[PATCH v2 8/8] fscrypt: Move d_revalidate configuration back into fscrypt

[Gabriel Krisman Bertazi <krisman@suse.de>]

This partially reverts commit bb9cd9106b22 ("fscrypt: Have filesystems
handle their d_ops"), which moved this handler out of fscrypt and into
the filesystems, in preparation to support casefold and fscrypt
combinations.  Now that we set casefolding operations through
->s_d_op, move this back into fscrypt, where it belongs, but take care
to handle filesystems that set their own sb->s_d_op.

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

---
changes since v1:
  - Fix unused definition warning (lkp)
---
 fs/crypto/hooks.c       |  8 ++++++++
 fs/ext4/namei.c         |  5 -----
 fs/f2fs/namei.c         |  5 -----
 fs/libfs.c              | 25 -------------------------
 fs/ubifs/dir.c          |  1 -
 include/linux/fs.h      |  1 -
 include/linux/fscrypt.h | 10 +++++-----
 7 files changed, 13 insertions(+), 42 deletions(-)

diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 52504dd478d3..166837d5af29 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -94,6 +94,10 @@ int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
 }
 EXPORT_SYMBOL_GPL(__fscrypt_prepare_rename);
 
+static const struct dentry_operations fscrypt_dentry_ops = {
+	.d_revalidate = fscrypt_d_revalidate,
+};
+
 int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
 			     struct fscrypt_name *fname)
 {
@@ -106,6 +110,10 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
 		spin_lock(&dentry->d_lock);
 		dentry->d_flags |= DCACHE_NOKEY_NAME;
 		spin_unlock(&dentry->d_lock);
+
+		/* Give preference to the filesystem hooks, if any. */
+		if (!dentry->d_op)
+			d_set_d_op(dentry, &fscrypt_dentry_ops);
 	}
 	return err;
 }
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 463e73fb5bf0..3f0b853a371e 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1762,11 +1762,6 @@ static struct buffer_head *ext4_lookup_entry(struct inode *dir,
 	struct buffer_head *bh;
 
 	err = ext4_fname_prepare_lookup(dir, dentry, &fname);
-
-	/* Case-insensitive volumes set dentry ops through sb->s_d_op. */
-	if (!dir->i_sb->s_d_op)
-		generic_set_encrypted_ci_d_ops(dentry);
-
 	if (err == -ENOENT)
 		return NULL;
 	if (err)
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 6aec21f0b5d6..b40c6c393bd6 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -532,11 +532,6 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
 	}
 
 	err = f2fs_prepare_lookup(dir, dentry, &fname);
-
-	/* Case-insensitive volumes set dentry ops through sb->s_d_op. */
-	if (!dir->i_sb->s_d_op)
-		generic_set_encrypted_ci_d_ops(dentry);
-
 	if (err == -ENOENT)
 		goto out_splice;
 	if (err)
diff --git a/fs/libfs.c b/fs/libfs.c
index 41c02c003265..a04d6c1ad77a 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1774,31 +1774,6 @@ const struct dentry_operations generic_ci_dentry_ops = {
 };
 #endif
 
-#ifdef CONFIG_FS_ENCRYPTION
-static const struct dentry_operations generic_encrypted_dentry_ops = {
-	.d_revalidate = fscrypt_d_revalidate,
-};
-#endif
-
-/**
- * generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
- * @dentry:	dentry to set ops on
- *
- * 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.
- */
-void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
-{
-#ifdef CONFIG_FS_ENCRYPTION
-	if (dentry->d_flags & DCACHE_NOKEY_NAME) {
-		d_set_d_op(dentry, &generic_encrypted_dentry_ops);
-		return;
-	}
-#endif
-}
-EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);
-
 /**
  * inode_maybe_inc_iversion - increments i_version
  * @inode: inode with the i_version that should be updated
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 3b13c648d490..51b9a10a9851 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -205,7 +205,6 @@ static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry,
 	dbg_gen("'%pd' in dir ino %lu", dentry, dir->i_ino);
 
 	err = fscrypt_prepare_lookup(dir, dentry, &nm);
-	generic_set_encrypted_ci_d_ops(dentry);
 	if (err == -ENOENT)
 		return d_splice_alias(NULL, dentry);
 	if (err)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 887a27d07f96..e5ae21f9f637 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3201,7 +3201,6 @@ 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 const struct dentry_operations generic_ci_dentry_ops;
 
 int may_setattr(struct mnt_idmap *idmap, struct inode *inode,
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 12f9e455d569..97a11280c2bd 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -961,11 +961,11 @@ static inline int fscrypt_prepare_rename(struct inode *old_dir,
  * key is available, then the lookup is assumed to be by plaintext name;
  * otherwise, it is assumed to be by no-key name.
  *
- * This will set DCACHE_NOKEY_NAME on the dentry if the lookup is by no-key
- * name.  In this case the filesystem must assign the dentry a dentry_operations
- * which contains fscrypt_d_revalidate (or contains a d_revalidate method that
- * calls fscrypt_d_revalidate), so that the dentry will be invalidated if the
- * directory's encryption key is later added.
+ * This also optionally installs a custom ->d_revalidate() method which will
+ * invalidate the dentry if it was created without the key and the key is later
+ * added.  If the filesystem provides its own ->d_op hooks, they will be used
+ * instead, but then the filesystem must make sure to call fscrypt_d_revalidate
+ * in its d_revalidate hook, to check if fscrypt considers the dentry stale.
  *
  * Return: 0 on success; -ENOENT if the directory's key is unavailable but the
  * filename isn't a valid no-key name, so a negative dentry should be created;
-- 
2.43.0