lustre/obdfs/dir.c

   1 /*
   2  *  linux/fs/ext2/dir.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  from
  10  *
  11  *  linux/fs/minix/dir.c
  12  *
  13  *  Copyright (C) 1991, 1992  Linus Torvalds
  14  *
  15  *  ext2 directory handling functions
  16  *
  17  *  Big-endian to little-endian byte-swapping/bitmaps by
  18  *        David S. Miller (davem@caip.rutgers.edu), 1995
  19  *
  20  *  Changes for use with Object Based Device File System
  21  *
  22  *  Copyright (C) 1999, Seagate Technology Inc.
  23  *   (author Peter J. Braam, braam@stelias.com)
  24  *
  25  */
  26
  27 #include <asm/uaccess.h>
  28
  29 #include <linux/errno.h>
  30 #include <linux/fs.h>
  31 #include <linux/ext2_fs.h>
  32 #include <linux/fcntl.h>
  33 #include <linux/sched.h>
  34 #include <linux/stat.h>
  35 #include <linux/string.h>
  36 #include <linux/locks.h>
  37 #include <linux/quotaops.h>
  38 #include <linux/iobuf.h>
  39 #include <linux/obd_support.h>
  40 #include <linux/obdfs.h>
  41
  42 static ssize_t obdfs_dir_read (struct file * filp, char * buf,
  43                               size_t count, loff_t *ppos)
  44 {
  45         return -EISDIR;
  46 }
  47
  48 static int obdfs_readdir(struct file *, void *, filldir_t);
  49
  50 struct file_operations obdfs_dir_operations = {
  51         NULL,                   /* lseek - default */
  52         obdfs_dir_read,         /* read */
  53         NULL,                   /* write - bad */
  54         obdfs_readdir,          /* readdir */
  55         NULL,                   /* poll - default */
  56         NULL,                   /* ioctl */
  57         NULL,                   /* mmap */
  58         NULL,                   /* no special open code */
  59         NULL,                   /* flush */
  60         NULL,                   /* no special release code */
  61         NULL,                   /* fsync */
  62         NULL,                   /* fasync */
  63         NULL                    /* lock */
  64 };
  65
  66 struct inode_operations obdfs_dir_inode_operations = {
  67         &obdfs_dir_operations,  /* default directory file-ops */
  68         obdfs_create,           /* create */
  69         obdfs_lookup,           /* lookup */
  70         obdfs_link,             /* link */
  71         obdfs_unlink,           /* unlink */
  72         obdfs_symlink,          /* symlink */
  73         obdfs_mkdir,            /* mkdir */
  74         obdfs_rmdir,            /* rmdir */
  75         obdfs_mknod,            /* mknod */
  76         obdfs_rename,           /* rename */
  77         NULL,                   /* readlink */
  78         NULL,                   /* follow_link */
  79         NULL,                   /* get_block */
  80         obdfs_readpage,         /* readpage */
  81         obdfs_writepage,        /* writepage */
  82         NULL,                   /* truncate */
  83         NULL,                   /* permission */
  84         NULL                    /* revalidate */
  85 };
  86
  87 int obdfs_check_dir_entry (const char * function, struct inode * dir,
  88                           struct ext2_dir_entry_2 * de,
  89                           struct page * page,
  90                           unsigned long offset)
  91 {
  92         const char * error_msg = NULL;
  93         return 1;
  94
  95         ENTRY;
  96         if ( !de ) {
  97                 error_msg = "null de passed";
  98                 return 1;
  99         }
 100
 101         if (le16_to_cpu(de->rec_len) < EXT2_DIR_REC_LEN(1))
 102                 error_msg = "rec_len is smaller than minimal";
 103         else if (le16_to_cpu(de->rec_len) % 4 != 0)
 104                 error_msg = "rec_len % 4 != 0";
 105         else if (le16_to_cpu(de->rec_len) < EXT2_DIR_REC_LEN(de->name_len))
 106                 error_msg = "rec_len is too small for name_len";
 107         else if (dir && ((char *) de - (char *)page_address(page)) + le16_to_cpu(de->rec_len) >
 108                  dir->i_sb->s_blocksize)
 109                 error_msg = "directory entry across blocks";
 110 #if 0 /* this one doesn't yet work for OBDFS */
 111         else
 112
 113 if (dir && le32_to_cpu(de->inode) > le32_to_cpu(dir->i_sb->u.ext2_sb.s_es->s_inodes_count))
 114                 error_msg = "inode out of bounds";
 115 #endif
 116         if (error_msg != NULL)
 117                 ext2_error (dir->i_sb, function, "bad entry in directory #%lu: %s - "
 118                             "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
 119                             dir->i_ino, error_msg, offset,
 120                             (unsigned long) le32_to_cpu(de->inode),
 121                             le16_to_cpu(de->rec_len), de->name_len);
 122         EXIT;
 123         return error_msg == NULL ? 1 : 0;
 124 }
 125
 126
 127 static int obdfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
 128 {
 129         int error = 0;
 130         unsigned long offset;
