[PATCH 5/8] xfs: factor out log write ordering from xlog_cil_push_work()

Dave Chinner
2021-06-17T08:26:25Z

From: Dave Chinner <dchinner@redhat.com>

So we can use it for start record ordering as well as commit record
ordering in future.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_log_cil.c | 89 ++++++++++++++++++++++++++------------------
1 file changed, 52 insertions(+), 37 deletions(-)

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index 35fc3e57d870..f993ec69fc97 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -784,9 +784,54 @@ xlog_cil_build_trans_hdr(
}

/*
- * Write out the commit record of a checkpoint transaction associated with the
- * given ticket to close off a running log write. Return the lsn of the commit
- * record.
+ * Ensure that the order of log writes follows checkpoint sequence order. This
+ * relies on the context LSN being zero until the log write has guaranteed the
+ * LSN that the log write will start at via xlog_state_get_iclog_space().
+ */
+static int
+xlog_cil_order_write(
+ struct xfs_cil *cil,
+ xfs_csn_t sequence)
+{
+ struct xfs_cil_ctx *ctx;
+
+restart:
+ spin_lock(&cil->xc_push_lock);
+ list_for_each_entry(ctx, &cil->xc_committing, committing) {
+ /*
+ * Avoid getting stuck in this loop because we were woken by the
+ * shutdown, but then went back to sleep once already in the
+ * shutdown state.
+ */
+ if (XLOG_FORCED_SHUTDOWN(cil->xc_log)) {
+ spin_unlock(&cil->xc_push_lock);
+ return -EIO;
+ }
+
+ /*
+ * Higher sequences will wait for this one so skip them.
+ * Don't wait for our own sequence, either.
+ */
+ if (ctx->sequence >= sequence)
+ continue;
+ if (!ctx->commit_lsn) {
+ /*
+ * It is still being pushed! Wait for the push to
+ * complete, then start again from the beginning.
+ */
+ xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
+ goto restart;
+ }
+ }
+ spin_unlock(&cil->xc_push_lock);
+ return 0;
+}
+
+/*
+ * Write out the commit record of a checkpoint transaction to close off a
+ * running log write. These commit records are strictly ordered in ascending CIL
+ * sequence order so that log recovery will always replay the checkpoints in the
+ * correct order.
*/
int
xlog_cil_write_commit_record(
@@ -816,6 +861,10 @@ xlog_cil_write_commit_record(
if (XLOG_FORCED_SHUTDOWN(log))
return -EIO;

+ error = xlog_cil_order_write(ctx->cil, ctx->sequence);
+ if (error)
+ return error;
+
/* account for space used by record data */
ctx->ticket->t_curr_res -= reg.i_len;
error = xlog_write(log, ctx, &lv_chain, ctx->ticket, iclog, reg.i_len);
@@ -1048,40 +1097,6 @@ xlog_cil_push_work(
if (error)
goto out_abort_free_ticket;

- /*
- * now that we've written the checkpoint into the log, strictly
- * order the commit records so replay will get them in the right order.
- */
-restart:
- spin_lock(&cil->xc_push_lock);
- list_for_each_entry(new_ctx, &cil->xc_committing, committing) {
- /*
- * Avoid getting stuck in this loop because we were woken by the
- * shutdown, but then went back to sleep once already in the
- * shutdown state.
- */
- if (XLOG_FORCED_SHUTDOWN(log)) {
- spin_unlock(&cil->xc_push_lock);
- goto out_abort_free_ticket;
- }
-
- /*
- * Higher sequences will wait for this one so skip them.
- * Don't wait for our own sequence, either.
- */
- if (new_ctx->sequence >= ctx->sequence)
- continue;
- if (!new_ctx->commit_lsn) {
- /*
- * It is still being pushed! Wait for the push to
- * complete, then start again from the beginning.
- */
- xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
- goto restart;
- }
- }
- spin_unlock(&cil->xc_push_lock);
-
error = xlog_cil_write_commit_record(ctx, &commit_iclog);
if (error)
goto out_abort_free_ticket;
--
2.31.1