287 lines
6.9 KiB
C
287 lines
6.9 KiB
C
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/*
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* QNX6 file system, Linux implementation.
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*
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* Version : 1.0.0
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*
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* History :
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*
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* 01-02-2012 by Kai Bankett (chaosman@ontika.net) : first release.
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* 16-02-2012 pagemap extension by Al Viro
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*
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*/
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#include "qnx6.h"
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static unsigned qnx6_lfile_checksum(char *name, unsigned size)
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{
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unsigned crc = 0;
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char *end = name + size;
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while (name < end) {
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crc = ((crc >> 1) + *(name++)) ^
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((crc & 0x00000001) ? 0x80000000 : 0);
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}
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return crc;
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}
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static struct page *qnx6_get_page(struct inode *dir, unsigned long n)
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{
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struct address_space *mapping = dir->i_mapping;
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struct page *page = read_mapping_page(mapping, n, NULL);
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if (!IS_ERR(page))
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kmap(page);
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return page;
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}
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static inline unsigned long dir_pages(struct inode *inode)
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{
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return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
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}
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static unsigned last_entry(struct inode *inode, unsigned long page_nr)
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{
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unsigned long last_byte = inode->i_size;
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last_byte -= page_nr << PAGE_CACHE_SHIFT;
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if (last_byte > PAGE_CACHE_SIZE)
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last_byte = PAGE_CACHE_SIZE;
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return last_byte / QNX6_DIR_ENTRY_SIZE;
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}
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static struct qnx6_long_filename *qnx6_longname(struct super_block *sb,
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struct qnx6_long_dir_entry *de,
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struct page **p)
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{
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struct qnx6_sb_info *sbi = QNX6_SB(sb);
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u32 s = fs32_to_cpu(sbi, de->de_long_inode); /* in block units */
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u32 n = s >> (PAGE_CACHE_SHIFT - sb->s_blocksize_bits); /* in pages */
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/* within page */
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u32 offs = (s << sb->s_blocksize_bits) & ~PAGE_CACHE_MASK;
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struct address_space *mapping = sbi->longfile->i_mapping;
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struct page *page = read_mapping_page(mapping, n, NULL);
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if (IS_ERR(page))
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return ERR_CAST(page);
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kmap(*p = page);
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return (struct qnx6_long_filename *)(page_address(page) + offs);
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}
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static int qnx6_dir_longfilename(struct inode *inode,
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struct qnx6_long_dir_entry *de,
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struct dir_context *ctx,
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unsigned de_inode)
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{
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struct qnx6_long_filename *lf;
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struct super_block *s = inode->i_sb;
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struct qnx6_sb_info *sbi = QNX6_SB(s);
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struct page *page;
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int lf_size;
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if (de->de_size != 0xff) {
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/* error - long filename entries always have size 0xff
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in direntry */
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pr_err("invalid direntry size (%i).\n", de->de_size);
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return 0;
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}
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lf = qnx6_longname(s, de, &page);
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if (IS_ERR(lf)) {
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pr_err("Error reading longname\n");
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return 0;
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}
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lf_size = fs16_to_cpu(sbi, lf->lf_size);
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if (lf_size > QNX6_LONG_NAME_MAX) {
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pr_debug("file %s\n", lf->lf_fname);
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pr_err("Filename too long (%i)\n", lf_size);
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qnx6_put_page(page);
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return 0;
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}
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/* calc & validate longfilename checksum
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mmi 3g filesystem does not have that checksum */
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if (!test_opt(s, MMI_FS) && fs32_to_cpu(sbi, de->de_checksum) !=
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qnx6_lfile_checksum(lf->lf_fname, lf_size))
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pr_info("long filename checksum error.\n");
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pr_debug("qnx6_readdir:%.*s inode:%u\n",
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lf_size, lf->lf_fname, de_inode);
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if (!dir_emit(ctx, lf->lf_fname, lf_size, de_inode, DT_UNKNOWN)) {
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qnx6_put_page(page);
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return 0;
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}
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qnx6_put_page(page);
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/* success */
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return 1;
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}
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static int qnx6_readdir(struct file *file, struct dir_context *ctx)
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{
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struct inode *inode = file_inode(file);
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struct super_block *s = inode->i_sb;
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struct qnx6_sb_info *sbi = QNX6_SB(s);
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loff_t pos = ctx->pos & ~(QNX6_DIR_ENTRY_SIZE - 1);
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unsigned long npages = dir_pages(inode);
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unsigned long n = pos >> PAGE_CACHE_SHIFT;
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unsigned start = (pos & ~PAGE_CACHE_MASK) / QNX6_DIR_ENTRY_SIZE;
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bool done = false;
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ctx->pos = pos;
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if (ctx->pos >= inode->i_size)
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return 0;
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for ( ; !done && n < npages; n++, start = 0) {
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struct page *page = qnx6_get_page(inode, n);
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int limit = last_entry(inode, n);
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struct qnx6_dir_entry *de;
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int i = start;
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if (IS_ERR(page)) {
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pr_err("%s(): read failed\n", __func__);
