--- zzzz-none-000/linux-3.10.107/fs/xfs/xfs_log_cil.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/fs/xfs/xfs_log_cil.c	2021-02-04 17:41:59.000000000 +0000
@@ -17,18 +17,19 @@
 
 #include "xfs.h"
 #include "xfs_fs.h"
-#include "xfs_types.h"
-#include "xfs_log.h"
-#include "xfs_trans.h"
-#include "xfs_trans_priv.h"
-#include "xfs_log_priv.h"
-#include "xfs_sb.h"
-#include "xfs_ag.h"
+#include "xfs_format.h"
+#include "xfs_log_format.h"
+#include "xfs_shared.h"
+#include "xfs_trans_resv.h"
 #include "xfs_mount.h"
 #include "xfs_error.h"
 #include "xfs_alloc.h"
 #include "xfs_extent_busy.h"
 #include "xfs_discard.h"
+#include "xfs_trans.h"
+#include "xfs_trans_priv.h"
+#include "xfs_log.h"
+#include "xfs_log_priv.h"
 
 /*
  * Allocate a new ticket. Failing to get a new ticket makes it really hard to
@@ -76,8 +77,53 @@
 {
 	log->l_cilp->xc_ctx->ticket = xlog_cil_ticket_alloc(log);
 	log->l_cilp->xc_ctx->sequence = 1;
-	log->l_cilp->xc_ctx->commit_lsn = xlog_assign_lsn(log->l_curr_cycle,
-								log->l_curr_block);
+}
+
+/*
+ * Prepare the log item for insertion into the CIL. Calculate the difference in
+ * log space and vectors it will consume, and if it is a new item pin it as
+ * well.
+ */
+STATIC void
+xfs_cil_prepare_item(
+	struct xlog		*log,
+	struct xfs_log_vec	*lv,
+	struct xfs_log_vec	*old_lv,
+	int			*diff_len,
+	int			*diff_iovecs)
+{
+	/* Account for the new LV being passed in */
+	if (lv->lv_buf_len != XFS_LOG_VEC_ORDERED) {
+		*diff_len += lv->lv_bytes;
+		*diff_iovecs += lv->lv_niovecs;
+	}
+
+	/*
+	 * If there is no old LV, this is the first time we've seen the item in
+	 * this CIL context and so we need to pin it. If we are replacing the
+	 * old_lv, then remove the space it accounts for and free it.
+	 */
+	if (!old_lv)
+		lv->lv_item->li_ops->iop_pin(lv->lv_item);
+	else if (old_lv != lv) {
+		ASSERT(lv->lv_buf_len != XFS_LOG_VEC_ORDERED);
+
+		*diff_len -= old_lv->lv_bytes;
+		*diff_iovecs -= old_lv->lv_niovecs;
+		kmem_free(old_lv);
+	}
+
+	/* attach new log vector to log item */
+	lv->lv_item->li_lv = lv;
+
+	/*
+	 * If this is the first time the item is being committed to the
+	 * CIL, store the sequence number on the log item so we can
+	 * tell in future commits whether this is the first checkpoint
+	 * the item is being committed into.
+	 */
+	if (!lv->lv_item->li_seq)
+		lv->lv_item->li_seq = log->l_cilp->xc_ctx->sequence;
 }
 
 /*
@@ -106,120 +152,119 @@
  * format the regions into the iclog as though they are being formatted
  * directly out of the objects themselves.
  */
-static struct xfs_log_vec *
-xlog_cil_prepare_log_vecs(
-	struct xfs_trans	*tp)
+static void
+xlog_cil_insert_format_items(
+	struct xlog		*log,
+	struct xfs_trans	*tp,
+	int			*diff_len,
+	int			*diff_iovecs)
 {
 	struct xfs_log_item_desc *lidp;
-	struct xfs_log_vec	*lv = NULL;
-	struct xfs_log_vec	*ret_lv = NULL;
 
 
 	/* Bail out if we didn't find a log item.  */
 	if (list_empty(&tp->t_items)) {
 		ASSERT(0);
-		return NULL;
+		return;
 	}
 
 	list_for_each_entry(lidp, &tp->t_items, lid_trans) {
-		struct xfs_log_vec *new_lv;
-		void	*ptr;
-		int	index;
-		int	len = 0;
-		uint	niovecs;
+		struct xfs_log_item *lip = lidp->lid_item;
+		struct xfs_log_vec *lv;
+		struct xfs_log_vec *old_lv;
+		int	niovecs = 0;
+		int	nbytes = 0;
+		int	buf_size;
+		bool	ordered = false;
 
 		/* Skip items which aren't dirty in this transaction. */
 		if (!(lidp->lid_flags & XFS_LID_DIRTY))
 			continue;
 
+		/* get number of vecs and size of data to be stored */
+		lip->li_ops->iop_size(lip, &niovecs, &nbytes);
+
 		/* Skip items that do not have any vectors for writing */
-		niovecs = IOP_SIZE(lidp->lid_item);
 		if (!niovecs)
 			continue;
 
-		new_lv = kmem_zalloc(sizeof(*new_lv) +
-				niovecs * sizeof(struct xfs_log_iovec),
-				KM_SLEEP|KM_NOFS);
-
-		/* The allocated iovec region lies beyond the log vector. */
-		new_lv->lv_iovecp = (struct xfs_log_iovec *)&new_lv[1];
-		new_lv->lv_niovecs = niovecs;
-		new_lv->lv_item = lidp->lid_item;
-
-		/* build the vector array and calculate it's length */
-		IOP_FORMAT(new_lv->lv_item, new_lv->lv_iovecp);
-		for (index = 0; index < new_lv->lv_niovecs; index++)
-			len += new_lv->lv_iovecp[index].i_len;
-
-		new_lv->lv_buf_len = len;
-		new_lv->lv_buf = kmem_alloc(new_lv->lv_buf_len,
-				KM_SLEEP|KM_NOFS);
-		ptr = new_lv->lv_buf;
-
-		for (index = 0; index < new_lv->lv_niovecs; index++) {
-			struct xfs_log_iovec *vec = &new_lv->lv_iovecp[index];
-
-			memcpy(ptr, vec->i_addr, vec->i_len);
-			vec->i_addr = ptr;
-			ptr += vec->i_len;
+		/*
+		 * Ordered items need to be tracked but we do not wish to write
+		 * them. We need a logvec to track the object, but we do not
+		 * need an iovec or buffer to be allocated for copying data.
+		 */
+		if (niovecs == XFS_LOG_VEC_ORDERED) {
+			ordered = true;
+			niovecs = 0;
+			nbytes = 0;
 		}
-		ASSERT(ptr == new_lv->lv_buf + new_lv->lv_buf_len);
-
-		if (!ret_lv)
-			ret_lv = new_lv;
-		else
-			lv->lv_next = new_lv;
-		lv = new_lv;
-	}
 
-	return ret_lv;
-}
+		/*
+		 * We 64-bit align the length of each iovec so that the start
+		 * of the next one is naturally aligned.  We'll need to
+		 * account for that slack space here. Then round nbytes up
+		 * to 64-bit alignment so that the initial buffer alignment is
+		 * easy to calculate and verify.
+		 */
+		nbytes += niovecs * sizeof(uint64_t);
+		nbytes = round_up(nbytes, sizeof(uint64_t));
 
-/*
- * Prepare the log item for insertion into the CIL. Calculate the difference in
- * log space and vectors it will consume, and if it is a new item pin it as
- * well.
- */
-STATIC void
-xfs_cil_prepare_item(
-	struct xlog		*log,
-	struct xfs_log_vec	*lv,
-	int			*len,
-	int			*diff_iovecs)
-{
-	struct xfs_log_vec	*old = lv->lv_item->li_lv;
+		/* grab the old item if it exists for reservation accounting */
+		old_lv = lip->li_lv;
 
