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authorChristoph Hellwig <hch@lst.de>2012-11-12 22:54:24 +1100
committerBen Myers <bpm@sgi.com>2012-11-19 20:18:41 -0600
commit0e446be44806240c779666591bb9e8cb0e86a50d (patch)
treebc88570369c1707e3adb5e32a655bfa28503ef57 /fs/xfs/xfs_log.c
parentbc02e8693d875c2a9b0037cfd37fe0b726d26403 (diff)
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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>
Diffstat (limited to 'fs/xfs/xfs_log.c')
-rw-r--r--fs/xfs/xfs_log.c132
1 files changed, 109 insertions, 23 deletions
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 1d6d2ee08495..c6d6e136ba77 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -35,6 +35,7 @@
#include "xfs_inode.h"
#include "xfs_trace.h"
#include "xfs_fsops.h"
+#include "xfs_cksum.h"
kmem_zone_t *xfs_log_ticket_zone;
@@ -1490,6 +1491,84 @@ xlog_grant_push_ail(
}
/*
+ * Stamp cycle number in every block
+ */
+STATIC void
+xlog_pack_data(
+ struct xlog *log,
+ struct xlog_in_core *iclog,
+ int roundoff)
+{
+ int i, j, k;
+ int size = iclog->ic_offset + roundoff;
+ __be32 cycle_lsn;
+ xfs_caddr_t dp;
+
+ cycle_lsn = CYCLE_LSN_DISK(iclog->ic_header.h_lsn);
+
+ dp = iclog->ic_datap;
+ for (i = 0; i < BTOBB(size); i++) {
+ if (i >= (XLOG_HEADER_CYCLE_SIZE / BBSIZE))
+ break;
+ iclog->ic_header.h_cycle_data[i] = *(__be32 *)dp;
+ *(__be32 *)dp = cycle_lsn;
+ dp += BBSIZE;
+ }
+
+ if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
+ xlog_in_core_2_t *xhdr = iclog->ic_data;
+
+ for ( ; i < BTOBB(size); i++) {
+ j = i / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
+ k = i % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
+ xhdr[j].hic_xheader.xh_cycle_data[k] = *(__be32 *)dp;
+ *(__be32 *)dp = cycle_lsn;
+ dp += BBSIZE;
+ }
+
+ for (i = 1; i < log->l_iclog_heads; i++)
+ xhdr[i].hic_xheader.xh_cycle = cycle_lsn;
+ }
+}
+
+/*
+ * Calculate the checksum for a log buffer.
+ *
+ * This is a little more complicated than it should be because the various
+ * headers and the actual data are non-contiguous.
+ */
+__be32
+xlog_cksum(
+ struct xlog *log,
+ struct xlog_rec_header *rhead,
+ char *dp,
+ int size)
+{
+ __uint32_t crc;
+
+ /* first generate the crc for the record header ... */
+ crc = xfs_start_cksum((char *)rhead,
+ sizeof(struct xlog_rec_header),
+ offsetof(struct xlog_rec_header, h_crc));
+
+ /* ... then for additional cycle data for v2 logs ... */
+ if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
+ union xlog_in_core2 *xhdr = (union xlog_in_core2 *)rhead;
+ int i;
+
+ for (i = 1; i < log->l_iclog_heads; i++) {
+ crc = crc32c(crc, &xhdr[i].hic_xheader,
+ sizeof(struct xlog_rec_ext_header));
+ }
+ }
+
+ /* ... and finally for the payload */
+ crc = crc32c(crc, dp, size);
+
+ return xfs_end_cksum(crc);
+}
+
+/*
* The bdstrat callback function for log bufs. This gives us a central
