diff options
Diffstat (limited to 'kernel/fs/ext2/dir.c')
| -rw-r--r-- | kernel/fs/ext2/dir.c | 730 |
1 files changed, 730 insertions, 0 deletions
diff --git a/kernel/fs/ext2/dir.c b/kernel/fs/ext2/dir.c new file mode 100644 index 000000000..796b491e6 --- /dev/null +++ b/kernel/fs/ext2/dir.c @@ -0,0 +1,730 @@ +/* + * linux/fs/ext2/dir.c + * + * Copyright (C) 1992, 1993, 1994, 1995 + * Remy Card (card@masi.ibp.fr) + * Laboratoire MASI - Institut Blaise Pascal + * Universite Pierre et Marie Curie (Paris VI) + * + * from + * + * linux/fs/minix/dir.c + * + * Copyright (C) 1991, 1992 Linus Torvalds + * + * ext2 directory handling functions + * + * Big-endian to little-endian byte-swapping/bitmaps by + * David S. Miller (davem@caip.rutgers.edu), 1995 + * + * All code that works with directory layout had been switched to pagecache + * and moved here. AV + */ + +#include "ext2.h" +#include <linux/buffer_head.h> +#include <linux/pagemap.h> +#include <linux/swap.h> + +typedef struct ext2_dir_entry_2 ext2_dirent; + +/* + * Tests against MAX_REC_LEN etc were put in place for 64k block + * sizes; if that is not possible on this arch, we can skip + * those tests and speed things up. + */ +static inline unsigned ext2_rec_len_from_disk(__le16 dlen) +{ + unsigned len = le16_to_cpu(dlen); + +#if (PAGE_CACHE_SIZE >= 65536) + if (len == EXT2_MAX_REC_LEN) + return 1 << 16; +#endif + return len; +} + +static inline __le16 ext2_rec_len_to_disk(unsigned len) +{ +#if (PAGE_CACHE_SIZE >= 65536) + if (len == (1 << 16)) + return cpu_to_le16(EXT2_MAX_REC_LEN); + else + BUG_ON(len > (1 << 16)); +#endif + return cpu_to_le16(len); +} + +/* + * ext2 uses block-sized chunks. Arguably, sector-sized ones would be + * more robust, but we have what we have + */ +static inline unsigned ext2_chunk_size(struct inode *inode) +{ + return inode->i_sb->s_blocksize; +} + +static inline void ext2_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; +} + +/* + * Return the offset into page `page_nr' of the last valid + * byte in that page, plus one. + */ +static unsigned +ext2_last_byte(struct inode *inode, unsigned long page_nr) +{ + unsigned last_byte = inode->i_size; + + last_byte -= page_nr << PAGE_CACHE_SHIFT; + if (last_byte > PAGE_CACHE_SIZE) + last_byte = PAGE_CACHE_SIZE; + return last_byte; +} + +static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len) +{ + struct address_space *mapping = page->mapping; + struct inode *dir = mapping->host; + int err = 0; + + dir->i_version++; + block_write_end(NULL, mapping, pos, len, len, page, NULL); + + if (pos+len > dir->i_size) { + i_size_write(dir, pos+len); + mark_inode_dirty(dir); + } + + if (IS_DIRSYNC(dir)) { + err = write_one_page(page, 1); + if (!err) + err = sync_inode_metadata(dir, 1); + } else { + unlock_page(page); + } + + return err; +} + +static void ext2_check_page(struct page *page, int quiet) +{ + struct inode *dir = page->mapping->host; + struct super_block *sb = dir->i_sb; + unsigned chunk_size = ext2_chunk_size(dir); + char *kaddr = page_address(page); + u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count); + unsigned offs, rec_len; + unsigned limit = PAGE_CACHE_SIZE; + ext2_dirent *p; + char *error; + + if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) { + limit = dir->i_size & ~PAGE_CACHE_MASK; + if (limit & (chunk_size - 1)) + goto Ebadsize; + if (!limit) + goto out; + } + for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) { + p = (ext2_dirent *)(kaddr + offs); + rec_len = ext2_rec_len_from_disk(p->rec_len); + + if (unlikely(rec_len < EXT2_DIR_REC_LEN(1))) + goto Eshort; + if (unlikely(rec_len & 3)) + goto Ealign; + if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len))) + goto