-	if (old) {
-		/* existing lv on log item, space used is a delta */
-		ASSERT(!list_empty(&lv->lv_item->li_cil));
-		ASSERT(old->lv_buf && old->lv_buf_len && old->lv_niovecs);
-
-		*len += lv->lv_buf_len - old->lv_buf_len;
-		*diff_iovecs += lv->lv_niovecs - old->lv_niovecs;
-		kmem_free(old->lv_buf);
-		kmem_free(old);
-	} else {
-		/* new lv, must pin the log item */
-		ASSERT(!lv->lv_item->li_lv);
-		ASSERT(list_empty(&lv->lv_item->li_cil));
+		/*
+		 * The data buffer needs to start 64-bit aligned, so round up
+		 * that space to ensure we can align it appropriately and not
+		 * overrun the buffer.
+		 */
+		buf_size = nbytes +
+			   round_up((sizeof(struct xfs_log_vec) +
+				     niovecs * sizeof(struct xfs_log_iovec)),
+				    sizeof(uint64_t));
+
+		/* compare to existing item size */
+		if (lip->li_lv && buf_size <= lip->li_lv->lv_size) {
+			/* same or smaller, optimise common overwrite case */
+			lv = lip->li_lv;
+			lv->lv_next = NULL;
 
-		*len += lv->lv_buf_len;
-		*diff_iovecs += lv->lv_niovecs;
-		IOP_PIN(lv->lv_item);
+			if (ordered)
+				goto insert;
 
-	}
+			/*
+			 * set the item up as though it is a new insertion so
+			 * that the space reservation accounting is correct.
+			 */
+			*diff_iovecs -= lv->lv_niovecs;
+			*diff_len -= lv->lv_bytes;
+		} else {
+			/* allocate new data chunk */
+			lv = kmem_zalloc(buf_size, KM_SLEEP|KM_NOFS);
+			lv->lv_item = lip;
+			lv->lv_size = buf_size;
+			if (ordered) {
+				/* track as an ordered logvec */
+				ASSERT(lip->li_lv == NULL);
+				lv->lv_buf_len = XFS_LOG_VEC_ORDERED;
+				goto insert;
+			}
+			lv->lv_iovecp = (struct xfs_log_iovec *)&lv[1];
+		}
 
-	/* attach new log vector to log item */
-	lv->lv_item->li_lv = lv;
+		/* Ensure the lv is set up according to ->iop_size */
+		lv->lv_niovecs = niovecs;
 
-	/*
-	 * If this is the first time the item is being committed to the
-	 * CIL, store the sequence number on the log item so we can
-	 * tell in future commits whether this is the first checkpoint
-	 * the item is being committed into.
-	 */
-	if (!lv->lv_item->li_seq)
-		lv->lv_item->li_seq = log->l_cilp->xc_ctx->sequence;
+		/* The allocated data region lies beyond the iovec region */
+		lv->lv_buf_len = 0;
+		lv->lv_bytes = 0;
+		lv->lv_buf = (char *)lv + buf_size - nbytes;
+		ASSERT(IS_ALIGNED((unsigned long)lv->lv_buf, sizeof(uint64_t)));
+
+		lip->li_ops->iop_format(lip, lv);
+insert:
+		ASSERT(lv->lv_buf_len <= nbytes);
+		xfs_cil_prepare_item(log, lv, old_lv, diff_len, diff_iovecs);
+	}
 }
 
 /*
@@ -232,47 +277,53 @@
 static void
 xlog_cil_insert_items(
 	struct xlog		*log,
-	struct xfs_log_vec	*log_vector,
-	struct xlog_ticket	*ticket)
+	struct xfs_trans	*tp)
 {
 	struct xfs_cil		*cil = log->l_cilp;
 	struct xfs_cil_ctx	*ctx = cil->xc_ctx;
-	struct xfs_log_vec	*lv;
+	struct xfs_log_item_desc *lidp;
 	int			len = 0;
 	int			diff_iovecs = 0;
 	int			iclog_space;
 
-	ASSERT(log_vector);
+	ASSERT(tp);
 
