Messages in this thread Patch in this message | | | Date | Wed, 10 Apr 2002 04:27:57 -0700 | From | Andrew Morton <> | Subject | Re: [patch] ext2 directory handling |
| |
That was an old version. This is it:
--- 2.5.8-pre3/fs/ext2/dir.c~dallocbase-55-ext2_dir Wed Apr 10 00:42:47 2002 +++ 2.5.8-pre3-akpm/fs/ext2/dir.c Wed Apr 10 03:11:50 2002 @@ -46,6 +46,21 @@ static inline unsigned long dir_pages(st 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, unsigned from, unsigned to) { struct inode *dir = page->mapping->host; @@ -78,10 +93,6 @@ static void ext2_check_page(struct page limit = dir->i_size & ~PAGE_CACHE_MASK; if (limit & (chunk_size - 1)) goto Ebadsize; - for (offs = limit; offs<PAGE_CACHE_SIZE; offs += chunk_size) { - ext2_dirent *p = (ext2_dirent*)(kaddr + offs); - p->rec_len = cpu_to_le16(chunk_size); - } if (!limit) goto out; } @@ -197,8 +208,11 @@ ext2_validate_entry(char *base, unsigned { ext2_dirent *de = (ext2_dirent*)(base + offset); ext2_dirent *p = (ext2_dirent*)(base + (offset&mask)); - while ((char*)p < (char*)de) + while ((char*)p < (char*)de) { + if (p->rec_len == 0) + break; p = ext2_next_entry(p); + } return (char *)p - base; } @@ -245,6 +259,7 @@ ext2_readdir (struct file * filp, void * unsigned chunk_mask = ~(ext2_chunk_size(inode)-1); unsigned char *types = NULL; int need_revalidate = (filp->f_version != inode->i_version); + int ret = 0; if (pos > inode->i_size - EXT2_DIR_REC_LEN(1)) goto done; @@ -265,8 +280,15 @@ ext2_readdir (struct file * filp, void * need_revalidate = 0; } de = (ext2_dirent *)(kaddr+offset); - limit = kaddr + PAGE_CACHE_SIZE - EXT2_DIR_REC_LEN(1); - for ( ;(char*)de <= limit; de = ext2_next_entry(de)) + 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, __FUNCTION__, + "zero-length directory entry"); + ret = -EIO; + ext2_put_page(page); + goto done; + } if (de->inode) { int over; unsigned char d_type = DT_UNKNOWN; @@ -283,6 +305,7 @@ ext2_readdir (struct file * filp, void * goto done; } } + } ext2_put_page(page); } @@ -326,8 +349,14 @@ struct ext2_dir_entry_2 * ext2_find_entr if (!IS_ERR(page)) { kaddr = page_address(page); de = (ext2_dirent *) kaddr; - kaddr += PAGE_CACHE_SIZE - reclen; + kaddr += ext2_last_byte(dir, n) - reclen; while ((char *) de <= kaddr) { + if (de->rec_len == 0) { + ext2_error(dir->i_sb, __FUNCTION__, + "zero-length directory entry"); + ext2_put_page(page); + goto out; + } if (ext2_match (namelen, name, de)) goto found; de = ext2_next_entry(de); @@ -337,6 +366,7 @@ struct ext2_dir_entry_2 * ext2_find_entr if (++n >= npages) n = 0; } while (n != start); +out: return NULL; found: @@ -401,6 +431,7 @@ int ext2_add_link (struct dentry *dentry struct inode *dir = dentry->d_parent->d_inode; 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; @@ -411,19 +442,41 @@ int ext2_add_link (struct dentry *dentry unsigned from, to; int err; - /* We take care of directory expansion in the same loop */ + /* + * 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); 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) { err = -EEXIST; if (ext2_match (namelen, name, de)) - goto out_page; + goto out_unlock; + if ((char *)de == dir_end) { + /* We hit i_size */ + name_len = 0; + rec_len = chunk_size; + de->rec_len = cpu_to_le16(chunk_size); + de->inode = 0; + goto got_it; + } + if (de->rec_len == 0) { + ext2_error(dir->i_sb, __FUNCTION__, + "zero-length directory entry"); + err = -EIO; + goto out_unlock; + } name_len = EXT2_DIR_REC_LEN(de->name_len); rec_len = le16_to_cpu(de->rec_len); if (!de->inode && rec_len >= reclen) @@ -432,6 +485,7 @@ int ext2_add_link (struct dentry *dentry goto got_it; de = (ext2_dirent *) ((char *) de + rec_len); } + unlock_page(page); ext2_put_page(page); } BUG(); @@ -440,7 +494,6 @@ int ext2_add_link (struct dentry *dentry got_it: from = (char*)de - (char*)page_address(page); to = from + rec_len; - lock_page(page); err = page->mapping->a_ops->prepare_write(NULL, page, from, to); if (err) goto out_unlock; @@ -460,7 +513,6 @@ got_it: /* OFFSET_CACHE */ out_unlock: UnlockPage(page); -out_page: ext2_put_page(page); out: return err; @@ -482,6 +534,12 @@ int ext2_delete_entry (struct ext2_dir_e int err; while ((char*)de < (char*)dir) { + if (de->rec_len == 0) { + ext2_error(inode->i_sb, __FUNCTION__, + "zero-length directory entry"); + err = -EIO; + goto out; + } pde = de; de = ext2_next_entry(de); } @@ -496,9 +554,10 @@ int ext2_delete_entry (struct ext2_dir_e dir->inode = 0; err = ext2_commit_chunk(page, from, to); UnlockPage(page); - ext2_put_page(page); inode->i_ctime = inode->i_mtime = CURRENT_TIME; mark_inode_dirty(inode); +out: + ext2_put_page(page); return err; } @@ -550,7 +609,7 @@ int ext2_empty_dir (struct inode * inode { struct page *page = NULL; unsigned long i, npages = dir_pages(inode); - + for (i = 0; i < npages; i++) { char *kaddr; ext2_dirent * de; @@ -561,9 +620,15 @@ int ext2_empty_dir (struct inode * inode kaddr = page_address(page); de = (ext2_dirent *)kaddr; - kaddr += PAGE_CACHE_SIZE-EXT2_DIR_REC_LEN(1); + 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, __FUNCTION__, + "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] != '.') - - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |