[PATCH] jbd2: Fix endian mixing problems in the checksumming code

["Darrick J. Wong" <darrick.wong@oracle.com>]

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>
---
 fs/jbd2/commit.c   |    6 +++---
 fs/jbd2/journal.c  |    5 +++--
 fs/jbd2/recovery.c |   24 ++++++++++++------------
 3 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 559bec1..cf2fc05 100644
--- a/fs/jbd2/commit.c
+++ b/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);
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 02c7ad9..5203264 100644
--- a/fs/jbd2/journal.c
+++ b/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;
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index d4851464..3929c50 100644
--- a/fs/jbd2/recovery.c
+++ b/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. */