From patchwork Tue Aug 13 09:13:10 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gao Xiang X-Patchwork-Id: 11091587 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5009614F7 for ; Tue, 13 Aug 2019 09:15:47 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4053A2861D for ; Tue, 13 Aug 2019 09:15:47 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 340A32864A; Tue, 13 Aug 2019 09:15:47 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 85774285CB for ; Tue, 13 Aug 2019 09:15:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728318AbfHMJOW (ORCPT ); Tue, 13 Aug 2019 05:14:22 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:4243 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728259AbfHMJOV (ORCPT ); Tue, 13 Aug 2019 05:14:21 -0400 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id CD52945F643DC7D0034F; Tue, 13 Aug 2019 17:14:19 +0800 (CST) Received: from architecture4.huawei.com (10.140.130.215) by smtp.huawei.com (10.3.19.208) with Microsoft SMTP Server (TLS) id 14.3.439.0; Tue, 13 Aug 2019 17:14:10 +0800 From: Gao Xiang To: linux-fsdevel , LKML , Alexander Viro CC: Greg Kroah-Hartman , Andrew Morton , Stephen Rothwell , Theodore Ts'o , Pavel Machek , David Sterba , Amir Goldstein , Christoph Hellwig , "Darrick J . Wong" , "Dave Chinner" , Jaegeuk Kim , Jan Kara , Richard Weinberger , Linus Torvalds , , , Chao Yu , Miao Xie , Li Guifu , Fang Wei , Gao Xiang Subject: [PATCH v7 08/24] erofs: add namei functions Date: Tue, 13 Aug 2019 17:13:10 +0800 Message-ID: <20190813091326.84652-9-gaoxiang25@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190813091326.84652-1-gaoxiang25@huawei.com> References: <20190813091326.84652-1-gaoxiang25@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.140.130.215] X-CFilter-Loop: Reflected Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This commit adds functions that transfer names to inodes. Signed-off-by: Gao Xiang --- fs/erofs/namei.c | 247 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 247 insertions(+) create mode 100644 fs/erofs/namei.c diff --git a/fs/erofs/namei.c b/fs/erofs/namei.c new file mode 100644 index 000000000000..73bf61637907 --- /dev/null +++ b/fs/erofs/namei.c @@ -0,0 +1,247 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/fs/erofs/namei.c + * + * Copyright (C) 2017-2018 HUAWEI, Inc. + * http://www.huawei.com/ + * Created by Gao Xiang + */ +#include "internal.h" + +#include + +struct erofs_qstr { + const unsigned char *name; + const unsigned char *end; +}; + +/* based on the end of qn is accurate and it must have the trailing '\0' */ +static inline int dirnamecmp(const struct erofs_qstr *qn, + const struct erofs_qstr *qd, + unsigned int *matched) +{ + unsigned int i = *matched; + + /* + * on-disk error, let's only BUG_ON in the debugging mode. + * otherwise, it will return 1 to just skip the invalid name + * and go on (in consideration of the lookup performance). + */ + DBG_BUGON(qd->name > qd->end); + + /* qd could not have trailing '\0' */ + /* However it is absolutely safe if < qd->end */ + while (qd->name + i < qd->end && qd->name[i] != '\0') { + if (qn->name[i] != qd->name[i]) { + *matched = i; + return qn->name[i] > qd->name[i] ? 1 : -1; + } + ++i; + } + *matched = i; + /* See comments in __d_alloc on the terminating NUL character */ + return qn->name[i] == '\0' ? 0 : 1; +} + +#define nameoff_from_disk(off, sz) (le16_to_cpu(off) & ((sz) - 1)) + +static struct erofs_dirent *find_target_dirent(struct erofs_qstr *name, + u8 *data, + unsigned int dirblksize, + const int ndirents) +{ + int head, back; + unsigned int startprfx, endprfx; + struct erofs_dirent *const de = (struct erofs_dirent *)data; + + /* since the 1st dirent has been evaluated previously */ + head = 1; + back = ndirents - 1; + startprfx = endprfx = 0; + + while (head <= back) { + const int mid = head + (back - head) / 2; + const int nameoff = nameoff_from_disk(de[mid].nameoff, + dirblksize); + unsigned int matched = min(startprfx, endprfx); + struct erofs_qstr