Merge tag 'vfs-6.11.casefold' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs casefolding updates from Christian Brauner:
 "This contains some work to simplify the handling of casefolded names:

   - Simplify the handling of casefolded names in f2fs and ext4 by
     keeping the names as a qstr to avoiding unnecessary conversions

   - Introduce a new generic_ci_match() libfs case-insensitive lookup
     helper and use it in both f2fs and ext4 allowing to remove the
     filesystem specific implementations

   - Remove a bunch of ifdefs by making the unicode build checks part of
     the code flow"

* tag 'vfs-6.11.casefold' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  f2fs: Move CONFIG_UNICODE defguards into the code flow
  ext4: Move CONFIG_UNICODE defguards into the code flow
  f2fs: Reuse generic_ci_match for ci comparisons
  ext4: Reuse generic_ci_match for ci comparisons
  libfs: Introduce case-insensitive string comparison helper
  f2fs: Simplify the handling of cached casefolded names
  ext4: Simplify the handling of cached casefolded names

5 files changed, 55 insertions, 93 deletions

diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 02c9355176d3..cbd7a5e96a37 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -42,35 +42,49 @@ static unsigned int bucket_blocks(unsigned int level)
 		return 4;
 }
 
+#if IS_ENABLED(CONFIG_UNICODE)
 /* If @dir is casefolded, initialize @fname->cf_name from @fname->usr_fname. */
 int f2fs_init_casefolded_name(const struct inode *dir,
 			      struct f2fs_filename *fname)
 {
-#if IS_ENABLED(CONFIG_UNICODE)
 	struct super_block *sb = dir->i_sb;
+	unsigned char *buf;
+	int len;
 
 	if (IS_CASEFOLDED(dir) &&
 	    !is_dot_dotdot(fname->usr_fname->name, fname->usr_fname->len)) {
-		fname->cf_name.name = f2fs_kmem_cache_alloc(f2fs_cf_name_slab,
-					GFP_NOFS, false, F2FS_SB(sb));
-		if (!fname->cf_name.name)
+		buf = f2fs_kmem_cache_alloc(f2fs_cf_name_slab,
+					    GFP_NOFS, false, F2FS_SB(sb));
+		if (!buf)
 			return -ENOMEM;
-		fname->cf_name.len = utf8_casefold(sb->s_encoding,
-						   fname->usr_fname,
-						   fname->cf_name.name,
-						   F2FS_NAME_LEN);
-		if ((int)fname->cf_name.len <= 0) {
-			kmem_cache_free(f2fs_cf_name_slab, fname->cf_name.name);
-			fname->cf_name.name = NULL;
+
+		len = utf8_casefold(sb->s_encoding, fname->usr_fname,
+				    buf, F2FS_NAME_LEN);
+		if (len <= 0) {
+			kmem_cache_free(f2fs_cf_name_slab, buf);
 			if (sb_has_strict_encoding(sb))
 				return -EINVAL;
 			/* fall back to treating name as opaque byte sequence */
+			return 0;
 		}
+		fname->cf_name.name = buf;
+		fname->cf_name.len = len;
 	}
-#endif
+
 	return 0;
 }
 
+void f2fs_free_casefolded_name(struct f2fs_filename *fname)
+{
+	unsigned char *buf = (unsigned char *)fname->cf_name.name;
+
+	if (buf) {
+		kmem_cache_free(f2fs_cf_name_slab, buf);
+		fname->cf_name.name = NULL;
+	}
+}
+#endif /* CONFIG_UNICODE */
+
 static int __f2fs_setup_filename(const struct inode *dir,
 				 const struct fscrypt_name *crypt_name,
 				 struct f2fs_filename *fname)
@@ -142,12 +156,7 @@ void f2fs_free_filename(struct f2fs_filename *fname)
 	kfree(fname->crypto_buf.name);
 	fname->crypto_buf.name = NULL;
 #endif
-#if IS_ENABLED(CONFIG_UNICODE)
-	if (fname->cf_name.name) {
-		kmem_cache_free(f2fs_cf_name_slab, fname->cf_name.name);
-		fname->cf_name.name = NULL;
-	}
-#endif
+	f2fs_free_casefolded_name(fname);
 }
 
 static unsigned long dir_block_index(unsigned int level,
@@ -176,58 +185,6 @@ static struct f2fs_dir_entry *find_in_block(struct inode *dir,
 	return f2fs_find_target_dentry(&d, fname, max_slots);
 }
 
