xfs: factor out log write ordering from xlog_cil_push_work()

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>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index 651118f..38917c9 100644 (file)
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -656,9 +656,54 @@ xlog_cil_set_ctx_write_state(
 
 
 /*
- * 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_is_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.
  */
 static int
 xlog_cil_write_commit_record(
@@ -904,39 +949,9 @@ 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_is_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_order_write(ctx->cil, ctx->sequence);
+       if (error)
+               goto out_abort_free_ticket;
 
        error = xlog_cil_write_commit_record(ctx, &commit_iclog);
        if (error)