/* * linux/fs/sysv/dir.c * * minix/dir.c * Copyright (C) 1991, 1992 Linus Torvalds * * coh/dir.c * Copyright (C) 1993 Pascal Haible, Bruno Haible * * sysv/dir.c * Copyright (C) 1993 Bruno Haible * * SystemV/Coherent directory handling functions */ #include <linux/pagemap.h> #include <linux/highmem.h> #include <linux/smp_lock.h> #include "sysv.h" static int sysv_readdir(struct file *, void *, filldir_t); const struct file_operations sysv_dir_operations = { .read = generic_read_dir, .readdir = sysv_readdir, .fsync = sysv_sync_file, }; static inline void dir_put_page(struct page *page) { kunmap(page); page_cache_release(page); } 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_mapping_page(mapping, n, NULL); if (!IS_ERR(page)) kmap(page); return page; } static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir) { unsigned long pos = filp->f_pos; struct inode *inode = filp->f_path.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); lock_kernel(); pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1); if (pos >= inode->i_size) goto done; for ( ; n < npages; n++, offset = 0) { char *kaddr, *limit; struct sysv_dir_entry *de; struct page *page = dir_get_page(inode, n); if (IS_ERR(page)) continue; kaddr = (char *)page_address(page); de = (struct sysv_dir_entry *)(kaddr+offset); limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE; for ( ;(char*)de <= limit; de++) { char *name = de->name; int over; if (!de->inode) continue; offset = (char *)de - kaddr; over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN), ((loff_t)n<<PAGE_CACHE_SHIFT) | offset, fs16_to_cpu(SYSV_SB(sb), de->inode), DT_UNKNOWN); if (over) { dir_put_page(page); goto done; } } dir_put_page(page); } done: filp->f_pos = ((loff_t)n << PAGE_CACHE_SHIFT) | offset; unlock_kernel(); return 0; } /* compare strings: name[0..len-1] (not zero-terminated) and * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1]) */ 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); } /* * sysv_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. */ struct sysv_dir_entry *sysv_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; unsigned long start, n; unsigned long npages = dir_pages(dir); struct page *page = NULL; struct sysv_dir_entry *de; *res_page = NULL; start = SYSV_I(dir)->i_dir_start_lookup; if (start >= npages) start = 0; n = start; do { char *kaddr; page = dir_get_page(dir, n); if (!IS_ERR(page)) { kaddr = (char*)page_address(page); de = (struct sysv_dir_entry *) kaddr; kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE; for ( ; (char *) de <= kaddr ; de++) { if (!de->inode) continue; if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) goto found; } } dir_put_page(page); if (++n >= npages) n = 0; } while (n != start); return NULL; found: SYSV_I(dir)->i_dir_start_lookup = n; *res_page = page; return de; } int sysv_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 page *page = NULL; struct sysv_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 */ for (n = 0; n <= npages; n++) { page = dir_get_page(dir, n); err = PTR_ERR(page); if (IS_ERR(page)) goto out; kaddr = (char*)page_address(page); de = (struct sysv_dir_entry *)kaddr; kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE; while ((char *)de <= kaddr) { if (!de->inode) goto got_it; err = -EEXIST; if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) goto out_page; de++; } dir_put_page(page); } BUG(); return -EINVAL; got_it: from = (char*)de - (char*)page_address(page); to = from + SYSV_DIRSIZE; lock_page(page); 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, SYSV_DIRSIZE - namelen - 2); de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); err = dir_commit_chunk(page, from, to); dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; mark_inode_dirty(dir); out_page: dir_put_page(page); out: return err; out_unlock: unlock_page(page); goto out_page; } int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page) { struct address_space *mapping = page->mapping; struct inode *inode = (struct inode*)mapping->host; char *kaddr = (char*)page_address(page); unsigned from = (char*)de - kaddr; unsigned to = from + SYSV_DIRSIZE; int err; lock_page(page); err = mapping->a_ops->prepare_write(NULL, page, from, to); BUG_ON(err); de->inode = 0; err = dir_commit_chunk(page, from, to); dir_put_page(page); inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; mark_inode_dirty(inode); return err; } int sysv_make_empty(struct inode *inode, struct inode *dir) { struct address_space *mapping = inode->i_mapping; struct page *page = grab_cache_page(mapping, 0); struct sysv_dir_entry * de; char *base; int err; if (!page) return -ENOMEM; kmap(page); err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * SYSV_DIRSIZE); if (err) { unlock_page(page); goto fail; } base = (char*)page_address(page); memset(base, 0, PAGE_CACHE_SIZE); de = (struct sysv_dir_entry *) base; de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); strcpy(de->name,"."); de++; de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino); strcpy(de->name,".."); err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE); fail: kunmap(page); page_cache_release(page); return err; } /* * routine to check that the specified directory is empty (for rmdir) */ int sysv_empty_dir(struct inode * inode) { struct super_block *sb = inode->i_sb; struct page *page = NULL; unsigned long i, npages = dir_pages(inode); for (i = 0; i < npages; i++) { char *kaddr; struct sysv_dir_entry * de; page = dir_get_page(inode, i); if (IS_ERR(page)) continue; kaddr = (char *)page_address(page); de = (struct sysv_dir_entry *)kaddr; kaddr += PAGE_CACHE_SIZE-SYSV_DIRSIZE; for ( ;(char *)de <= kaddr; de++) { if (!de->inode) continue; /* check for . and .. */ if (de->name[0] != '.') goto not_empty; if (!de->name[1]) { if (de->inode == cpu_to_fs16(SYSV_SB(sb), inode->i_ino)) continue; goto not_empty; } if (de->name[1] != '.' || de->name[2]) goto not_empty; } dir_put_page(page); } return 1; not_empty: dir_put_page(page); return 0; } /* Releases the page */ void sysv_set_link(struct sysv_dir_entry *de, struct page *page, struct inode *inode) { struct inode *dir = (struct inode*)page->mapping->host; unsigned from = (char *)de-(char*)page_address(page); unsigned to = from + SYSV_DIRSIZE; int err; lock_page(page); err = page->mapping->a_ops->prepare_write(NULL, page, from, to); BUG_ON(err); de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); err = dir_commit_chunk(page, from, to); dir_put_page(page); dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; mark_inode_dirty(dir); } struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p) { struct page *page = dir_get_page(dir, 0); struct sysv_dir_entry *de = NULL; if (!IS_ERR(page)) { de = (struct sysv_dir_entry*) page_address(page) + 1; *p = page; } return de; } ino_t sysv_inode_by_name(struct dentry *dentry) { struct page *page; struct sysv_dir_entry *de = sysv_find_entry (dentry, &page); ino_t res = 0; if (de) { res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode); dir_put_page(page); } return res; }