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>

diff --git a/fs/jbd2/Kconfig b/fs/jbd2/Kconfig
index f32f346f4b0a521a5b6bbaedc7b0a5a7750c4b1e..69a48c2944da682c8a133fe75183c086ef08813b 100644 (file)
--- 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 63175f9391abf8f6ef5d694bb1a5d446f59d5685..f04ab6c4b428035373d372dafc24ad7dab379845 100644 (file)
--- 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 */

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 809c439066c55d79013388c166312301a1a56c0a..71e77dddebf11225246474cfa15fb60770afee7d 100644 (file)
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -31,6 +31,7 @@
 #include <linux/mutex.h>
 #include <linux/timer.h>
 #include <linux/slab.h>
+#include <crypto/hash.h>
 #endif
 
 #define journal_oom_retry 1
@@ -965,6 +966,9 @@ struct journal_s
         * superblock pointer here
         */
        void *j_private;
+
+       /* Reference to checksum algorithm driver via cryptoapi */
+       struct crypto_shash *j_chksum_driver;
 };
 
 /*
@@ -1294,6 +1298,25 @@ static inline int jbd_space_needed(journal_t *journal)
 
 extern int jbd_blocks_per_page(struct inode *inode);
 
+static inline u32 jbd2_chksum(journal_t *journal, u32 crc,
+                             const void *address, unsigned int length)
+{
+       struct {
+               struct shash_desc shash;
+               char ctx[crypto_shash_descsize(journal->j_chksum_driver)];
+       } desc;
+       int err;
+
+       desc.shash.tfm = journal->j_chksum_driver;
+       desc.shash.flags = 0;
+       *(u32 *)desc.ctx = crc;
+
+       err = crypto_shash_update(&desc.shash, address, length);
+       BUG_ON(err);
+
+       return *(u32 *)desc.ctx;
+}
+
 #ifdef __KERNEL__
 
 #define buffer_trace_init(bh)  do {} while (0)