Enamelen; + if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))) + goto Espan; + if (unlikely(le32_to_cpu(p->inode) > max_inumber)) + goto Einumber; + } + if (offs != limit) + goto Eend; +out: + SetPageChecked(page); + return; + + /* Too bad, we had an error */ + +Ebadsize: + if (!quiet) + ext2_error(sb, __func__, + "size of directory #%lu is not a multiple " + "of chunk size", dir->i_ino); + goto fail; +Eshort: + error = "rec_len is smaller than minimal"; + goto bad_entry; +Ealign: + error = "unaligned directory entry"; + goto bad_entry; +Enamelen: + error = "rec_len is too small for name_len"; + goto bad_entry; +Espan: + error = "directory entry across blocks"; + goto bad_entry; +Einumber: + error = "inode out of bounds"; +bad_entry: + if (!quiet) + ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - " + "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", + dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs, + (unsigned long) le32_to_cpu(p->inode), + rec_len, p->name_len); + goto fail; +Eend: + if (!quiet) { + p = (ext2_dirent *)(kaddr + offs); + ext2_error(sb, "ext2_check_page", + "entry in directory #%lu spans the page boundary" + "offset=%lu, inode=%lu", + dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs, + (unsigned long) le32_to_cpu(p->inode)); + } +fail: + SetPageChecked(page); + SetPageError(page); +} + +static struct page * ext2_get_page(struct inode *dir, unsigned long n, + int quiet) +{ + struct address_space *mapping = dir->i_mapping; + struct page *page = read_mapping_page(mapping, n, NULL); + if (!IS_ERR(page)) { + kmap(page); + if (!PageChecked(page)) + ext2_check_page(page, quiet); + if (PageError(page)) + goto fail; + } + return page; + +fail: + ext2_put_page(page); + return ERR_PTR(-EIO); +} + +/* + * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure. + * + * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller. + */ +static inline int ext2_match (int len, const char * const name, + struct ext2_dir_entry_2 * de) +{ + if (len != de->name_len) + return 0; + if (!de->inode) + return 0; + return !memcmp(name, de->name, len); +} + +/* + * p is at least 6 bytes before the end of page + */ +static inline ext2_dirent *ext2_next_entry(ext2_dirent *p) +{ + return (ext2_dirent *)((char *)p + + ext2_rec_len_from_disk(p->rec_len)); +} + +static inline unsigned +ext2_validate_entry(char *base, unsigned offset, unsigned mask) +{ + ext2_dirent *de = (ext2_dirent*)(base + offset); + ext2_dirent *p = (ext2_dirent*)(base + (offset&mask)); + while ((char*)p < (char*)de) { + if (p->rec_len == 0) + break; + p = ext2_next_entry(p); + } + return (char *)p - base; +} + +static unsigned char ext2_filetype_table[EXT2_FT_MAX] = { + [EXT2_FT_UNKNOWN] = DT_UNKNOWN, + [EXT2_FT_REG_FILE] = DT_REG, + [EXT2_FT_DIR] = DT_DIR, + [EXT2_FT_CHRDEV] = DT_CHR, + [EXT2_FT_BLKDEV] = DT_BLK, + [EXT2_FT_FIFO] = DT_FIFO, + [EXT2_FT_SOCK] = DT_SOCK, + [EXT2_FT_SYMLINK] = DT_LNK, +}; + +#define S_SHIFT 12 +static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = { + [S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE, + [S_IFDIR >> S_SHIFT] = EXT2_FT_DIR, + [S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV, + [S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV, + [S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO, + [S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK, + [S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK, +}; + +static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode) +{ + umode_t mode = inode->i_mode; + if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) + de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT]; + else + de->file_type = 0; +} + +static int +ext2_readdir(struct file *file, struct dir_context *ctx) +{ + loff_t pos = ctx->pos; + struct inode *inode = file_inode(file); + struct super_block *sb = inode->i_sb; + unsigned int offset = pos & ~PAGE_CACHE_MASK; + unsigned long n = pos >> PAGE_CACHE_SHIFT; + unsigned long npages = dir_pages(inode); + unsigned chunk_mask = ~(ext2_chunk_size(inode)-1); + unsigned char *types = NULL; + int need_revalidate = file->f_version != inode->i_version; + + if (pos > inode->i_size - EXT2_DIR_REC_LEN(1)) + return 0; + + if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) + types = ext2_filetype_table; + + for ( ; n < npages; n++, offset = 0) { + char *kaddr, *limit; + ext2_dirent *de; + struct page *page = ext2_get_page(inode, n, 0); + + if (IS_ERR(page)) { + ext2_error(sb, __func__, + "bad page in #%lu", + inode->i_ino); + ctx->pos += PAGE_CACHE_SIZE - offset; + return PTR_ERR(page); + } + kaddr = page_address(page); + if (unlikely(need_revalidate)) { + if (offset) { + offset = ext2_validate_entry(kaddr, offset, chunk_mask); + ctx->pos = (n<<PAGE_CACHE_SHIFT) + offset; + } + file->f_version = inode->i_version; + need_revalidate = 0; + } + de = (ext2_dirent *)(kaddr+offset); + limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1); + for ( ;(char*)de <= limit; de = ext2_next_entry(de)) { + if (de->rec_len == 0) { + ext2_error(sb, __func__, + "zero-length directory entry"); + ext2_put_page(page); + return -EIO; + } + if (de->inode) { + unsigned char d_type = DT_UNKNOWN; + + if (types && de->file_type < EXT2_FT_MAX) + d_type = types[de->file_type]; + + if (!dir_emit(ctx, de->name, de->name_len, + le32_to_cpu(de->inode), + d_type)) { + ext2_put_page(page); + return 0; + } + } + ctx->pos += ext2_rec_len_from_disk(de->rec_len); + } + ext2_put_page(page); + } + return 0; +} + +/* + * ext2_find_entry() + * + * finds an entry in the specified directory with the wanted name. It + * returns the page in which the entry was found (as a parameter - res_page), + * and the entry itself. Page is returned mapped and unlocked. + * Entry is guaranteed to be valid. + */ +struct ext2_dir_entry_2 *ext2_find_entry (struct inode * dir, + struct qstr *child, struct page ** res_page) +{ + const char *name = child->name; + int namelen = child->len; + unsigned reclen = EXT2_DIR_REC_LEN(namelen); + unsigned long start, n; + unsigned long npages = dir_pages(dir); + struct page *page = NULL; + struct ext2_inode_info *ei = EXT2_I(dir); + ext2_dirent * de; + int dir_has_error = 0; + + if (npages == 0) + goto out; + + /* OFFSET_CACHE */ + *res_page = NULL; + + start = ei->i_dir_start_lookup; + if (start >= npages) + start = 0; + n = start; + do { + char *kaddr; + page = ext2_get_page(dir, n, dir_has_error); + if (!IS_ERR(page)) { + kaddr = page_address(page); + de = (ext2_dirent *) kaddr; + kaddr += ext2_last_byte(dir, n) - reclen; + while ((char *) de <= kaddr) { + if (de->rec_len == 0) { + ext2_error(dir->i_sb, __func__, + "zero-length directory entry"); + ext2_put_page(page); + goto out; + } + if (ext2_match (namelen, name, de)) + goto found; + de = ext2_next_entry(de); + } + ext2_put_page(page); + } else + dir_has_error = 1; + + if (++n >= npages) + n = 0; + /* next page is past the blocks we've got */ + if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) { + ext2_error(dir->i_sb, __func__, + "dir %lu size %lld exceeds block count %llu", + dir->i_ino, dir->i_size, + (unsigned long long)dir->i_blocks); + goto out; + } + } while (n != start); +out: + return NULL; + +found: + *res_page = page; + ei->i_dir_start_lookup = n; + return de; +} + +struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p) +{ + struct page *page = ext2_get_page(dir, 0, 0); + ext2_dirent *de = NULL; + + if (!IS_ERR(page)) { + de = ext2_next_entry((ext2_dirent *) page_address(page)); + *p = page; + } + return de; +} + +ino_t ext2_inode_by_name(struct inode *dir, struct qstr *child) +{ + ino_t res = 0; + struct ext2_dir_entry_2 *de; + struct page *page; + + de = ext2_find_entry (dir, child, &page); + if (de) { + res = le32_to_cpu(de->inode); + ext2_put_page(page); + } + return res; +} + +static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len) +{ + return __block_write_begin(page, pos, len, ext2_get_block); +} + +/* Releases the page */ +void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de, + struct page *page, struct inode *inode, int update_times) +{ + loff_t pos = page_offset(page) + + (char *) de - (char *) page_address(page); + unsigned len = ext2_rec_len_from_disk(de->rec_len); + int err; + + lock_page(page); + err = ext2_prepare_chunk(page, pos, len); + BUG_ON(err); + de->inode = cpu_to_le32(inode->i_ino); + ext2_set_de_type(de, inode); + err = ext2_commit_chunk(page, pos, len); + ext2_put_page(page); + if (update_times) + dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; + EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; + mark_inode_dirty(dir); +} + +/* + * Parent is locked. + */ +int ext2_add_link (struct dentry *dentry, struct inode *inode) +{ + struct inode *dir = d_inode(dentry->d_parent); + const char *name = dentry->d_name.name; + int namelen = dentry->d_name.len; + unsigned chunk_size = ext2_chunk_size(dir); + unsigned reclen = EXT2_DIR_REC_LEN(namelen); + unsigned short rec_len, name_len; + struct page *page = NULL; + ext2_dirent * de; + unsigned long npages = dir_pages(dir); + unsigned long n; + char *kaddr; + loff_t pos; + 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 = ext2_get_page(dir, n, 0); + err = PTR_ERR(page); + if (IS_ERR(page)) + goto out; + lock_page(page); + kaddr = page_address(page); + dir_end = kaddr + ext2_last_byte(dir, n); + de = (ext2_dirent *)kaddr; + kaddr += PAGE_CACHE_SIZE - reclen; + while ((char *)de <= kaddr) { + if ((char *)de == dir_end) { + /* We hit i_size */ + name_len = 0; + rec_len = chunk_size; + de->rec_len = ext2_rec_len_to_disk(chunk_size); + de->inode = 0; + goto got_it; + } + if (de->rec_len == 0) { + ext2_error(dir->i_sb, __func__, + "zero-length directory entry"); + err = -EIO; + goto out_unlock; + } + err = -EEXIST; + if (ext2_match (namelen, name, de)) + goto out_unlock; + name_len = EXT2_DIR_REC_LEN(de->name_len); + rec_len = ext2_rec_len_from_disk(de->rec_len); + if (!de->inode && rec_len >= reclen) + goto got_it; + if (rec_len >= name_len + reclen) + goto got_it; + de = (ext2_dirent *) ((char *) de + rec_len); + } + unlock_page(page); + ext2_put_page(page); + } + BUG(); + return -EINVAL; + +got_it: + pos = page_offset(page) + + (char*)de - (char*)page_address(page); + err = ext2_prepare_chunk(page, pos, rec_len); + if (err) + goto out_unlock; + if (de->inode) { + ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len); + de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len); + de->rec_len = ext2_rec_len_to_disk(name_len); + de = de1; + } + de->name_len = namelen; + memcpy(de->name, name, namelen); + de->inode = cpu_to_le32(inode->i_ino); + ext2_set_de_type (de, inode); + err = ext2_commit_chunk(page, pos, rec_len); + dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; + EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; + mark_inode_dirty(dir); + /* OFFSET_CACHE */ +out_put: + ext2_put_page(page); +out: + return err; +out_unlock: + unlock_page(page); + goto out_put; +} + +/* + * ext2_delete_entry deletes a directory entry