[PATCH 4/9] xfs: use byte ranges for write cleanup ranges

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

xfs_buffered_write_iomap_end() currently converts the byte ranges
passed to it to filesystem blocks to pass them to the bmap code to
punch out delalloc blocks, but then has to convert filesytem
blocks back to byte ranges for page cache truncate.

We're about to make the page cache truncate go away and replace it
with a page cache walk, so having to convert everything to/from/to
filesystem blocks is messy and error-prone. It is much easier to
pass around byte ranges and convert to page indexes and/or
filesystem blocks only where those units are needed.

In preparation for the page cache walk being added, add a helper
that converts byte ranges to filesystem blocks and calls
xfs_bmap_punch_delalloc_range() and convert
xfs_buffered_write_iomap_end() to calculate limits in byte ranges.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_iomap.c | 40 +++++++++++++++++++++++++---------------
 1 file changed, 25 insertions(+), 15 deletions(-)

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index a2e45ea1b0cb..7bb55dbc19d3 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -1120,6 +1120,20 @@ xfs_buffered_write_iomap_begin(
 	return error;
 }
 
+static int
+xfs_buffered_write_delalloc_punch(
+	struct inode		*inode,
+	loff_t			start_byte,
+	loff_t			end_byte)
+{
+	struct xfs_mount	*mp = XFS_M(inode->i_sb);
+	xfs_fileoff_t		start_fsb = XFS_B_TO_FSBT(mp, start_byte);
+	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, end_byte);
+
+	return xfs_bmap_punch_delalloc_range(XFS_I(inode), start_fsb,
+				end_fsb - start_fsb);
+}
+
 static int
 xfs_buffered_write_iomap_end(
 	struct inode		*inode,
@@ -1129,10 +1143,9 @@ xfs_buffered_write_iomap_end(
 	unsigned		flags,
 	struct iomap		*iomap)
 {
-	struct xfs_inode	*ip = XFS_I(inode);
-	struct xfs_mount	*mp = ip->i_mount;
-	xfs_fileoff_t		start_fsb;
-	xfs_fileoff_t		end_fsb;
+	struct xfs_mount	*mp = XFS_M(inode->i_sb);
+	loff_t			start_byte;
+	loff_t			end_byte;
 	int			error = 0;
 
 	if (iomap->type != IOMAP_DELALLOC)
@@ -1157,13 +1170,13 @@ xfs_buffered_write_iomap_end(
 	 * the range.
 	 */
 	if (unlikely(!written))
-		start_fsb = XFS_B_TO_FSBT(mp, offset);
+		start_byte = round_down(offset, mp->m_sb.sb_blocksize);
 	else
-		start_fsb = XFS_B_TO_FSB(mp, offset + written);
-	end_fsb = XFS_B_TO_FSB(mp, offset + length);
+		start_byte = round_up(offset + written, mp->m_sb.sb_blocksize);
+	end_byte = round_up(offset + length, mp->m_sb.sb_blocksize);
 
 	/* Nothing to do if we've written the entire delalloc extent */
-	if (start_fsb >= end_fsb)
+	if (start_byte >= end_byte)
 		return 0;
 
 	/*
@@ -1173,15 +1186,12 @@ xfs_buffered_write_iomap_end(
 	 * leave dirty pages with no space reservation in the cache.
 	 */
 	filemap_invalidate_lock(inode->i_mapping);
-	truncate_pagecache_range(VFS_I(ip), XFS_FSB_TO_B(mp, start_fsb),
-				 XFS_FSB_TO_B(mp, end_fsb) - 1);
-
-	error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
-				       end_fsb - start_fsb);
+	truncate_pagecache_range(inode, start_byte, end_byte - 1);
+	error = xfs_buffered_write_delalloc_punch(inode, start_byte, end_byte);
 	filemap_invalidate_unlock(inode->i_mapping);
 	if (error && !xfs_is_shutdown(mp)) {
-		xfs_alert(mp, "%s: unable to clean up ino %lld",
-			__func__, ip->i_ino);
+		xfs_alert(mp, "%s: unable to clean up ino 0x%llx",
+			__func__, XFS_I(inode)->i_ino);
 		return error;
 	}
 	return 0;
-- 
2.37.2