xfs: add log recovery tracepoint for head/tail

Torn write detection and tail overwrite detection can shift the log
head and tail respectively in the event of CRC mismatch or
corruption errors. Add a high-level log recovery tracepoint to dump
the final log head/tail and make those values easily attainable in
debug/diagnostic situations.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 43d5df3a563f7aa3b234356f29c64b341fd22ccc..a36239980cf71f7c347e3550833060ddcad42dc7 100644 (file)
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -5598,6 +5598,8 @@ xlog_do_recover(
        xfs_buf_t       *bp;
        xfs_sb_t        *sbp;
 
+       trace_xfs_log_recover(log, head_blk, tail_blk);
+
        /*
         * First replay the images in the log.
         */

diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index bcc3cdf8e1c5da7797463bf6023171860268f3d6..68810477ef2c2737879ce466154a1af7e9c92eaf 100644 (file)
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -1963,6 +1963,24 @@ DEFINE_EVENT(xfs_swap_extent_class, name, \
 DEFINE_SWAPEXT_EVENT(xfs_swap_extent_before);
 DEFINE_SWAPEXT_EVENT(xfs_swap_extent_after);
 
+TRACE_EVENT(xfs_log_recover,
+       TP_PROTO(struct xlog *log, xfs_daddr_t headblk, xfs_daddr_t tailblk),
+       TP_ARGS(log, headblk, tailblk),
+       TP_STRUCT__entry(
+               __field(dev_t, dev)
+               __field(xfs_daddr_t, headblk)
+               __field(xfs_daddr_t, tailblk)
+       ),
+       TP_fast_assign(
+               __entry->dev = log->l_mp->m_super->s_dev;
+               __entry->headblk = headblk;
+               __entry->tailblk = tailblk;
+       ),
+       TP_printk("dev %d:%d headblk 0x%llx tailblk 0x%llx",
+                 MAJOR(__entry->dev), MINOR(__entry->dev), __entry->headblk,
+                 __entry->tailblk)
+)
+
 TRACE_EVENT(xfs_log_recover_record,
        TP_PROTO(struct xlog *log, struct xlog_rec_header *rhead, int pass),
        TP_ARGS(log, rhead, pass),