xfs: simplify buffer to transaction matching

We currenly have a routine xfs_trans_buf_item_match_all which checks
if any log item in a transaction contains a given buffer, and a
second one that only does this check for the first, embedded chunk
of log items.  We only use the second routine if we know we only
have that log item chunk, so get rid of the limited routine and
always use the more complete one.

Also rename the old xfs_trans_buf_item_match_all to
xfs_trans_buf_item_match and update various surrounding comments,
and move the remaining xfs_trans_buf_item_match on top of the file
to avoid a forward prototype.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

fs/xfs/xfs_trans_buf.c

@@ -40,11 +40,51 @@
 #include "xfs_rw.h"
 #include "xfs_trace.h"
 
+/*
+ * Check to see if a buffer matching the given parameters is already
+ * a part of the given transaction.
+ */
+STATIC struct xfs_buf *
+xfs_trans_buf_item_match(
+	struct xfs_trans	*tp,
+	struct xfs_buftarg	*target,
+	xfs_daddr_t		blkno,
+	int			len)
+{
+	xfs_log_item_chunk_t	*licp;
+	xfs_log_item_desc_t	*lidp;
+	xfs_buf_log_item_t	*blip;
+	int			i;
 
-STATIC xfs_buf_t *xfs_trans_buf_item_match(xfs_trans_t *, xfs_buftarg_t *,
-		xfs_daddr_t, int);
-STATIC xfs_buf_t *xfs_trans_buf_item_match_all(xfs_trans_t *, xfs_buftarg_t *,
-		xfs_daddr_t, int);
+	len = BBTOB(len);
+	for (licp = &tp->t_items; licp != NULL; licp = licp->lic_next) {
+		if (xfs_lic_are_all_free(licp)) {
+			ASSERT(licp == &tp->t_items);
+			ASSERT(licp->lic_next == NULL);
+			return NULL;
+		}
+
+		for (i = 0; i < licp->lic_unused; i++) {
+			/*
+			 * Skip unoccupied slots.
+			 */
+			if (xfs_lic_isfree(licp, i))
+				continue;
+
+			lidp = xfs_lic_slot(licp, i);
+			blip = (xfs_buf_log_item_t *)lidp->lid_item;
+			if (blip->bli_item.li_type != XFS_LI_BUF)
+				continue;
+
+			if (XFS_BUF_TARGET(blip->bli_buf) == target &&
+			    XFS_BUF_ADDR(blip->bli_buf) == blkno &&
+			    XFS_BUF_COUNT(blip->bli_buf) == len)
+				return blip->bli_buf;
+		}
+	}
+
+	return NULL;
+}
 
 /*
  * Add the locked buffer to the transaction.
@@ -112,14 +152,6 @@ xfs_trans_bjoin(
  * within the transaction, just increment its lock recursion count
  * and return a pointer to it.
  *
- * Use the fast path function xfs_trans_buf_item_match() or the buffer
- * cache routine incore_match() to find the buffer
- * if it is already owned by this transaction.
- *
- * If we don't already own the buffer, use get_buf() to get it.
- * If it doesn't yet have an associated xfs_buf_log_item structure,
- * then allocate one and add the item to this transaction.
- *
  * If the transaction pointer is NULL, make this just a normal
  * get_buf() call.
  */
@@ -149,11 +181,7 @@ xfs_trans_get_buf(xfs_trans_t	*tp,
 	 * have it locked.  In this case we just increment the lock
 	 * recursion count and return the buffer to the caller.
 	 */
-	if (tp->t_items.lic_next == NULL) {
-		bp = xfs_trans_buf_item_match(tp, target_dev, blkno, len);
-	} else {
-		bp  = xfs_trans_buf_item_match_all(tp, target_dev, blkno, len);
-	}
+	bp = xfs_trans_buf_item_match(tp, target_dev, blkno, len);
 	if (bp != NULL) {
 		ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
 		if (XFS_FORCED_SHUTDOWN(tp->t_mountp))
@@ -259,14 +287,6 @@ int	xfs_error_mod = 33;
  * within the transaction and already read in, just increment its
  * lock recursion count and return a pointer to it.
  *
- * Use the fast path function xfs_trans_buf_item_match() or the buffer
- * cache routine incore_match() to find the buffer
- * if it is already owned by this transaction.
- *
- * If we don't already own the buffer, use read_buf() to get it.
- * If it doesn't yet have an associated xfs_buf_log_item structure,
- * then allocate one and add the item to this transaction.
- *
  * If the transaction pointer is NULL, make this just a normal
  * read_buf() call.
  */
@@ -328,11 +348,7 @@ xfs_trans_read_buf(
 	 * If the buffer is not yet read in, then we read it in, increment
 	 * the lock recursion count, and return it to the caller.
 	 */
-	if (tp->t_items.lic_next == NULL) {
-		bp = xfs_trans_buf_item_match(tp, target, blkno, len);
-	} else {
-		bp = xfs_trans_buf_item_match_all(tp, target, blkno, len);
-	}
+	bp = xfs_trans_buf_item_match(tp, target, blkno, len);
 	if (bp != NULL) {
 		ASSERT(XFS_BUF_VALUSEMA(bp) <= 0);
 		ASSERT(XFS_BUF_FSPRIVATE2(bp, xfs_trans_t *) == tp);
@@ -901,111 +917,3 @@ xfs_trans_dquot_buf(
 