 	/*
-	 * Do all the accounting aggregation and switching of log vectors
-	 * around in a separate loop to the insertion of items into the CIL.
-	 * Then we can do a separate loop to update the CIL within a single
-	 * lock/unlock pair. This reduces the number of round trips on the CIL
-	 * lock from O(nr_logvectors) to O(1) and greatly reduces the overall
-	 * hold time for the transaction commit.
-	 *
-	 * If this is the first time the item is being placed into the CIL in
-	 * this context, pin it so it can't be written to disk until the CIL is
-	 * flushed to the iclog and the iclog written to disk.
-	 *
 	 * We can do this safely because the context can't checkpoint until we
 	 * are done so it doesn't matter exactly how we update the CIL.
 	 */
-	for (lv = log_vector; lv; lv = lv->lv_next)
-		xfs_cil_prepare_item(log, lv, &len, &diff_iovecs);
-
-	/* account for space used by new iovec headers  */
-	len += diff_iovecs * sizeof(xlog_op_header_t);
+	xlog_cil_insert_format_items(log, tp, &len, &diff_iovecs);
 
+	/*
+	 * Now (re-)position everything modified at the tail of the CIL.
+	 * We do this here so we only need to take the CIL lock once during
+	 * the transaction commit.
+	 */
 	spin_lock(&cil->xc_cil_lock);
+	list_for_each_entry(lidp, &tp->t_items, lid_trans) {
+		struct xfs_log_item	*lip = lidp->lid_item;
+
+		/* Skip items which aren't dirty in this transaction. */
+		if (!(lidp->lid_flags & XFS_LID_DIRTY))
+			continue;
 
-	/* move the items to the tail of the CIL */
-	for (lv = log_vector; lv; lv = lv->lv_next)
-		list_move_tail(&lv->lv_item->li_cil, &cil->xc_cil);
+		/*
+		 * Only move the item if it isn't already at the tail. This is
+		 * to prevent a transient list_empty() state when reinserting
+		 * an item that is already the only item in the CIL.
+		 */
+		if (!list_is_last(&lip->li_cil, &cil->xc_cil))
+			list_move_tail(&lip->li_cil, &cil->xc_cil);
+	}
 
+	/* account for space used by new iovec headers  */
+	len += diff_iovecs * sizeof(xlog_op_header_t);
 	ctx->nvecs += diff_iovecs;
 
+	/* attach the transaction to the CIL if it has any busy extents */
+	if (!list_empty(&tp->t_busy))
+		list_splice_init(&tp->t_busy, &ctx->busy_extents);
+
 	/*
 	 * Now transfer enough transaction reservation to the context ticket
 	 * for the checkpoint. The context ticket is special - the unit
@@ -281,10 +332,8 @@
 	 * during the transaction commit.
 	 */
 	if (ctx->ticket->t_curr_res == 0) {
-		/* first commit in checkpoint, steal the header reservation */
-		ASSERT(ticket->t_curr_res >= ctx->ticket->t_unit_res + len);
 		ctx->ticket->t_curr_res = ctx->ticket->t_unit_res;
-		ticket->t_curr_res -= ctx->ticket->t_unit_res;
+		tp->t_ticket->t_curr_res -= ctx->ticket->t_unit_res;
 	}
 
 	/* do we need space for more log record headers? */
@@ -298,10 +347,10 @@
 		hdrs *= log->l_iclog_hsize + sizeof(struct xlog_op_header);
 		ctx->ticket->t_unit_res += hdrs;
 		ctx->ticket->t_curr_res += hdrs;
-		ticket->t_curr_res -= hdrs;
-		ASSERT(ticket->t_curr_res >= len);
+		tp->t_ticket->t_curr_res -= hdrs;
+		ASSERT(tp->t_ticket->t_curr_res >= len);
 	}
-	ticket->t_curr_res -= len;
+	tp->t_ticket->t_curr_res -= len;
 	ctx->space_used += len;
 
 	spin_unlock(&cil->xc_cil_lock);
@@ -315,7 +364,6 @@
 
 	for (lv = log_vector; lv; ) {
 		struct xfs_log_vec *next = lv->lv_next;
-		kmem_free(lv->lv_buf);
 		kmem_free(lv);
 		lv = next;
 	}
@@ -341,9 +389,17 @@
 	xfs_extent_busy_clear(mp, &ctx->busy_extents,
 			     (mp->m_flags & XFS_MOUNT_DISCARD) && !abort);
 
