fscrypt: export fscrypt_d_revalidate()

From: Eric Biggers <[email protected]>

Dentries that represent no-key names must have a dentry_operations that includes fscrypt_d_revalidate(). Currently, this is handled by fscrypt_prepare_lookup() installing fscrypt_d_ops.

However, ceph support for encryption
(https://lore.kernel.org/r/[email protected])
can't use fscrypt_d_ops, since ceph already has its own dentry_operations.

Similarly, ext4 and f2fs support for directories that are both encrypted and casefolded
(https://lore.kernel.org/r/[email protected])
can't use fscrypt_d_ops either, since casefolding requires some dentry operations too.

To satisfy both users, we need to move the responsibility of installing the dentry_operations to filesystems.

In preparation for this, export fscrypt_d_revalidate() and give it a !CONFIG_FS_ENCRYPTION stub.

Signed-off-by Eric Biggers <[email protected]>

---

Compared to the versions of this patch from Jeff and Daniel, I've improved the commit message and added a !CONFIG_FS_ENCRYPTION stub, which was missing. I'm planning to apply this for 5.10 in preparation for both the ceph patchset and the encrypt+casefold patchset.

 fs/crypto/fname.c       | 3 ++-
 include/linux/fscrypt.h | 7 +++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

fs/crypto/fname.c +2 -1

index c65979452844..1fbe6c24d705 100644
@@ -530,7 +530,7 @@ EXPORT_SYMBOL_GPL(fscrypt_fname_siphash);
  * Validate dentries in encrypted directories to make sure we aren't potentially
  * caching stale dentries after a key has been added.
  */
-static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
+int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
 {
 	struct dentry *dir;
 	int err;

@@ -569,6 +569,7 @@ static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
 
 	return valid;
 }
+EXPORT_SYMBOL_GPL(fscrypt_d_revalidate);
 
 const struct dentry_operations fscrypt_d_ops = {
 	.d_revalidate = fscrypt_d_revalidate,

include/linux/fscrypt.h +1 -0

index f1757e73162d..a8f7a43f031b 100644
@@ -197,6 +197,7 @@ int fscrypt_fname_disk_to_usr(const struct inode *inode,
 bool fscrypt_match_name(const struct fscrypt_name *fname,
 			const u8 *de_name, u32 de_name_len);
 u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name);
+int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags);
 
 /* bio.c */
 void fscrypt_decrypt_bio(struct bio *bio);

@@ -454,6 +455,12 @@ static inline u64 fscrypt_fname_siphash(const struct inode *dir,
 	return 0;
 }

From: Eric Biggers <[email protected]>

Dentries that represent no-key names must have a dentry_operations that includes fscrypt_d_revalidate(). Currently, this is handled by fscrypt_prepare_lookup() installing fscrypt_d_ops.

However, ceph support for encryption
(https://lore.kernel.org/r/[email protected])
can't use fscrypt_d_ops, since ceph already has its own dentry_operations.

Similarly, ext4 and f2fs support for directories that are both encrypted and casefolded
(https://lore.kernel.org/r/[email protected])
can't use fscrypt_d_ops either, since casefolding requires some dentry operations too.

To satisfy both users, we need to move the responsibility of installing the dentry_operations to filesystems.

In preparation for this, export fscrypt_d_revalidate() and give it a !CONFIG_FS_ENCRYPTION stub.

Signed-off-by Eric Biggers <[email protected]>

---

Compared to the versions of this patch from Jeff and Daniel, I've improved the commit message and added a !CONFIG_FS_ENCRYPTION stub, which was missing. I'm planning to apply this for 5.10 in preparation for both the ceph patchset and the encrypt+casefold patchset.

 fs/crypto/fname.c       | 3 ++-
 include/linux/fscrypt.h | 7 +++++++
 2 files changed, 9 insertions(+), 1 deletion(-)