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[/] [or1k/] [trunk/] [rc203soc/] [sw/] [uClinux/] [fs/] [ext2/] [dir.c] - Blame information for rev 1765

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Line No. Rev Author Line
1 1628 jcastillo
/*
2
 *  linux/fs/ext2/dir.c
3
 *
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 * Copyright (C) 1992, 1993, 1994, 1995
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 * Remy Card (card@masi.ibp.fr)
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 * Laboratoire MASI - Institut Blaise Pascal
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 * Universite Pierre et Marie Curie (Paris VI)
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 *
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 *  from
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 *
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 *  linux/fs/minix/dir.c
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 *
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 *  Copyright (C) 1991, 1992  Linus Torvalds
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 *
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 *  ext2 directory handling functions
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 *
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 *  Big-endian to little-endian byte-swapping/bitmaps by
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 *        David S. Miller (davem@caip.rutgers.edu), 1995
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 */
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#include <asm/segment.h>
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#include <linux/errno.h>
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#include <linux/fs.h>
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#include <linux/ext2_fs.h>
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#include <linux/sched.h>
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#include <linux/stat.h>
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static int ext2_dir_read (struct inode * inode, struct file * filp,
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                            char * buf, int count)
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{
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        return -EISDIR;
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}
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static int ext2_readdir (struct inode *, struct file *, void *, filldir_t);
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static struct file_operations ext2_dir_operations = {
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        NULL,                   /* lseek - default */
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        ext2_dir_read,          /* read */
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        NULL,                   /* write - bad */
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        ext2_readdir,           /* readdir */
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        NULL,                   /* select - default */
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        ext2_ioctl,             /* ioctl */
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        NULL,                   /* mmap */
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        NULL,                   /* no special open code */
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        NULL,                   /* no special release code */
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        ext2_sync_file,         /* fsync */
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        NULL,                   /* fasync */
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        NULL,                   /* check_media_change */
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        NULL                    /* revalidate */
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};
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/*
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 * directories can handle most operations...
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 */
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struct inode_operations ext2_dir_inode_operations = {
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        &ext2_dir_operations,   /* default directory file-ops */
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        ext2_create,            /* create */
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        ext2_lookup,            /* lookup */
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        ext2_link,              /* link */
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        ext2_unlink,            /* unlink */
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        ext2_symlink,           /* symlink */
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        ext2_mkdir,             /* mkdir */
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        ext2_rmdir,             /* rmdir */
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        ext2_mknod,             /* mknod */
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        ext2_rename,            /* rename */
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        NULL,                   /* readlink */
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        NULL,                   /* follow_link */
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        NULL,                   /* readpage */
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        NULL,                   /* writepage */
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        NULL,                   /* bmap */
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        ext2_truncate,          /* truncate */
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        ext2_permission,        /* permission */
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        NULL                    /* smap */
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};
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int ext2_check_dir_entry (const char * function, struct inode * dir,
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                          struct ext2_dir_entry * de, struct buffer_head * bh,
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                          unsigned long offset)
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{
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        const char * error_msg = NULL;
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        if (swab16(de->rec_len) < EXT2_DIR_REC_LEN(1))
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                error_msg = "rec_len is smaller than minimal";
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        else if (swab16(de->rec_len) % 4 != 0)
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                error_msg = "rec_len % 4 != 0";
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        else if (swab16(de->rec_len) < EXT2_DIR_REC_LEN(swab16(de->name_len)))
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                error_msg = "rec_len is too small for name_len";
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        else if (dir && ((char *) de - bh->b_data) + swab16(de->rec_len) >
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                 dir->i_sb->s_blocksize)
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                error_msg = "directory entry across blocks";
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        else if (dir && swab32(de->inode) > swab32(dir->i_sb->u.ext2_sb.s_es->s_inodes_count))
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                error_msg = "inode out of bounds";
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95
        if (error_msg != NULL)
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                ext2_error (dir->i_sb, function, "bad entry in directory #%lu: %s - "
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                            "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
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                            dir->i_ino, error_msg, offset,
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                            (unsigned long) swab32(de->inode),
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                            swab16(de->rec_len), swab16(de->name_len));
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        return error_msg == NULL ? 1 : 0;
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}
103
 
