From a4277b3d0f7221fccaabfce9b3b4b6bed64ee103 Mon Sep 17 00:00:00 2001
From: szaka <szaka>
Date: Sun, 9 Sep 2007 21:39:37 +0000
Subject: [PATCH] ntfs_attr_pwrite: write cluster size blocks if it's possible
 when expanding attributes. This will cause the kernel not to seek and read
 disk blocks for filling the end of the buffer which increases write speed at
 least by 2-11 fold typically. (David Fox, Szabolcs Szakacsits)

---
 libntfs-3g/attrib.c | 36 +++++++++++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/libntfs-3g/attrib.c b/libntfs-3g/attrib.c
index 091e3260..feb28489 100644
--- a/libntfs-3g/attrib.c
+++ b/libntfs-3g/attrib.c
@@ -1281,11 +1281,37 @@ s64 ntfs_attr_pwrite(ntfs_attr *na, const s64 pos, s64 count, const void *b)
 retry:
 		ntfs_log_trace("Writing %lld bytes to vcn %lld, lcn %lld, ofs "
 			       "%lld.\n", to_write, rl->vcn, rl->lcn, ofs);
-		if (!NVolReadOnly(vol))
-			written = ntfs_pwrite(vol->dev, (rl->lcn <<
-					vol->cluster_size_bits) + ofs,
-					to_write, b);
-		else
+		if (!NVolReadOnly(vol)) {
+			
+			s64 pos = (rl->lcn << vol->cluster_size_bits) + ofs;
+			int bsize = vol->cluster_size;
+
+			/*
+			 * Write cluster size blocks if it's possible. This will 
+			 * cause the kernel not to seek and read disk blocks for
+			 * filling the end of the buffer which increases write
+			 * speed at least by 2-11 fold typically.
+			 */
+			if (!(ofs % bsize) && (to_write % bsize) && 
+			    ((ofs + to_write) == na->initialized_size)) {
+				
+				s64 rounded = (to_write + bsize - 1) & ~(bsize - 1);
+				char *cb = ntfs_malloc(rounded);
+				
+				if (!cb)
+					goto err_out;
+				
+				memcpy(cb, b, to_write);
+				memset(cb + to_write, 0, rounded - to_write);
+				
+				written = ntfs_pwrite(vol->dev, pos, rounded, cb); 
+				if (written == rounded)
+					written = to_write;
+				
+				free(cb);
+			} else
+				written = ntfs_pwrite(vol->dev, pos, to_write, b);
+		} else
 			written = to_write;
 		/* If everything ok, update progress counters and continue. */
 		if (written > 0) {