[PATCH 8/9] xfs: introduce xfs_buf_submit[_wait]

[Christoph Hellwig]

On Sat, Aug 16, 2014 at 09:37:43AM +1000, Dave Chinner wrote:
> xfs_zero_remaining_bytes is uses an uncached buffer, so we're not
> using the buffer cache at all for the blocks being zeroed. That is
> why it does the flag twiddling dance it does. However, consolidation
> all the different block zeroing functions we have is an exercise for
> a different day....

Well, we're using buffers.  Anyway, below is what I think it should
look like when using buffers.   Although I wonder how either the old
or new variant pass the verifier check in _xfs_buf_ioapply for v5
filesystems given that we don't pass any ops in.

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 2f1e30d..c495dce 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1122,14 +1122,6 @@ xfs_zero_remaining_bytes(
 	if (endoff > XFS_ISIZE(ip))
 		endoff = XFS_ISIZE(ip);
 
-	bp = xfs_buf_get_uncached(XFS_IS_REALTIME_INODE(ip) ?
-					mp->m_rtdev_targp : mp->m_ddev_targp,
-				  BTOBB(mp->m_sb.sb_blocksize), 0);
-	if (!bp)
-		return -ENOMEM;
-
-	xfs_buf_unlock(bp);
-
 	for (offset = startoff; offset <= endoff; offset = lastoffset + 1) {
 		uint lock_mode;
 
@@ -1152,42 +1144,26 @@ xfs_zero_remaining_bytes(
 		ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
 		if (imap.br_state == XFS_EXT_UNWRITTEN)
 			continue;
-		XFS_BUF_UNDONE(bp);
-		XFS_BUF_UNWRITE(bp);
-		XFS_BUF_READ(bp);
-		XFS_BUF_SET_ADDR(bp, xfs_fsb_to_db(ip, imap.br_startblock));
 
-		if (XFS_FORCED_SHUTDOWN(mp)) {
-			error = -EIO;
-			break;
-		}
-		xfs_buf_iorequest(bp);
-		error = xfs_buf_iowait(bp);
-		if (error) {
-			xfs_buf_ioerror_alert(bp,
-					"xfs_zero_remaining_bytes(read)");
-			break;
+		bp = xfs_buf_read_uncached(XFS_IS_REALTIME_INODE(ip) ?
+				mp->m_rtdev_targp : mp->m_ddev_targp,
+				xfs_fsb_to_db(ip, imap.br_startblock),
+				BTOBB(mp->m_sb.sb_blocksize),
+				0, NULL);
+		if (!bp)
+			return -ENOMEM;
+		if (bp->b_error) {
+			error = bp->b_error;
+			xfs_buf_relse(bp);
+			return error;
 		}
+
 		memset(bp->b_addr +
 			(offset - XFS_FSB_TO_B(mp, imap.br_startoff)),
 		      0, lastoffset - offset + 1);
-		XFS_BUF_UNDONE(bp);
-		XFS_BUF_UNREAD(bp);
-		XFS_BUF_WRITE(bp);
 
-		if (XFS_FORCED_SHUTDOWN(mp)) {
-			error = -EIO;
-			break;
-		}
-		xfs_buf_iorequest(bp);
-		error = xfs_buf_iowait(bp);
-		if (error) {
-			xfs_buf_ioerror_alert(bp,
-					"xfs_zero_remaining_bytes(write)");
-			break;
-		}
+		xfs_bwrite(bp);
 	}
-	xfs_buf_free(bp);
 	return error;
 }