xfs: return log item size in IOP_SIZE

To begin optimising the CIL commit process, we need to have IOP_SIZE
return both the number of vectors and the size of the data pointed
to by the vectors. This enables us to calculate the size ofthe
memory allocation needed before the formatting step and reduces the
number of memory allocations per item by one.

While there, kill the IOP_SIZE macro.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 32 insertions, 20 deletions

diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index bfc4e0c26fd3..9358504e4b68 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -39,6 +39,14 @@ static inline struct xfs_buf_log_item *BUF_ITEM(struct xfs_log_item *lip)
 
 STATIC void	xfs_buf_do_callbacks(struct xfs_buf *bp);
 
+static inline int
+xfs_buf_log_format_size(
+	struct xfs_buf_log_format *blfp)
+{
+	return offsetof(struct xfs_buf_log_format, blf_data_map) +
+			(blfp->blf_map_size * sizeof(blfp->blf_data_map[0]));
+}
+
 /*
  * This returns the number of log iovecs needed to log the
  * given buf log item.
@@ -49,25 +57,27 @@ STATIC void	xfs_buf_do_callbacks(struct xfs_buf *bp);
  *
  * If the XFS_BLI_STALE flag has been set, then log nothing.
  */
-STATIC uint
+STATIC void
 xfs_buf_item_size_segment(
 	struct xfs_buf_log_item	*bip,
-	struct xfs_buf_log_format *blfp)
+	struct xfs_buf_log_format *blfp,
+	int			*nvecs,
+	int			*nbytes)
 {
 	struct xfs_buf		*bp = bip->bli_buf;
-	uint			nvecs;
 	int			next_bit;
 	int			last_bit;
 
 	last_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
 	if (last_bit == -1)
-		return 0;
+		return;
 
 	/*
 	 * initial count for a dirty buffer is 2 vectors - the format structure
 	 * and the first dirty region.
 	 */
-	nvecs = 2;
+	*nvecs += 2;
+	*nbytes += xfs_buf_log_format_size(blfp) + XFS_BLF_CHUNK;
 
 	while (last_bit != -1) {
 		/*
@@ -87,18 +97,17 @@ xfs_buf_item_size_segment(
 			break;
 		} else if (next_bit != last_bit + 1) {
 			last_bit = next_bit;
-			nvecs++;
+			(*nvecs)++;
 		} else if (xfs_buf_offset(bp, next_bit * XFS_BLF_CHUNK) !=
 			   (xfs_buf_offset(bp, last_bit * XFS_BLF_CHUNK) +
 			    XFS_BLF_CHUNK)) {
 			last_bit = next_bit;
-			nvecs++;
+			(*nvecs)++;
 		} else {
 			last_bit++;
 		}
+		*nbytes += XFS_BLF_CHUNK;
 	}
-
-	return nvecs;
 }
 
 /*
@@ -118,12 +127,13 @@ xfs_buf_item_size_segment(
  * If the XFS_BLI_STALE flag has been set, then log nothing but the buf log
  * format structures.
  */
-STATIC uint
+STATIC void
 xfs_buf_item_size(
-	struct xfs_log_item	*lip)
+	struct xfs_log_item	*lip,
+	int			*nvecs,
+	int			*nbytes)
 {
 	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);
-	uint			nvecs;
 	int			i;
 
 	ASSERT(atomic_read(&bip->bli_refcount) > 0);
@@ -135,7 +145,11 @@ xfs_buf_item_size(
 		 */
 		trace_xfs_buf_item_size_stale(bip);
 		ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
-		return bip->bli_format_count;
+		*nvecs += bip->bli_format_count;
+		for (i = 0; i < bip->bli_format_count; i++) {
+			*nbytes += xfs_buf_log_format_size(&bip->bli_formats[i]);
+		}
+		return;
 	}
 
 	ASSERT(bip->bli_flags & XFS_BLI_LOGGED);
@@ -147,7 +161,8 @@ xfs_buf_item_size(
 		 * commit, so no vectors are used at all.
 		 */
 		trace_xfs_buf_item_size_ordered(bip);
-		return XFS_LOG_VEC_ORDERED;
+		*nvecs = XFS_LOG_VEC_ORDERED;
+		return;
 	}
 
 	/*
@@ -159,13 +174,11 @@ xfs_buf_item_size(
 	 * count for the extra buf log format structure that will need to be
 	 * written.
 	 */
-	nvecs = 0;
 	for (i = 0; i < bip->bli_format_count; i++) {
-		nvecs += xfs_buf_item_size_segment(bip, &bip->bli_formats[i]);
+		xfs_buf_item_size_segment(bip, &bip->bli_formats[i],
+					  nvecs, nbytes);
 	}
-
 	trace_xfs_buf_item_size(bip);
-	return nvecs;
 }
 
 static struct xfs_log_iovec *
@@ -192,8 +205,7 @@ xfs_buf_item_format_segment(
 	 * the actual size of the dirty bitmap rather than the size of the in
 	 * memory structure.
 	 */
-	base_size = offsetof(struct xfs_buf_log_format, blf_data_map) +
-			(blfp->blf_map_size * sizeof(blfp->blf_data_map[0]));
+	base_size = xfs_buf_log_format_size(blfp);
 
 	nvecs = 0;
 	first_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);