bcachefs: opts.casefold_disabled

Add an option for completely disabling casefolding on a filesystem, as a
workaround for overlayfs.

This should only be needed as a temporary workaround, until the
overlayfs fix arrives.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/bcachefs.h

@@ -863,9 +863,7 @@ struct bch_fs {
 	DARRAY(enum bcachefs_metadata_version)
 				incompat_versions_requested;
 
-#ifdef CONFIG_UNICODE
 	struct unicode_map	*cf_encoding;
-#endif
 
 	struct bch_sb_handle	disk_sb;
 
@@ -1285,4 +1283,13 @@ static inline bool bch2_discard_opt_enabled(struct bch_fs *c, struct bch_dev *ca
 		: ca->mi.discard;
 }
 
+static inline bool bch2_fs_casefold_enabled(struct bch_fs *c)
+{
+#ifdef CONFIG_UNICODE
+	return !c->opts.casefold_disabled;
+#else
+	return false;
+#endif
+}
+
 #endif /* _BCACHEFS_H */

fs/bcachefs/dirent.c

@@ -18,7 +18,9 @@ int bch2_casefold(struct btree_trans *trans, const struct bch_hash_info *info,
 {
 	*out_cf = (struct qstr) QSTR_INIT(NULL, 0);
 
-#ifdef CONFIG_UNICODE
+	if (!bch2_fs_casefold_enabled(trans->c))
+		return -EOPNOTSUPP;
+
 	unsigned char *buf = bch2_trans_kmalloc(trans, BCH_NAME_MAX + 1);
 	int ret = PTR_ERR_OR_ZERO(buf);
 	if (ret)
@@ -30,9 +32,6 @@ int bch2_casefold(struct btree_trans *trans, const struct bch_hash_info *info,
 
 	*out_cf = (struct qstr) QSTR_INIT(buf, ret);
 	return 0;
-#else
-	return -EOPNOTSUPP;
-#endif
 }
 
 static unsigned bch2_dirent_name_bytes(struct bkey_s_c_dirent d)
@@ -231,7 +230,8 @@ void bch2_dirent_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c
 	prt_printf(out, " type %s", bch2_d_type_str(d.v->d_type));
 }
 
-int bch2_dirent_init_name(struct bkey_i_dirent *dirent,
+int bch2_dirent_init_name(struct bch_fs *c,
+			  struct bkey_i_dirent *dirent,
 			  const struct bch_hash_info *hash_info,
 			  const struct qstr *name,
 			  const struct qstr *cf_name)
@@ -251,7 +251,9 @@ int bch2_dirent_init_name(struct bkey_i_dirent *dirent,
 		       offsetof(struct bch_dirent, d_name) -
 		       name->len);
 	} else {
-#ifdef CONFIG_UNICODE
+		if (!bch2_fs_casefold_enabled(c))
+			return -EOPNOTSUPP;
+
 		memcpy(&dirent->v.d_cf_name_block.d_names[0], name->name, name->len);
 
 		char *cf_out = &dirent->v.d_cf_name_block.d_names[name->len];
@@ -277,9 +279,6 @@ int bch2_dirent_init_name(struct bkey_i_dirent *dirent,
 		dirent->v.d_cf_name_block.d_cf_name_len = cpu_to_le16(cf_len);
 
 		EBUG_ON(bch2_dirent_get_casefold_name(dirent_i_to_s_c(dirent)).len != cf_len);
-#else
-	return -EOPNOTSUPP;
-#endif
 	}
 
 	unsigned u64s = dirent_val_u64s(name->len, cf_len);
@@ -313,7 +312,7 @@ struct bkey_i_dirent *bch2_dirent_create_key(struct btree_trans *trans,
 	dirent->v.d_type = type;
 	dirent->v.d_unused = 0;
 
