[PATCH 42/67] xfs: create a new inode fork block unmap helper

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Source kernel commit: a59eb5fc21b2a6dc160ee6cdf77f20bc186a88fd

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

Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Bill O'Donnell <bodonnel@xxxxxxxxxx>
---
 libxfs/xfs_bmap.c |   41 ++++++++++++++++++++++++++++++++++++++++-
 libxfs/xfs_bmap.h |    5 ++---
 2 files changed, 42 insertions(+), 4 deletions(-)


diff --git a/libxfs/xfs_bmap.c b/libxfs/xfs_bmap.c
index 534a516b5..3520235b5 100644
--- a/libxfs/xfs_bmap.c
+++ b/libxfs/xfs_bmap.c
@@ -5233,7 +5233,7 @@ xfs_bmap_del_extent_real(
  * that value.  If not all extents in the block range can be removed then
  * *done is set.
  */
-int						/* error */
+static int
 __xfs_bunmapi(
 	struct xfs_trans	*tp,		/* transaction pointer */
 	struct xfs_inode	*ip,		/* incore inode */
@@ -6214,3 +6214,42 @@ 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,
+	uint32_t		flags,
+	xfs_fileoff_t		startoff,
+	xfs_fileoff_t		endoff)
+{
+	xfs_filblks_t		unmap_len = endoff - startoff + 1;
+	int			error = 0;
+
+	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+
+	while (unmap_len > 0) {
+		ASSERT((*tpp)->t_highest_agno == NULLAGNUMBER);
+		error = __xfs_bunmapi(*tpp, ip, startoff, &unmap_len, flags,
+				XFS_ITRUNC_MAX_EXTENTS);
+		if (error)
+			goto out;
+
+		/* free the just unmapped extents */
+		error = xfs_defer_finish(tpp);
+		if (error)
+			goto out;
+	}
+out:
+	return error;
+}
diff --git a/libxfs/xfs_bmap.h b/libxfs/xfs_bmap.h
index 8518324db..4b83f6148 100644
--- a/libxfs/xfs_bmap.h
+++ b/libxfs/xfs_bmap.h
@@ -190,9 +190,6 @@ int	xfs_bmapi_read(struct xfs_inode *ip, xfs_fileoff_t bno,
 int	xfs_bmapi_write(struct xfs_trans *tp, struct xfs_inode *ip,
 		xfs_fileoff_t bno, xfs_filblks_t len, uint32_t flags,
 		xfs_extlen_t total, struct xfs_bmbt_irec *mval, int *nmap);
-int	__xfs_bunmapi(struct xfs_trans *tp, struct xfs_inode *ip,
-		xfs_fileoff_t bno, xfs_filblks_t *rlen, uint32_t flags,
-		xfs_extnum_t nexts);
 int	xfs_bunmapi(struct xfs_trans *tp, struct xfs_inode *ip,
 		xfs_fileoff_t bno, xfs_filblks_t len, uint32_t flags,
 		xfs_extnum_t nexts, int *done);
@@ -273,6 +270,8 @@ int xfs_bmap_complain_bad_rec(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,
 		uint32_t flags);
+int	xfs_bunmapi_range(struct xfs_trans **tpp, struct xfs_inode *ip,
+		uint32_t flags, xfs_fileoff_t startoff, xfs_fileoff_t endoff);
 
 extern struct kmem_cache	*xfs_bmap_intent_cache;