linux-kernel - [PATCH v8 6/8] libfs: Add generic function for setting dentry

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Message-Id: <20200307023611.204708-7-drosen@google.com>
Date:   Fri,  6 Mar 2020 18:36:09 -0800
From:   Daniel Rosenberg <drosen@...gle.com>
To:     "Theodore Ts'o" <tytso@....edu>, linux-ext4@...r.kernel.org,
        Jaegeuk Kim <jaegeuk@...nel.org>, Chao Yu <chao@...nel.org>,
        linux-f2fs-devel@...ts.sourceforge.net,
        Eric Biggers <ebiggers@...nel.org>,
        linux-fscrypt@...r.kernel.org,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Richard Weinberger <richard@....at>
Cc:     linux-mtd@...ts.infradead.org,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        kernel-team@...roid.com, Daniel Rosenberg <drosen@...gle.com>
Subject: [PATCH v8 6/8] libfs: Add generic function for setting dentry_ops

This adds a function to set dentry operations at lookup time that will
work for both encrypted files and casefolded filenames.

A filesystem that supports both features simultaneously can use this
function during lookup preperations to set up its dentry operations once
fscrypt no longer does that itself.

Signed-off-by: Daniel Rosenberg <drosen@...gle.com>
---
 fs/libfs.c         | 50 ++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h |  2 ++
 2 files changed, 52 insertions(+)

diff --git a/fs/libfs.c b/fs/libfs.c
index 0eaa63a9ae037..bdda03c8ece9e 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1474,4 +1474,54 @@ int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
 	return ret;
 }
 EXPORT_SYMBOL(generic_ci_d_hash);
+
+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
+
+#if IS_ENABLED(CONFIG_UNICODE) && IS_ENABLED(CONFIG_FS_ENCRYPTION)
+static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
+	.d_hash = generic_ci_d_hash,
+	.d_compare = generic_ci_d_compare,
+	.d_revalidate = fscrypt_d_revalidate,
+};
+#endif
+
+/**
+ * generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
+ * @dir:	parent of dentry whose ops to set
+ * @dentry:	dentry to set ops on
+ *
+ * This function sets the dentry ops for the given dentry to handle both
+ * casefolding and encryption of the dentry name.
+ */
+void generic_set_encrypted_ci_d_ops(struct inode *dir, struct dentry *dentry)
+{
+#ifdef CONFIG_FS_ENCRYPTION
+	if (dentry->d_flags & DCACHE_ENCRYPTED_NAME) {
+#ifdef CONFIG_UNICODE
+		if (dir->i_sb->s_encoding) {
+			d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
+			return;
+		}
 #endif
+		d_set_d_op(dentry, &generic_encrypted_dentry_ops);
+		return;
+	}
+#endif
+#ifdef CONFIG_UNICODE
+	if (dir->i_sb->s_encoding) {
+		d_set_d_op(dentry, &generic_ci_dentry_ops);
+		return;
+	}
+#endif
+}
+EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8d20a3daa49a0..dc433bc4f0602 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3389,6 +3389,8 @@ static inline bool needs_casefold(const struct inode *dir)
 	return false;
 }
 #endif
+extern void generic_set_encrypted_ci_d_ops(struct inode *dir,
+					   struct dentry *dentry);
 
 #ifdef CONFIG_MIGRATION
 extern int buffer_migrate_page(struct address_space *,
-- 
2.25.1.481.gfbce0eb801-goog