-	int ret = bch2_dirent_init_name(dirent, hash_info, name, cf_name);
+	int ret = bch2_dirent_init_name(trans->c, dirent, hash_info, name, cf_name);
 	if (ret)
 		return ERR_PTR(ret);
 

fs/bcachefs/dirent.h

@@ -59,7 +59,8 @@ static inline void dirent_copy_target(struct bkey_i_dirent *dst,
 	dst->v.d_type = src.v->d_type;
 }
 
-int bch2_dirent_init_name(struct bkey_i_dirent *,
+int bch2_dirent_init_name(struct bch_fs *,
+			  struct bkey_i_dirent *,
 			  const struct bch_hash_info *,
 			  const struct qstr *,
 			  const struct qstr *);

fs/bcachefs/fs.c

@@ -722,7 +722,6 @@ static struct dentry *bch2_lookup(struct inode *vdir, struct dentry *dentry,
 	if (IS_ERR(inode))
 		inode = NULL;
 
-#ifdef CONFIG_UNICODE
 	if (!inode && IS_CASEFOLDED(vdir)) {
 		/*
 		 * Do not cache a negative dentry in casefolded directories
@@ -737,7 +736,6 @@ static struct dentry *bch2_lookup(struct inode *vdir, struct dentry *dentry,
 		 */
 		return NULL;
 	}
-#endif
 
 	return d_splice_alias(&inode->v, dentry);
 }
@@ -2566,9 +2564,10 @@ got_sb:
 	sb->s_shrink->seeks = 0;
 
 #ifdef CONFIG_UNICODE
+	if (bch2_fs_casefold_enabled(c))
 		sb->s_encoding = c->cf_encoding;
-#endif
 	generic_set_sb_d_ops(sb);
+#endif
 
 	vinode = bch2_vfs_inode_get(c, BCACHEFS_ROOT_SUBVOL_INUM);
 	ret = PTR_ERR_OR_ZERO(vinode);

fs/bcachefs/fsck.c

@@ -2302,9 +2302,7 @@ static int check_dirent(struct btree_trans *trans, struct btree_iter *iter,
 		*hash_info = bch2_hash_info_init(c, &i->inode);
 	dir->first_this_inode = false;
 
-#ifdef CONFIG_UNICODE
 	hash_info->cf_encoding = bch2_inode_casefold(c, &i->inode) ? c->cf_encoding : NULL;
-#endif
 
 	ret = bch2_str_hash_check_key(trans, s, &bch2_dirent_hash_desc, hash_info,
 				      iter, k, need_second_pass);

fs/bcachefs/inode.c

@@ -1265,7 +1265,14 @@ int bch2_inode_set_casefold(struct btree_trans *trans, subvol_inum inum,
 {
 	struct bch_fs *c = trans->c;
 
-#ifdef CONFIG_UNICODE
+#ifndef CONFIG_UNICODE
+	bch_err(c, "Cannot use casefolding on a kernel without CONFIG_UNICODE");
+	return -EOPNOTSUPP;
+#endif
+
+	if (c->opts.casefold_disabled)
+		return -EOPNOTSUPP;
+
 	int ret = 0;
 	/* Not supported on individual files. */
 	if (!S_ISDIR(bi->bi_mode))
@@ -1289,10 +1296,6 @@ int bch2_inode_set_casefold(struct btree_trans *trans, subvol_inum inum,
 	bi->bi_fields_set |= BIT(Inode_opt_casefold);
 
 	return bch2_maybe_propagate_has_case_insensitive(trans, inum, bi);
-#else
-	bch_err(c, "Cannot use casefolding on a kernel without CONFIG_UNICODE");
-	return -EOPNOTSUPP;
-#endif
 }
 
 static noinline int __bch2_inode_rm_snapshot(struct btree_trans *trans, u64 inum, u32 snapshot)

