jbd2: change disk layout for metadata checksumming
Define flags and allocate space in on-disk journal structures to support
checksumming of journal metadata.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 840f70f..69d7803 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -627,7 +627,7 @@
tag = (journal_block_tag_t *) tagp;
write_tag_block(tag_bytes, tag, jh2bh(jh)->b_blocknr);
- tag->t_flags = cpu_to_be32(tag_flag);
+ tag->t_flags = cpu_to_be16(tag_flag);
tagp += tag_bytes;
space_left -= tag_bytes;
@@ -651,7 +651,7 @@
submitting the IOs. "tag" still points to
the last tag we set up. */
- tag->t_flags |= cpu_to_be32(JBD2_FLAG_LAST_TAG);
+ tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);
start_journal_io:
for (i = 0; i < bufs; i++) {
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index c1a0335..980f3d6 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -193,10 +193,10 @@
nr++;
tagp += tag_bytes;
- if (!(tag->t_flags & cpu_to_be32(JBD2_FLAG_SAME_UUID)))
+ if (!(tag->t_flags & cpu_to_be16(JBD2_FLAG_SAME_UUID)))
tagp += 16;
- if (tag->t_flags & cpu_to_be32(JBD2_FLAG_LAST_TAG))
+ if (tag->t_flags & cpu_to_be16(JBD2_FLAG_LAST_TAG))
break;
}
@@ -485,7 +485,7 @@
unsigned long io_block;
tag = (journal_block_tag_t *) tagp;
- flags = be32_to_cpu(tag->t_flags);
+ flags = be16_to_cpu(tag->t_flags);
io_block = next_log_block++;
wrap(journal, next_log_block);
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 912c30a..809c439 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -147,12 +147,24 @@
#define JBD2_CRC32_CHKSUM 1
#define JBD2_MD5_CHKSUM 2
#define JBD2_SHA1_CHKSUM 3
+#define JBD2_CRC32C_CHKSUM 4
#define JBD2_CRC32_CHKSUM_SIZE 4
#define JBD2_CHECKSUM_BYTES (32 / sizeof(u32))
/*
* Commit block header for storing transactional checksums:
+ *
+ * NOTE: If FEATURE_COMPAT_CHECKSUM (checksum v1) is set, the h_chksum*
+ * fields are used to store a checksum of the descriptor and data blocks.
+ *
+ * If FEATURE_INCOMPAT_CSUM_V2 (checksum v2) is set, then the h_chksum
+ * field is used to store crc32c(uuid+commit_block). Each journal metadata
+ * block gets its own checksum, and data block checksums are stored in
+ * journal_block_tag (in the descriptor). The other h_chksum* fields are
+ * not used.
+ *
+ * Checksum v1 and v2 are mutually exclusive features.
*/
struct commit_header {
__be32 h_magic;
@@ -175,13 +187,19 @@
typedef struct journal_block_tag_s
{
__be32 t_blocknr; /* The on-disk block number */
- __be32 t_flags; /* See below */
+ __be16 t_checksum; /* truncated crc32c(uuid+seq+block) */
+ __be16 t_flags; /* See below */
__be32 t_blocknr_high; /* most-significant high 32bits. */
} journal_block_tag_t;
#define JBD2_TAG_SIZE32 (offsetof(journal_block_tag_t, t_blocknr_high))
#define JBD2_TAG_SIZE64 (sizeof(journal_block_tag_t))
+/* Tail of descriptor block, for checksumming */
+struct jbd2_journal_block_tail {
+ __be32 t_checksum; /* crc32c(uuid+descr_block) */
+};
+
/*
* The revoke descriptor: used on disk to describe a series of blocks to
* be revoked from the log
@@ -192,6 +210,10 @@
__be32 r_count; /* Count of bytes used in the block */
} jbd2_journal_revoke_header_t;
+/* Tail of revoke block, for checksumming */
+struct jbd2_journal_revoke_tail {
+ __be32 r_checksum; /* crc32c(uuid+revoke_block) */
+};
/* Definitions for the journal tag flags word: */
#define JBD2_FLAG_ESCAPE 1 /* on-disk block is escaped */
@@ -241,7 +263,10 @@
__be32 s_max_trans_data; /* Limit of data blocks per trans. */
/* 0x0050 */
- __u32 s_padding[44];
+ __u8 s_checksum_type; /* checksum type */
+ __u8 s_padding2[3];
+ __u32 s_padding[42];
+ __be32 s_checksum; /* crc32c(superblock) */
/* 0x0100 */
__u8 s_users[16*48]; /* ids of all fs'es sharing the log */
@@ -263,6 +288,7 @@
#define JBD2_FEATURE_INCOMPAT_REVOKE 0x00000001
#define JBD2_FEATURE_INCOMPAT_64BIT 0x00000002
#define JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT 0x00000004
+#define JBD2_FEATURE_INCOMPAT_CSUM_V2 0x00000008
/* Features known to this kernel version: */
#define JBD2_KNOWN_COMPAT_FEATURES JBD2_FEATURE_COMPAT_CHECKSUM