f2fs: move crypt info pointer to fs-specific part of inode

Move the fscrypt_inode_info pointer into the filesystem-specific part of
the inode by adding the field f2fs_inode_info::i_crypt_info and
configuring fscrypt_operations::inode_info_offs accordingly.

This is a prerequisite for a later commit that removes
inode::i_crypt_info, saving memory and improving cache efficiency with
filesystems that don't support fscrypt.

Co-developed-by: Christian Brauner <[e-mail]>
Signed-off-by: Eric Biggers <[e-mail]>
Link: https://lore.kernel.org/[e-mail]
Signed-off-by: Christian Brauner <[e-mail]>

fs/f2fs/f2fs.h

···
 
 	unsigned int atomic_write_cnt;
 	loff_t original_i_size;		/* original i_size before atomic write */
+#ifdef CONFIG_FS_ENCRYPTION
+	struct fscrypt_inode_info *i_crypt_info; /* filesystem encryption info */
+#endif
 };
 
 static inline void get_read_extent_info(struct extent_info *ext,

fs/f2fs/super.c

···
 	struct f2fs_inode_info *fi = (struct f2fs_inode_info *) foo;
 
 	inode_init_once(&fi->vfs_inode);
+#ifdef CONFIG_FS_ENCRYPTION
+	fi->i_crypt_info = NULL;
+#endif
 }
 
 #ifdef CONFIG_QUOTA
···
 }
 
 static const struct fscrypt_operations f2fs_cryptops = {
+	.inode_info_offs	= (int)offsetof(struct f2fs_inode_info, i_crypt_info) -
+				  (int)offsetof(struct f2fs_inode_info, vfs_inode),
 	.needs_bounce_pages	= 1,
 	.has_32bit_inodes	= 1,
 	.supports_subblock_data_units = 1,
···
 	.has_stable_inodes	= f2fs_has_stable_inodes,
 	.get_devices		= f2fs_get_devices,
 };
-#endif
+#endif /* CONFIG_FS_ENCRYPTION */
 
 static struct inode *f2fs_nfs_get_inode(struct super_block *sb,
 		u64 ino, u32 generation)