by merging it with the + * previous entry. Page is up-to-date. Releases the page. + */ +int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page ) +{ + struct inode *inode = page->mapping->host; + char *kaddr = page_address(page); + unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1); + unsigned to = ((char *)dir - kaddr) + + ext2_rec_len_from_disk(dir->rec_len); + loff_t pos; + ext2_dirent * pde = NULL; + ext2_dirent * de = (ext2_dirent *) (kaddr + from); + int err; + + while ((char*)de < (char*)dir) { + if (de->rec_len == 0) { + ext2_error(inode->i_sb, __func__, + "zero-length directory entry"); + err = -EIO; + goto out; + } + pde = de; + de = ext2_next_entry(de); + } + if (pde) + from = (char*)pde - (char*)page_address(page); + pos = page_offset(page) + from; + lock_page(page); + err = ext2_prepare_chunk(page, pos, to - from); + BUG_ON(err); + if (pde) + pde->rec_len = ext2_rec_len_to_disk(to - from); + dir->inode = 0; + err = ext2_commit_chunk(page, pos, to - from); + inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; + EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL; + mark_inode_dirty(inode); +out: + ext2_put_page(page); + return err; +} + +/* + * Set the first fragment of directory. + */ +int ext2_make_empty(struct inode *inode, struct inode *parent) +{ + struct page *page = grab_cache_page(inode->i_mapping, 0); + unsigned chunk_size = ext2_chunk_size(inode); + struct ext2_dir_entry_2 * de; + int err; + void *kaddr; + + if (!page) + return -ENOMEM; + + err = ext2_prepare_chunk(page, 0, chunk_size); + if (err) { + unlock_page(page); + goto fail; + } + kaddr = kmap_atomic(page); + memset(kaddr, 0, chunk_size); + de = (struct ext2_dir_entry_2 *)kaddr; + de->name_len = 1; + de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1)); + memcpy (de->name, ".\0\0", 4); + de->inode = cpu_to_le32(inode->i_ino); + ext2_set_de_type (de, inode); + + de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1)); + de->name_len = 2; + de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1)); + de->inode = cpu_to_le32(parent->i_ino); + memcpy (de->name, "..\0", 4); + ext2_set_de_type (de, inode); + kunmap_atomic(kaddr); + err = ext2_commit_chunk(page, 0, chunk_size); +fail: + page_cache_release(page); + return err; +} + +/* + * routine to check that the specified directory is empty (for rmdir) + */ +int ext2_empty_dir (struct inode * inode) +{ + struct page *page = NULL; + unsigned long i, npages = dir_pages(inode); + int dir_has_error = 0; + + for (i = 0; i < npages; i++) { + char *kaddr; + ext2_dirent * de; + page = ext2_get_page(inode, i, dir_has_error); + + if (IS_ERR(page)) { + dir_has_error = 1; + continue; + } + + kaddr = page_address(page); + de = (ext2_dirent *)kaddr; + kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1); + + while ((char *)de <= kaddr) { + if (de->rec_len == 0) { + ext2_error(inode->i_sb, __func__, + "zero-length directory entry"); + printk("kaddr=%p, de=%p\n", kaddr, de); + goto not_empty; + } + if (de->inode != 0) { + /* check for . and .. */ + if (de->name[0] != '.') + goto not_empty; + if (de->name_len > 2) + goto not_empty; + if (de->name_len < 2) { + if (de->inode != + cpu_to_le32(inode->i_ino)) + goto not_empty; + } else if (de->name[1] != '.') + goto not_empty; + } + de = ext2_next_entry(de); + } + ext2_put_page(page); + } + return 1; + +not_empty: + ext2_put_page(page); + return 0; +} + +const struct file_operations ext2_dir_operations = { + .llseek = generic_file_llseek, + .read = generic_read_dir, + .iterate = ext2_readdir, + .unlocked_ioctl = ext2_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = ext2_compat_ioctl, +#endif + .fsync = ext2_fsync, +}; |