jbd2: enable journal clients to enable v2 checksumming

Add in the necessary code so that journal clients can enable the new
journal checksumming features.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 50 insertions, 0 deletions

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 1afb701..63175f9 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -97,6 +97,15 @@ EXPORT_SYMBOL(jbd2_inode_cache);
 static void __journal_abort_soft (journal_t *journal, int errno);
 static int jbd2_journal_create_slab(size_t slab_size);
 
+/* Checksumming functions */
+int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb)
+{
+	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+		return 1;
+
+	return sb->s_checksum_type == JBD2_CRC32C_CHKSUM;
+}
+
 /*
  * Helper function used to manage commit timeouts
  */
@@ -1376,6 +1385,9 @@ static int journal_get_superblock(journal_t *journal)
 		}
 	}
 
+	if (buffer_verified(bh))
+		return 0;
+
 	sb = journal->j_superblock;
 
 	err = -EINVAL;
@@ -1413,6 +1425,21 @@ static int journal_get_superblock(journal_t *journal)
 		goto out;
 	}
 
+	if (JBD2_HAS_COMPAT_FEATURE(journal, JBD2_FEATURE_COMPAT_CHECKSUM) &&
+	    JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2)) {
+		/* Can't have checksum v1 and v2 on at the same time! */
+		printk(KERN_ERR "JBD: Can't enable checksumming v1 and v2 "
+		       "at the same time!\n");
+		goto out;
+	}
+
+	if (!jbd2_verify_csum_type(journal, sb)) {
+		printk(KERN_ERR "JBD: Unknown checksum type\n");
+		goto out;
+	}
+
+	set_buffer_verified(bh);
+
 	return 0;
 
 out:
@@ -1653,6 +1680,10 @@ int jbd2_journal_check_available_features (journal_t *journal, unsigned long com
 int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
 			  unsigned long ro, unsigned long incompat)
 {
+#define INCOMPAT_FEATURE_ON(f) \
+		((incompat & (f)) && !(sb->s_feature_incompat & cpu_to_be32(f)))
+#define COMPAT_FEATURE_ON(f) \
+		((compat & (f)) && !(sb->s_feature_compat & cpu_to_be32(f)))
 	journal_superblock_t *sb;
 
 	if (jbd2_journal_check_used_features(journal, compat, ro, incompat))
@@ -1661,16 +1692,35 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
 	if (!jbd2_journal_check_available_features(journal, compat, ro, incompat))
 		return 0;
 
+	/* Asking for checksumming v2 and v1?  Only give them v2. */
+	if (incompat & JBD2_FEATURE_INCOMPAT_CSUM_V2 &&
+	    compat & JBD2_FEATURE_COMPAT_CHECKSUM)
+		compat &= ~JBD2_FEATURE_COMPAT_CHECKSUM;
+
 	jbd_debug(1, "Setting new features 0x%lx/0x%lx/0x%lx\n",
 		  compat, ro, incompat);
 
 	sb = journal->j_superblock;
 
+	/* If enabling v2 checksums, update superblock */
+	if (INCOMPAT_FEATURE_ON(JBD2_FEATURE_INCOMPAT_CSUM_V2)) {
+		sb->s_checksum_type = JBD2_CRC32C_CHKSUM;
+		sb->s_feature_compat &=
+			~cpu_to_be32(JBD2_FEATURE_COMPAT_CHECKSUM);
+	}
+
+	/* If enabling v1 checksums, downgrade superblock */
+	if (COMPAT_FEATURE_ON(JBD2_FEATURE_COMPAT_CHECKSUM))
+		sb->s_feature_incompat &=
+			~cpu_to_be32(JBD2_FEATURE_INCOMPAT_CSUM_V2);
+
 	sb->s_feature_compat    |= cpu_to_be32(compat);
 	sb->s_feature_ro_compat |= cpu_to_be32(ro);
 	sb->s_feature_incompat  |= cpu_to_be32(incompat);
 
 	return 1;
+#undef COMPAT_FEATURE_ON
+#undef INCOMPAT_FEATURE_ON
 }
 
 /*