Btrfs: switch to crc32c instead of sha256

Signed-off-by: Chris Mason <chris.mason@oracle.com>

3 files changed, 28 insertions, 23 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 92a6078de827..d8caeba5d758 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -30,6 +30,8 @@ extern struct kmem_cache *btrfs_path_cachep;
 
 /* 32 bytes in various csum fields */
 #define BTRFS_CSUM_SIZE 32
+/* four bytes for CRC32 */
+#define BTRFS_CRC32_SIZE 4
 
 /*
  * the key defines the order in the tree, and so it also defines (optimal)
@@ -235,7 +237,7 @@ struct btrfs_file_extent_item {
 } __attribute__ ((__packed__));
 
 struct btrfs_csum_item {
-        u8 csum[BTRFS_CSUM_SIZE];
+        u8 csum;
 } __attribute__ ((__packed__));
 
 struct btrfs_device_item {
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 2dbf422a2b9a..678456d1e2f9 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -196,14 +196,14 @@ int btrfs_csum_data(struct btrfs_root * root, char *data, size_t len,
         ret = crypto_hash_digest(&desc, &sg, 1, result);
         spin_unlock(&root->fs_info->hash_lock);
         if (ret) {
-                printk("sha256 digest failed\n");
+                printk("digest failed\n");
         }
         return ret;
 }
 static int csum_tree_block(struct btrfs_root *root, struct buffer_head *bh,
                            int verify)
 {
-        char result[BTRFS_CSUM_SIZE];
+        char result[BTRFS_CRC32_SIZE];
         int ret;
         struct btrfs_node *node;
 
@@ -212,14 +212,14 @@ static int csum_tree_block(struct btrfs_root *root, struct buffer_head *bh,
         if (ret)
                 return ret;
         if (verify) {
-                if (memcmp(bh->b_data, result, BTRFS_CSUM_SIZE)) {
+                if (memcmp(bh->b_data, result, BTRFS_CRC32_SIZE)) {
                         printk("checksum verify failed on %Lu\n",
                                bh_blocknr(bh));
                         return 1;
                 }
         } else {
                 node = btrfs_buffer_node(bh);
-                memcpy(node->header.csum, result, BTRFS_CSUM_SIZE);
+                memcpy(node->header.csum, result, BTRFS_CRC32_SIZE);
         }
         return 0;
 }
@@ -576,10 +576,10 @@ struct btrfs_root *open_ctree(struct super_block *sb)
                sizeof(struct btrfs_key));
         insert_inode_hash(fs_info->btree_inode);
         mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
-        fs_info->hash_tfm = crypto_alloc_hash("sha256", 0, CRYPTO_ALG_ASYNC);
+        fs_info->hash_tfm = crypto_alloc_hash("crc32c", 0, CRYPTO_ALG_ASYNC);
         spin_lock_init(&fs_info->hash_lock);
         if (!fs_info->hash_tfm || IS_ERR(fs_info->hash_tfm)) {
-                printk("failed to allocate sha256 hash\n");
+                printk("failed to allocate digest hash\n");
                 return NULL;
         }
         mutex_init(&fs_info->trans_mutex);
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 10e4cf08e9ed..a66709e6d036 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -4,8 +4,8 @@
 #include "transaction.h"
 
 #define MAX_CSUM_ITEMS(r) ((((BTRFS_LEAF_DATA_SIZE(r) - \
-                                 sizeof(struct btrfs_item) * 2) / \
-                                sizeof(struct btrfs_csum_item)) - 1))
+                               sizeof(struct btrfs_item) * 2) / \
+                               BTRFS_CRC32_SIZE) - 1))
 int btrfs_insert_file_extent(struct btrfs_trans_handle *trans,
                                struct btrfs_root *root,
                                u64 objectid, u64 pos,
@@ -78,7 +78,7 @@ struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
                 csum_offset = (offset - found_key.offset) >>
                                 root->fs_info->sb->s_blocksize_bits;
                 csums_in_item = btrfs_item_size(leaf->items + path->slots[0]);
-                csums_in_item /= sizeof(struct btrfs_csum_item);
+                csums_in_item /= BTRFS_CRC32_SIZE;
 
