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>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 809c439066c..71e77dddebf 100644
--- 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)