xfs: convert log vector chain to use list heads

Because the next change is going to require sorting log vectors, and
that requires arbitrary rearrangement of the list which cannot be
done easily with a single linked list.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

1 files changed, 30 insertions, 24 deletions

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index a0792b8db38b..0e69e855d710 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -105,6 +105,7 @@ xlog_cil_ctx_alloc(void)
 	INIT_LIST_HEAD(&ctx->committing);
 	INIT_LIST_HEAD(&ctx->busy_extents);
 	INIT_LIST_HEAD(&ctx->log_items);
+	INIT_LIST_HEAD(&ctx->lv_chain);
 	INIT_WORK(&ctx->push_work, xlog_cil_push_work);
 	return ctx;
 }
@@ -338,6 +339,7 @@ xlog_cil_alloc_shadow_bufs(
 
 			memset(lv, 0, xlog_cil_iovec_space(niovecs));
 
+			INIT_LIST_HEAD(&lv->lv_list);
 			lv->lv_item = lip;
 			lv->lv_size = buf_size;
 			if (ordered)
@@ -353,7 +355,6 @@ xlog_cil_alloc_shadow_bufs(
 			else
 				lv->lv_buf_len = 0;
 			lv->lv_bytes = 0;
-			lv->lv_next = NULL;
 		}
 
 		/* Ensure the lv is set up according to ->iop_size */
@@ -480,7 +481,6 @@ xlog_cil_insert_format_items(
 		if (lip->li_lv && shadow->lv_size <= lip->li_lv->lv_size) {
 			/* same or smaller, optimise common overwrite case */
 			lv = lip->li_lv;
-			lv->lv_next = NULL;
 
 			if (ordered)
 				goto insert;
@@ -685,14 +685,14 @@ xlog_cil_insert_items(
 
 static void
 xlog_cil_free_logvec(
-	struct xfs_log_vec	*log_vector)
+	struct list_head	*lv_chain)
 {
 	struct xfs_log_vec	*lv;
 
-	for (lv = log_vector; lv; ) {
-		struct xfs_log_vec *next = lv->lv_next;
+	while (!list_empty(lv_chain)) {
+		lv = list_first_entry(lv_chain, struct xfs_log_vec, lv_list);
+		list_del_init(&lv->lv_list);
 		kmem_free(lv);
-		lv = next;
 	}
 }
 
@@ -792,7 +792,7 @@ xlog_cil_committed(
 		spin_unlock(&ctx->cil->xc_push_lock);
 	}
 
-	xfs_trans_committed_bulk(ctx->cil->xc_log->l_ailp, ctx->lv_chain,
+	xfs_trans_committed_bulk(ctx->cil->xc_log->l_ailp, &ctx->lv_chain,
 					ctx->start_lsn, abort);
 
 	xfs_extent_busy_sort(&ctx->busy_extents);
@@ -803,7 +803,7 @@ xlog_cil_committed(
 	list_del(&ctx->committing);
 	spin_unlock(&ctx->cil->xc_push_lock);
 
-	xlog_cil_free_logvec(ctx->lv_chain);
+	xlog_cil_free_logvec(&ctx->lv_chain);
 
 	if (!list_empty(&ctx->busy_extents))
 		xlog_discard_busy_extents(mp, ctx);
@@ -962,7 +962,6 @@ restart:
 static int
 xlog_cil_write_chain(
 	struct xfs_cil_ctx	*ctx,
-	struct xfs_log_vec	*chain,
 	uint32_t		chain_len)
 {
 	struct xlog		*log = ctx->cil->xc_log;
@@ -971,7 +970,7 @@ xlog_cil_write_chain(
 	error = xlog_cil_order_write(ctx->cil, ctx->sequence, _START_RECORD);
 	if (error)
 		return error;
-	return xlog_write(log, ctx, chain, ctx->ticket, chain_len);
+	return xlog_write(log, ctx, &ctx->lv_chain, ctx->ticket, chain_len);
 }
 
