erofs: kill __packed for on-disk structures

As Christoph suggested "Please don't add __packed" [1],
remove all __packed except struct erofs_dirent here.

Note that all on-disk fields except struct erofs_dirent
(12 bytes with a 8-byte nid) in EROFS are naturally aligned.

[1] https://lore.kernel.org/r/20190829095954.GB20598@infradead.org/Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-5-gaoxiang25@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/erofs/erofs_fs.h

@@ -38,7 +38,7 @@ struct erofs_super_block {
 	__le32 requirements;    /* (aka. feature_incompat) */
 
 	__u8 reserved2[44];
-} __packed;
+};
 
 /*
  * erofs inode data mapping:
@@ -91,12 +91,12 @@ struct erofs_inode_v1 {
 
 		/* for device files, used to indicate old/new device # */
 		__le32 rdev;
-	} i_u __packed;
+	} i_u;
 	__le32 i_ino;           /* only used for 32-bit stat compatibility */
 	__le16 i_uid;
 	__le16 i_gid;
 	__le32 i_reserved2;
-} __packed;
+};
 
 /* 32 bytes on-disk inode */
 #define EROFS_INODE_LAYOUT_V1   0
@@ -119,7 +119,7 @@ struct erofs_inode_v2 {
 
 		/* for device files, used to indicate old/new device # */
 		__le32 rdev;
-	} i_u __packed;
+	} i_u;
 
 	/* only used for 32-bit stat compatibility */
 	__le32 i_ino;
@@ -130,7 +130,7 @@ struct erofs_inode_v2 {
 	__le32 i_ctime_nsec;
 	__le32 i_nlink;
 	__u8   i_reserved2[16];
-} __packed;
+};
 
 #define EROFS_MAX_SHARED_XATTRS         (128)
 /* h_shared_count between 129 ... 255 are special # */
@@ -152,7 +152,7 @@ struct erofs_xattr_ibody_header {
 	__u8   h_shared_count;
 	__u8   h_reserved2[7];
 	__le32 h_shared_xattrs[0];      /* shared xattr id array */
-} __packed;
+};
 
 /* Name indexes */
 #define EROFS_XATTR_INDEX_USER              1
@@ -169,7 +169,7 @@ struct erofs_xattr_entry {
 	__le16 e_value_size;    /* size of attribute value */
 	/* followed by e_name and e_value */
 	char   e_name[0];       /* attribute name */
-} __packed;
+};
 
 static inline unsigned int erofs_xattr_ibody_size(__le16 i_xattr_icount)
 {
@@ -273,8 +273,8 @@ struct z_erofs_vle_decompressed_index {
 		 * [1] - pointing to the tail cluster
 		 */
 		__le16 delta[2];
-	} di_u __packed;
-} __packed;
+	} di_u;
+};
 
 #define Z_EROFS_VLE_LEGACY_INDEX_ALIGN(size) \
 	(round_up(size, sizeof(struct z_erofs_vle_decompressed_index)) + \