name(struct inode *dip, struct dentry *dp)
 175 {
 176         struct vxfs_direct              *de;
 177         struct page                     *pp;
 178         ino_t                           ino = 0;
 179
 180         de = vxfs_find_entry(dip, dp, &pp);
 181         if (de) {
 182                 ino = de->d_ino;
 183                 kunmap(pp);
 184                 page_cache_release(pp);
 185         }
 186
 187         return (ino);
 188 }
 189
 190 /**
 191  * vxfs_lookup - lookup pathname component
 192  * @dip:        dir in which we lookup
 193  * @dp:         dentry we lookup
 194  * @nd:         lookup nameidata
 195  *
 196  * Description:
 197  *   vxfs_lookup tries to lookup the pathname component described
 198  *   by @dp in @dip.
 199  *
 200  * Returns:
 201  *   A NULL-pointer on success, else an negative error code encoded
 202  *   in the return pointer.
 203  */
 204 static struct dentry *
 205 vxfs_lookup(struct inode *dip, struct dentry *dp, struct nameidata *nd)
 206 {
 207         struct inode            *ip = NULL;
 208         ino_t                   ino;
 209
 210         if (dp->d_name.len > VXFS_NAMELEN)
 211                 return ERR_PTR(-ENAMETOOLONG);
 212
 213         lock_kernel();
 214         ino = vxfs_inode_by_name(dip, dp);
 215         if (ino) {
 216                 ip = iget(dip->i_sb, ino);
 217                 if (!ip) {
 218                         unlock_kernel();
 219                         return ERR_PTR(-EACCES);
 220                 }
 221         }
 222         unlock_kernel();
 223         d_add(dp, ip);
 224         return NULL;
 225 }
 226
 227 /**
 228  * vxfs_readdir - read a directory
 229  * @fp:         the directory to read
 230  * @retp:       return buffer
 231  * @filler:     filldir callback
 232  *
 233  * Description:
 234  *   vxfs_readdir fills @retp with directory entries from @fp
 235  *   using the VFS supplied callback @filler.
 236  *
 237  * Returns:
 238  *   Zero.
 239  */
 240 static int
 241 vxfs_readdir(struct file *fp, void *retp, filldir_t filler)
 242 {
 243         struct inode            *ip = fp->f_path.dentry->d_inode;
 244         struct super_block      *sbp = ip->i_sb;
 245         u_long                  bsize = sbp->s_blocksize;
 246         u_long                  page, npages, block, pblocks, nblocks, offset;
 247         loff_t                  pos;
 248
 249         lock_kernel();
 250
 251         switch ((long)fp->f_pos) {
 252         case 0:
 253                 if (filler(retp, ".", 1, fp->f_pos, ip->i_ino, DT_DIR) < 0)
 254                         goto out;
 255                 fp->f_pos++;
 256                 /* fallthrough */
 257         case 1:
 258                 if (filler(retp, "..", 2, fp->f_pos, VXFS_INO(ip)->vii_dotdot, DT_DIR) < 0)
 259                         goto out;
 260                 fp->f_pos++;
 261                 /* fallthrough */
 262         }
 263
 264         pos = fp->f_pos - 2;
 265
 266         if (pos > VXFS_DIRROUND(ip->i_size)) {
 267                 unlock_kernel();
 268                 return 0;
 269         }
 270
 271         npages = dir_pages(ip);
 272         nblocks = dir_blocks(ip);
 273         pblocks = VXFS_BLOCK_PER_PAGE(sbp);
 274
 275         page = pos >> PAGE_CACHE_SHIFT;
 276         offset = pos & ~PAGE_CACHE_MASK;
 277         block = (u_long)(pos >> sbp->s_blocksize_bits) % pblocks;
 278
 279         for (; page < npages; page++, block = 0) {
 280                 caddr_t                 kaddr;
 281                 struct page             *pp;
 282
 283                 pp = vxfs_get_page(ip->i_mapping, page);
 284                 if (IS_ERR(pp))
 285                         continue;
 286                 kaddr = (caddr_t)page_address(pp);
 287
 288                 for (; block <= nblocks && block <= pblocks; block++) {
 289                         caddr_t                 baddr, limit;
 290                         struct vxfs_dirblk      *dbp;
 291                         struct vxfs_direct      *de;
 292
 293                         baddr = kaddr + (block * bsize);
 294                         limit = baddr + bsize - VXFS_DIRLEN(1);
 295
 296                         dbp = (struct vxfs_dirblk *)baddr;
 297                         de = (struct vxfs_direct *)
 298                                 (offset ?
 299                                  (kaddr + offset) :
 300                                  (baddr + VXFS_DIRBLKOV(dbp)));
 301
 302                         for (; (caddr_t)de <= limit; de = vxfs_next_entry(de)) {
 303                                 int     over;
 304
 305                                 if (!de->d_reclen)
 306                                         break;
 307                                 if (!de->d_ino)
 308                                         continue;
 309
 310                                 offset = (caddr_t)de - kaddr;
 311                                 over = filler(retp, de->d_name, de->d_namelen,
 312                                         ((page << PAGE_CACHE_SHIFT) | offset) + 2,
 313                                         de->d_ino, DT_UNKNOWN);
 314                                 if (over) {
 315                                         vxfs_put_page(pp);
 316                                         goto done;
 317                                 }
 318                         }
 319                         offset = 0;
 320                 }
 321                 vxfs_put_page(pp);
 322                 offset = 0;
 323         }
 324
 325 done:
 326         fp->f_pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
 327 out:
 328         unlock_kernel();
 329         return 0;
 330 }