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469 lines
11 KiB
469 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0 |
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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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* minix directory handling functions |
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* |
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* Updated to filesystem version 3 by Daniel Aragones |
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*/ |
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#include "minix.h" |
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#include <linux/buffer_head.h> |
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#include <linux/highmem.h> |
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#include <linux/swap.h> |
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typedef struct minix_dir_entry minix_dirent; |
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typedef struct minix3_dir_entry minix3_dirent; |
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static int minix_readdir(struct file *, struct dir_context *); |
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const struct file_operations minix_dir_operations = { |
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.llseek = generic_file_llseek, |
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.read = generic_read_dir, |
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.iterate_shared = minix_readdir, |
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.fsync = generic_file_fsync, |
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}; |
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static inline void dir_put_page(struct page *page) |
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{ |
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kunmap(page); |
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put_page(page); |
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} |
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/* |
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* Return the offset into page `page_nr' of the last valid |
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* byte in that page, plus one. |
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*/ |
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static unsigned |
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minix_last_byte(struct inode *inode, unsigned long page_nr) |
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{ |
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unsigned last_byte = PAGE_SIZE; |
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if (page_nr == (inode->i_size >> PAGE_SHIFT)) |
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last_byte = inode->i_size & (PAGE_SIZE - 1); |
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return last_byte; |
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} |
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static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len) |
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{ |
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struct address_space *mapping = page->mapping; |
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struct inode *dir = mapping->host; |
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int err = 0; |
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block_write_end(NULL, mapping, pos, len, len, page, NULL); |
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if (pos+len > dir->i_size) { |
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i_size_write(dir, pos+len); |
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mark_inode_dirty(dir); |
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} |
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if (IS_DIRSYNC(dir)) |
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err = write_one_page(page); |
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else |
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unlock_page(page); |
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return err; |
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} |
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static struct page * dir_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 void *minix_next_entry(void *de, struct minix_sb_info *sbi) |
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{ |
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return (void*)((char*)de + sbi->s_dirsize); |
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} |
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static int minix_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 *sb = inode->i_sb; |
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struct minix_sb_info *sbi = minix_sb(sb); |
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unsigned chunk_size = sbi->s_dirsize; |
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unsigned long npages = dir_pages(inode); |
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unsigned long pos = ctx->pos; |
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unsigned offset; |
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unsigned long n; |
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ctx->pos = pos = ALIGN(pos, chunk_size); |
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if (pos >= inode->i_size) |
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return 0; |
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offset = pos & ~PAGE_MASK; |
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n = pos >> PAGE_SHIFT; |
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for ( ; n < npages; n++, offset = 0) { |
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char *p, *kaddr, *limit; |
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struct page *page = dir_get_page(inode, n); |
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if (IS_ERR(page)) |
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continue; |
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kaddr = (char *)page_address(page); |
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p = kaddr+offset; |
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limit = kaddr + minix_last_byte(inode, n) - chunk_size; |
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for ( ; p <= limit; p = minix_next_entry(p, sbi)) { |
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const char *name; |
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__u32 inumber; |
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if (sbi->s_version == MINIX_V3) { |
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minix3_dirent *de3 = (minix3_dirent *)p; |
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name = de3->name; |
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inumber = de3->inode; |
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} else { |
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minix_dirent *de = (minix_dirent *)p; |
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name = de->name; |
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inumber = de->inode; |
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} |
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if (inumber) { |
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unsigned l = strnlen(name, sbi->s_namelen); |
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if (!dir_emit(ctx, name, l, |
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inumber, DT_UNKNOWN)) { |
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dir_put_page(page); |
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return 0; |
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} |
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} |
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ctx->pos += chunk_size; |
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} |
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dir_put_page(page); |
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} |
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return 0; |
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} |
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static inline int namecompare(int len, int maxlen, |
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const char * name, const char * buffer) |
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{ |
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if (len < maxlen && buffer[len]) |
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return 0; |
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return !memcmp(name, buffer, len); |
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} |
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/* |
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* minix_find_entry() |
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* |
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* finds an entry in the specified directory with the wanted name. It |
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* returns the cache buffer in which the entry was found, and the entry |
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* itself (as a parameter - res_dir). It does NOT read the inode of the |
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* entry - you'll have to do that yourself if you want to. |
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*/ |
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minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page) |
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{ |
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const char * name = dentry->d_name.name; |
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int namelen = dentry->d_name.len; |
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struct inode * dir = d_inode(dentry->d_parent); |
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struct super_block * sb = dir->i_sb; |
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struct minix_sb_info * sbi = minix_sb(sb); |
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unsigned long n; |
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unsigned long npages = dir_pages(dir); |
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struct page *page = NULL; |
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char *p; |
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char *namx; |
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__u32 inumber; |
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*res_page = NULL; |