-	spin_lock(&ctx->cil->xc_cil_lock);
+	/*
+	 * If we are aborting the commit, wake up anyone waiting on the
+	 * committing list.  If we don't, then a shutdown we can leave processes
+	 * waiting in xlog_cil_force_lsn() waiting on a sequence commit that
+	 * will never happen because we aborted it.
+	 */
+	spin_lock(&ctx->cil->xc_push_lock);
+	if (abort)
+		wake_up_all(&ctx->cil->xc_commit_wait);
 	list_del(&ctx->committing);
-	spin_unlock(&ctx->cil->xc_cil_lock);
+	spin_unlock(&ctx->cil->xc_push_lock);
 
 	xlog_cil_free_logvec(ctx->lv_chain);
 
@@ -381,9 +437,7 @@
 	struct xfs_cil_ctx	*new_ctx;
 	struct xlog_in_core	*commit_iclog;
 	struct xlog_ticket	*tic;
-	int			num_lv;
 	int			num_iovecs;
-	int			len;
 	int			error = 0;
 	struct xfs_trans_header thdr;
 	struct xfs_log_iovec	lhdr;
@@ -400,7 +454,7 @@
 	down_write(&cil->xc_ctx_lock);
 	ctx = cil->xc_ctx;
 
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	push_seq = cil->xc_push_seq;
 	ASSERT(push_seq <= ctx->sequence);
 
@@ -411,15 +465,43 @@
 	 */
 	if (list_empty(&cil->xc_cil)) {
 		cil->xc_push_seq = 0;
-		spin_unlock(&cil->xc_cil_lock);
+		spin_unlock(&cil->xc_push_lock);
 		goto out_skip;
 	}
-	spin_unlock(&cil->xc_cil_lock);
 
 
 	/* check for a previously pushed seqeunce */
-	if (push_seq < cil->xc_ctx->sequence)
+	if (push_seq < cil->xc_ctx->sequence) {
+		spin_unlock(&cil->xc_push_lock);
 		goto out_skip;
+	}
+
+	/*
+	 * We are now going to push this context, so add it to the committing
+	 * list before we do anything else. This ensures that anyone waiting on
+	 * this push can easily detect the difference between a "push in
+	 * progress" and "CIL is empty, nothing to do".
+	 *
+	 * IOWs, a wait loop can now check for:
+	 *	the current sequence not being found on the committing list;
+	 *	an empty CIL; and
+	 *	an unchanged sequence number
+	 * to detect a push that had nothing to do and therefore does not need
+	 * waiting on. If the CIL is not empty, we get put on the committing
+	 * list before emptying the CIL and bumping the sequence number. Hence
+	 * an empty CIL and an unchanged sequence number means we jumped out
+	 * above after doing nothing.
+	 *
+	 * Hence the waiter will either find the commit sequence on the
+	 * committing list or the sequence number will be unchanged and the CIL
+	 * still dirty. In that latter case, the push has not yet started, and
+	 * so the waiter will have to continue trying to check the CIL
+	 * committing list until it is found. In extreme cases of delay, the
+	 * sequence may fully commit between the attempts the wait makes to wait
+	 * on the commit sequence.
+	 */
+	list_add(&ctx->committing, &cil->xc_committing);
+	spin_unlock(&cil->xc_push_lock);
 
 	/*
 	 * pull all the log vectors off the items in the CIL, and
@@ -428,12 +510,9 @@
 	 * side which is currently locked out by the flush lock.
 	 */
 	lv = NULL;
-	num_lv = 0;
 	num_iovecs = 0;
-	len = 0;
 	while (!list_empty(&cil->xc_cil)) {
 		struct xfs_log_item	*item;
-		int			i;
 
 		item = list_first_entry(&cil->xc_cil,
 					struct xfs_log_item, li_cil);
@@ -444,11 +523,7 @@
 			lv->lv_next = item->li_lv;
 		lv = item->li_lv;
 		item->li_lv = NULL;
-
-		num_lv++;
 		num_iovecs += lv->lv_niovecs;
-		for (i = 0; i < lv->lv_niovecs; i++)
-			len += lv->lv_iovecp[i].i_len;
 	}
 