 /*
@@ -1000,6 +999,8 @@ xlog_cil_write_commit_record(
 		.lv_iovecp = &reg,
 	};
 	int			error;
+	LIST_HEAD(lv_chain);
+	list_add(&vec.lv_list, &lv_chain);
 
 	if (xlog_is_shutdown(log))
 		return -EIO;
@@ -1010,7 +1011,7 @@ xlog_cil_write_commit_record(
 
 	/* account for space used by record data */
 	ctx->ticket->t_curr_res -= reg.i_len;
-	error = xlog_write(log, ctx, &vec, ctx->ticket, reg.i_len);
+	error = xlog_write(log, ctx, &lv_chain, ctx->ticket, reg.i_len);
 	if (error)
 		xlog_force_shutdown(log, SHUTDOWN_LOG_IO_ERROR);
 	return error;
@@ -1076,7 +1077,6 @@ xlog_cil_build_trans_hdr(
 	lvhdr->lv_niovecs = 2;
 	lvhdr->lv_iovecp = &hdr->lhdr[0];
 	lvhdr->lv_bytes = hdr->lhdr[0].i_len + hdr->lhdr[1].i_len;
-	lvhdr->lv_next = ctx->lv_chain;
 
 	tic->t_curr_res -= lvhdr->lv_bytes;
 }
@@ -1117,12 +1117,11 @@ xlog_cil_build_lv_chain(
 	uint32_t		*num_iovecs,
 	uint32_t		*num_bytes)
 {
-	struct xfs_log_vec	*lv = NULL;
-
 	list_sort(NULL, &ctx->log_items, xlog_cil_order_cmp);
 
 	while (!list_empty(&ctx->log_items)) {
 		struct xfs_log_item	*item;
+		struct xfs_log_vec	*lv;
 
 		item = list_first_entry(&ctx->log_items,
 					struct xfs_log_item, li_cil);
@@ -1133,19 +1132,17 @@ xlog_cil_build_lv_chain(
 			continue;
 		}
 
-		list_del_init(&item->li_cil);
-		item->li_order_id = 0;
-		if (!ctx->lv_chain)
-			ctx->lv_chain = item->li_lv;
-		else
-			lv->lv_next = item->li_lv;
 		lv = item->li_lv;
-		item->li_lv = NULL;
-		*num_iovecs += lv->lv_niovecs;
 
 		/* we don't write ordered log vectors */
 		if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED)
 			*num_bytes += lv->lv_bytes;
+		*num_iovecs += lv->lv_niovecs;
+		list_add_tail(&lv->lv_list, &ctx->lv_chain);
+
+		list_del_init(&item->li_cil);
+		item->li_order_id = 0;
+		item->li_lv = NULL;
 	}
 }
 
@@ -1189,7 +1186,7 @@ xlog_cil_push_work(
 	int			num_bytes = 0;
 	int			error = 0;
 	struct xlog_cil_trans_hdr thdr;
-	struct xfs_log_vec	lvhdr = { NULL };
+	struct xfs_log_vec	lvhdr = {};
 	xfs_csn_t		push_seq;
 	bool			push_commit_stable;
 	LIST_HEAD		(whiteouts);
@@ -1299,11 +1296,20 @@ xlog_cil_push_work(
 	 * Build a checkpoint transaction header and write it to the log to
 	 * begin the transaction. We need to account for the space used by the
 	 * transaction header here as it is not accounted for in xlog_write().
+	 * Add the lvhdr to the head of the lv chain we pass to xlog_write() so
+	 * it gets written into the iclog first.
 	 */
 	xlog_cil_build_trans_hdr(ctx, &thdr, &lvhdr, num_iovecs);
 	num_bytes += lvhdr.lv_bytes;
+	list_add(&lvhdr.lv_list, &ctx->lv_chain);
 
-	error = xlog_cil_write_chain(ctx, &lvhdr, num_bytes);
+	/*
+	 * Take the lvhdr back off the lv_chain immediately after calling
+	 * xlog_cil_write_chain() as it should not be passed to log IO
+	 * completion.
+	 */
+	error = xlog_cil_write_chain(ctx, num_bytes);
+	list_del(&lvhdr.lv_list);
 	if (error)
 		goto out_abort_free_ticket;