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for (n = 0; n < npages; n++) { |
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char *kaddr, *limit; |
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page = dir_get_page(dir, n); |
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if (IS_ERR(page)) |
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continue; |
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kaddr = (char*)page_address(page); |
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limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize; |
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for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { |
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if (sbi->s_version == MINIX_V3) { |
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minix3_dirent *de3 = (minix3_dirent *)p; |
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namx = de3->name; |
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inumber = de3->inode; |
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} else { |
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minix_dirent *de = (minix_dirent *)p; |
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namx = de->name; |
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inumber = de->inode; |
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} |
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if (!inumber) |
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continue; |
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if (namecompare(namelen, sbi->s_namelen, name, namx)) |
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goto found; |
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} |
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dir_put_page(page); |
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} |
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return NULL; |
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found: |
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*res_page = page; |
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return (minix_dirent *)p; |
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} |
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int minix_add_link(struct dentry *dentry, struct inode *inode) |
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{ |
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struct inode *dir = d_inode(dentry->d_parent); |
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const char * name = dentry->d_name.name; |
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int namelen = dentry->d_name.len; |
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struct super_block * sb = dir->i_sb; |
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struct minix_sb_info * sbi = minix_sb(sb); |
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struct page *page = NULL; |
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unsigned long npages = dir_pages(dir); |
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unsigned long n; |
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char *kaddr, *p; |
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minix_dirent *de; |
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minix3_dirent *de3; |
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loff_t pos; |
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int err; |
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char *namx = NULL; |
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__u32 inumber; |
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/* |
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* We take care of directory expansion in the same loop |
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* This code plays outside i_size, so it locks the page |
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* to protect that region. |
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*/ |
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for (n = 0; n <= npages; n++) { |
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char *limit, *dir_end; |
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page = dir_get_page(dir, n); |
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err = PTR_ERR(page); |
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if (IS_ERR(page)) |
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goto out; |
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lock_page(page); |
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kaddr = (char*)page_address(page); |
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dir_end = kaddr + minix_last_byte(dir, n); |
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limit = kaddr + PAGE_SIZE - sbi->s_dirsize; |
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for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { |
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de = (minix_dirent *)p; |
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de3 = (minix3_dirent *)p; |
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if (sbi->s_version == MINIX_V3) { |
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namx = de3->name; |
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inumber = de3->inode; |
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} else { |
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namx = de->name; |
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inumber = de->inode; |
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} |
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if (p == dir_end) { |
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/* We hit i_size */ |
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if (sbi->s_version == MINIX_V3) |
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de3->inode = 0; |
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else |
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de->inode = 0; |
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goto got_it; |
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} |
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if (!inumber) |
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goto got_it; |
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err = -EEXIST; |
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if (namecompare(namelen, sbi->s_namelen, name, namx)) |
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goto out_unlock; |
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} |
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unlock_page(page); |
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dir_put_page(page); |
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} |
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BUG(); |
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return -EINVAL; |
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got_it: |
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pos = page_offset(page) + p - (char *)page_address(page); |
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err = minix_prepare_chunk(page, pos, sbi->s_dirsize); |
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if (err) |
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goto out_unlock; |
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memcpy (namx, name, namelen); |
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if (sbi->s_version == MINIX_V3) { |
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memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4); |
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de3->inode = inode->i_ino; |
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} else { |
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memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2); |
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de->inode = inode->i_ino; |
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} |
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err = dir_commit_chunk(page, pos, sbi->s_dirsize); |
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dir->i_mtime = dir->i_ctime = current_time(dir); |
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mark_inode_dirty(dir); |
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out_put: |
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dir_put_page(page); |
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out: |
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return err; |
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out_unlock: |
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unlock_page(page); |
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goto out_put; |
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} |
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int minix_delete_entry(struct minix_dir_entry *de, struct page *page) |
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{ |
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struct inode *inode = page->mapping->host; |
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char *kaddr = page_address(page); |
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loff_t pos = page_offset(page) + (char*)de - kaddr; |
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struct minix_sb_info *sbi = minix_sb(inode->i_sb); |
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unsigned len = sbi->s_dirsize; |
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int err; |
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lock_page(page); |
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err = minix_prepare_chunk(page, pos, len); |
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if (err == 0) { |
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if (sbi->s_version == MINIX_V3) |
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((minix3_dirent *) de)->inode = 0; |
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else |
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de->inode = 0; |
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err = dir_commit_chunk(page, pos, len); |
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} else { |
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unlock_page(page); |
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} |
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dir_put_page(page); |
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inode->i_ctime = inode->i_mtime = current_time(inode); |
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mark_inode_dirty(inode); |
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return err; |
