[PATCH] eCryptfs: Load each file decryption key only once

[Trevor Highland <thighlan@gmail.com>]

eCryptfs: Load each file decryption key only once

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>
---
 fs/ecryptfs/crypto.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 70f7aab..949fe44 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -353,7 +353,6 @@ static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 		ecryptfs_dump_hex(crypt_stat->key,
 				  crypt_stat->key_size);
 	}
-	/* Consider doing this once, when the file is opened */
 	mutex_lock(&crypt_stat->cs_tfm_mutex);
 	if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
 		rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
@@ -687,10 +686,12 @@ static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 	};
 	int rc = 0;
 
-	/* 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);
-- 
1.5.2.5