mirror of https://gitee.com/openkylin/linux.git
510 lines
13 KiB
C
510 lines
13 KiB
C
/*
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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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* Hash Tree Directory indexing (c) 2001 Daniel Phillips
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*
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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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#include <linux/buffer_head.h>
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#include <linux/slab.h>
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#include <linux/rbtree.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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static int ext3_dx_readdir(struct file * filp,
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void * dirent, filldir_t filldir);
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static int ext3_release_dir (struct inode * inode,
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struct file * filp);
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const struct file_operations ext3_dir_operations = {
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.llseek = generic_file_llseek,
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.read = generic_read_dir,
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.readdir = ext3_readdir, /* we take BKL. needed?*/
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.ioctl = ext3_ioctl, /* BKL held */
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#ifdef CONFIG_COMPAT
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.compat_ioctl = ext3_compat_ioctl,
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#endif
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.fsync = ext3_sync_file, /* BKL held */
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.release = ext3_release_dir,
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};
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static unsigned char get_dtype(struct super_block *sb, int filetype)
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{
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if (!EXT3_HAS_INCOMPAT_FEATURE(sb, EXT3_FEATURE_INCOMPAT_FILETYPE) ||
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(filetype >= EXT3_FT_MAX))
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return DT_UNKNOWN;
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return (ext3_filetype_table[filetype]);
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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 = ext3_rec_len_from_disk(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(EXT3_SB(dir->i_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;
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int i, stored;
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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_path.dentry->d_inode;
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int ret = 0;
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sb = inode->i_sb;
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if (EXT3_HAS_COMPAT_FEATURE(inode->i_sb,
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EXT3_FEATURE_COMPAT_DIR_INDEX) &&
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((EXT3_I(inode)->i_flags & EXT3_INDEX_FL) ||
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((inode->i_size >> sb->s_blocksize_bits) == 1))) {
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err = ext3_dx_readdir(filp, dirent, filldir);
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if (err != ERR_BAD_DX_DIR) {
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ret = err;
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goto out;
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}
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/*
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* We don't set the inode dirty flag since it's not
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* critical that it get flushed back to the disk.
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*/
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EXT3_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT3_INDEX_FL;
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}
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stored = 0;
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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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unsigned long blk = filp->f_pos >> EXT3_BLOCK_SIZE_BITS(sb);
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struct buffer_head map_bh;
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struct buffer_head *bh = NULL;
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map_bh.b_state = 0;
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err = ext3_get_blocks_handle(NULL, inode, blk, 1,
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&map_bh, 0, 0);
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if (err > 0) {
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pgoff_t index = map_bh.b_blocknr >>
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(PAGE_CACHE_SHIFT - inode->i_blkbits);
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if (!ra_has_index(&filp->f_ra, index))
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page_cache_sync_readahead(
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sb->s_bdev->bd_inode->i_mapping,
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&filp->f_ra, filp,
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index, 1);
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filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
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bh = ext3_bread(NULL, inode, blk, 0, &err);
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}
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/*
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* We ignore I/O errors on directories so users have a chance
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* of recovering data when there's a bad sector
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*/
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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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/* corrupt size? Maybe no more blocks to read */
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if (filp->f_pos > inode->i_blocks << 9)
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break;
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filp->f_pos += sb->s_blocksize - offset;
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continue;
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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 (ext3_rec_len_from_disk(de->rec_len) <
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EXT3_DIR_REC_LEN(1))
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break;
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i += ext3_rec_len_from_disk(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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ret = stored;
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goto out;
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}
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offset += ext3_rec_len_from_disk(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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u64 version = filp->f_version;
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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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get_dtype(sb, de->file_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 += ext3_rec_len_from_disk(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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out:
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return ret;
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}
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/*
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* These functions convert from the major/minor hash to an f_pos
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* value.
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*
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* Currently we only use major hash numer. This is unfortunate, but
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* on 32-bit machines, the same VFS interface is used for lseek and
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* llseek, so if we use the 64 bit offset, then the 32-bit versions of
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* lseek/telldir/seekdir will blow out spectacularly, and from within
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* the ext2 low-level routine, we don't know if we're being called by
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* a 64-bit version of the system call or the 32-bit version of the
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* system call. Worse yet, NFSv2 only allows for a 32-bit readdir
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* cookie. Sigh.