104
static int ext2_readdir (struct inode * inode, struct file * filp,
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                         void * dirent, filldir_t filldir)
106
{
107
        int error = 0;
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        unsigned long offset, blk;
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        int i, num, stored;
110
        struct buffer_head * bh, * tmp, * bha[16];
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        struct ext2_dir_entry * de;
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        struct super_block * sb;
113
        int err;
114
 
115
        if (!inode || !S_ISDIR(inode->i_mode))
116
                return -EBADF;
117
        sb = inode->i_sb;
118
 
119
        stored = 0;
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        bh = NULL;
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        offset = filp->f_pos & (sb->s_blocksize - 1);
122
 
123
        while (!error && !stored && filp->f_pos < inode->i_size) {
124
                blk = (filp->f_pos) >> EXT2_BLOCK_SIZE_BITS(sb);
125
                bh = ext2_bread (inode, blk, 0, &err);
126
                if (!bh) {
127
                        ext2_error (sb, "ext2_readdir",
128
                                    "directory #%lu contains a hole at offset %lu",
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                                    inode->i_ino, (unsigned long)filp->f_pos);
130
                        filp->f_pos += sb->s_blocksize - offset;
131
                        continue;
132
                }
133
 
134
                /*
135
                 * Do the readahead
136
                 */
137
                if (!offset) {
138
                        for (i = 16 >> (EXT2_BLOCK_SIZE_BITS(sb) - 9), num = 0;
139
                             i > 0; i--) {
140
                                tmp = ext2_getblk (inode, ++blk, 0, &err);
141
                                if (tmp && !buffer_uptodate(tmp) && !buffer_locked(tmp))
142
                                        bha[num++] = tmp;
143
                                else
144
                                        brelse (tmp);
145
                        }
146
                        if (num) {
147
                                ll_rw_block (READA, num, bha);
148
                                for (i = 0; i < num; i++)
149
                                        brelse (bha[i]);
150
                        }
151
                }
152
 
153
revalidate:
154
                /* If the dir block has changed since the last call to
155
                 * readdir(2), then we might be pointing to an invalid
156
                 * dirent right now.  Scan from the start of the block
157
                 * to make sure. */
158
                if (filp->f_version != inode->i_version) {
159
                        for (i = 0; i < sb->s_blocksize && i < offset; ) {
160
                                de = (struct ext2_dir_entry *)
161
                                        (bh->b_data + i);
162
                                /* It's too expensive to do a full
163
                                 * dirent test each time round this
164
                                 * loop, but we do have to test at
165
                                 * least that it is non-zero.  A
166
                                 * failure will be detected in the
167
                                 * dirent test below. */
168
                                if (swab16(de->rec_len) < EXT2_DIR_REC_LEN(1))
169
                                        break;
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                                i += swab16(de->rec_len);
171
                        }
172
                        offset = i;
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                        filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
174
                                | offset;
175
                        filp->f_version = inode->i_version;
176
                }
177
 
178
                while (!error && filp->f_pos < inode->i_size
179
                       && offset < sb->s_blocksize) {
180
                        de = (struct ext2_dir_entry *) (bh->b_data + offset);
181
                        if (!ext2_check_dir_entry ("ext2_readdir", inode, de,
182
                                                   bh, offset)) {
183
                                /* On error, skip the f_pos to the
184
                                   next block. */
185
                                filp->f_pos = (filp->f_pos & (sb->s_blocksize - 1))
186
                                              + sb->s_blocksize;
187
                                brelse (bh);
188
                                return stored;
189
                        }
190
                        offset += swab16(de->rec_len);
191
                        if (swab32(de->inode)) {
192
                                /* We might block in the next section
193
                                 * if the data destination is
194
                                 * currently swapped out.  So, use a
195
                                 * version stamp to detect whether or
196
                                 * not the directory has been modified
197
                                 * during the copy operation. */
198
                                unsigned long version;
199
                                dcache_add(inode, de->name, swab16(de->name_len),
200
                                           swab32(de->inode));
201
                                version = inode->i_version;
202
                                error = filldir(dirent, de->name, swab16(de->name_len), filp->f_pos, swab32(de->inode));
203
                                if (error)
204
                                        break;
205
                                if (version != inode->i_version)
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                                        goto revalidate;
207
                                stored ++;
208
                        }
209
                        filp->f_pos += swab16(de->rec_len);
210
                }
211
                offset = 0;
212
                brelse (bh);
213
        }
214
        UPDATE_ATIME(inode);
215
        return 0;
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}

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