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} |
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int minix_make_empty(struct inode *inode, struct inode *dir) |
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{ |
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struct page *page = grab_cache_page(inode->i_mapping, 0); |
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struct minix_sb_info *sbi = minix_sb(inode->i_sb); |
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char *kaddr; |
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int err; |
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if (!page) |
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return -ENOMEM; |
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err = minix_prepare_chunk(page, 0, 2 * sbi->s_dirsize); |
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if (err) { |
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unlock_page(page); |
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goto fail; |
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} |
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kaddr = kmap_atomic(page); |
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memset(kaddr, 0, PAGE_SIZE); |
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if (sbi->s_version == MINIX_V3) { |
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minix3_dirent *de3 = (minix3_dirent *)kaddr; |
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de3->inode = inode->i_ino; |
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strcpy(de3->name, "."); |
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de3 = minix_next_entry(de3, sbi); |
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de3->inode = dir->i_ino; |
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strcpy(de3->name, ".."); |
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} else { |
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minix_dirent *de = (minix_dirent *)kaddr; |
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de->inode = inode->i_ino; |
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strcpy(de->name, "."); |
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de = minix_next_entry(de, sbi); |
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de->inode = dir->i_ino; |
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strcpy(de->name, ".."); |
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} |
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kunmap_atomic(kaddr); |
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err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize); |
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fail: |
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put_page(page); |
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return err; |
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} |
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/* |
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* routine to check that the specified directory is empty (for rmdir) |
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*/ |
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int minix_empty_dir(struct inode * inode) |
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{ |
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struct page *page = NULL; |
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unsigned long i, npages = dir_pages(inode); |
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struct minix_sb_info *sbi = minix_sb(inode->i_sb); |
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char *name; |
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__u32 inumber; |
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for (i = 0; i < npages; i++) { |
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char *p, *kaddr, *limit; |
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page = dir_get_page(inode, i); |
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if (IS_ERR(page)) |
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continue; |
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kaddr = (char *)page_address(page); |
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limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize; |
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for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) { |
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if (sbi->s_version == MINIX_V3) { |
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minix3_dirent *de3 = (minix3_dirent *)p; |
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name = de3->name; |
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inumber = de3->inode; |
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} else { |
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minix_dirent *de = (minix_dirent *)p; |
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name = de->name; |
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inumber = de->inode; |
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} |
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if (inumber != 0) { |
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/* check for . and .. */ |
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if (name[0] != '.') |
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goto not_empty; |
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if (!name[1]) { |
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if (inumber != inode->i_ino) |
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goto not_empty; |
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} else if (name[1] != '.') |
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goto not_empty; |
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else if (name[2]) |
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goto not_empty; |
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} |
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} |
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dir_put_page(page); |
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} |
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return 1; |
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not_empty: |
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dir_put_page(page); |
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return 0; |
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} |
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/* Releases the page */ |
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void minix_set_link(struct minix_dir_entry *de, struct page *page, |
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struct inode *inode) |
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{ |
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struct inode *dir = page->mapping->host; |
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struct minix_sb_info *sbi = minix_sb(dir->i_sb); |
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loff_t pos = page_offset(page) + |
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(char *)de-(char*)page_address(page); |
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int err; |
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lock_page(page); |
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err = minix_prepare_chunk(page, pos, sbi->s_dirsize); |
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if (err == 0) { |
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if (sbi->s_version == MINIX_V3) |
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((minix3_dirent *) de)->inode = inode->i_ino; |
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else |
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de->inode = inode->i_ino; |
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err = dir_commit_chunk(page, pos, sbi->s_dirsize); |
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} else { |
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unlock_page(page); |
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} |
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dir_put_page(page); |
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dir->i_mtime = dir->i_ctime = current_time(dir); |
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mark_inode_dirty(dir); |
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} |
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struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p) |
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{ |
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struct page *page = dir_get_page(dir, 0); |
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struct minix_sb_info *sbi = minix_sb(dir->i_sb); |
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struct minix_dir_entry *de = NULL; |
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if (!IS_ERR(page)) { |
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de = minix_next_entry(page_address(page), sbi); |
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*p = page; |
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} |
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return de; |
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} |
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ino_t minix_inode_by_name(struct dentry *dentry) |
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{ |
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struct page *page; |
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struct minix_dir_entry *de = minix_find_entry(dentry, &page); |
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ino_t res = 0; |
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if (de) { |
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struct address_space *mapping = page->mapping; |
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struct inode *inode = mapping->host; |
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struct minix_sb_info *sbi = minix_sb(inode->i_sb); |
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if (sbi->s_version == MINIX_V3) |
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res = ((minix3_dirent *) de)->inode; |
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else |
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res = de->inode; |
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dir_put_page(page); |
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} |
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return res; |
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}
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