 	/*
@@ -464,13 +539,6 @@
 	cil->xc_ctx = new_ctx;
 
 	/*
-	 * mirror the new sequence into the cil structure so that we can do
-	 * unlocked checks against the current sequence in log forces without
-	 * risking deferencing a freed context pointer.
-	 */
-	cil->xc_current_sequence = new_ctx->sequence;
-
-	/*
 	 * The switch is now done, so we can drop the context lock and move out
 	 * of a shared context. We can't just go straight to the commit record,
 	 * though - we need to synchronise with previous and future commits so
@@ -488,10 +556,16 @@
 	 * Hence we need to add this context to the committing context list so
 	 * that higher sequences will wait for us to write out a commit record
 	 * before they do.
+	 *
+	 * xfs_log_force_lsn requires us to mirror the new sequence into the cil
+	 * structure atomically with the addition of this sequence to the
+	 * committing list. This also ensures that we can do unlocked checks
+	 * against the current sequence in log forces without risking
+	 * deferencing a freed context pointer.
 	 */
-	spin_lock(&cil->xc_cil_lock);
-	list_add(&ctx->committing, &cil->xc_committing);
-	spin_unlock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
+	cil->xc_current_sequence = new_ctx->sequence;
+	spin_unlock(&cil->xc_push_lock);
 	up_write(&cil->xc_ctx_lock);
 
 	/*
@@ -526,11 +600,21 @@
 	 * order the commit records so replay will get them in the right order.
 	 */
 restart:
-	spin_lock(&cil->xc_cil_lock);
+	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 own own sequence, either.
+		 * Don't wait for our own sequence, either.
 		 */
 		if (new_ctx->sequence >= ctx->sequence)
 			continue;
@@ -539,14 +623,14 @@
 			 * 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_cil_lock);
+			xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
 			goto restart;
 		}
 	}
-	spin_unlock(&cil->xc_cil_lock);
+	spin_unlock(&cil->xc_push_lock);
 
 	/* xfs_log_done always frees the ticket on error. */
-	commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, 0);
+	commit_lsn = xfs_log_done(log->l_mp, tic, &commit_iclog, false);
 	if (commit_lsn == -1)
 		goto out_abort;
 
@@ -562,10 +646,10 @@
 	 * callbacks to the iclog we can assign the commit LSN to the context
 	 * and wake up anyone who is waiting for the commit to complete.
 	 */
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	ctx->commit_lsn = commit_lsn;
 	wake_up_all(&cil->xc_commit_wait);
-	spin_unlock(&cil->xc_cil_lock);
+	spin_unlock(&cil->xc_push_lock);
 
 	/* release the hounds! */
 	return xfs_log_release_iclog(log->l_mp, commit_iclog);
@@ -580,7 +664,7 @@
 	xfs_log_ticket_put(tic);
 out_abort:
 	xlog_cil_committed(ctx, XFS_LI_ABORTED);
-	return XFS_ERROR(EIO);
+	return -EIO;
 }
 
 static void
@@ -618,17 +702,23 @@
 	if (cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
 		return;
 
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	if (cil->xc_push_seq < cil->xc_current_sequence) {
 		cil->xc_push_seq = cil->xc_current_sequence;
 		queue_work(log->l_mp->m_cil_workqueue, &cil->xc_push_work);
 	}
-	spin_unlock(&cil->xc_cil_lock);
+	spin_unlock(&cil->xc_push_lock);
 