 	bip->bli_format.blf_flags |= type;
 }
-
-/*
- * Check to see if a buffer matching the given parameters is already
- * a part of the given transaction.  Only check the first, embedded
- * chunk, since we don't want to spend all day scanning large transactions.
- */
-STATIC xfs_buf_t *
-xfs_trans_buf_item_match(
-	xfs_trans_t	*tp,
-	xfs_buftarg_t	*target,
-	xfs_daddr_t	blkno,
-	int		len)
-{
-	xfs_log_item_chunk_t	*licp;
-	xfs_log_item_desc_t	*lidp;
-	xfs_buf_log_item_t	*blip;
-	xfs_buf_t		*bp;
-	int			i;
-
-	bp = NULL;
-	len = BBTOB(len);
-	licp = &tp->t_items;
-	if (!xfs_lic_are_all_free(licp)) {
-		for (i = 0; i < licp->lic_unused; i++) {
-			/*
-			 * Skip unoccupied slots.
-			 */
-			if (xfs_lic_isfree(licp, i)) {
-				continue;
-			}
-
-			lidp = xfs_lic_slot(licp, i);
-			blip = (xfs_buf_log_item_t *)lidp->lid_item;
-			if (blip->bli_item.li_type != XFS_LI_BUF) {
-				continue;
-			}
-
-			bp = blip->bli_buf;
-			if ((XFS_BUF_TARGET(bp) == target) &&
-			    (XFS_BUF_ADDR(bp) == blkno) &&
-			    (XFS_BUF_COUNT(bp) == len)) {
-				/*
-				 * We found it.  Break out and
-				 * return the pointer to the buffer.
-				 */
-				break;
-			} else {
-				bp = NULL;
-			}
-		}
-	}
-	return bp;
-}
-
-/*
- * Check to see if a buffer matching the given parameters is already
- * a part of the given transaction.  Check all the chunks, we
- * want to be thorough.
- */
-STATIC xfs_buf_t *
-xfs_trans_buf_item_match_all(
-	xfs_trans_t	*tp,
-	xfs_buftarg_t	*target,
-	xfs_daddr_t	blkno,
-	int		len)
-{
-	xfs_log_item_chunk_t	*licp;
-	xfs_log_item_desc_t	*lidp;
-	xfs_buf_log_item_t	*blip;
-	xfs_buf_t		*bp;
-	int			i;
-
-	bp = NULL;
-	len = BBTOB(len);
-	for (licp = &tp->t_items; licp != NULL; licp = licp->lic_next) {
-		if (xfs_lic_are_all_free(licp)) {
-			ASSERT(licp == &tp->t_items);
-			ASSERT(licp->lic_next == NULL);
-			return NULL;
-		}
-		for (i = 0; i < licp->lic_unused; i++) {
-			/*
-			 * Skip unoccupied slots.
-			 */
-			if (xfs_lic_isfree(licp, i)) {
-				continue;
-			}
-
-			lidp = xfs_lic_slot(licp, i);
-			blip = (xfs_buf_log_item_t *)lidp->lid_item;
-			if (blip->bli_item.li_type != XFS_LI_BUF) {
-				continue;
-			}
-
-			bp = blip->bli_buf;
-			if ((XFS_BUF_TARGET(bp) == target) &&
-			    (XFS_BUF_ADDR(bp) == blkno) &&
-			    (XFS_BUF_COUNT(bp) == len)) {
-				/*
-				 * We found it.  Break out and
-				 * return the pointer to the buffer.
-				 */
-				return bp;
-			}
-		}
-	}
-	return NULL;
-}