ext4: fix fast commit alignment issues

Fast commit recovery data on disk may not be aligned. So, when the
recovery code reads it, this patch makes sure that fast commit info
found on-disk is first memcpy-ed into an aligned variable before
accessing it. As a consequence of it, we also remove some macros that
could resulted in unaligned accesses.

Cc: stable@kernel.org
Fixes: 8016e29f ("ext4: fast commit recovery path")
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20210519215920.2037527-1-harshads@google.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/fast_commit.h

@@ -153,13 +153,6 @@ struct ext4_fc_replay_state {
 #define region_last(__region) (((__region)->lblk) + ((__region)->len) - 1)
 #endif
 
-#define fc_for_each_tl(__start, __end, __tl)				\
-	for (tl = (struct ext4_fc_tl *)(__start);			\
-	     (__u8 *)tl < (__u8 *)(__end);				\
-		tl = (struct ext4_fc_tl *)((__u8 *)tl +			\
-					sizeof(struct ext4_fc_tl) +	\
-					+ le16_to_cpu(tl->fc_len)))
-
 static inline const char *tag2str(__u16 tag)
 {
 	switch (tag) {
@@ -186,16 +179,4 @@ static inline const char *tag2str(__u16 tag)
 	}
 }
 
-/* Get length of a particular tlv */
-static inline int ext4_fc_tag_len(struct ext4_fc_tl *tl)
-{
-	return le16_to_cpu(tl->fc_len);
-}
-
-/* Get a pointer to "value" of a tlv */
-static inline __u8 *ext4_fc_tag_val(struct ext4_fc_tl *tl)
-{
-	return (__u8 *)tl + sizeof(*tl);
-}
-
 #endif /* __FAST_COMMIT_H__ */