ext4: use ext4_fc_tl_mem in fast-commit replay path

To avoid 'sparse' warnings about missing endianness conversions, don't
store native endianness values into struct ext4_fc_tl.  Instead, use a
separate struct type, ext4_fc_tl_mem.

Fixes: dcc5827 ("ext4: factor out ext4_fc_get_tl()")
Cc: Ye Bin <yebin10@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20221217050212.150665-1-ebiggers@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Author: ebiggers

fs/ext4/fast_commit.c

@@ -1332,8 +1332,14 @@ struct dentry_info_args {
 	char *dname;
 };
 
+/* Same as struct ext4_fc_tl, but uses native endianness fields */
+struct ext4_fc_tl_mem {
+	u16 fc_tag;
+	u16 fc_len;
+};
+
 static inline void tl_to_darg(struct dentry_info_args *darg,
-			      struct ext4_fc_tl *tl, u8 *val)
+			      struct ext4_fc_tl_mem *tl, u8 *val)
 {
 	struct ext4_fc_dentry_info fcd;
 
@@ -1345,16 +1351,18 @@ static inline void tl_to_darg(struct dentry_info_args *darg,
 	darg->dname_len = tl->fc_len - sizeof(struct ext4_fc_dentry_info);
 }
 
-static inline void ext4_fc_get_tl(struct ext4_fc_tl *tl, u8 *val)
+static inline void ext4_fc_get_tl(struct ext4_fc_tl_mem *tl, u8 *val)
 {
-	memcpy(tl, val, EXT4_FC_TAG_BASE_LEN);
-	tl->fc_len = le16_to_cpu(tl->fc_len);
-	tl->fc_tag = le16_to_cpu(tl->fc_tag);
+	struct ext4_fc_tl tl_disk;
+
+	memcpy(&tl_disk, val, EXT4_FC_TAG_BASE_LEN);
+	tl->fc_len = le16_to_cpu(tl_disk.fc_len);
+	tl->fc_tag = le16_to_cpu(tl_disk.fc_tag);
 }
 
 /* Unlink replay function */
-static int ext4_fc_replay_unlink(struct super_block *sb, struct ext4_fc_tl *tl,
-				 u8 *val)
+static int ext4_fc_replay_unlink(struct super_block *sb,
+				 struct ext4_fc_tl_mem *tl, u8 *val)
 {
 	struct inode *inode, *old_parent;
 	struct qstr entry;
@@ -1451,8 +1459,8 @@ static int ext4_fc_replay_link_internal(struct super_block *sb,
 }
 
 /* Link replay function */
-static int ext4_fc_replay_link(struct super_block *sb, struct ext4_fc_tl *tl,
-			       u8 *val)
+static int ext4_fc_replay_link(struct super_block *sb,
+			       struct ext4_fc_tl_mem *tl, u8 *val)
 {
 	struct inode *inode;
 	struct dentry_info_args darg;
@@ -1506,8 +1514,8 @@ static int ext4_fc_record_modified_inode(struct super_block *sb, int ino)
 /*
  * Inode replay function
  */
-static int ext4_fc_replay_inode(struct super_block *sb, struct ext4_fc_tl *tl,
-				u8 *val)
+static int ext4_fc_replay_inode(struct super_block *sb,
+				struct ext4_fc_tl_mem *tl, u8 *val)
 {
 	struct ext4_fc_inode fc_inode;
 	struct ext4_inode *raw_inode;
@@ -1609,8 +1617,8 @@ static int ext4_fc_replay_inode(struct super_block *sb, struct ext4_fc_tl *tl,
  * inode for which we are trying to create a dentry here, should already have
  * been replayed before we start here.
  */
-static int ext4_fc_replay_create(struct super_block *sb, struct ext4_fc_tl *tl,
-				 u8 *val)
+static int ext4_fc_replay_create(struct super_block *sb,
+				 struct ext4_fc_tl_mem *tl, u8 *val)
 {
 	int ret = 0;
 	struct inode *inode = NULL;
@@ -1708,7 +1716,7 @@ int ext4_fc_record_regions(struct super_block *sb, int ino,
 
 /* Replay add range tag */
 static int ext4_fc_replay_add_range(struct super_block *sb,
-				    struct ext4_fc_tl *tl, u8 *val)
+				    struct ext4_fc_tl_mem *tl, u8 *val)
 {
 	struct ext4_fc_add_range fc_add_ex;
 	struct ext4_extent newex, *ex;
@@ -1828,8 +1836,8 @@ static int ext4_fc_replay_add_range(struct super_block *sb,
 
 /* Replay DEL_RANGE tag */
 static int
-ext4_fc_replay_del_range(struct super_block *sb, struct ext4_fc_tl *tl,
-			 u8 *val)
+ext4_fc_replay_del_range(struct super_block *sb,
+			 struct ext4_fc_tl_mem *tl, u8 *val)
 {
 	struct inode *inode;
 	struct ext4_fc_del_range lrange;
@@ -2025,7 +2033,7 @@ static int ext4_fc_replay_scan(journal_t *journal,
 	struct ext4_fc_replay_state *state;
 	int ret = JBD2_FC_REPLAY_CONTINUE;
 	struct ext4_fc_add_range ext;
-	struct ext4_fc_tl tl;
+	struct ext4_fc_tl_mem tl;
 	struct ext4_fc_tail tail;
 	__u8 *start, *end, *cur, *val;
 	struct ext4_fc_head head;
@@ -2144,7 +2152,7 @@ static int ext4_fc_replay(journal_t *journal, struct buffer_head *bh,
 {
 	struct super_block *sb = journal->j_private;
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	struct ext4_fc_tl tl;
+	struct ext4_fc_tl_mem tl;
 	__u8 *start, *end, *cur, *val;
 	int ret = JBD2_FC_REPLAY_CONTINUE;
 	struct ext4_fc_replay_state *state = &sbi->s_fc_replay_state;