 }
 
+/*
+ * xlog_cil_push_now() is used to trigger an immediate CIL push to the sequence
+ * number that is passed. When it returns, the work will be queued for
+ * @push_seq, but it won't be completed. The caller is expected to do any
+ * waiting for push_seq to complete if it is required.
+ */
 static void
-xlog_cil_push_foreground(
+xlog_cil_push_now(
 	struct xlog	*log,
 	xfs_lsn_t	push_seq)
 {
@@ -646,17 +736,29 @@
 	 * If the CIL is empty or we've already pushed the sequence then
 	 * there's no work we need to do.
 	 */
-	spin_lock(&cil->xc_cil_lock);
+	spin_lock(&cil->xc_push_lock);
 	if (list_empty(&cil->xc_cil) || push_seq <= cil->xc_push_seq) {
-		spin_unlock(&cil->xc_cil_lock);
+		spin_unlock(&cil->xc_push_lock);
 		return;
 	}
 
 	cil->xc_push_seq = push_seq;
-	spin_unlock(&cil->xc_cil_lock);
+	queue_work(log->l_mp->m_cil_workqueue, &cil->xc_push_work);
+	spin_unlock(&cil->xc_push_lock);
+}
+
+bool
+xlog_cil_empty(
+	struct xlog	*log)
+{
+	struct xfs_cil	*cil = log->l_cilp;
+	bool		empty = false;
 
-	/* do the push now */
-	xlog_cil_push(log);
+	spin_lock(&cil->xc_push_lock);
+	if (list_empty(&cil->xc_cil))
+		empty = true;
+	spin_unlock(&cil->xc_push_lock);
+	return empty;
 }
 
 /*
@@ -672,51 +774,30 @@
  * background commit, returns without it held once background commits are
  * allowed again.
  */
-int
+void
 xfs_log_commit_cil(
 	struct xfs_mount	*mp,
 	struct xfs_trans	*tp,
 	xfs_lsn_t		*commit_lsn,
-	int			flags)
+	bool			regrant)
 {
 	struct xlog		*log = mp->m_log;
-	int			log_flags = 0;
-	struct xfs_log_vec	*log_vector;
-
-	if (flags & XFS_TRANS_RELEASE_LOG_RES)
-		log_flags = XFS_LOG_REL_PERM_RESERV;
-
-	/*
-	 * Do all the hard work of formatting items (including memory
-	 * allocation) outside the CIL context lock. This prevents stalling CIL
-	 * pushes when we are low on memory and a transaction commit spends a
-	 * lot of time in memory reclaim.
-	 */
-	log_vector = xlog_cil_prepare_log_vecs(tp);
-	if (!log_vector)
-		return ENOMEM;
+	struct xfs_cil		*cil = log->l_cilp;
 
 	/* lock out background commit */
-	down_read(&log->l_cilp->xc_ctx_lock);
-	if (commit_lsn)
-		*commit_lsn = log->l_cilp->xc_ctx->sequence;
+	down_read(&cil->xc_ctx_lock);
 
-	xlog_cil_insert_items(log, log_vector, tp->t_ticket);
+	xlog_cil_insert_items(log, tp);
 
 	/* check we didn't blow the reservation */
 	if (tp->t_ticket->t_curr_res < 0)
-		xlog_print_tic_res(log->l_mp, tp->t_ticket);
+		xlog_print_tic_res(mp, tp->t_ticket);
 
-	/* attach the transaction to the CIL if it has any busy extents */
-	if (!list_empty(&tp->t_busy)) {
-		spin_lock(&log->l_cilp->xc_cil_lock);
-		list_splice_init(&tp->t_busy,
-					&log->l_cilp->xc_ctx->busy_extents);
-		spin_unlock(&log->l_cilp->xc_cil_lock);
-	}
+	tp->t_commit_lsn = cil->xc_ctx->sequence;
+	if (commit_lsn)
+		*commit_lsn = tp->t_commit_lsn;
 
-	tp->t_commit_lsn = *commit_lsn;
-	xfs_log_done(mp, tp->t_ticket, NULL, log_flags);
+	xfs_log_done(mp, tp->t_ticket, NULL, regrant);
 	xfs_trans_unreserve_and_mod_sb(tp);
 
