1 files changed, 19 insertions, 20 deletions

diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index fb69879e4b2b..1cb087b320b1 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -74,14 +74,12 @@ xfs_buf_item_straddle(
 }
 
 /*
- * This returns the number of log iovecs needed to log the
- * given buf log item.
+ * Return the number of log iovecs and space needed to log the given buf log
+ * item segment.
  *
- * It calculates this as 1 iovec for the buf log format structure
- * and 1 for each stretch of non-contiguous chunks to be logged.
- * Contiguous chunks are logged in a single iovec.
- *
- * If the XFS_BLI_STALE flag has been set, then log nothing.
+ * It calculates this as 1 iovec for the buf log format structure and 1 for each
+ * stretch of non-contiguous chunks to be logged.  Contiguous chunks are logged
+ * in a single iovec.
  */
 STATIC void
 xfs_buf_item_size_segment(
@@ -168,11 +166,8 @@ slow_scan:
 }
 
 /*
- * This returns the number of log iovecs needed to log the given buf log item.
- *
- * It calculates this as 1 iovec for the buf log format structure and 1 for each
- * stretch of non-contiguous chunks to be logged.  Contiguous chunks are logged
- * in a single iovec.
+ * Return the number of log iovecs and space needed to log the given buf log
+ * item.
  *
  * Discontiguous buffers need a format structure per region that is being
  * logged. This makes the changes in the buffer appear to log recovery as though
@@ -182,7 +177,11 @@ slow_scan:
  * what ends up on disk.
  *
  * If the XFS_BLI_STALE flag has been set, then log nothing but the buf log
- * format structures.
+ * format structures. If the item has previously been logged and has dirty
+ * regions, we do not relog them in stale buffers. This has the effect of
+ * reducing the size of the relogged item by the amount of dirty data tracked
+ * by the log item. This can result in the committing transaction reducing the
+ * amount of space being consumed by the CIL.
  */
 STATIC void
 xfs_buf_item_size(
@@ -199,9 +198,9 @@ xfs_buf_item_size(
 	ASSERT(atomic_read(&bip->bli_refcount) > 0);
 	if (bip->bli_flags & XFS_BLI_STALE) {
 		/*
-		 * The buffer is stale, so all we need to log
-		 * is the buf log format structure with the
-		 * cancel flag in it.
+		 * The buffer is stale, so all we need to log is the buf log
+		 * format structure with the cancel flag in it as we are never
+		 * going to replay the changes tracked in the log item.
 		 */
 		trace_xfs_buf_item_size_stale(bip);
 		ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
@@ -216,9 +215,9 @@ xfs_buf_item_size(
 
 	if (bip->bli_flags & XFS_BLI_ORDERED) {
 		/*
-		 * The buffer has been logged just to order it.
-		 * It is not being included in the transaction
-		 * commit, so no vectors are used at all.
+		 * The buffer has been logged just to order it. It is not being
+		 * included in the transaction commit, so no vectors are used at
+		 * all.
 		 */
 		trace_xfs_buf_item_size_ordered(bip);
 		*nvecs = XFS_LOG_VEC_ORDERED;
@@ -714,7 +713,7 @@ xfs_buf_item_release(
 STATIC void
 xfs_buf_item_committing(
 	struct xfs_log_item	*lip,
-	xfs_lsn_t		commit_lsn)
+	xfs_csn_t		seq)
 {
 	return xfs_buf_item_release(lip);
 }