[PATCH 10/14] xfs: convert log vector chain to use list heads

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

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        | 11 ++++-----
 fs/xfs/xfs_log.h        |  2 +-
 fs/xfs/xfs_log_cil.c    | 49 +++++++++++++++++++++++------------------
 fs/xfs/xfs_log_priv.h   |  4 ++--
 fs/xfs/xfs_trans.c      |  4 ++--
 fs/xfs/xfs_trans_priv.h |  3 ++-
 6 files changed, 41 insertions(+), 32 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 3af810f41d02..2fa8b0009d63 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -958,6 +958,8 @@ xlog_write_unmount_record(
 		.lv_niovecs = 1,
 		.lv_iovecp = &reg,
 	};
+	LIST_HEAD(lv_chain);
+	list_add(&vec.lv_list, &lv_chain);
 
 	BUILD_BUG_ON((sizeof(struct xlog_op_header) +
 		      sizeof(struct xfs_unmount_log_format)) !=
@@ -966,7 +968,7 @@ xlog_write_unmount_record(
 	/* account for space used by record data */
 	ticket->t_curr_res -= sizeof(unmount_rec);
 
-	return xlog_write(log, NULL, &vec, ticket, reg.i_len);
+	return xlog_write(log, NULL, &lv_chain, ticket, reg.i_len);
 }
 
 /*
@@ -2482,13 +2484,13 @@ int
 xlog_write(
 	struct xlog		*log,
 	struct xfs_cil_ctx	*ctx,
-	struct xfs_log_vec	*log_vector,
+	struct list_head	*lv_chain,
 	struct xlog_ticket	*ticket,
 	uint32_t		len)
 
 {
 	struct xlog_in_core	*iclog = NULL;
-	struct xfs_log_vec	*lv = log_vector;
+	struct xfs_log_vec	*lv;
 	uint32_t		record_cnt = 0;
 	uint32_t		data_cnt = 0;
 	int			error = 0;
@@ -2516,7 +2518,7 @@ xlog_write(
 	if (ctx)
 		xlog_cil_set_ctx_write_state(ctx, iclog);
 
-	while (lv) {
+	list_for_each_entry(lv, lv_chain, 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.
@@ -2537,7 +2539,6 @@ xlog_write(
 			xlog_write_full(lv, ticket, iclog, &log_offset,
 					 &len, &record_cnt, &data_cnt);
 		}
-		lv = lv->lv_next;
 	}
 	ASSERT(len == 0);
 
diff --git a/fs/xfs/xfs_log.h b/fs/xfs/xfs_log.h
index f4b96991870d..31e8a9f15c32 100644
--- a/fs/xfs/xfs_log.h
+++ b/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 */
diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index 0ff1069dd008..aa3a86ca3d25 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/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;
 }
@@ -281,6 +282,7 @@ xlog_cil_alloc_shadow_bufs(
 			lv = kvmalloc(buf_size, GFP_KERNEL);
 			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)
@@ -296,7 +298,6 @@ 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 */
@@ -423,7 +424,6 @@ 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;
@@ -590,14 +590,14 @@ 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;
 	}
 }
 
@@ -697,7 +697,7 @@ 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);
@@ -708,7 +708,7 @@ 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);
@@ -857,7 +857,6 @@ xlog_cil_order_write(
 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;
@@ -866,7 +865,7 @@ 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);
 }
 
 /*
@@ -895,6 +894,8 @@ 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;
@@ -905,7 +906,7 @@ 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)
 		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
 	return error;
@@ -970,7 +971,6 @@ 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;
 }
@@ -1023,7 +1023,7 @@ 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_lsn_t		preflush_tail_lsn;
 	xfs_csn_t		push_seq;
 	struct bio		bio;
@@ -1117,25 +1117,23 @@ 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);
+
 	}
 
 	/*
@@ -1172,9 +1170,12 @@ 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
@@ -1182,7 +1183,13 @@ xlog_cil_push_work(
 	 */
 	wait_for_completion(&bdev_flush);
 
-	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;
 
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 5bb7faea2c4f..f3b665362ac3 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -225,7 +225,7 @@ 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;
@@ -499,7 +499,7 @@ struct xlog_ticket *xlog_ticket_alloc(struct xlog *log, int unit_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_cil_ctx *ctx,
-		struct xfs_log_vec *log_vector, struct xlog_ticket *tic,
+		struct list_head *lv_chain, struct xlog_ticket *tic,
 		uint32_t len);
 void	xfs_log_ticket_ungrant(struct xlog *log, struct xlog_ticket *ticket);
 void	xfs_log_ticket_regrant(struct xlog *log, struct xlog_ticket *ticket);
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 196ee8aeee35..7307f833bfbb 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -732,7 +732,7 @@ 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)
 {
@@ -747,7 +747,7 @@ 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;
 
diff --git a/fs/xfs/xfs_trans_priv.h b/fs/xfs/xfs_trans_priv.h
index 3004aeac9110..fc8667c728e3 100644
--- a/fs/xfs/xfs_trans_priv.h
+++ b/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.
-- 
2.33.0