bcachefs: Check for unsupported features

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

fs/bcachefs/bcachefs_format.h

@@ -1234,7 +1234,8 @@ enum bch_sb_features {
 	BCH_FEATURE_LZ4			= 0,
 	BCH_FEATURE_GZIP		= 1,
 	BCH_FEATURE_ZSTD		= 2,
-	BCH_FEATURE_ATOMIC_NLINK	= 3,
+	BCH_FEATURE_ATOMIC_NLINK	= 3, /* should have gone under compat */
+	BCH_FEATURE_NR,
 };
 
 /* options: */

fs/bcachefs/opts.c

@@ -3,6 +3,7 @@
 #include <linux/kernel.h>
 
 #include "bcachefs.h"
+#include "compress.h"
 #include "disk_groups.h"
 #include "opts.h"
 #include "super-io.h"
@@ -269,6 +270,20 @@ void bch2_opt_to_text(struct printbuf *out, struct bch_fs *c,
 	}
 }
 
+int bch2_opt_check_may_set(struct bch_fs *c, int id, u64 v)
+{
+	int ret = 0;
+
+	switch (id) {
+	case Opt_compression:
+	case Opt_background_compression:
+		ret = bch2_check_set_has_compressed_data(c, v);
+		break;
+	}
+
+	return ret;
+}
+
 int bch2_parse_mount_opts(struct bch_opts *opts, char *options)
 {
 	char *opt, *name, *val;

fs/bcachefs/opts.h

@@ -269,6 +269,7 @@ int bch2_opt_parse(struct bch_fs *, const struct bch_option *, const char *, u64
 void bch2_opt_to_text(struct printbuf *, struct bch_fs *,
 		      const struct bch_option *, u64, unsigned);
 
+int bch2_opt_check_may_set(struct bch_fs *, int, u64);
 int bch2_parse_mount_opts(struct bch_opts *, char *);
 
 /* inode opts: */

fs/bcachefs/super-io.c

@@ -230,6 +230,10 @@ const char *bch2_sb_validate(struct bch_sb_handle *disk_sb)
 	    le16_to_cpu(sb->version) > BCH_SB_VERSION_MAX)
 		return "Unsupported superblock version";
 
+	if (sb->features[1] ||
+	    (le64_to_cpu(sb->features[0]) & (~0ULL << BCH_FEATURE_NR)))
+		return "Filesystem has incompatible features";
+
 	if (le16_to_cpu(sb->version) < BCH_SB_VERSION_EXTENT_MAX) {
 		SET_BCH_SB_ENCODED_EXTENT_MAX_BITS(sb, 7);
 		SET_BCH_SB_POSIX_ACL(sb, 1);

fs/bcachefs/sysfs.c

@@ -10,7 +10,6 @@
 
 #include "bcachefs.h"
 #include "alloc_background.h"
-#include "compress.h"
 #include "sysfs.h"
 #include "btree_cache.h"
 #include "btree_io.h"
@@ -581,14 +580,9 @@ STORE(bch2_fs_opts_dir)
 	if (ret < 0)
 		return ret;
 
-	if (id == Opt_compression ||
-	    id == Opt_background_compression) {
-		int ret = bch2_check_set_has_compressed_data(c, v);
-		if (ret) {
-			mutex_unlock(&c->sb_lock);
-			return ret;
-		}
-	}
+	ret = bch2_opt_check_may_set(c, id, v);
+	if (ret < 0)
+		return ret;
 
 	if (opt->set_sb != SET_NO_SB_OPT) {
 		mutex_lock(&c->sb_lock);

fs/bcachefs/xattr.c

@@ -3,7 +3,6 @@
 #include "bcachefs.h"
 #include "bkey_methods.h"
 #include "btree_update.h"
-#include "compress.h"
 #include "extents.h"
 #include "fs.h"
 #include "rebalance.h"
@@ -433,12 +432,9 @@ static int bch2_xattr_bcachefs_set(const struct xattr_handler *handler,
 		if (ret < 0)
 			return ret;
 
-		if (s.id == Opt_compression ||
-		    s.id == Opt_background_compression) {
-			ret = bch2_check_set_has_compressed_data(c, s.v);
-			if (ret)
-				return ret;
-		}
+		ret = bch2_opt_check_may_set(c, s.id, s.v);
+		if (ret < 0)
+			return ret;
 
 		s.defined = true;
 	} else {