jbd2: switch to check format version in superblock directly

We should only check and set extented features if journal format version
is 2, and now we check the in memory copy of the superblock
'journal->j_format_version', which relys on the parameter initialization
sequence, switch to use the h_blocktype in superblock cloud be more
clear.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230315013128.3911115-5-chengzhihao1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Author: zhangyi089

fs/jbd2/journal.c

@@ -2062,10 +2062,12 @@ int jbd2_journal_load(journal_t *journal)
 		return err;
 
 	sb = journal->j_superblock;
-	/* If this is a V2 superblock, then we have to check the
-	 * features flags on it. */
 
-	if (journal->j_format_version >= 2) {
+	/*
+	 * If this is a V2 superblock, then we have to check the
+	 * features flags on it.
+	 */
+	if (jbd2_format_support_feature(journal)) {
 		if ((sb->s_feature_ro_compat &
 		     ~cpu_to_be32(JBD2_KNOWN_ROCOMPAT_FEATURES)) ||
 		    (sb->s_feature_incompat &
@@ -2227,7 +2229,7 @@ int jbd2_journal_check_used_features(journal_t *journal, unsigned long compat,
 	if (journal->j_format_version == 0 &&
 	    journal_get_superblock(journal) != 0)
 		return 0;
-	if (journal->j_format_version == 1)
+	if (!jbd2_format_support_feature(journal))
 		return 0;
 
 	sb = journal->j_superblock;
@@ -2257,11 +2259,7 @@ int jbd2_journal_check_available_features(journal_t *journal, unsigned long comp
 	if (!compat && !ro && !incompat)
 		return 1;
 
-	/* We can support any known requested features iff the
-	 * superblock is in version 2.  Otherwise we fail to support any
-	 * extended sb features. */
-
-	if (journal->j_format_version != 2)
+	if (!jbd2_format_support_feature(journal))
 		return 0;
 
 	if ((compat   & JBD2_KNOWN_COMPAT_FEATURES) == compat &&

include/linux/jbd2.h

@@ -1313,11 +1313,22 @@ struct journal_s
 		rwsem_release(&j->j_trans_commit_map, _THIS_IP_); \
 	} while (0)
 
+/*
+ * We can support any known requested features iff the
+ * superblock is not in version 1.  Otherwise we fail to support any
+ * extended sb features.
+ */
+static inline bool jbd2_format_support_feature(journal_t *j)
+{
+	return j->j_superblock->s_header.h_blocktype !=
+					cpu_to_be32(JBD2_SUPERBLOCK_V1);
+}
+
 /* journal feature predicate functions */
 #define JBD2_FEATURE_COMPAT_FUNCS(name, flagname) \
 static inline bool jbd2_has_feature_##name(journal_t *j) \
 { \
-	return ((j)->j_format_version >= 2 && \
+	return (jbd2_format_support_feature(j) && \
 		((j)->j_superblock->s_feature_compat & \
 		 cpu_to_be32(JBD2_FEATURE_COMPAT_##flagname)) != 0); \
 } \
@@ -1335,7 +1346,7 @@ static inline void jbd2_clear_feature_##name(journal_t *j) \
 #define JBD2_FEATURE_RO_COMPAT_FUNCS(name, flagname) \
 static inline bool jbd2_has_feature_##name(journal_t *j) \
 { \
-	return ((j)->j_format_version >= 2 && \
+	return (jbd2_format_support_feature(j) && \
 		((j)->j_superblock->s_feature_ro_compat & \
 		 cpu_to_be32(JBD2_FEATURE_RO_COMPAT_##flagname)) != 0); \
 } \
@@ -1353,7 +1364,7 @@ static inline void jbd2_clear_feature_##name(journal_t *j) \
 #define JBD2_FEATURE_INCOMPAT_FUNCS(name, flagname) \
 static inline bool jbd2_has_feature_##name(journal_t *j) \
 { \
-	return ((j)->j_format_version >= 2 && \
+	return (jbd2_format_support_feature(j) && \
 		((j)->j_superblock->s_feature_incompat & \
 		 cpu_to_be32(JBD2_FEATURE_INCOMPAT_##flagname)) != 0); \
 } \