linux-ext4 - [PATCH v3 05/10] libfs: Merge encrypted_ci_dentry_ops and ci_dentry

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Message-ID: <20240119184742.31088-6-krisman@suse.de>
Date: Fri, 19 Jan 2024 15:47:37 -0300
From: Gabriel Krisman Bertazi <krisman@...e.de>
To: viro@...iv.linux.org.uk,
	ebiggers@...nel.org,
	jaegeuk@...nel.org,
	tytso@....edu
Cc: linux-ext4@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	linux-fsdevel@...r.kernel.org,
	amir73il@...il.com,
	Gabriel Krisman Bertazi <krisman@...e.de>
Subject: [PATCH v3 05/10] libfs: Merge encrypted_ci_dentry_ops and ci_dentry_ops

In preparation to get case-insensitive dentry operations from
sb->s_d_op again, use the same structure for case-insensitive
filesystems with and without fscrypt.

This means that on a casefolded filesystem without fscrypt, we end up
having to call fscrypt_d_revalidate once per dentry, which does the
function call extra cost.  We could avoid it by calling
d_set_always_valid in generic_set_encrypted_ci_d_ops, but this entire
function will go away in the following patches, and it is not worth the
extra complexity. Also, since the first fscrypt_d_revalidate will call
d_set_always_valid for us, we'll only have only pay the cost once, and
not per-lookup.

Signed-off-by: Gabriel Krisman Bertazi <krisman@...e.de>

---
Changes since v1:
  - fix header guard (eric)
---
 fs/libfs.c | 34 ++++++----------------------------
 1 file changed, 6 insertions(+), 28 deletions(-)

diff --git a/fs/libfs.c b/fs/libfs.c
index c2aa6fd4795c..c4be0961faf0 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1776,19 +1776,14 @@ static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
 static const struct dentry_operations generic_ci_dentry_ops = {
 	.d_hash = generic_ci_d_hash,
 	.d_compare = generic_ci_d_compare,
-};
-#endif
-
 #ifdef CONFIG_FS_ENCRYPTION
-static const struct dentry_operations generic_encrypted_dentry_ops = {
 	.d_revalidate = fscrypt_d_revalidate,
+#endif
 };
 #endif
 
-#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
-static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
-	.d_hash = generic_ci_d_hash,
-	.d_compare = generic_ci_d_compare,
+#ifdef CONFIG_FS_ENCRYPTION
+static const struct dentry_operations generic_encrypted_dentry_ops = {
 	.d_revalidate = fscrypt_d_revalidate,
 };
 #endif
@@ -1809,38 +1804,21 @@ static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
  * Encryption works differently in that the only dentry operation it needs is
  * d_revalidate, which it only needs on dentries that have the no-key name flag.
  * The no-key flag can't be set "later", so we don't have to worry about that.
- *
- * Finally, to maximize compatibility with overlayfs (which isn't compatible
- * with certain dentry operations) and to avoid taking an unnecessary
- * performance hit, we use custom dentry_operations for each possible
- * combination rather than always installing all operations.
  */
 void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
 {
-#ifdef CONFIG_FS_ENCRYPTION
-	bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME;
-#endif
 #if IS_ENABLED(CONFIG_UNICODE)
-	bool needs_ci_ops = dentry->d_sb->s_encoding;
-#endif
-#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
-	if (needs_encrypt_ops && needs_ci_ops) {
-		d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
+	if (dentry->d_sb->s_encoding) {
+		d_set_d_op(dentry, &generic_ci_dentry_ops);
 		return;
 	}
 #endif
 #ifdef CONFIG_FS_ENCRYPTION
-	if (needs_encrypt_ops) {
+	if (dentry->d_flags & DCACHE_NOKEY_NAME) {
 		d_set_d_op(dentry, &generic_encrypted_dentry_ops);
 		return;
 	}
 #endif
-#if IS_ENABLED(CONFIG_UNICODE)
-	if (needs_ci_ops) {
-		d_set_d_op(dentry, &generic_ci_dentry_ops);
-		return;
-	}
-#endif
 }
 EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);
 
-- 
2.43.0