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_CACHE_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 =              vxfs_readdir,
  62 };
  63
  64
  65 static inline u_long
  66 dir_pages(struct inode *inode)
  67 {
  68         return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
  69 }
  70
  71 static inline u_long
  72 dir_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  */
  83 static inline int
  84 vxfs_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
  93 static inline struct vxfs_direct *
  94 vxfs_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  */
 113 static struct vxfs_direct *
 114 vxfs_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  */
 174 static ino_t
 175 vxfs_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  * @flags:      lookup flags
 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  */
 205 static struct dentry *
 206 vxfs_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  */
 237 static int
 238 vxfs_readdir(struct file *fp, struct dir_context *ctx)
 239 {
 240         struct inode            *ip = file_inode(fp);
 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         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_CACHE_SHIFT;
 266         offset = pos & ~PAGE_CACHE_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(dbp)));
 291
 292                         for (; (char *)de <= limit; de = vxfs_next_entry(de)) {
 293                                 if (!de->d_reclen)
 294                                         break;
 295                                 if (!de->d_ino)
 296                                         continue;
 297
 298                                 offset = (char *)de - kaddr;
 299                                 ctx->pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
 300                                 if (!dir_emit(ctx, de->d_name, de->d_namelen,
 301                                         de->d_ino, DT_UNKNOWN)) {
 302                                         vxfs_put_page(pp);
 303                                         return 0;
 304                                 }
 305                         }
 306                         offset = 0;
 307                 }
 308                 vxfs_put_page(pp);
 309                 offset = 0;
 310         }
 311         ctx->pos = ((page << PAGE_CACHE_SHIFT) | offset) + 2;
 312         return 0;
 313 }