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>

fs/xfs/xfs_log.c

@@ -848,6 +848,9 @@ xlog_write_unmount_record(
 		.lv_niovecs = 1,
 		.lv_iovecp = &reg,
 	};
+	LIST_HEAD(lv_chain);
+	INIT_LIST_HEAD(&vec.lv_list);
+	list_add(&vec.lv_list, &lv_chain);
 
 	BUILD_BUG_ON((sizeof(struct xlog_op_header) +
 		      sizeof(struct xfs_unmount_log_format)) !=
@@ -863,7 +866,7 @@ xlog_write_unmount_record(
 	 */
 	if (log->l_targ != log->l_mp->m_ddev_targp)
 		blkdev_issue_flush(log->l_targ->bt_bdev);
-	return xlog_write(log, &vec, ticket, NULL, NULL, reg.i_len);
+	return xlog_write(log, &lv_chain, ticket, NULL, NULL, reg.i_len);
 }
 
 /*
@@ -1581,13 +1584,16 @@ xlog_commit_record(
 		.lv_iovecp = &reg,
 	};
 	int	error;
+	LIST_HEAD(lv_chain);
+	INIT_LIST_HEAD(&vec.lv_list);
+	list_add(&vec.lv_list, &lv_chain);
 
 	if (XLOG_FORCED_SHUTDOWN(log))
 		return -EIO;
 
 	/* account for space used by record data */
 	ticket->t_curr_res -= reg.i_len;
-	error = xlog_write(log, &vec, ticket, lsn, iclog, reg.i_len);
+	error = xlog_write(log, &lv_chain, ticket, lsn, iclog, reg.i_len);
 	if (error)
 		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
 	return error;
@@ -2118,6 +2124,7 @@ xlog_print_trans(
  */
 static struct xfs_log_vec *
 xlog_write_single(
+	struct list_head	*lv_chain,
 	struct xfs_log_vec	*log_vector,
 	struct xlog_ticket	*ticket,
 	struct xlog_in_core	*iclog,
@@ -2134,7 +2141,9 @@ xlog_write_single(
 		iclog->ic_state == XLOG_STATE_WANT_SYNC);
 
 	ptr = iclog->ic_datap + *log_offset;
-	for (lv = log_vector; lv; lv = lv->lv_next) {
+	for (lv = log_vector;
+	     !list_entry_is_head(lv, lv_chain, lv_list);
+	     lv = list_next_entry(lv, lv_list)) {
 		/*
 		 * If the entire log vec does not fit in the iclog, punt it to
 		 * the partial copy loop which can handle this case.
@@ -2163,6 +2172,8 @@ xlog_write_single(
 			*data_cnt += reg->i_len;
 		}
 	}
+	if (list_entry_is_head(lv, lv_chain, lv_list))
+		lv = NULL;
 	ASSERT(*len == 0 || lv);
 	return lv;
 }
@@ -2208,6 +2219,7 @@ xlog_write_get_more_iclog_space(
 static struct xfs_log_vec *
 xlog_write_partial(
 	struct xlog		*log,
+	struct list_head	*lv_chain,
 	struct xfs_log_vec	*log_vector,
 	struct xlog_ticket	*ticket,
 	struct xlog_in_core	**iclogp,
@@ -2347,7 +2359,10 @@ xlog_write_partial(
 	 * the caller so it can go back to fast path copying.
 	 */
 	*iclogp = iclog;
-	return lv->lv_next;
+	lv = list_next_entry(lv, lv_list);
+	if (list_entry_is_head(lv, lv_chain, lv_list))
+		return NULL;
+	return lv;
 }
 
 /*
@@ -2393,14 +2408,14 @@ xlog_write_partial(
 int
 xlog_write(
 	struct xlog		*log,
-	struct xfs_log_vec	*log_vector,
+	struct list_head	*lv_chain,
 	struct xlog_ticket	*ticket,
 	xfs_lsn_t		*start_lsn,
 	struct xlog_in_core	**commit_iclog,
 	uint32_t		len)
 {
 	struct xlog_in_core	*iclog = NULL;
-	struct xfs_log_vec	*lv = log_vector;
+	struct xfs_log_vec	*lv;
 	int			record_cnt = 0;
 	int			data_cnt = 0;
 	int			error = 0;
@@ -2422,14 +2437,16 @@ xlog_write(
 	if (start_lsn)
 		*start_lsn = be64_to_cpu(iclog->ic_header.h_lsn);
 
+	lv = list_first_entry_or_null(lv_chain, struct xfs_log_vec, lv_list);
 	while (lv) {
-		lv = xlog_write_single(lv, ticket, iclog, &log_offset,
+		lv = xlog_write_single(lv_chain, lv, ticket, iclog, &log_offset,
 					&len, &record_cnt, &data_cnt);
 		if (!lv)
 			break;
 
