From: Dave Chinner <dchinner@xxxxxxxxxx>
Before waiting on a iclog in xfs_log_force_lsn(), we don't check to
see if the iclog has already been completed and the contents on
stable storage. We check for completed iclogs in xfs_log_force(), so
we should do the same thing for xfs_log_force_lsn().
This fixed some random up-to-30s pauses seen in unmounting
filesystems in some tests. A log force ends up waiting on completed
iclog, and that doesn't then get flushed (and hence the log force
get completed) until the background log worker issues a log force
that flushes the iclog in question. Then the unmount unblocks and
continues.
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
fs/xfs/xfs_log.c | 42 +++++++++++++++++++++++++++++++++++++-----
1 file changed, 37 insertions(+), 5 deletions(-)
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 160b8bb7ee60..1c328efdca66 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -3143,6 +3143,35 @@ xlog_state_switch_iclogs(
log->l_iclog = iclog->ic_next;
}
+/*
+ * Force the iclog to disk and check if the iclog has been completed before
+ * xlog_force_iclog() returns. This can happen on synchronous (e.g.
+ * pmem) or fast async storage because we drop the icloglock to issue the IO.
+ * If completion has already occurred, tell the caller so that it can avoid an
+ * unnecessary wait on the iclog.
+ */
+static int
+xlog_force_and_check_iclog(
+ struct xlog_in_core *iclog,
+ bool *completed)
+{
+ xfs_lsn_t lsn = be64_to_cpu(iclog->ic_header.h_lsn);
+ int error;
+
+ *completed = false;
+ error = xlog_force_iclog(iclog);
+ if (error)
+ return error;
+
+ /*
+ * If the iclog has already been completed and reused the header LSN
+ * will have been rewritten by completion
+ */
+ if (be64_to_cpu(iclog->ic_header.h_lsn) != lsn)
+ *completed = true;
+ return 0;
+}
+
/*
* Write out all data in the in-core log as of this exact moment in time.
*
@@ -3177,7 +3206,6 @@ xfs_log_force(
{
struct xlog *log = mp->m_log;
struct xlog_in_core *iclog;
- xfs_lsn_t lsn;
XFS_STATS_INC(mp, xs_log_force);
trace_xfs_log_force(mp, 0, _RET_IP_);
@@ -3206,11 +3234,12 @@ xfs_log_force(
} else if (iclog->ic_state == XLOG_STATE_ACTIVE) {
if (atomic_read(&iclog->ic_refcnt) == 0) {
/* We have exclusive access to this iclog. */
- lsn = be64_to_cpu(iclog->ic_header.h_lsn);
- if (xlog_force_iclog(iclog))
+ bool completed;
+
+ if (xlog_force_and_check_iclog(iclog, &completed))
goto out_error;
- if (be64_to_cpu(iclog->ic_header.h_lsn) != lsn)
+ if (completed)
goto out_unlock;
} else {
/*
@@ -3250,6 +3279,7 @@ xlog_force_lsn(
bool already_slept)
{
struct xlog_in_core *iclog;
+ bool completed;
spin_lock(&log->l_icloglock);
iclog = log->l_iclog;
@@ -3287,10 +3317,12 @@ xlog_force_lsn(
&log->l_icloglock);
return -EAGAIN;
}
- if (xlog_force_iclog(iclog))
+ if (xlog_force_and_check_iclog(iclog, &completed))
goto out_error;
if (log_flushed)
*log_flushed = 1;
+ if (completed)
+ goto out_unlock;
break;
case XLOG_STATE_WANT_SYNC:
/*
--
2.31.1
