[PATCH 4/6] xfs: create a new inode fork block unmap helper

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Create a new helper to unmap blocks from an inode's fork.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c |   43 +++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_bmap.h |    3 +++
 fs/xfs/xfs_inode.c       |   29 ++++-------------------------
 3 files changed, 50 insertions(+), 25 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 84ddd4654975..f15cc7cc3b62 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -6327,3 +6327,46 @@ xfs_bmap_validate_extent(
 	return xfs_bmap_validate_extent_raw(ip->i_mount,
 			XFS_IS_REALTIME_INODE(ip), whichfork, irec);
 }
+
+/*
+ * Used in xfs_itruncate_extents().  This is the maximum number of extents
+ * freed from a file in a single transaction.
+ */
+#define	XFS_ITRUNC_MAX_EXTENTS	2
+
+/*
+ * Unmap every extent in part of an inode's fork.  We don't do any higher level
+ * invalidation work at all.
+ */
+int
+xfs_bunmapi_range(
+	struct xfs_trans	**tpp,
+	struct xfs_inode	*ip,
+	int			whichfork,
+	xfs_fileoff_t		startoff,
+	xfs_filblks_t		unmap_len,
+	int			bunmapi_flags)
+{
+	int			error = 0;
+
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+
+	bunmapi_flags |= xfs_bmapi_aflag(whichfork);
+	while (unmap_len > 0) {
+		ASSERT((*tpp)->t_firstblock == NULLFSBLOCK);
+		error = __xfs_bunmapi(*tpp, ip, startoff, &unmap_len,
+				bunmapi_flags, XFS_ITRUNC_MAX_EXTENTS);
+		if (error)
+			goto out;
+
+		/*
+		 * Duplicate the transaction that has the permanent
+		 * reservation and commit the old transaction.
+		 */
+		error = xfs_defer_finish(tpp);
+		if (error)
+			goto out;
+	}
+out:
+	return error;
+}
diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
index 07c9726d40c2..ec29d5012a49 100644
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -286,5 +286,8 @@ xfs_failaddr_t xfs_bmap_validate_extent(struct xfs_inode *ip, int whichfork,
 int	xfs_bmapi_remap(struct xfs_trans *tp, struct xfs_inode *ip,
 		xfs_fileoff_t bno, xfs_filblks_t len, xfs_fsblock_t startblock,
 		int flags);
+int	xfs_bunmapi_range(struct xfs_trans **tpp, struct xfs_inode *ip,
+		int whichfork, xfs_fileoff_t startoff, xfs_filblks_t unmap_len,
+		int bunmapi_flags);
 
 #endif	/* __XFS_BMAP_H__ */
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index c6986517074e..8a424fac2d27 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -38,12 +38,6 @@
 
 kmem_zone_t *xfs_inode_zone;
 
-/*
- * Used in xfs_itruncate_extents().  This is the maximum number of extents
- * freed from a file in a single transaction.
- */
-#define	XFS_ITRUNC_MAX_EXTENTS	2
-
 STATIC int xfs_iflush_int(struct xfs_inode *, struct xfs_buf *);
 STATIC int xfs_iunlink(struct xfs_trans *, struct xfs_inode *);
 STATIC int xfs_iunlink_remove(struct xfs_trans *, struct xfs_inode *);
@@ -1519,7 +1513,6 @@ xfs_itruncate_extents_flags(
 	struct xfs_trans	*tp = *tpp;
 	xfs_fileoff_t		first_unmap_block;
 	xfs_fileoff_t		last_block;
-	xfs_filblks_t		unmap_len;
 	int			error = 0;
 
 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
@@ -1533,8 +1526,6 @@ xfs_itruncate_extents_flags(
 
 	trace_xfs_itruncate_extents_start(ip, new_size);
 
-	flags |= xfs_bmapi_aflag(whichfork);
-
 	/*
 	 * Since it is possible for space to become allocated beyond
 	 * the end of the file (in a crash where the space is allocated
@@ -1550,22 +1541,10 @@ xfs_itruncate_extents_flags(
 		return 0;
 
 	ASSERT(first_unmap_block < last_block);
-	unmap_len = last_block - first_unmap_block + 1;
-	while (unmap_len > 0) {
-		ASSERT(tp->t_firstblock == NULLFSBLOCK);
-		error = __xfs_bunmapi(tp, ip, first_unmap_block, &unmap_len,
-				flags, XFS_ITRUNC_MAX_EXTENTS);
-		if (error)
-			goto out;
-
-		/*
-		 * Duplicate the transaction that has the permanent
-		 * reservation and commit the old transaction.
-		 */
-		error = xfs_defer_finish(&tp);
-		if (error)
-			goto out;
-	}
+	error = xfs_bunmapi_range(&tp, ip, whichfork, first_unmap_block,
+			last_block - first_unmap_block + 1, flags);
+	if (error)
+		goto out;
 
 	if (whichfork == XFS_DATA_FORK) {
 		/* Remove all pending CoW reservations. */