ecryptfs: check for existing key_tfm at mount time
Jeff Moyer pointed out that a mount; umount loop of ecryptfs, with the same
cipher & other mount options, created a new ecryptfs_key_tfm_cache item
each time, and the cache could grow quite large this way.
Looking at this with mhalcrow, we saw that ecryptfs_parse_options()
unconditionally called ecryptfs_add_new_key_tfm(), which is what was adding
these items.
Refactor ecryptfs_get_tfm_and_mutex_for_cipher_name() to create a new
helper function, ecryptfs_tfm_exists(), which checks for the cipher on the
cached key_tfm_list, and sets a pointer to it if it exists. This can then
be called from ecryptfs_parse_options(), and new key_tfm's can be added
only when a cached one is not found.
With list locking changes suggested by akpm.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index dc620fc..778c420 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -410,9 +410,13 @@
if (!cipher_key_bytes_set) {
mount_crypt_stat->global_default_cipher_key_size = 0;
}
- rc = ecryptfs_add_new_key_tfm(
- NULL, mount_crypt_stat->global_default_cipher_name,
- mount_crypt_stat->global_default_cipher_key_size);
+ mutex_lock(&key_tfm_list_mutex);
+ if (!ecryptfs_tfm_exists(mount_crypt_stat->global_default_cipher_name,
+ NULL))
+ rc = ecryptfs_add_new_key_tfm(
+ NULL, mount_crypt_stat->global_default_cipher_name,
+ mount_crypt_stat->global_default_cipher_key_size);
+ mutex_unlock(&key_tfm_list_mutex);
if (rc) {
printk(KERN_ERR "Error attempting to initialize cipher with "
"name = [%s] and key size = [%td]; rc = [%d]\n",