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From: Gao Xiang <gaoxiang25@huawei.com>
To: <linux-fsdevel@vger.kernel.org>, <devel@driverdev.osuosl.org>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Theodore Ts'o <tytso@mit.edu>, "Pavel Machek" <pavel@denx.de>,
	David Sterba <dsterba@suse.cz>,
	Amir Goldstein <amir73il@gmail.com>,
	Christoph Hellwig <hch@infradead.org>,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	Dave Chinner <david@fromorbit.com>,
	"Jaegeuk Kim" <jaegeuk@kernel.org>, Jan Kara <jack@suse.cz>,
	Richard Weinberger <richard@nod.at>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	<linux-erofs@lists.ozlabs.org>, Chao Yu <yuchao0@huawei.com>,
	Miao Xie <miaoxie@huawei.com>,
	Li Guifu <bluce.liguifu@huawei.com>,
	Fang Wei <fangwei1@huawei.com>, Gao Xiang <gaoxiang25@huawei.com>
Subject: [PATCH v8 08/24] erofs: add namei functions
Date: Thu, 15 Aug 2019 12:41:39 +0800	[thread overview]
Message-ID: <20190815044155.88483-9-gaoxiang25@huawei.com> (raw)
In-Reply-To: <20190815044155.88483-1-gaoxiang25@huawei.com>

This commit adds functions that transfer names to inodes.

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
 fs/erofs/namei.c | 249 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 249 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..98b9e8cebca5
--- /dev/null
+++ b/fs/erofs/namei.c
@@ -0,0 +1,249 @@
+// 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 <gaoxiang25@huawei.com>
+ */
+#include "internal.h"
+
+#include <trace/events/erofs.h>
+
+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)) {
+				kunmap_atomic(de);
+				put_page(page);
+				errln("corrupted dir block %d @ nid %llu",
+				      mid, EROFS_V(dir)->nid);
+				DBG_BUGON(1);
+				page = ERR_PTR(-EFSCORRUPTED);
+				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,
+};
+
-- 
2.17.1


  parent reply	other threads:[~2019-08-15  4:42 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-15  4:41 [PATCH v8 00/24] erofs: promote erofs from staging v8 Gao Xiang
2019-08-15  4:41 ` [PATCH v8 01/24] erofs: add on-disk layout Gao Xiang
2019-08-15  4:41 ` [PATCH v8 02/24] erofs: add erofs in-memory stuffs Gao Xiang
2019-08-15  4:41 ` [PATCH v8 03/24] erofs: add super block operations Gao Xiang
2019-08-15  4:41 ` [PATCH v8 04/24] erofs: add raw address_space operations Gao Xiang
2019-08-15  4:41 ` [PATCH v8 05/24] erofs: add inode operations Gao Xiang
2019-08-15  4:41 ` [PATCH v8 06/24] erofs: support special inode Gao Xiang
2019-08-15  4:41 ` [PATCH v8 07/24] erofs: add directory operations Gao Xiang
2019-08-15 16:13   ` Linus Torvalds
2019-08-15 16:46     ` Gao Xiang
2019-08-15  4:41 ` Gao Xiang [this message]
2019-08-15  4:41 ` [PATCH v8 09/24] erofs: support tracepoint Gao Xiang
2019-08-15  4:41 ` [PATCH v8 10/24] erofs: update Kconfig and Makefile Gao Xiang
2019-08-15  4:41 ` [PATCH v8 11/24] erofs: introduce xattr & posixacl support Gao Xiang
2019-09-02 12:57   ` Christoph Hellwig
2019-09-02 13:05     ` Gao Xiang
2019-09-02 13:06     ` David Sterba
2019-09-02 13:51       ` Chao Yu
2019-09-02 14:20         ` David Sterba
2019-09-02 15:06           ` Christoph Hellwig
2019-09-02 15:10             ` Gao Xiang
2019-09-02 15:21             ` Gao Xiang
2019-09-03  6:30           ` Chao Yu
2019-08-15  4:41 ` [PATCH v8 12/24] erofs: introduce tagged pointer Gao Xiang
2019-08-15  4:41 ` [PATCH v8 13/24] erofs: add compression indexes support Gao Xiang
2019-08-15  4:41 ` [PATCH v8 14/24] erofs: introduce superblock registration Gao Xiang
2019-08-15  4:41 ` [PATCH v8 15/24] erofs: introduce erofs shrinker Gao Xiang
2019-08-15  4:41 ` [PATCH v8 16/24] erofs: introduce workstation for decompression Gao Xiang
2019-08-15  4:41 ` [PATCH v8 17/24] erofs: introduce per-CPU buffers implementation Gao Xiang
2019-08-15  4:41 ` [PATCH v8 18/24] erofs: introduce pagevec for decompression subsystem Gao Xiang
2019-08-15  4:41 ` [PATCH v8 19/24] erofs: add erofs_allocpage() Gao Xiang
2019-08-15  4:41 ` [PATCH v8 20/24] erofs: introduce generic decompression backend Gao Xiang
2019-08-30 16:35   ` Christoph Hellwig
2019-08-30 16:52     ` Gao Xiang
2019-08-30 16:55       ` Christoph Hellwig
2019-08-15  4:41 ` [PATCH v8 21/24] erofs: introduce LZ4 decompression inplace Gao Xiang
2019-08-15  4:41 ` [PATCH v8 22/24] erofs: introduce the decompression frontend Gao Xiang
2019-08-15  4:41 ` [PATCH v8 23/24] erofs: introduce cached decompression Gao Xiang
2019-08-15  4:41 ` [PATCH v8 24/24] erofs: add document Gao Xiang
2019-08-15  9:06 ` [PATCH v8 00/24] erofs: promote erofs from staging v8 Greg Kroah-Hartman
2019-08-15 16:18   ` Linus Torvalds
2019-08-15 17:04     ` Gao Xiang
2019-08-22 14:16   ` Gao Xiang
2019-08-29 17:11 ` Miao Xie
2019-08-30  7:48 ` Chao Yu

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