-#if IS_ENABLED(CONFIG_UNICODE)
-/*
- * Test whether a case-insensitive directory entry matches the filename
- * being searched for.
- *
- * Returns 1 for a match, 0 for no match, and -errno on an error.
- */
-static int f2fs_match_ci_name(const struct inode *dir, const struct qstr *name,
-			       const u8 *de_name, u32 de_name_len)
-{
-	const struct super_block *sb = dir->i_sb;
-	const struct unicode_map *um = sb->s_encoding;
-	struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len);
-	struct qstr entry = QSTR_INIT(de_name, de_name_len);
-	int res;
-
-	if (IS_ENCRYPTED(dir)) {
-		const struct fscrypt_str encrypted_name =
-			FSTR_INIT((u8 *)de_name, de_name_len);
-
-		if (WARN_ON_ONCE(!fscrypt_has_encryption_key(dir)))
-			return -EINVAL;
-
-		decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL);
-		if (!decrypted_name.name)
-			return -ENOMEM;
-		res = fscrypt_fname_disk_to_usr(dir, 0, 0, &encrypted_name,
-						&decrypted_name);
-		if (res < 0)
-			goto out;
-		entry.name = decrypted_name.name;
-		entry.len = decrypted_name.len;
-	}
-
-	res = utf8_strncasecmp_folded(um, name, &entry);
-	/*
-	 * In strict mode, ignore invalid names.  In non-strict mode,
-	 * fall back to treating them as opaque byte sequences.
-	 */
-	if (res < 0 && !sb_has_strict_encoding(sb)) {
-		res = name->len == entry.len &&
-				memcmp(name->name, entry.name, name->len) == 0;
-	} else {
-		/* utf8_strncasecmp_folded returns 0 on match */
-		res = (res == 0);
-	}
-out:
-	kfree(decrypted_name.name);
-	return res;
-}
-#endif /* CONFIG_UNICODE */
-
 static inline int f2fs_match_name(const struct inode *dir,
 				   const struct f2fs_filename *fname,
 				   const u8 *de_name, u32 de_name_len)
@@ -235,11 +192,11 @@ static inline int f2fs_match_name(const struct inode *dir,
 	struct fscrypt_name f;
 
 #if IS_ENABLED(CONFIG_UNICODE)
-	if (fname->cf_name.name) {
-		struct qstr cf = FSTR_TO_QSTR(&fname->cf_name);
+	if (fname->cf_name.name)
+		return generic_ci_match(dir, fname->usr_fname,
+					&fname->cf_name,
+					de_name, de_name_len);
 
-		return f2fs_match_ci_name(dir, &cf, de_name, de_name_len);
-	}
 #endif
 	f.usr_fname = fname->usr_fname;
 	f.disk_name = fname->disk_name;
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 1974b6aff397..8a9d910aa552 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -531,7 +531,7 @@ struct f2fs_filename {
 	 * internal operation where usr_fname is also NULL.  In all these cases
 	 * we fall back to treating the name as an opaque byte sequence.
 	 */
-	struct fscrypt_str cf_name;
+	struct qstr cf_name;
 #endif
 };
 
