[PATCH v8 6/8] libfs: Add generic function for setting dentry_ops

Daniel Rosenberg
2020-03-07T02:37:09Z

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@google.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