fs/bcachefs/opts.h

@@ -234,6 +234,11 @@ enum fsck_err_opts {
 	  OPT_BOOL(),							\
 	  BCH_SB_CASEFOLD,		false,				\
 	  NULL,		"Dirent lookups are casefolded")		\
+	x(casefold_disabled,			u8,			\
+	  OPT_FS|OPT_MOUNT,						\
+	  OPT_BOOL(),							\
+	  BCH2_NO_SB_OPT,		false,				\
+	  NULL,		"Disable casefolding filesystem wide")		\
 	x(inodes_32bit,			u8,				\
 	  OPT_FS|OPT_INODE|OPT_FORMAT|OPT_MOUNT|OPT_RUNTIME,		\
 	  OPT_BOOL(),							\

fs/bcachefs/str_hash.c

@@ -38,6 +38,7 @@ static int bch2_fsck_rename_dirent(struct btree_trans *trans,
 				   struct bkey_s_c_dirent old,
 				   bool *updated_before_k_pos)
 {
+	struct bch_fs *c = trans->c;
 	struct qstr old_name = bch2_dirent_get_name(old);
 	struct bkey_i_dirent *new = bch2_trans_kmalloc(trans, BKEY_U64s_MAX * sizeof(u64));
 	int ret = PTR_ERR_OR_ZERO(new);
@@ -60,7 +61,7 @@ static int bch2_fsck_rename_dirent(struct btree_trans *trans,
 					sprintf(renamed_buf, "%.*s.fsck_renamed-%u",
 						old_name.len, old_name.name, i));
 
-		ret = bch2_dirent_init_name(new, hash_info, &renamed_name, NULL);
+		ret = bch2_dirent_init_name(c, new, hash_info, &renamed_name, NULL);
 		if (ret)
 			return ret;
 
@@ -79,7 +80,7 @@ static int bch2_fsck_rename_dirent(struct btree_trans *trans,
 	}
 
 	ret = ret ?: bch2_fsck_update_backpointers(trans, s, desc, hash_info, &new->k_i);
-	bch_err_fn(trans->c, ret);
+	bch_err_fn(c, ret);
 	return ret;
 }
 

fs/bcachefs/str_hash.h

@@ -48,9 +48,7 @@ bch2_hash_info_init(struct bch_fs *c, const struct bch_inode_unpacked *bi)
 	struct bch_hash_info info = {
 		.inum_snapshot	= bi->bi_snapshot,
 		.type		= INODE_STR_HASH(bi),
-#ifdef CONFIG_UNICODE
 		.cf_encoding	= bch2_inode_casefold(c, bi) ? c->cf_encoding : NULL,
-#endif
 		.siphash_key	= { .k0 = bi->bi_hash_seed }
 	};
 

fs/bcachefs/super.c

@@ -1025,6 +1025,7 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts *opts,
 	}
 
 #ifdef CONFIG_UNICODE
+	if (bch2_fs_casefold_enabled(c)) {
 		/* Default encoding until we can potentially have more as an option. */
 		c->cf_encoding = utf8_load(BCH_FS_DEFAULT_UTF8_ENCODING);
 		if (IS_ERR(c->cf_encoding)) {
@@ -1035,6 +1036,7 @@ static struct bch_fs *bch2_fs_alloc(struct bch_sb *sb, struct bch_opts *opts,
 			ret = -EINVAL;
 			goto err;
 		}
+	}
 #else
 	if (c->sb.features & BIT_ULL(BCH_FEATURE_casefolding)) {
 		printk(KERN_ERR "Cannot mount a filesystem with casefolding on a kernel without CONFIG_UNICODE\n");
@@ -1160,12 +1162,11 @@ int bch2_fs_start(struct bch_fs *c)
 
 	print_mount_opts(c);
 
-#ifdef CONFIG_UNICODE
+	if (c->cf_encoding)
 		bch_info(c, "Using encoding defined by superblock: utf8-%u.%u.%u",
 			 unicode_major(BCH_FS_DEFAULT_UTF8_ENCODING),
 			 unicode_minor(BCH_FS_DEFAULT_UTF8_ENCODING),
 			 unicode_rev(BCH_FS_DEFAULT_UTF8_ENCODING));
-#endif
 
 	if (!bch2_fs_may_start(c))
 		return bch_err_throw(c, insufficient_devices_to_start);