                 if (csum_offset >= csums_in_item) {
                         ret = -EFBIG;
@@ -86,7 +86,8 @@ struct btrfs_csum_item *btrfs_lookup_csum(struct btrfs_trans_handle *trans,
                 }
         }
         item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
-        item += csum_offset;
+        item = (struct btrfs_csum_item *)((unsigned char *)item +
+                                          csum_offset * BTRFS_CRC32_SIZE);
         return item;
 fail:
         if (ret > 0)
@@ -143,8 +144,7 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
                 /* we found one, but it isn't big enough yet */
                 leaf = btrfs_buffer_leaf(path->nodes[0]);
                 item_size = btrfs_item_size(leaf->items + path->slots[0]);
-                if ((item_size / sizeof(struct btrfs_csum_item)) >=
-                    MAX_CSUM_ITEMS(root)) {
+                if ((item_size / BTRFS_CRC32_SIZE) >= MAX_CSUM_ITEMS(root)) {
                         /* already at max size, make a new one */
                         goto insert;
                 }
@@ -159,7 +159,7 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
          */
         btrfs_release_path(root, path);
         ret = btrfs_search_slot(trans, root, &file_key, path,
-                                sizeof(struct btrfs_csum_item), 1);
+                                BTRFS_CRC32_SIZE, 1);
         if (ret < 0)
                 goto fail;
         if (ret == 0) {
@@ -180,10 +180,10 @@ int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
                 goto insert;
         }
         if (csum_offset >= btrfs_item_size(leaf->items + path->slots[0]) /
-            sizeof(struct btrfs_csum_item)) {
-                u32 diff = (csum_offset + 1) * sizeof(struct btrfs_csum_item);
+            BTRFS_CRC32_SIZE) {
+                u32 diff = (csum_offset + 1) * BTRFS_CRC32_SIZE;
                 diff = diff - btrfs_item_size(leaf->items + path->slots[0]);
-                WARN_ON(diff != sizeof(struct btrfs_csum_item));
+                WARN_ON(diff != BTRFS_CRC32_SIZE);
                 ret = btrfs_extend_item(trans, root, path, diff);
                 BUG_ON(ret);
                 goto csum;
@@ -193,7 +193,7 @@ insert:
         btrfs_release_path(root, path);
         csum_offset = 0;
         ret = btrfs_insert_empty_item(trans, root, path, &file_key,
-                                      sizeof(struct btrfs_csum_item));
+                                      BTRFS_CRC32_SIZE);
         if (ret != 0) {
                 printk("at insert for %Lu %u %Lu ret is %d\n", file_key.objectid, file_key.flags, file_key.offset, ret);
                 WARN_ON(1);
@@ -203,10 +203,13 @@ csum:
         item = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
                               struct btrfs_csum_item);
         ret = 0;
-        item += csum_offset;
+        item = (struct btrfs_csum_item *)((unsigned char *)item +
+                                          csum_offset * BTRFS_CRC32_SIZE);
 found:
-        btrfs_check_bounds(item->csum, BTRFS_CSUM_SIZE, path->nodes[0]->b_data, root->fs_info->sb->s_blocksize);
-        ret = btrfs_csum_data(root, data, len, item->csum);
+        btrfs_check_bounds(&item->csum, BTRFS_CRC32_SIZE,
+                           path->nodes[0]->b_data,
+                           root->fs_info->sb->s_blocksize);
+        ret = btrfs_csum_data(root, data, len, &item->csum);
         btrfs_mark_buffer_dirty(path->nodes[0]);
 fail:
         btrfs_release_path(root, path);
@@ -222,7 +225,7 @@ int btrfs_csum_verify_file_block(struct btrfs_root *root,
         struct btrfs_key file_key;
         struct btrfs_path *path;
         struct btrfs_csum_item *item;
-        char result[BTRFS_CSUM_SIZE];
+        char result[BTRFS_CRC32_SIZE];
 
         path = btrfs_alloc_path();
         BUG_ON(!path);
@@ -244,7 +247,7 @@ int btrfs_csum_verify_file_block(struct btrfs_root *root,
 
         ret = btrfs_csum_data(root, data, len, result);
         WARN_ON(ret);
-        if (memcmp(result, item->csum, BTRFS_CSUM_SIZE))
+        if (memcmp(result, &item->csum, BTRFS_CRC32_SIZE))
                 ret = 1;
 fail:
         btrfs_release_path(root, path);