eCryptfs: set inode key only once per crypto operation

There is no need to keep re-setting the same key for any given eCryptfs inode.
This patch optimizes the use of the crypto API and helps performance a bit.

Signed-off-by: Trevor Highland <trevor.highland@gmail.com>
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 6 insertions, 2 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 4d1b2b4eb79e..7eaa395a77bd 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -355,8 +355,11 @@ static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
         }
         /* Consider doing this once, when the file is opened */
         mutex_lock(&crypt_stat->cs_tfm_mutex);
-        rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
-                                     crypt_stat->key_size);
+        if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
+                rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
+                                             crypt_stat->key_size);
+                crypt_stat->flags |= ECRYPTFS_KEY_SET;
+        }
         if (rc) {
                 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
                                 rc);
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 3d637e9ca36a..2a6103954c1e 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -234,6 +234,7 @@ struct ecryptfs_crypt_stat {
 #define ECRYPTFS_KEY_VALID          0x00000080
 #define ECRYPTFS_METADATA_IN_XATTR  0x00000100
 #define ECRYPTFS_VIEW_AS_ENCRYPTED  0x00000200
+#define ECRYPTFS_KEY_SET            0x00000400
         u32 flags;
         unsigned int file_version;
         size_t iv_bytes;