1 files changed, 130 insertions, 2 deletions

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 1afb701622b0..e9a3c4c85594 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -97,6 +97,43 @@ 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;
+}
+
+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
  */
@@ -1348,6 +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);
@@ -1376,6 +1414,9 @@ static int journal_get_superblock(journal_t *journal)
                 }
         }
 
+        if (buffer_verified(bh))
+                return 0;
+
         sb = journal->j_superblock;
 
         err = -EINVAL;
@@ -1413,6 +1454,43 @@ 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;
+        }
+
+        /* Load the checksum driver */
+        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2)) {
+                journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
+                if (IS_ERR(journal->j_chksum_driver)) {
+                        printk(KERN_ERR "JBD: Cannot load crc32c driver.\n");
+                        err = PTR_ERR(journal->j_chksum_driver);
+                        journal->j_chksum_driver = NULL;
+                        goto out;
+                }
+        }
+
+        /* 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;
 
 out:
@@ -1564,6 +1642,8 @@ int jbd2_journal_destroy(journal_t *journal)
                 iput(journal->j_inode);
         if (journal->j_revoke)
                 jbd2_journal_destroy_revoke(journal);
+        if (journal->j_chksum_driver)
+                crypto_free_shash(journal->j_chksum_driver);
         kfree(journal->j_wbuf);
         kfree(journal);
 
@@ -1653,6 +1733,10 @@ 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 +1745,54 @@ 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);
+
+                /* Load the checksum driver */
+                if (journal->j_chksum_driver == NULL) {
+                        journal->j_chksum_driver = crypto_alloc_shash("crc32c",
+                                                                      0, 0);
+                        if (IS_ERR(journal->j_chksum_driver)) {
+                                printk(KERN_ERR "JBD: Cannot load crc32c "
+                                       "driver.\n");
+                                journal->j_chksum_driver = NULL;
+                                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 */
+        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
 }
 
 /*
@@ -1975,10 +2097,16 @@ int jbd2_journal_blocks_per_page(struct inode *inode)
  */
 size_t journal_tag_bytes(journal_t *journal)
 {
+        journal_block_tag_t tag;
+        size_t x = 0;
+
+        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))
+                x += sizeof(tag.t_checksum);
+
         if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
-                return JBD2_TAG_SIZE64;
+                return x + JBD2_TAG_SIZE64;
         else
-                return JBD2_TAG_SIZE32;
+                return x + JBD2_TAG_SIZE32;
 }
 
 /*