From 0b246d07292a454ecba0a81dd2934d2ed05c1b0a Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@us.ibm.com>
Date: Sun, 27 May 2012 08:08:22 -0400
Subject: [PATCH] --- yaml --- r: 309949 b: refs/heads/master c:
 4fd5ea43bc11602bfabe2c8f5378586d34bd2b0a h: refs/heads/master i:   309947:
 812c1e0cb3f77a4151b854a00c67010dae84cb3f v: v3

---
 [refs]                     |  2 +-
 trunk/fs/jbd2/journal.c    | 47 ++++++++++++++++++++++++++++++++++++++
 trunk/include/linux/jbd2.h |  3 +++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 7a51c929fcb8..e4c1e6372788 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 01b5adcebb977bc61b64167adce6d8260c9da33c
+refs/heads/master: 4fd5ea43bc11602bfabe2c8f5378586d34bd2b0a
diff --git a/trunk/fs/jbd2/journal.c b/trunk/fs/jbd2/journal.c
index f04ab6c4b428..9072f03d30b5 100644
--- a/trunk/fs/jbd2/journal.c
+++ b/trunk/fs/jbd2/journal.c
@@ -106,6 +106,34 @@ int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb)
 	return sb->s_checksum_type == JBD2_CRC32C_CHKSUM;
 }
 
+static __u32 jbd2_superblock_csum(journal_t *j, journal_superblock_t *sb)
+{
+	__u32 csum, old_csum;
+
+	old_csum = sb->s_checksum;
+	sb->s_checksum = 0;
+	csum = jbd2_chksum(j, ~0, (char *)sb, sizeof(journal_superblock_t));
+	sb->s_checksum = old_csum;
+
+	return cpu_to_be32(csum);
+}
+
+int jbd2_superblock_csum_verify(journal_t *j, journal_superblock_t *sb)
+{
+	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+		return 1;
+
+	return sb->s_checksum == jbd2_superblock_csum(j, sb);
+}
+
+void jbd2_superblock_csum_set(journal_t *j, journal_superblock_t *sb)
+{
+	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+		return;
+
+	sb->s_checksum = jbd2_superblock_csum(j, sb);
+}
+
 /*
  * Helper function used to manage commit timeouts
  */
@@ -1357,6 +1385,7 @@ static void jbd2_journal_update_sb_errno(journal_t *journal)
 	jbd_debug(1, "JBD2: updating superblock error (errno %d)\n",
 		  journal->j_errno);
 	sb->s_errno    = cpu_to_be32(journal->j_errno);
+	jbd2_superblock_csum_set(journal, sb);
 	read_unlock(&journal->j_state_lock);
 
 	jbd2_write_superblock(journal, WRITE_SYNC);
@@ -1449,6 +1478,17 @@ static int journal_get_superblock(journal_t *journal)
 		}
 	}
 
+	/* Check superblock checksum */
+	if (!jbd2_superblock_csum_verify(journal, sb)) {
+		printk(KERN_ERR "JBD: journal checksum error\n");
+		goto out;
+	}
+
+	/* Precompute checksum seed for all metadata */
+	if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+		journal->j_csum_seed = jbd2_chksum(journal, ~0, sb->s_uuid,
+						   sizeof(sb->s_uuid));
+
 	set_buffer_verified(bh);
 
 	return 0;
@@ -1732,6 +1772,13 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
 				return 0;
 			}
 		}
+
+		/* Precompute checksum seed for all metadata */
+		if (JBD2_HAS_INCOMPAT_FEATURE(journal,
+					      JBD2_FEATURE_INCOMPAT_CSUM_V2))
+			journal->j_csum_seed = jbd2_chksum(journal, ~0,
+							   sb->s_uuid,
+							   sizeof(sb->s_uuid));
 	}
 
 	/* If enabling v1 checksums, downgrade superblock */
diff --git a/trunk/include/linux/jbd2.h b/trunk/include/linux/jbd2.h
index 71e77dddebf1..a9632bc55d97 100644
--- a/trunk/include/linux/jbd2.h
+++ b/trunk/include/linux/jbd2.h
@@ -969,6 +969,9 @@ struct journal_s
 
 	/* Reference to checksum algorithm driver via cryptoapi */
 	struct crypto_shash *j_chksum_driver;
+
+	/* Precomputed journal UUID checksum for seeding other checksums */
+	__u32 j_csum_seed;
 };
 
 /*