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1275 |
phoenix |
/*
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* linux/fs/ext3/dir.c
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*
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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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* ext3 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 <linux/fs.h>
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#include <linux/jbd.h>
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#include <linux/ext3_fs.h>
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static unsigned char ext3_filetype_table[] = {
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DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
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};
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static int ext3_readdir(struct file *, void *, filldir_t);
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struct file_operations ext3_dir_operations = {
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read: generic_read_dir,
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readdir: ext3_readdir, /* BKL held */
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ioctl: ext3_ioctl, /* BKL held */
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fsync: ext3_sync_file, /* BKL held */
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};
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int ext3_check_dir_entry (const char * function, struct inode * dir,
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struct ext3_dir_entry_2 * de,
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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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const int rlen = le16_to_cpu(de->rec_len);
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if (rlen < EXT3_DIR_REC_LEN(1))
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error_msg = "rec_len is smaller than minimal";
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else if (rlen % 4 != 0)
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error_msg = "rec_len % 4 != 0";
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else if (rlen < EXT3_DIR_REC_LEN(de->name_len))
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error_msg = "rec_len is too small for name_len";
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else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize)
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error_msg = "directory entry across blocks";
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else if (le32_to_cpu(de->inode) >
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le32_to_cpu(dir->i_sb->u.ext3_sb.s_es->s_inodes_count))
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error_msg = "inode out of bounds";
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if (error_msg != NULL)
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ext3_error (dir->i_sb, function,
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"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) le32_to_cpu(de->inode),
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rlen, de->name_len);
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return error_msg == NULL ? 1 : 0;
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}
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static int ext3_readdir(struct file * filp,
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void * dirent, filldir_t filldir)
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{
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int error = 0;
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unsigned long offset, blk;
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int i, num, stored;
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struct buffer_head * bh, * tmp, * bha[16];
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struct ext3_dir_entry_2 * de;
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struct super_block * sb;
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int err;
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struct inode *inode = filp->f_dentry->d_inode;
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sb = inode->i_sb;
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stored = 0;
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bh = NULL;
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offset = filp->f_pos & (sb->s_blocksize - 1);
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while (!error && !stored && filp->f_pos < inode->i_size) {
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blk = (filp->f_pos) >> EXT3_BLOCK_SIZE_BITS(sb);
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bh = ext3_bread (0, inode, blk, 0, &err);
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if (!bh) {
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ext3_error (sb, "ext3_readdir",
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"directory #%lu contains a hole at offset %lu",
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inode->i_ino, (unsigned long)filp->f_pos);
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filp->f_pos += sb->s_blocksize - offset;
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continue;
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}
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/*
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* Do the readahead
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*/
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if (!offset) {
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for (i = 16 >> (EXT3_BLOCK_SIZE_BITS(sb) - 9), num = 0;
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i > 0; i--) {
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tmp = ext3_getblk (NULL, inode, ++blk, 0, &err);
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if (tmp && !buffer_uptodate(tmp) &&
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!buffer_locked(tmp))
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bha[num++] = tmp;
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else
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brelse (tmp);
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}
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if (num) {
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ll_rw_block (READA, num, bha);
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for (i = 0; i < num; i++)
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brelse (bha[i]);
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}
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}
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revalidate:
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/* If the dir block has changed since the last call to
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* readdir(2), then we might be pointing to an invalid
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* dirent right now. Scan from the start of the block
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* to make sure. */
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if (filp->f_version != inode->i_version) {
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for (i = 0; i < sb->s_blocksize && i < offset; ) {
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de = (struct ext3_dir_entry_2 *)
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(bh->b_data + i);
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/* It's too expensive to do a full
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* dirent test each time round this
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* loop, but we do have to test at
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* least that it is non-zero. A
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* failure will be detected in the
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* dirent test below. */
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if (le16_to_cpu(de->rec_len) <
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EXT3_DIR_REC_LEN(1))
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break;
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i += le16_to_cpu(de->rec_len);
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}
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offset = i;
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filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
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| offset;
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filp->f_version = inode->i_version;
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}
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while (!error && filp->f_pos < inode->i_size
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&& offset < sb->s_blocksize) {
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de = (struct ext3_dir_entry_2 *) (bh->b_data + offset);
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if (!ext3_check_dir_entry ("ext3_readdir", inode, de,
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bh, offset)) {
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/* On error, skip the f_pos to the
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next block. */
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filp->f_pos = (filp->f_pos |
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(sb->s_blocksize - 1)) + 1;
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brelse (bh);
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return stored;
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}
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offset += le16_to_cpu(de->rec_len);
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if (le32_to_cpu(de->inode)) {
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/* We might block in the next section
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* if the data destination is
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* currently swapped out. So, use a
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* version stamp to detect whether or
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* not the directory has been modified
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* during the copy operation.
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*/
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unsigned long version = filp->f_version;
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unsigned char d_type = DT_UNKNOWN;
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if (EXT3_HAS_INCOMPAT_FEATURE(sb,
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EXT3_FEATURE_INCOMPAT_FILETYPE)
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&& de->file_type < EXT3_FT_MAX)
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d_type =
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ext3_filetype_table[de->file_type];
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error = filldir(dirent, de->name,
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de->name_len,
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filp->f_pos,
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le32_to_cpu(de->inode),
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d_type);
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if (error)
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break;
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if (version != filp->f_version)
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goto revalidate;
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stored ++;
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}
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filp->f_pos += le16_to_cpu(de->rec_len);
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}
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offset = 0;
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brelse (bh);
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}
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UPDATE_ATIME(inode);
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return 0;
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}
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