 131         int stored;
 132         struct ext2_dir_entry_2 * de;
 133         struct super_block * sb;
 134         struct page *page;
 135         struct inode *inode = filp->f_dentry->d_inode;
 136
 137         ENTRY;
 138
 139         sb = inode->i_sb;
 140
 141         stored = 0;
 142         offset = filp->f_pos & (PAGE_SIZE - 1);
 143
 144         OIDEBUG(inode);
 145         while (!error && !stored && filp->f_pos < inode->i_size) {
 146                 page = obdfs_getpage(inode, offset, 0, LOCKED);
 147                 PDEBUG(page, "readdir");
 148                 if (!page) {
 149                         ext2_error (sb, "ext2_readdir",
 150                                     "directory #%lu contains a hole at offset %lu",
 151                                     inode->i_ino, (unsigned long)filp->f_pos);
 152                         filp->f_pos += PAGE_SIZE - offset;
 153                         continue;
 154                 }
 155
 156 #if 0
 157                 /* XXX need to do read ahead and support stuff below */
 158 revalidate:
 159                 /* If the dir block has changed since the last call to
 160                  * readdir(2), then we might be pointing to an invalid
 161                  * dirent right now.  Scan from the start of the block
 162                  * to make sure. */
 163                 if (filp->f_version != inode->i_version) {
 164                         for (i = 0; i < sb->s_blocksize && i < offset; ) {
 165                                 de = (struct ext2_dir_entry_2 *)
 166                                         (bh->b_data + i);
 167                                 /* It's too expensive to do a full
 168                                  * dirent test each time round this
 169                                  * loop, but we do have to test at
 170                                  * least that it is non-zero.  A
 171                                  * failure will be detected in the
 172                                  * dirent test below. */
 173                                 if (le16_to_cpu(de->rec_len) < EXT2_DIR_REC_LEN(1))
 174                                         break;
 175                                 i += le16_to_cpu(de->rec_len);
 176                         }
 177                         offset = i;
 178                         filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
 179                                 | offset;
 180                         filp->f_version = inode->i_version;
 181                 }
 182 #endif
 183                 while (!error && filp->f_pos < inode->i_size
 184                        && offset < PAGE_SIZE) {
 185                         de = (struct ext2_dir_entry_2 *) ((char *)page_address(page) + offset);
 186 #if 0
 187                         if (!obdfs_check_dir_entry ("ext2_readdir", inode, de,
 188                                                    bh, offset)) {
 189                                 /* On error, skip the f_pos to the
 190                                    next block. */
 191                                 filp->f_pos = (filp->f_pos & (sb->s_blocksize - 1))
 192                                               + sb->s_blocksize;
 193                                 brelse (bh);
 194                                 return stored;
 195                         }
 196 #endif
 197                         offset += le16_to_cpu(de->rec_len);
 198                         if (le32_to_cpu(de->inode)) {
 199                                 /* We might block in the next section
 200                                  * if the data destination is
 201                                  * currently swapped out.  So, use a
 202                                  * version stamp to detect whether or
 203                                  * not the directory has been modified
 204                                  * during the copy operation.
 205                                  */
 206                                 /* XXX
 207                                 unsigned long version = inode->i_version;
 208                                  */
 209                                 error = filldir(dirent, de->name,
 210                                                 de->name_len,
 211                                                 filp->f_pos, le32_to_cpu(de->inode));
 212                                 if (error)
 213                                         break;
 214 #if 0
 215                                 if (version != inode->i_version)
 216                                         goto revalidate;
 217 #endif
 218                                 stored ++;
 219                         }
 220                         filp->f_pos += le16_to_cpu(de->rec_len);
 221                 }
 222                 offset = 0;
 223                 UnlockPage(page);
 224                 page_cache_release(page);
 225         }
 226         UPDATE_ATIME(inode);
 227         EXIT;
 228         return 0;
 229 }