[PATCH v6 06/10] libfs: Add helper to choose dentry operations at mount-time

Gabriel Krisman Bertazi
2024-02-13T02:13:54Z

In preparation to drop the similar helper that sets d_op at lookup time,
add a version to set the right d_op filesystem-wide, through sb->s_d_op.
The operations structures are shared across filesystems supporting
fscrypt and/or casefolding, therefore we can keep it in common libfs
code.

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

---
changes since v3:
- Fix typo in comment (Eric)
---
fs/libfs.c | 28 ++++++++++++++++++++++++++++
include/linux/fs.h | 1 +
2 files changed, 29 insertions(+)

diff --git a/fs/libfs.c b/fs/libfs.c
index c4be0961faf0..0aa388ee82ff 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1822,6 +1822,34 @@ void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
}
EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);

+/**
+ * generic_set_sb_d_ops - helper for choosing the set of
+ * filesystem-wide dentry operations for the enabled features
+ * @sb: superblock to be configured
+ *
+ * Filesystems supporting casefolding and/or fscrypt can call this
+ * helper at mount-time to configure sb->s_d_op to best set of dentry
+ * operations required for the enabled features. The helper must be
+ * called after these have been configured, but before the root dentry
+ * is created.
+ */
+void generic_set_sb_d_ops(struct super_block *sb)
+{
+#if IS_ENABLED(CONFIG_UNICODE)
+ if (sb->s_encoding) {
+ sb->s_d_op = &generic_ci_dentry_ops;
+ return;
+ }
+#endif
+#ifdef CONFIG_FS_ENCRYPTION
+ if (sb->s_cop) {
+ sb->s_d_op = &generic_encrypted_dentry_ops;
+ return;
+ }
+#endif
+}
+EXPORT_SYMBOL(generic_set_sb_d_ops);
+
/**
* inode_maybe_inc_iversion - increments i_version
* @inode: inode with the i_version that should be updated
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e6667ece5e64..c985d9392b61 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3202,6 +3202,7 @@ extern int generic_file_fsync(struct file *, loff_t, loff_t, int);
extern int generic_check_addressable(unsigned, u64);

extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry);
+extern void generic_set_sb_d_ops(struct super_block *sb);

static inline bool sb_has_encoding(const struct super_block *sb)
{
--
2.43.0