[PATCH v3 03/10] fscrypt: Drop d_revalidate for valid dentries during lookup

[Gabriel Krisman Bertazi <krisman@suse.de>]

Unencrypted and encrypted-dentries where the key is available don't need
to be revalidated with regards to fscrypt, since they don't go stale
from under VFS and the key cannot be removed for the encrypted case
without evicting the dentry.  Mark them with d_set_always_valid, to
avoid unnecessary revalidation, in preparation to always configuring
d_op through sb->s_d_op.

Since the filesystem might have other features that require
revalidation, only apply this optimization if the d_revalidate handler
is fscrypt_d_revalidate itself.

Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
---
 fs/crypto/hooks.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 41df986d1230..53381acc83e7 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -127,6 +127,15 @@ int fscrypt_prepare_lookup_dentry(struct inode *dir,
 	spin_lock(&dentry->d_lock);
 	if (nokey_name) {
 		dentry->d_flags |= DCACHE_NOKEY_NAME;
+	} else if (dentry->d_flags & DCACHE_OP_REVALIDATE &&
+		   dentry->d_op->d_revalidate == fscrypt_d_revalidate) {
+		/*
+		 * Unencrypted dentries and encrypted dentries where the
+		 * key is available are always valid from fscrypt
+		 * perspective. Avoid the cost of calling
+		 * fscrypt_d_revalidate unnecessarily.
+		 */
+		dentry->d_flags &= ~DCACHE_OP_REVALIDATE;
 	}
 	spin_unlock(&dentry->d_lock);
 
-- 
2.43.0