-		lv = xlog_write_partial(log, lv, ticket, &iclog, &log_offset,
-					&len, &record_cnt, &data_cnt);
+		lv = xlog_write_partial(log, lv_chain, lv, ticket, &iclog,
+					&log_offset, &len, &record_cnt,
+					&data_cnt);
 		if (IS_ERR_OR_NULL(lv)) {
 			error = PTR_ERR_OR_ZERO(lv);
 			break;

fs/xfs/xfs_log.h

@@ -9,7 +9,7 @@
 struct xfs_cil_ctx;
 
 struct xfs_log_vec {
-	struct xfs_log_vec	*lv_next;	/* next lv in build list */
+	struct list_head	lv_list;	/* CIL lv chain ptrs */
 	int			lv_niovecs;	/* number of iovecs in lv */
 	struct xfs_log_iovec	*lv_iovecp;	/* iovec array */
 	struct xfs_log_item	*lv_item;	/* owner */

fs/xfs/xfs_log_cil.c

@@ -73,6 +73,7 @@ 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;
 }
@@ -274,6 +275,7 @@ xlog_cil_alloc_shadow_bufs(
 			lv = kmem_alloc_large(buf_size, KM_NOFS);
 			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)
@@ -289,7 +291,6 @@ 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 */
@@ -416,7 +417,6 @@ 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;
@@ -583,14 +583,14 @@ 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;
 	}
 }
 
@@ -689,7 +689,7 @@ 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);
@@ -700,7 +700,7 @@ 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);
@@ -780,7 +780,6 @@ 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;
 }
@@ -920,25 +919,23 @@ xlog_cil_push_work(
 	xlog_cil_pcp_aggregate(cil, ctx);
 
 	list_sort(NULL, &ctx->log_items, xlog_cil_order_cmp);
-
 	while (!list_empty(&ctx->log_items)) {
 		struct xfs_log_item	*item;
 
 		item = list_first_entry(&ctx->log_items,
 					struct xfs_log_item, li_cil);
+		lv = item->li_lv;
 		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;
 
+		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;
+
+		list_add_tail(&lv->lv_list, &ctx->lv_chain);
+
 	}
 
 	/*
@@ -975,9 +972,12 @@ 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);
 
 	/*
 	 * Before we format and submit the first iclog, we have to ensure that
@@ -991,8 +991,14 @@ xlog_cil_push_work(
 	 * use the commit record lsn then we can move the tail beyond the grant
 	 * write head.
 	 */
-	error = xlog_write(log, &lvhdr, ctx->ticket, &ctx->start_lsn, NULL,
-				num_bytes);
+	error = xlog_write(log, &ctx->lv_chain, ctx->ticket, &ctx->start_lsn,
+				NULL, num_bytes);
+
+	/*
+	 * Take the lvhdr back off the lv_chain as it should not be passed
+	 * to log IO completion.
+	 */
+	list_del(&lvhdr.lv_list);
 	if (error)
 		goto out_abort_free_ticket;
 

fs/xfs/xfs_log_priv.h

@@ -221,7 +221,7 @@ struct xfs_cil_ctx {
 	atomic_t		space_used;	/* aggregate size of regions */
 	struct list_head	busy_extents;	/* busy extents in chkpt */
 	struct list_head	log_items;	/* log items in chkpt */
-	struct xfs_log_vec	*lv_chain;	/* logvecs being pushed */
+	struct list_head	lv_chain;	/* logvecs being pushed */
 	struct list_head	iclog_entry;
 	struct list_head	committing;	/* ctx committing list */
 	struct work_struct	discard_endio_work;
@@ -477,7 +477,7 @@ xlog_write_adv_cnt(void **ptr, int *len, int *off, size_t bytes)
 
 void	xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
 void	xlog_print_trans(struct xfs_trans *);
-int	xlog_write(struct xlog *log, struct xfs_log_vec *log_vector,
+int	xlog_write(struct xlog *log, struct list_head *lv_chain,
 		struct xlog_ticket *tic, xfs_lsn_t *start_lsn,
 		struct xlog_in_core **commit_iclog, uint32_t len);
 int	xlog_commit_record(struct xlog *log, struct xlog_ticket *ticket,

fs/xfs/xfs_trans.c

@@ -735,7 +735,7 @@ xfs_log_item_batch_insert(
 void
 xfs_trans_committed_bulk(
 	struct xfs_ail		*ailp,
-	struct xfs_log_vec	*log_vector,
+	struct list_head	*lv_chain,
 	xfs_lsn_t		commit_lsn,
 	bool			aborted)
 {
@@ -750,7 +750,7 @@ xfs_trans_committed_bulk(
 	spin_unlock(&ailp->ail_lock);
 
 	/* unpin all the log items */
-	for (lv = log_vector; lv; lv = lv->lv_next ) {
+	list_for_each_entry(lv, lv_chain, lv_list) {
 		struct xfs_log_item	*lip = lv->lv_item;
 		xfs_lsn_t		item_lsn;
 

fs/xfs/xfs_trans_priv.h

@@ -18,7 +18,8 @@ void	xfs_trans_add_item(struct xfs_trans *, struct xfs_log_item *);
 void	xfs_trans_del_item(struct xfs_log_item *);
 void	xfs_trans_unreserve_and_mod_sb(struct xfs_trans *tp);
 
-void	xfs_trans_committed_bulk(struct xfs_ail *ailp, struct xfs_log_vec *lv,
+void	xfs_trans_committed_bulk(struct xfs_ail *ailp,
+				struct list_head *lv_chain,
 				xfs_lsn_t commit_lsn, bool aborted);
 /*
  * AIL traversal cursor.