xfs: add CRC checks to the log
Implement CRCs for the log buffers. We re-use a field in
struct xlog_rec_header that was used for a weak checksum of the
log buffer payload in debug builds before.
The new checksumming uses the crc32c checksum we will use elsewhere
in XFS, and also protects the record header and addition cycle data.
Due to this there are some interesting changes in xlog_sync, as we
need to do the cycle wrapping for the split buffer case much earlier,
as we would touch the buffer after generating the checksum otherwise.
The CRC calculation is always enabled, even for non-CRC filesystems,
as adding this CRC does not change the log format. On non-CRC
filesystems, only issue an alert if a CRC mismatch is found and
allow recovery to continue - this will act as an indicator that
log recovery problems are a result of log corruption. On CRC enabled
filesystems, however, log recovery will fail.
Note that existing debug kernels will write a simple checksum value
to the log, so the first time this is run on a filesystem taht was
last used on a debug kernel it will through CRC mismatch warning
errors. These can be ignored.
Initially based on a patch from Dave Chinner, then modified
significantly by Christoph Hellwig. Modified again by Dave Chinner
to get to this version.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 9a4e0e5..dc3498b 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -139,7 +139,6 @@
/*
* Flags for log structure
*/
-#define XLOG_CHKSUM_MISMATCH 0x1 /* used only during recovery */
#define XLOG_ACTIVE_RECOVERY 0x2 /* in the middle of recovery */
#define XLOG_RECOVERY_NEEDED 0x4 /* log was recovered */
#define XLOG_IO_ERROR 0x8 /* log hit an I/O error, and being
@@ -291,7 +290,7 @@
__be32 h_len; /* len in bytes; should be 64-bit aligned: 4 */
__be64 h_lsn; /* lsn of this LR : 8 */
__be64 h_tail_lsn; /* lsn of 1st LR w/ buffers not committed: 8 */
- __be32 h_chksum; /* may not be used; non-zero if used : 4 */
+ __le32 h_crc; /* crc of log record : 4 */
__be32 h_prev_block; /* block number to previous LR : 4 */
__be32 h_num_logops; /* number of log operations in this LR : 4 */
__be32 h_cycle_data[XLOG_HEADER_CYCLE_SIZE / BBSIZE];
@@ -555,11 +554,9 @@
extern int
xlog_recover_finish(
struct xlog *log);
-extern void
-xlog_pack_data(
- struct xlog *log,
- struct xlog_in_core *iclog,
- int);
+
+extern __be32 xlog_cksum(struct xlog *log, struct xlog_rec_header *rhead,
+ char *dp, int size);
extern kmem_zone_t *xfs_log_ticket_zone;
struct xlog_ticket *