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*/
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#define hash2pos(major, minor) (major >> 1)
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#define pos2maj_hash(pos) ((pos << 1) & 0xffffffff)
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#define pos2min_hash(pos) (0)
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/*
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* This structure holds the nodes of the red-black tree used to store
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* the directory entry in hash order.
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*/
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struct fname {
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__u32 hash;
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__u32 minor_hash;
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struct rb_node rb_hash;
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struct fname *next;
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__u32 inode;
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__u8 name_len;
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__u8 file_type;
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char name[0];
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};
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/*
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* This functoin implements a non-recursive way of freeing all of the
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* nodes in the red-black tree.
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*/
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static void free_rb_tree_fname(struct rb_root *root)
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{
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struct rb_node *n = root->rb_node;
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struct rb_node *parent;
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struct fname *fname;
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while (n) {
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/* Do the node's children first */
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if (n->rb_left) {
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n = n->rb_left;
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continue;
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}
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if (n->rb_right) {
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n = n->rb_right;
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continue;
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}
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/*
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* The node has no children; free it, and then zero
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* out parent's link to it. Finally go to the
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* beginning of the loop and try to free the parent
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* node.
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*/
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parent = rb_parent(n);
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fname = rb_entry(n, struct fname, rb_hash);
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while (fname) {
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struct fname * old = fname;
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fname = fname->next;
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kfree (old);
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}
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if (!parent)
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root->rb_node = NULL;
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else if (parent->rb_left == n)
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parent->rb_left = NULL;
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else if (parent->rb_right == n)
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parent->rb_right = NULL;
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n = parent;
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}
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}
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static struct dir_private_info *ext3_htree_create_dir_info(loff_t pos)
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{
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struct dir_private_info *p;
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p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
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if (!p)
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return NULL;
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p->curr_hash = pos2maj_hash(pos);
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p->curr_minor_hash = pos2min_hash(pos);
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return p;
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}
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void ext3_htree_free_dir_info(struct dir_private_info *p)
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{
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free_rb_tree_fname(&p->root);
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kfree(p);
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}
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/*
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* Given a directory entry, enter it into the fname rb tree.
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*/
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int ext3_htree_store_dirent(struct file *dir_file, __u32 hash,
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__u32 minor_hash,
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struct ext3_dir_entry_2 *dirent)
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{
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struct rb_node **p, *parent = NULL;
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struct fname * fname, *new_fn;
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struct dir_private_info *info;
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int len;
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info = (struct dir_private_info *) dir_file->private_data;
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p = &info->root.rb_node;
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/* Create and allocate the fname structure */
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len = sizeof(struct fname) + dirent->name_len + 1;
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new_fn = kzalloc(len, GFP_KERNEL);
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if (!new_fn)
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return -ENOMEM;
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new_fn->hash = hash;
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new_fn->minor_hash = minor_hash;
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new_fn->inode = le32_to_cpu(dirent->inode);
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new_fn->name_len = dirent->name_len;
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new_fn->file_type = dirent->file_type;
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memcpy(new_fn->name, dirent->name, dirent->name_len);
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new_fn->name[dirent->name_len] = 0;
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while (*p) {
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parent = *p;
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fname = rb_entry(parent, struct fname, rb_hash);
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/*
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* If the hash and minor hash match up, then we put
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* them on a linked list. This rarely happens...
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*/
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if ((new_fn->hash == fname->hash) &&
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(new_fn->minor_hash == fname->minor_hash)) {
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new_fn->next = fname->next;
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fname->next = new_fn;
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return 0;
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}
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if (new_fn->hash < fname->hash)
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p = &(*p)->rb_left;
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else if (new_fn->hash > fname->hash)
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p = &(*p)->rb_right;
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else if (new_fn->minor_hash < fname->minor_hash)
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p = &(*p)->rb_left;
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else /* if (new_fn->minor_hash > fname->minor_hash) */
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p = &(*p)->rb_right;
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}
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rb_link_node(&new_fn->rb_hash, parent, p);
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rb_insert_color(&new_fn->rb_hash, &info->root);
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return 0;
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}
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/*
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* This is a helper function for ext3_dx_readdir. It calls filldir
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* for all entres on the fname linked list. (Normally there is only
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* one entry on the linked list, unless there are 62 bit hash collisions.)
