fscrypt: make fscrypt_operations.max_namelen an integer

Now ->max_namelen() is only called to limit the filename length when
adding NUL padding, and only for real filenames -- not symlink targets.
It also didn't give the correct length for symlink targets anyway since
it forgot to subtract 'sizeof(struct fscrypt_symlink_data)'.

Thus, change ->max_namelen from a function to a simple 'unsigned int'
that gives the filesystem's maximum filename length.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 8ab3303..b28e44b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1173,19 +1173,13 @@
 	return DUMMY_ENCRYPTION_ENABLED(EXT4_SB(inode->i_sb));
 }
 
-static unsigned ext4_max_namelen(struct inode *inode)
-{
-	return S_ISLNK(inode->i_mode) ? inode->i_sb->s_blocksize :
-		EXT4_NAME_LEN;
-}
-
 static const struct fscrypt_operations ext4_cryptops = {
 	.key_prefix		= "ext4:",
 	.get_context		= ext4_get_context,
 	.set_context		= ext4_set_context,
 	.dummy_context		= ext4_dummy_context,
 	.empty_dir		= ext4_empty_dir,
-	.max_namelen		= ext4_max_namelen,
+	.max_namelen		= EXT4_NAME_LEN,
 };
 #endif