@@ -3533,8 +3533,22 @@ int f2fs_get_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
 /*
  * dir.c
  */
+#if IS_ENABLED(CONFIG_UNICODE)
 int f2fs_init_casefolded_name(const struct inode *dir,
 			      struct f2fs_filename *fname);
+void f2fs_free_casefolded_name(struct f2fs_filename *fname);
+#else
+static inline int f2fs_init_casefolded_name(const struct inode *dir,
+					    struct f2fs_filename *fname)
+{
+	return 0;
+}
+
+static inline void f2fs_free_casefolded_name(struct f2fs_filename *fname)
+{
+}
+#endif /* CONFIG_UNICODE */
+
 int f2fs_setup_filename(struct inode *dir, const struct qstr *iname,
 			int lookup, struct f2fs_filename *fname);
 int f2fs_prepare_lookup(struct inode *dir, struct dentry *dentry,
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index e54f8c08bda8..1ecde2b45e99 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -576,8 +576,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
 		goto out_iput;
 	}
 out_splice:
-#if IS_ENABLED(CONFIG_UNICODE)
-	if (!inode && IS_CASEFOLDED(dir)) {
+	if (IS_ENABLED(CONFIG_UNICODE) && !inode && IS_CASEFOLDED(dir)) {
 		/* Eventually we want to call d_add_ci(dentry, NULL)
 		 * for negative dentries in the encoding case as
 		 * well.  For now, prevent the negative dentry
@@ -586,7 +585,7 @@ out_splice:
 		trace_f2fs_lookup_end(dir, dentry, ino, err);
 		return NULL;
 	}
-#endif
+
 	new = d_splice_alias(inode, dentry);
 	trace_f2fs_lookup_end(dir, !IS_ERR_OR_NULL(new) ? new : dentry,
 				ino, IS_ERR(new) ? PTR_ERR(new) : err);
@@ -639,16 +638,15 @@ static int f2fs_unlink(struct inode *dir, struct dentry *dentry)
 	f2fs_delete_entry(de, page, dir, inode);
 	f2fs_unlock_op(sbi);
 
-#if IS_ENABLED(CONFIG_UNICODE)
 	/* VFS negative dentries are incompatible with Encoding and
 	 * Case-insensitiveness. Eventually we'll want avoid
 	 * invalidating the dentries here, alongside with returning the
 	 * negative dentries at f2fs_lookup(), when it is better
 	 * supported by the VFS for the CI case.
 	 */
-	if (IS_CASEFOLDED(dir))
+	if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
 		d_invalidate(dentry);
-#endif
+
 	if (IS_DIRSYNC(dir))
 		f2fs_sync_fs(sbi->sb, 1);
 fail:
diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index 496aee53c38a..8712e264071f 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -46,10 +46,6 @@
 
 static struct kmem_cache *fsync_entry_slab;
 
-#if IS_ENABLED(CONFIG_UNICODE)
-extern struct kmem_cache *f2fs_cf_name_slab;
-#endif
-
 bool f2fs_space_for_roll_forward(struct f2fs_sb_info *sbi)
 {
 	s64 nalloc = percpu_counter_sum_positive(&sbi->alloc_valid_block_count);
@@ -153,11 +149,8 @@ static int init_recovered_filename(const struct inode *dir,
 		if (err)
 			return err;
 		f2fs_hash_filename(dir, fname);
-#if IS_ENABLED(CONFIG_UNICODE)
 		/* Case-sensitive match is fine for recovery */
-		kmem_cache_free(f2fs_cf_name_slab, fname->cf_name.name);
-		fname->cf_name.name = NULL;
-#endif
+		f2fs_free_casefolded_name(fname);
 	} else {
 		f2fs_hash_filename(dir, fname);
 	}
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 1f1b3647a998..df4cf31f93df 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -321,7 +321,7 @@ struct kmem_cache *f2fs_cf_name_slab;
 static int __init f2fs_create_casefold_cache(void)
 {
 	f2fs_cf_name_slab = f2fs_kmem_cache_create("f2fs_casefolded_name",
-							F2FS_NAME_LEN);
+						   F2FS_NAME_LEN);
 	return f2fs_cf_name_slab ? 0 : -ENOMEM;
 }
 
@@ -1326,13 +1326,13 @@ default_check:
 		return -EINVAL;
 	}
 #endif
-#if !IS_ENABLED(CONFIG_UNICODE)
-	if (f2fs_sb_has_casefold(sbi)) {
+
+	if (!IS_ENABLED(CONFIG_UNICODE) && f2fs_sb_has_casefold(sbi)) {
 		f2fs_err(sbi,
 			"Filesystem with casefold feature cannot be mounted without CONFIG_UNICODE");
 		return -EINVAL;
 	}
-#endif
+
 	/*
 	 * The BLKZONED feature indicates that the drive was formatted with
 	 * zone alignment optimization. This is optional for host-aware