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*/
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static int call_filldir(struct file * filp, void * dirent,
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filldir_t filldir, struct fname *fname)
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{
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struct dir_private_info *info = filp->private_data;
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loff_t curr_pos;
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struct inode *inode = filp->f_path.dentry->d_inode;
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struct super_block * sb;
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int error;
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sb = inode->i_sb;
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if (!fname) {
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printk("call_filldir: called with null fname?!?\n");
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return 0;
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}
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curr_pos = hash2pos(fname->hash, fname->minor_hash);
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while (fname) {
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error = filldir(dirent, fname->name,
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fname->name_len, curr_pos,
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fname->inode,
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get_dtype(sb, fname->file_type));
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if (error) {
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filp->f_pos = curr_pos;
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info->extra_fname = fname->next;
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return error;
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}
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fname = fname->next;
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}
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return 0;
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}
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static int ext3_dx_readdir(struct file * filp,
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void * dirent, filldir_t filldir)
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{
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struct dir_private_info *info = filp->private_data;
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struct inode *inode = filp->f_path.dentry->d_inode;
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struct fname *fname;
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int ret;
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if (!info) {
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info = ext3_htree_create_dir_info(filp->f_pos);
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if (!info)
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return -ENOMEM;
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filp->private_data = info;
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}
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if (filp->f_pos == EXT3_HTREE_EOF)
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return 0; /* EOF */
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/* Some one has messed with f_pos; reset the world */
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if (info->last_pos != filp->f_pos) {
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free_rb_tree_fname(&info->root);
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info->curr_node = NULL;
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info->extra_fname = NULL;
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info->curr_hash = pos2maj_hash(filp->f_pos);
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info->curr_minor_hash = pos2min_hash(filp->f_pos);
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}
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/*
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* If there are any leftover names on the hash collision
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* chain, return them first.
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*/
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if (info->extra_fname &&
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call_filldir(filp, dirent, filldir, info->extra_fname))
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goto finished;
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if (!info->curr_node)
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info->curr_node = rb_first(&info->root);
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while (1) {
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/*
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* Fill the rbtree if we have no more entries,
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* or the inode has changed since we last read in the
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* cached entries.
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*/
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if ((!info->curr_node) ||
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(filp->f_version != inode->i_version)) {
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info->curr_node = NULL;
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free_rb_tree_fname(&info->root);
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filp->f_version = inode->i_version;
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ret = ext3_htree_fill_tree(filp, info->curr_hash,
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info->curr_minor_hash,
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&info->next_hash);
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if (ret < 0)
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return ret;
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if (ret == 0) {
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filp->f_pos = EXT3_HTREE_EOF;
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break;
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}
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info->curr_node = rb_first(&info->root);
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}
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fname = rb_entry(info->curr_node, struct fname, rb_hash);
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info->curr_hash = fname->hash;
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info->curr_minor_hash = fname->minor_hash;
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if (call_filldir(filp, dirent, filldir, fname))
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break;
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info->curr_node = rb_next(info->curr_node);
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if (!info->curr_node) {
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if (info->next_hash == ~0) {
|
|
filp->f_pos = EXT3_HTREE_EOF;
|
|
break;
|
|
}
|
|
info->curr_hash = info->next_hash;
|
|
info->curr_minor_hash = 0;
|
|
}
|
|
}
|
|
finished:
|
|
info->last_pos = filp->f_pos;
|
|
return 0;
|
|
}
|
|
|
|
static int ext3_release_dir (struct inode * inode, struct file * filp)
|
|
{
|
|
if (filp->private_data)
|
|
ext3_htree_free_dir_info(filp->private_data);
|
|
|
|
return 0;
|
|
}
|