 	/*
@@ -730,12 +811,11 @@
 	 * the log items. This affects (at least) processing of stale buffers,
 	 * inodes and EFIs.
 	 */
-	xfs_trans_free_items(tp, *commit_lsn, 0);
+	xfs_trans_free_items(tp, tp->t_commit_lsn, false);
 
 	xlog_cil_push_background(log);
 
-	up_read(&log->l_cilp->xc_ctx_lock);
-	return 0;
+	up_read(&cil->xc_ctx_lock);
 }
 
 /*
@@ -764,7 +844,8 @@
 	 * xlog_cil_push() handles racing pushes for the same sequence,
 	 * so no need to deal with it here.
 	 */
-	xlog_cil_push_foreground(log, sequence);
+restart:
+	xlog_cil_push_now(log, sequence);
 
 	/*
 	 * See if we can find a previous sequence still committing.
@@ -772,9 +853,15 @@
 	 * before allowing the force of push_seq to go ahead. Hence block
 	 * on commits for those as well.
 	 */
-restart:
-	spin_lock(&cil->xc_cil_lock);
+	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(log))
+			goto out_shutdown;
 		if (ctx->sequence > sequence)
 			continue;
 		if (!ctx->commit_lsn) {
@@ -782,7 +869,7 @@
 			 * 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_cil_lock);
+			xlog_wait(&cil->xc_commit_wait, &cil->xc_push_lock);
 			goto restart;
 		}
 		if (ctx->sequence != sequence)
@@ -790,8 +877,41 @@
 		/* found it! */
 		commit_lsn = ctx->commit_lsn;
 	}
-	spin_unlock(&cil->xc_cil_lock);
+
+	/*
+	 * The call to xlog_cil_push_now() executes the push in the background.
+	 * Hence by the time we have got here it our sequence may not have been
+	 * pushed yet. This is true if the current sequence still matches the
+	 * push sequence after the above wait loop and the CIL still contains
+	 * dirty objects. This is guaranteed by the push code first adding the
+	 * context to the committing list before emptying the CIL.
+	 *
+	 * Hence if we don't find the context in the committing list and the
+	 * current sequence number is unchanged then the CIL contents are
+	 * significant.  If the CIL is empty, if means there was nothing to push
+	 * and that means there is nothing to wait for. If the CIL is not empty,
+	 * it means we haven't yet started the push, because if it had started
+	 * we would have found the context on the committing list.
+	 */
+	if (sequence == cil->xc_current_sequence &&
+	    !list_empty(&cil->xc_cil)) {
+		spin_unlock(&cil->xc_push_lock);
+		goto restart;
+	}
+
+	spin_unlock(&cil->xc_push_lock);
 	return commit_lsn;
+
+	/*
+	 * We detected a shutdown in progress. We need to trigger the log force
+	 * to pass through it's iclog state machine error handling, even though
+	 * we are already in a shutdown state. Hence we can't return
+	 * NULLCOMMITLSN here as that has special meaning to log forces (i.e.
+	 * LSN is already stable), so we return a zero LSN instead.
+	 */
+out_shutdown:
+	spin_unlock(&cil->xc_push_lock);
+	return 0;
 }
 
 /*
@@ -836,18 +956,19 @@
 
 	cil = kmem_zalloc(sizeof(*cil), KM_SLEEP|KM_MAYFAIL);
 	if (!cil)
-		return ENOMEM;
+		return -ENOMEM;
 
 	ctx = kmem_zalloc(sizeof(*ctx), KM_SLEEP|KM_MAYFAIL);
 	if (!ctx) {
 		kmem_free(cil);
-		return ENOMEM;
+		return -ENOMEM;
 	}
 
 	INIT_WORK(&cil->xc_push_work, xlog_cil_push_work);
 	INIT_LIST_HEAD(&cil->xc_cil);
 	INIT_LIST_HEAD(&cil->xc_committing);
 	spin_lock_init(&cil->xc_cil_lock);
+	spin_lock_init(&cil->xc_push_lock);
 	init_rwsem(&cil->xc_ctx_lock);
 	init_waitqueue_head(&cil->xc_commit_wait);