Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 224 insertions, 0 deletions

diff --git a/fs/erofs/namei.c b/fs/erofs/namei.c
new file mode 100644
index 000000000..d4f631d39
--- /dev/null
+++ b/fs/erofs/namei.c
@@ -0,0 +1,224 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017-2018 HUAWEI, Inc.
+ *             https://www.huawei.com/
+ * Copyright (C) 2022, Alibaba Cloud
+ */
+#include "xattr.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 erofs_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 = mid >= ndirents - 1 ?
+				data + dirblksize :
+				data + nameoff_from_disk(de[mid + 1].nameoff,
+							 dirblksize)
+		};
+
+		/* string comparison without already matched prefix */
+		int ret = erofs_dirnamecmp(name, &dname, &matched);
+
+		if (!ret) {
+			return de + mid;
+		} else if (ret > 0) {
+			head = mid + 1;
+			startprfx = matched;
+		} else {
+			back = mid - 1;
+			endprfx = matched;
+		}
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+
+static void *erofs_find_target_block(struct erofs_buf *target,
+		struct inode *dir, struct erofs_qstr *name, int *_ndirents)
+{
+	unsigned int bsz = i_blocksize(dir);
+	int head = 0, back = erofs_iblks(dir) - 1;
+	unsigned int startprfx = 0, endprfx = 0;
+	void *candidate = ERR_PTR(-ENOENT);
+
+	while (head <= back) {
+		const int mid = head + (back - head) / 2;
+		struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
+		struct erofs_dirent *de;
+
+		buf.inode = dir;
+		de = erofs_bread(&buf, mid, EROFS_KMAP);
+		if (!IS_ERR(de)) {
+			const int nameoff = nameoff_from_disk(de->nameoff, bsz);
+			const int ndirents = nameoff / sizeof(*de);
+			int diff;
+			unsigned int matched;
+			struct erofs_qstr dname;
+
+			if (!ndirents) {
+				erofs_put_metabuf(&buf);
+				erofs_err(dir->i_sb,
+					  "corrupted dir block %d @ nid %llu",
+					  mid, EROFS_I(dir)->nid);
+				DBG_BUGON(1);
+				de = ERR_PTR(-EFSCORRUPTED);
+				goto out;
+			}
+
+			matched = min(startprfx, endprfx);
+
+			dname.name = (u8 *)de + nameoff;
+			if (ndirents == 1)
+				dname.end = (u8 *)de + bsz;
+			else
+				dname.end = (u8 *)de +
+					nameoff_from_disk(de[1].nameoff, bsz);
+
+			/* string comparison without already matched prefix */
+			diff = erofs_dirnamecmp(name, &dname, &matched);
+
+			if (!diff) {
+				*_ndirents = 0;
+				goto out;
+			} else if (diff > 0) {
+				head = mid + 1;
+				startprfx = matched;
+
+				if (!IS_ERR(candidate))
+					erofs_put_metabuf(target);
+				*target = buf;
+				candidate = de;
+				*_ndirents = ndirents;
+			} else {
+				erofs_put_metabuf(&buf);
+
+				back = mid - 1;
+				endprfx = matched;
+			}
+			continue;
+		}
+out:		/* free if the candidate is valid */
+		if (!IS_ERR(candidate))
+			erofs_put_metabuf(target);
+		return de;
+	}
+	return candidate;
+}
+
+int erofs_namei(struct inode *dir, const struct qstr *name, erofs_nid_t *nid,
+		unsigned int *d_type)
+{
+	int ndirents;
+	struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
+	struct erofs_dirent *de;
+	struct erofs_qstr qn;
+
+	if (!dir->i_size)
+		return -ENOENT;
+
+	qn.name = name->name;
+	qn.end = name->name + name->len;
+	buf.inode = dir;
+
+	ndirents = 0;
+	de = erofs_find_target_block(&buf, dir, &qn, &ndirents);
+	if (IS_ERR(de))
+		return PTR_ERR(de);
+
+	if (ndirents)
+		de = find_target_dirent(&qn, (u8 *)de, i_blocksize(dir),
+					ndirents);
+
+	if (!IS_ERR(de)) {
+		*nid = le64_to_cpu(de->nid);
+		*d_type = de->file_type;
+	}
+	erofs_put_metabuf(&buf);
+	return PTR_ERR_OR_ZERO(de);
+}
+
+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;
+
+	trace_erofs_lookup(dir, dentry, flags);
+
+	if (dentry->d_name.len > EROFS_NAME_LEN)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	err = erofs_namei(dir, &dentry->d_name, &nid, &d_type);
+
+	if (err == -ENOENT)
+		/* negative dentry */
+		inode = NULL;
+	else if (err)
+		inode = ERR_PTR(err);
+	else
+		inode = erofs_iget(dir->i_sb, nid);
+	return d_splice_alias(inode, dentry);
+}
+
+const struct inode_operations erofs_dir_iops = {
+	.lookup = erofs_lookup,
+	.getattr = erofs_getattr,
+	.listxattr = erofs_listxattr,
+	.get_inode_acl = erofs_get_acl,
+	.fiemap = erofs_fiemap,
+};