* place to trap bufs in case we get hit by a log I/O error and need to
* shutdown. Actually, in practice, even when we didn't get a log error,
@@ -1549,7 +1628,6 @@ xlog_sync(
struct xlog *log,
struct xlog_in_core *iclog)
{
- xfs_caddr_t dptr; /* pointer to byte sized element */
xfs_buf_t *bp;
int i;
uint count; /* byte count of bwrite */
@@ -1558,6 +1636,7 @@ xlog_sync(
int split = 0; /* split write into two regions */
int error;
int v2 = xfs_sb_version_haslogv2(&log->l_mp->m_sb);
+ int size;
XFS_STATS_INC(xs_log_writes);
ASSERT(atomic_read(&iclog->ic_refcnt) == 0);
@@ -1588,13 +1667,10 @@ xlog_sync(
xlog_pack_data(log, iclog, roundoff);
/* real byte length */
- if (v2) {
- iclog->ic_header.h_len =
- cpu_to_be32(iclog->ic_offset + roundoff);
- } else {
- iclog->ic_header.h_len =
- cpu_to_be32(iclog->ic_offset);
- }
+ size = iclog->ic_offset;
+ if (v2)
+ size += roundoff;
+ iclog->ic_header.h_len = cpu_to_be32(size);
bp = iclog->ic_bp;
XFS_BUF_SET_ADDR(bp, BLOCK_LSN(be64_to_cpu(iclog->ic_header.h_lsn)));
@@ -1603,12 +1679,36 @@ xlog_sync(
/* Do we need to split this write into 2 parts? */
if (XFS_BUF_ADDR(bp) + BTOBB(count) > log->l_logBBsize) {
+ char *dptr;
+
split = count - (BBTOB(log->l_logBBsize - XFS_BUF_ADDR(bp)));
count = BBTOB(log->l_logBBsize - XFS_BUF_ADDR(bp));
- iclog->ic_bwritecnt = 2; /* split into 2 writes */
+ iclog->ic_bwritecnt = 2;
+
+ /*
+ * Bump the cycle numbers at the start of each block in the
+ * part of the iclog that ends up in the buffer that gets
+ * written to the start of the log.
+ *
+ * Watch out for the header magic number case, though.
+ */
+ dptr = (char *)&iclog->ic_header + count;
+ for (i = 0; i < split; i += BBSIZE) {
+ __uint32_t cycle = be32_to_cpu(*(__be32 *)dptr);
+ if (++cycle == XLOG_HEADER_MAGIC_NUM)
+ cycle++;
+ *(__be32 *)dptr = cpu_to_be32(cycle);
+
+ dptr += BBSIZE;
+ }
} else {
iclog->ic_bwritecnt = 1;
}
+
+ /* calculcate the checksum */
+ iclog->ic_header.h_crc = xlog_cksum(log, &iclog->ic_header,
+ iclog->ic_datap, size);
+
bp->b_io_length = BTOBB(count);
bp->b_fspriv = iclog;
XFS_BUF_ZEROFLAGS(bp);
@@ -1662,19 +1762,6 @@ xlog_sync(
bp->b_flags |= XBF_SYNCIO;
if (log->l_mp->m_flags & XFS_MOUNT_BARRIER)
bp->b_flags |= XBF_FUA;
- dptr = bp->b_addr;
- /*
- * Bump the cycle numbers at the start of each block
- * since this part of the buffer is at the start of
- * a new cycle. Watch out for the header magic number
- * case, though.
- */
- for (i = 0; i < split; i += BBSIZE) {
- be32_add_cpu((__be32 *)dptr, 1);
- if (be32_to_cpu(*(__be32 *)dptr) == XLOG_HEADER_MAGIC_NUM)
- be32_add_cpu((__be32 *)dptr, 1);
- dptr += BBSIZE;
- }
ASSERT(XFS_BUF_ADDR(bp) <= log->l_logBBsize-1);
ASSERT(XFS_BUF_ADDR(bp) + BTOBB(count) <= log->l_logBBsize);
@@ -1691,7 +1778,6 @@ xlog_sync(
return 0;
} /* xlog_sync */
-
/*
* Deallocate a log structure
*/