jbd2: Fix endian mixing problems in the checksumming code

In the jbd2 checksumming code, explicitly declare separate variables with
endianness information so that we don't get confused and screw things up again.
Also fixes sparse warnings.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/jbd2/commit.c

@@ -343,14 +343,14 @@ static void jbd2_block_tag_csum_set(journal_t *j, journal_block_tag_t *tag,
 	struct page *page = bh->b_page;
 	__u8 *addr;
 	__u32 csum32;
+	__be32 seq;
 
 	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 		return;
 
-	sequence = cpu_to_be32(sequence);
+	seq = cpu_to_be32(sequence);
 	addr = kmap_atomic(page);
-	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,
-			     sizeof(sequence));
+	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 	csum32 = jbd2_chksum(j, csum32, addr + offset_in_page(bh->b_data),
 			     bh->b_size);
 	kunmap_atomic(addr);

fs/jbd2/journal.c

@@ -130,9 +130,10 @@ int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb)
 	return sb->s_checksum_type == JBD2_CRC32C_CHKSUM;
 }
 
-static __u32 jbd2_superblock_csum(journal_t *j, journal_superblock_t *sb)
+static __be32 jbd2_superblock_csum(journal_t *j, journal_superblock_t *sb)
 {
-	__u32 csum, old_csum;
+	__u32 csum;
+	__be32 old_csum;
 
 	old_csum = sb->s_checksum;
 	sb->s_checksum = 0;

fs/jbd2/recovery.c

@@ -178,7 +178,8 @@ static int jbd2_descr_block_csum_verify(journal_t *j,
 					void *buf)
 {
 	struct jbd2_journal_block_tail *tail;
-	__u32 provided, calculated;
+	__be32 provided;
+	__u32 calculated;
 
 	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 		return 1;
@@ -190,8 +191,7 @@ static int jbd2_descr_block_csum_verify(journal_t *j,
 	calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 	tail->t_checksum = provided;
 
-	provided = be32_to_cpu(provided);
-	return provided == calculated;
+	return provided == cpu_to_be32(calculated);
 }
 
 /*
@@ -381,7 +381,8 @@ static int calc_chksums(journal_t *journal, struct buffer_head *bh,
 static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 {
 	struct commit_header *h;
-	__u32 provided, calculated;
+	__be32 provided;
+	__u32 calculated;
 
 	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 		return 1;
@@ -392,21 +393,20 @@ static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
 	calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 	h->h_chksum[0] = provided;
 
-	provided = be32_to_cpu(provided);
-	return provided == calculated;
+	return provided == cpu_to_be32(calculated);
 }
 
 static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
 				      void *buf, __u32 sequence)
 {
 	__u32 csum32;
+	__be32 seq;
 
 	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 		return 1;
 
-	sequence = cpu_to_be32(sequence);
-	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&sequence,
-			     sizeof(sequence));
+	seq = cpu_to_be32(sequence);
+	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
 	csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);
 
 	return tag->t_checksum == cpu_to_be16(csum32);
@@ -808,7 +808,8 @@ static int jbd2_revoke_block_csum_verify(journal_t *j,
 					 void *buf)
 {
 	struct jbd2_journal_revoke_tail *tail;
-	__u32 provided, calculated;
+	__be32 provided;
+	__u32 calculated;
 
 	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))
 		return 1;
@@ -820,8 +821,7 @@ static int jbd2_revoke_block_csum_verify(journal_t *j,
 	calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
 	tail->r_checksum = provided;
 
-	provided = be32_to_cpu(provided);
-	return provided == calculated;
+	return provided == cpu_to_be32(calculated);
 }
 
 /* Scan a revoke record, marking all blocks mentioned as revoked. */