/* * linux/fs/minix/dir.c * * Copyright (C) 1991, 1992 Linus Torvalds * * minix directory handling functions */ #include "minix.h" #include <linux/highmem.h> #include <linux/smp_lock.h> typedef struct minix_dir_entry minix_dirent; static int minix_readdir(struct file *, void *, filldir_t); struct file_operations minix_dir_operations = { .read = generic_read_dir, .readdir = minix_readdir, .fsync = minix_sync_file, }; static inline void dir_put_page(struct page *page) { kunmap(page); page_cache_release(page); } /* * Return the offset into page `page_nr' of the last valid * byte in that page, plus one. */ static unsigned minix_last_byte(struct inode *inode, unsigned long page_nr) { unsigned last_byte = PAGE_CACHE_SIZE; if (page_nr == (inode->i_size >> PAGE_CACHE_SHIFT)) last_byte = inode->i_size & (PAGE_CACHE_SIZE - 1); return last_byte; } static inline unsigned long dir_pages(struct inode *inode) { return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT; } static int dir_commit_chunk(struct page *page, unsigned from, unsigned to) { struct inode *dir = (struct inode *)page->mapping->host; int err = 0; page->mapping->a_ops->commit_write(NULL, page, from, to); if (IS_DIRSYNC(dir)) err = write_one_page(page, 1); else unlock_page(page); return err; } static struct page * dir_get_page(struct inode *dir, unsigned long n) { struct address_space *mapping = dir->i_mapping; struct page *page = read_cache_page(mapping, n, (filler_t*)mapping->a_ops->readpage, NULL); if (!IS_ERR(page)) { wait_on_page_locked(page); kmap(page); if (!PageUptodate(page)) goto fail; } return page; fail: dir_put_page(page); return ERR_PTR(-EIO); } static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi) { return (void*)((char*)de + sbi->s_dirsize); } static int minix_readdir(struct file * filp, void * dirent, filldir_t filldir) { unsigned long pos = filp->f_pos; struct inode *inode = filp->f_dentry->d_inode; struct super_block *sb = inode->i_sb; unsigned offset = pos & ~PAGE_CACHE_MASK; unsigned long n = pos >> PAGE_CACHE_SHIFT; unsigned long npages = dir_pages(inode); struct minix_sb_info *sbi = minix_sb(sb); unsigned chunk_size = sbi->s_dirsize; lock_kernel(); pos = (pos + chunk_size-1) & ~(chunk_size-1); if (pos >= inode->i_size) goto done; for ( ; n < npages; n++, offset = 0) { char *p, *kaddr, *limit; struct page *page = dir_get_page(inode, n); if (IS_ERR(page)) continue; kaddr = (char *)page_address(page); p = kaddr+offset; limit = kaddr + minix_last_byte(inode, n) - chunk_size; for ( ; p <= limit ; p = minix_next_entry(p, sbi)) { minix_dirent *de = (minix_dirent *)p; if (de->inode) { int over; unsigned l = strnlen(de->name,sbi->s_namelen); offset = p - kaddr; over = filldir(dirent, de->name, l, (n<<PAGE_CACHE_SHIFT) | offset, de->inode, DT_UNKNOWN); if (over) { dir_put_page(page); goto done; } } } dir_put_page(page); } done: filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset; unlock_kernel(); return 0; } static inline int namecompare(int len, int maxlen, const char * name, const char * buffer) { if (len < maxlen && buffer[len]) return 0; return !memcmp(name, buffer, len); } /* * minix_find_entry() * * finds an entry in the specified directory with the wanted name. It * returns the cache buffer in which the entry was found, and the entry * itself (as a parameter - res_dir). It does NOT read the inode of the * entry - you'll have to do that yourself if you want to. */ minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page) { const char * name = dentry->d_name.name; int namelen = dentry->d_name.len; struct inode * dir = dentry->d_parent->d_inode; struct super_block * sb = dir->i_sb; struct minix_sb_info * sbi = minix_sb(sb); unsigned long n; unsigned long npages = dir_pages(dir); struct page *page = NULL; struct minix_dir_entry *de; *res_page = NULL; for (n = 0; n < npages; n++) { char *kaddr; page = dir_get_page(dir, n); if (IS_ERR(page)) continue; kaddr = (char*)page_address(page); de = (struct minix_dir_entry *) kaddr; kaddr += minix_last_byte(dir, n) - sbi->s_dirsize; for ( ; (char *) de <= kaddr ; de = minix_next_entry(de,sbi)) { if (!de->inode) continue; if (namecompare(namelen,sbi->s_namelen,name,de->name)) goto found; } dir_put_page(page); } return NULL; found: *res_page = page; return de; } int minix_add_link(struct dentry *dentry, struct inode *inode) { struct inode *dir = dentry->d_parent->d_inode; const char * name = dentry->d_name.name; int namelen = dentry->d_name.len; struct super_block * sb = dir->i_sb; struct minix_sb_info * sbi = minix_sb(sb); struct page *page = NULL; struct minix_dir_entry * de; unsigned long npages = dir_pages(dir); unsigned long n; char *kaddr; unsigned from, to; int err; /* * We take care of directory expansion in the same loop * This code plays outside i_size, so it locks the page * to protect that region. */ for (n = 0; n <= npages; n++) { char *dir_end; page = dir_get_page(dir, n); err = PTR_ERR(page); if (IS_ERR(page)) goto out; lock_page(page); kaddr = (char*)page_address(page); dir_end = kaddr + minix_last_byte(dir, n); de = (minix_dirent *)kaddr; kaddr += PAGE_CACHE_SIZE - sbi->s_dirsize; while ((char *)de <= kaddr) { if ((char *)de == dir_end) { /* We hit i_size */ de->inode = 0; goto got_it; } if (!de->inode) goto got_it; err = -EEXIST; if (namecompare(namelen,sbi->s_namelen,name,de->name)) goto out_unlock; de = minix_next_entry(de, sbi); } unlock_page(page); dir_put_page(page); } BUG(); return -EINVAL; got_it: from = (char*)de - (char*)page_address(page); to = from + sbi->s_dirsize; err = page->mapping->a_ops->prepare_write(NULL, page, from, to); if (err) goto out_unlock; memcpy (de->name, name, namelen); memset (de->name + namelen, 0, sbi->s_dirsize - namelen - 2); de->inode = inode->i_ino; err = dir_commit_chunk(page, from, to); dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; mark_inode_dirty(dir); out_put: dir_put_page(page); out: return err; out_unlock: unlock_page(page); goto out_put; } int minix_delete_entry(struct minix_dir_entry *de, struct page *page) { struct address_space *mapping = page->mapping; struct inode *inode = (struct inode*)mapping->host; char *kaddr = page_address(page); unsigned from = (char*)de - kaddr; unsigned to = from + minix_sb(inode->i_sb)->s_dirsize; int err; lock_page(page); err = mapping->a_ops->prepare_write(NULL, page, from, to); if (err == 0) { de->inode = 0; err = dir_commit_chunk(page, from, to); } else { unlock_page(page); } dir_put_page(page); inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; mark_inode_dirty(inode); return err; } int minix_make_empty(struct inode *inode, struct inode *dir) { struct address_space *mapping = inode->i_mapping; struct page *page = grab_cache_page(mapping, 0); struct minix_sb_info * sbi = minix_sb(inode->i_sb); struct minix_dir_entry * de; char *kaddr; int err; if (!page) return -ENOMEM; err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * sbi->s_dirsize); if (err) { unlock_page(page); goto fail; } kaddr = kmap_atomic(page, KM_USER0); memset(kaddr, 0, PAGE_CACHE_SIZE); de = (struct minix_dir_entry *)kaddr; de->inode = inode->i_ino; strcpy(de->name,"."); de = minix_next_entry(de, sbi); de->inode = dir->i_ino; strcpy(de->name,".."); kunmap_atomic(kaddr, KM_USER0); err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize); fail: page_cache_release(page); return err; } /* * routine to check that the specified directory is empty (for rmdir) */ int minix_empty_dir(struct inode * inode) { struct page *page = NULL; unsigned long i, npages = dir_pages(inode); struct minix_sb_info *sbi = minix_sb(inode->i_sb); for (i = 0; i < npages; i++) { char *kaddr; minix_dirent * de; page = dir_get_page(inode, i); if (IS_ERR(page)) continue; kaddr = (char *)page_address(page); de = (minix_dirent *)kaddr; kaddr += minix_last_byte(inode, i) - sbi->s_dirsize; while ((char *)de <= kaddr) { if (de->inode != 0) { /* check for . and .. */ if (de->name[0] != '.') goto not_empty; if (!de->name[1]) { if (de->inode != inode->i_ino) goto not_empty; } else if (de->name[1] != '.') goto not_empty; else if (de->name[2]) goto not_empty; } de = minix_next_entry(de, sbi); } dir_put_page(page); } return 1; not_empty: dir_put_page(page); return 0; } /* Releases the page */ void minix_set_link(struct minix_dir_entry *de, struct page *page, struct inode *inode) { struct inode *dir = (struct inode*)page->mapping->host; struct minix_sb_info *sbi = minix_sb(dir->i_sb); unsigned from = (char *)de-(char*)page_address(page); unsigned to = from + sbi->s_dirsize; int err; lock_page(page); err = page->mapping->a_ops->prepare_write(NULL, page, from, to); if (err == 0) { de->inode = inode->i_ino; err = dir_commit_chunk(page, from, to); } else { unlock_page(page); } dir_put_page(page); dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; mark_inode_dirty(dir); } struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p) { struct page *page = dir_get_page(dir, 0); struct minix_sb_info *sbi = minix_sb(dir->i_sb); struct minix_dir_entry *de = NULL; if (!IS_ERR(page)) { de = minix_next_entry(page_address(page), sbi); *p = page; } return de; } ino_t minix_inode_by_name(struct dentry *dentry) { struct page *page; struct minix_dir_entry *de = minix_find_entry(dentry, &page); ino_t res = 0; if (de) { res = de->inode; dir_put_page(page); } return res; }