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ctx->pos = (n + 1) << PAGE_CACHE_SHIFT;
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return PTR_ERR(page);
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}
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de = ((struct qnx6_dir_entry *)page_address(page)) + start;
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for (; i < limit; i++, de++, ctx->pos += QNX6_DIR_ENTRY_SIZE) {
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int size = de->de_size;
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u32 no_inode = fs32_to_cpu(sbi, de->de_inode);
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if (!no_inode || !size)
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continue;
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if (size > QNX6_SHORT_NAME_MAX) {
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/* long filename detected
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get the filename from long filename
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structure / block */
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if (!qnx6_dir_longfilename(inode,
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(struct qnx6_long_dir_entry *)de,
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ctx, no_inode)) {
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done = true;
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break;
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}
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} else {
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pr_debug("%s():%.*s inode:%u\n",
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__func__, size, de->de_fname,
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no_inode);
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if (!dir_emit(ctx, de->de_fname, size,
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no_inode, DT_UNKNOWN)) {
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done = true;
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break;
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}
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}
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}
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qnx6_put_page(page);
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}
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return 0;
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}
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/*
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* check if the long filename is correct.
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*/
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static unsigned qnx6_long_match(int len, const char *name,
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struct qnx6_long_dir_entry *de, struct inode *dir)
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{
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struct super_block *s = dir->i_sb;
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struct qnx6_sb_info *sbi = QNX6_SB(s);
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struct page *page;
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int thislen;
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struct qnx6_long_filename *lf = qnx6_longname(s, de, &page);
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if (IS_ERR(lf))
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return 0;
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thislen = fs16_to_cpu(sbi, lf->lf_size);
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if (len != thislen) {
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qnx6_put_page(page);
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return 0;
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}
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if (memcmp(name, lf->lf_fname, len) == 0) {
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qnx6_put_page(page);
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return fs32_to_cpu(sbi, de->de_inode);
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}
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qnx6_put_page(page);
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return 0;
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}
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/*
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* check if the filename is correct.
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*/
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static unsigned qnx6_match(struct super_block *s, int len, const char *name,
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struct qnx6_dir_entry *de)
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{
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struct qnx6_sb_info *sbi = QNX6_SB(s);
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if (memcmp(name, de->de_fname, len) == 0)
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return fs32_to_cpu(sbi, de->de_inode);
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return 0;
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}
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unsigned qnx6_find_entry(int len, struct inode *dir, const char *name,
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struct page **res_page)
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{
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struct super_block *s = dir->i_sb;
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struct qnx6_inode_info *ei = QNX6_I(dir);
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struct page *page = NULL;
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unsigned long start, n;
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unsigned long npages = dir_pages(dir);
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unsigned ino;
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struct qnx6_dir_entry *de;
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struct qnx6_long_dir_entry *lde;
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*res_page = NULL;
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if (npages == 0)
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return 0;
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start = ei->i_dir_start_lookup;
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if (start >= npages)
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start = 0;
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n = start;
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do {
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page = qnx6_get_page(dir, n);
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if (!IS_ERR(page)) {
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int limit = last_entry(dir, n);
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int i;
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de = (struct qnx6_dir_entry *)page_address(page);
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for (i = 0; i < limit; i++, de++) {
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if (len <= QNX6_SHORT_NAME_MAX) {
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/* short filename */
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if (len != de->de_size)
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continue;
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ino = qnx6_match(s, len, name, de);
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if (ino)
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goto found;
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} else if (de->de_size == 0xff) {
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/* deal with long filename */
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lde = (struct qnx6_long_dir_entry *)de;
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ino = qnx6_long_match(len,
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name, lde, dir);
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if (ino)
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goto found;
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} else
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pr_err("undefined filename size in inode.\n");
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}
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qnx6_put_page(page);
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}
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if (++n >= npages)
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n = 0;
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} while (n != start);
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return 0;
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found:
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*res_page = page;
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ei->i_dir_start_lookup = n;
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return ino;
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}
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const struct file_operations qnx6_dir_operations = {
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.llseek = generic_file_llseek,
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.read = generic_read_dir,
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.iterate = qnx6_readdir,
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.fsync = generic_file_fsync,
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};
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const struct inode_operations qnx6_dir_inode_operations = {
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.lookup = qnx6_lookup,
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};
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