btrfs: add boilerplate code for directly including the crypto framework

Add boilerplate code for directly including the crypto framework.  This
helps us flipping the switch for new algorithms.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

2 files changed, 47 insertions, 7 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index a66ed58058d9..2e908c557fb2 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -73,6 +73,7 @@ struct btrfs_ref;
 
 /* four bytes for CRC32 */
 static const int btrfs_csum_sizes[] = { 4 };
+static const char *btrfs_csum_names[] = { "crc32c" };
 
 #define BTRFS_EMPTY_DIR_SIZE 0
 
@@ -1163,6 +1164,8 @@ struct btrfs_fs_info {
         spinlock_t swapfile_pins_lock;
         struct rb_root swapfile_pins;
 
+        struct crypto_shash *csum_shash;
+
 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
         spinlock_t ref_verify_lock;
         struct rb_root block_tree;
@@ -2454,6 +2457,11 @@ static inline int btrfs_super_csum_size(const struct btrfs_super_block *s)
         return btrfs_csum_sizes[t];
 }
 
+static inline const char *btrfs_super_csum_name(u16 csum_type)
+{
+        /* csum type is validated at mount time */
+        return btrfs_csum_names[csum_type];
+}
 
 /*
  * The leaf data grows from end-to-front in the node.
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c9ce0b002008..34222bbe4b48 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -19,6 +19,7 @@
 #include <linux/crc32c.h>
 #include <linux/sched/mm.h>
 #include <asm/unaligned.h>
+#include <crypto/hash.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
@@ -2256,6 +2257,29 @@ static int btrfs_init_workqueues(struct btrfs_fs_info *fs_info,
         return 0;
 }
 
+static int btrfs_init_csum_hash(struct btrfs_fs_info *fs_info, u16 csum_type)
+{
+        struct crypto_shash *csum_shash;
+        const char *csum_name = btrfs_super_csum_name(csum_type);
+
+        csum_shash = crypto_alloc_shash(csum_name, 0, 0);
+
+        if (IS_ERR(csum_shash)) {
+                btrfs_err(fs_info, "error allocating %s hash for checksum",
+                          csum_name);
+                return PTR_ERR(csum_shash);
+        }
+
+        fs_info->csum_shash = csum_shash;
+
+        return 0;
+}
+
+static void btrfs_free_csum_hash(struct btrfs_fs_info *fs_info)
+{
+        crypto_free_shash(fs_info->csum_shash);
+}
+
 static int btrfs_replay_log(struct btrfs_fs_info *fs_info,
                             struct btrfs_fs_devices *fs_devices)
 {
@@ -2820,6 +2844,12 @@ int open_ctree(struct super_block *sb,
                 goto fail_alloc;
         }
 
+        ret = btrfs_init_csum_hash(fs_info, csum_type);
+        if (ret) {
+                err = ret;
+                goto fail_alloc;
+        }
+
         /*
          * We want to check superblock checksum, the type is stored inside.
          * Pass the whole disk block of size BTRFS_SUPER_INFO_SIZE (4k).
@@ -2828,7 +2858,7 @@ int open_ctree(struct super_block *sb,
                 btrfs_err(fs_info, "superblock checksum mismatch");
                 err = -EINVAL;
                 brelse(bh);
-                goto fail_alloc;
+                goto fail_csum;
         }
 
         /*
@@ -2865,11 +2895,11 @@ int open_ctree(struct super_block *sb,
         if (ret) {
                 btrfs_err(fs_info, "superblock contains fatal errors");
                 err = -EINVAL;
-                goto fail_alloc;
+                goto fail_csum;
         }
 
         if (!btrfs_super_root(disk_super))
-                goto fail_alloc;
+                goto fail_csum;
 
         /* check FS state, whether FS is broken. */
         if (btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_ERROR)
@@ -2891,7 +2921,7 @@ int open_ctree(struct super_block *sb,
         ret = btrfs_parse_options(fs_info, options, sb->s_flags);
         if (ret) {
                 err = ret;
-                goto fail_alloc;
+                goto fail_csum;
         }
 
         features = btrfs_super_incompat_flags(disk_super) &
@@ -2901,7 +2931,7 @@ int open_ctree(struct super_block *sb,
                     "cannot mount because of unsupported optional features (%llx)",
                     features);
                 err = -EINVAL;
-                goto fail_alloc;
+                goto fail_csum;
         }
 
         features = btrfs_super_incompat_flags(disk_super);
@@ -2945,7 +2975,7 @@ int open_ctree(struct super_block *sb,
                 btrfs_err(fs_info,
 "unequal nodesize/sectorsize (%u != %u) are not allowed for mixed block groups",
                         nodesize, sectorsize);
-                goto fail_alloc;
+                goto fail_csum;
         }
 
         /*
@@ -2961,7 +2991,7 @@ int open_ctree(struct super_block *sb,
         "cannot mount read-write because of unsupported optional features (%llx)",
                        features);
                 err = -EINVAL;
-                goto fail_alloc;
+                goto fail_csum;
         }
 
         ret = btrfs_init_workqueues(fs_info, fs_devices);
@@ -3339,6 +3369,8 @@ fail_tree_roots:
 fail_sb_buffer:
         btrfs_stop_all_workers(fs_info);
         btrfs_free_block_groups(fs_info);
+fail_csum:
+        btrfs_free_csum_hash(fs_info);
 fail_alloc:
 fail_iput:
         btrfs_mapping_tree_free(&fs_info->mapping_tree);