Merge tag 'vfs-6.13.tmpfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull tmpfs case folding updates from Christian Brauner:
 "This adds case-insensitive support for tmpfs.

  The work contained in here adds support for case-insensitive file
  names lookups in tmpfs. The main difference from other casefold
  filesystems is that tmpfs has no information on disk, just on RAM, so
  we can't use mkfs to create a case-insensitive tmpfs. For this
  implementation, there's a mount option for casefolding. The rest of
  the patchset follows a similar approach as ext4 and f2fs.

  The use case for this feature is similar to the use case for ext4, to
  better support compatibility layers (like Wine), particularly in
  combination with sandboxing/container tools (like Flatpak).

  Those containerization tools can share a subset of the host filesystem
  with an application. In the container, the root directory and any
  parent directories required for a shared directory are on tmpfs, with
  the shared directories bind-mounted into the container's view of the
  filesystem.

  If the host filesystem is using case-insensitive directories, then the
  application can do lookups inside those directories in a
  case-insensitive way, without this needing to be implemented in
  user-space. However, if the host is only sharing a subset of a
  case-insensitive directory with the application, then the parent
  directories of the mount point will be part of the container's root
  tmpfs. When the application tries to do case-insensitive lookups of
  those parent directories on a case-sensitive tmpfs, the lookup will
  fail"

* tag 'vfs-6.13.tmpfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  tmpfs: Initialize sysfs during tmpfs init
  tmpfs: Fix type for sysfs' casefold attribute
  libfs: Fix kernel-doc warning in generic_ci_validate_strict_name
  docs: tmpfs: Add casefold options
  tmpfs: Expose filesystem features via sysfs
  tmpfs: Add flag FS_CASEFOLD_FL support for tmpfs dirs
  tmpfs: Add casefold lookup support
  libfs: Export generic_ci_ dentry functions
  unicode: Recreate utf8_parse_version()
  unicode: Export latest available UTF-8 version number
  ext4: Use generic_ci_validate_strict_name helper
  libfs: Create the helper function generic_ci_validate_strict_name()

4 files changed, 36 insertions, 10 deletions

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 790db7eac6c2..612ccbeb493b 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2395,11 +2395,8 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
 	if (fscrypt_is_nokey_name(dentry))
 		return -ENOKEY;
 
-#if IS_ENABLED(CONFIG_UNICODE)
-	if (sb_has_strict_encoding(sb) && IS_CASEFOLDED(dir) &&
-	    utf8_validate(sb->s_encoding, &dentry->d_name))
+	if (!generic_ci_validate_strict_name(dir, &dentry->d_name))
 		return -EINVAL;
-#endif
 
 	retval = ext4_fname_setup_filename(dir, &dentry->d_name, 0, &fname);
 	if (retval)
diff --git a/fs/libfs.c b/fs/libfs.c
index 46966fd8bcf9..a168ece5cc61 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -77,6 +77,10 @@ struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned
 		return ERR_PTR(-ENAMETOOLONG);
 	if (!dentry->d_sb->s_d_op)
 		d_set_d_op(dentry, &simple_dentry_operations);
+
+	if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
+		return NULL;
+
 	d_add(dentry, NULL);
 	return NULL;
 }
@@ -1791,8 +1795,8 @@ bool is_empty_dir_inode(struct inode *inode)
  *
  * Return: 0 if names match, 1 if mismatch, or -ERRNO
  */
-static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
-				const char *str, const struct qstr *name)
+int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
+			 const char *str, const struct qstr *name)
 {
 	const struct dentry *parent;
 	const struct inode *dir;
@@ -1835,6 +1839,7 @@ static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
 
 	return utf8_strncasecmp(dentry->d_sb->s_encoding, name, &qstr);
 }
+EXPORT_SYMBOL(generic_ci_d_compare);
 
 /**
  * generic_ci_d_hash - generic d_hash implementation for casefolding filesystems
@@ -1843,7 +1848,7 @@ static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
  *
  * Return: 0 if hash was successful or unchanged, and -EINVAL on error
  */
-static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
+int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
 {
 	const struct inode *dir = READ_ONCE(dentry->d_inode);
 	struct super_block *sb = dentry->d_sb;
@@ -1858,6 +1863,7 @@ static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
 		return -EINVAL;
 	return 0;
 }
+EXPORT_SYMBOL(generic_ci_d_hash);
 
 static const struct dentry_operations generic_ci_dentry_ops = {
 	.d_hash = generic_ci_d_hash,
diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c
index 8395066341a4..7f7cb14e01ce 100644
--- a/fs/unicode/utf8-core.c
+++ b/fs/unicode/utf8-core.c
@@ -214,3 +214,29 @@ void utf8_unload(struct unicode_map *um)
 }
 EXPORT_SYMBOL(utf8_unload);
 
+/**
+ * utf8_parse_version - Parse a UTF-8 version number from a string
+ *
+ * @version: input string
+ *
+ * Returns the parsed version on success, negative code on error
+ */
+int utf8_parse_version(char *version)
+{
+	substring_t args[3];
+	unsigned int maj, min, rev;
+	static const struct match_token token[] = {
+		{1, "%d.%d.%d"},
+		{0, NULL}
+	};
+
+	if (match_token(version, token, args) != 1)
+		return -EINVAL;
+
+	if (match_int(&args[0], &maj) || match_int(&args[1], &min) ||
+	    match_int(&args[2], &rev))
+		return -EINVAL;
+
+	return UNICODE_AGE(maj, min, rev);
+}
+EXPORT_SYMBOL(utf8_parse_version);
diff --git a/fs/unicode/utf8-selftest.c b/fs/unicode/utf8-selftest.c
index 600e15efe9ed..5ddaf27b21a6 100644
--- a/fs/unicode/utf8-selftest.c
+++ b/fs/unicode/utf8-selftest.c
@@ -17,9 +17,6 @@
 static unsigned int failed_tests;
 static unsigned int total_tests;
 
-/* Tests will be based on this version. */
-#define UTF8_LATEST	UNICODE_AGE(12, 1, 0)
-
 #define _test(cond, func, line, fmt, ...) do {				\
 		total_tests++;						\
 		if (!cond) {						\