jbd2: Grab a reference to the crc32c driver if necessary

Obtain a reference to the crc32c driver if needed for the v2 checksum.

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

2 files changed, 27 insertions, 0 deletions

diff --git a/fs/jbd2/Kconfig b/fs/jbd2/Kconfig
index f32f346f4b0a..69a48c2944da 100644
--- a/fs/jbd2/Kconfig
+++ b/fs/jbd2/Kconfig
@@ -1,6 +1,8 @@
 config JBD2
         tristate
         select CRC32
+        select CRYPTO
+        select CRYPTO_CRC32C
         help
           This is a generic journaling layer for block devices that support
           both 32-bit and 64-bit block numbers.  It is currently used by
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 63175f9391ab..f04ab6c4b428 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1438,6 +1438,17 @@ static int journal_get_superblock(journal_t *journal)
                 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;
+                }
+        }
+
         set_buffer_verified(bh);
 
         return 0;
@@ -1591,6 +1602,8 @@ 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);
 
@@ -1707,6 +1720,18 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
                 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;
+                        }
+                }
         }
 
         /* If enabling v1 checksums, downgrade superblock */