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