dname = { + .name = data + nameoff, + .end = unlikely(mid >= ndirents - 1) ? + data + dirblksize : + data + nameoff_from_disk(de[mid + 1].nameoff, + dirblksize) + }; + + /* string comparison without already matched prefix */ + int ret = dirnamecmp(name, &dname, &matched); + + if (unlikely(!ret)) { + return de + mid; + } else if (ret > 0) { + head = mid + 1; + startprfx = matched; + } else { + back = mid - 1; + endprfx = matched; + } + } + + return ERR_PTR(-ENOENT); +} + +static struct page *find_target_block_classic(struct inode *dir, + struct erofs_qstr *name, + int *_ndirents) +{ + unsigned int startprfx, endprfx; + int head, back; + struct address_space *const mapping = dir->i_mapping; + struct page *candidate = ERR_PTR(-ENOENT); + + startprfx = endprfx = 0; + head = 0; + back = inode_datablocks(dir) - 1; + + while (head <= back) { + const int mid = head + (back - head) / 2; + struct page *page = read_mapping_page(mapping, mid, NULL); + + if (!IS_ERR(page)) { + struct erofs_dirent *de = kmap_atomic(page); + const int nameoff = nameoff_from_disk(de->nameoff, + EROFS_BLKSIZ); + const int ndirents = nameoff / sizeof(*de); + int diff; + unsigned int matched; + struct erofs_qstr dname; + + if (unlikely(!ndirents)) { + DBG_BUGON(1); + kunmap_atomic(de); + put_page(page); + page = ERR_PTR(-EIO); + goto out; + } + + matched = min(startprfx, endprfx); + + dname.name = (u8 *)de + nameoff; + if (ndirents == 1) + dname.end = (u8 *)de + EROFS_BLKSIZ; + else + dname.end = (u8 *)de + + nameoff_from_disk(de[1].nameoff, + EROFS_BLKSIZ); + + /* string comparison without already matched prefix */ + diff = dirnamecmp(name, &dname, &matched); + kunmap_atomic(de); + + if (unlikely(!diff)) { + *_ndirents = 0; + goto out; + } else if (diff > 0) { + head = mid + 1; + startprfx = matched; + + if (!IS_ERR(candidate)) + put_page(candidate); + candidate = page; + *_ndirents = ndirents; + } else { + put_page(page); + + back = mid - 1; + endprfx = matched; + } + continue; + } +out: /* free if the candidate is valid */ + if (!IS_ERR(candidate)) + put_page(candidate); + return page; + } + return candidate; +} + +int erofs_namei(struct inode *dir, + struct qstr *name, + erofs_nid_t *nid, unsigned int *d_type) +{ + int ndirents; + struct page *page; + void *data; + struct erofs_dirent *de; + struct erofs_qstr qn; + + if (unlikely(!dir->i_size)) + return -ENOENT; + + qn.name = name->name; + qn.end = name->name + name->len; + + ndirents = 0; + page = find_target_block_classic(dir, &qn, &ndirents); + + if (IS_ERR(page)) + return PTR_ERR(page); + + data = kmap_atomic(page); + /* the target page has been mapped */ + if (ndirents) + de = find_target_dirent(&qn, data, EROFS_BLKSIZ, ndirents); + else + de = (struct erofs_dirent *)data; + + if (!IS_ERR(de)) { + *nid = le64_to_cpu(de->nid); + *d_type = de->file_type; + } + + kunmap_atomic(data); + put_page(page); + + return PTR_ERR_OR_ZERO(de); +} + +/* NOTE: i_mutex is already held by vfs */ +static struct dentry *erofs_lookup(struct inode *dir, + struct dentry *dentry, + unsigned int flags) +{ + int err; + erofs_nid_t nid; + unsigned int d_type; + struct inode *inode; + + DBG_BUGON(!d_really_is_negative(dentry)); + /* dentry must be unhashed in lookup, no need to worry about */ + DBG_BUGON(!d_unhashed(dentry)); + + trace_erofs_lookup(dir, dentry, flags); + + /* file name exceeds fs limit */ + if (unlikely(dentry->d_name.len > EROFS_NAME_LEN)) + return ERR_PTR(-ENAMETOOLONG); + + /* false uninitialized warnings on gcc 4.8.x */ + err = erofs_namei(dir, &dentry->d_name, &nid, &d_type); + + if (err == -ENOENT) { + /* negative dentry */ + inode = NULL; + } else if (unlikely(err)) { + inode = ERR_PTR(err); + } else { + debugln("%s, %s (nid %llu) found, d_type %u", __func__, + dentry->d_name.name, nid, d_type); + inode = erofs_iget(dir->i_sb, nid, d_type == EROFS_FT_DIR); + } + return d_splice_alias(inode, dentry); +} + +const struct inode_operations erofs_dir_iops = { + .lookup = erofs_lookup, + .getattr = erofs_getattr, +}; +