r6949: Back-port Volker's cache fix, plus my change.

Jeremy.
(This used to be commit 27d43f6d36b3f6abc368ec6a00ef9803cb27c324)

1 files changed, 38 insertions, 0 deletions

diff --git a/source3/smbd/fileio.c b/source3/smbd/fileio.c
index 9b39bf8fe1..69b8b57642 100644
--- a/source3/smbd/fileio.c
+++ b/source3/smbd/fileio.c
@@ -509,6 +509,44 @@ nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 
 			write_path = 3;
 
+                } else if ( (pos >= wcp->file_size) && 
+			    (n == 1) &&
+			    (pos < wcp->offset + 2*wcp->alloc_size) &&
+			    (wcp->file_size == wcp->offset + wcp->data_size)) {
+
+                        /*
+                        +---------------+
+                        | Cached data   |
+                        +---------------+
+
+                                                         +--------+
+                                                         | 1 Byte |
+                                                         +--------+
+
+			MS-Office seems to do this a lot to determine if there's enough
+			space on the filesystem to write a new file.
+                        */
+
+			SMB_BIG_UINT new_start = wcp->offset + wcp->data_size;
+
+			flush_write_cache(fsp, WRITE_FLUSH);
+			wcp->offset = new_start;
+			wcp->data_size = pos - new_start + 1;
+			memset(wcp->data, '\0', wcp->data_size);
+			memcpy(wcp->data + wcp->data_size-1, data, 1);
+
+			/*
+			 * Update the file size if changed.
+			 */
+
+			if (wcp->offset + wcp->data_size > wcp->file_size) {
+				if (wcp_file_size_change(fsp) == -1) {
+					return -1;
+				}
+			}
+
+			return n;
+
 		} else {
 
 			/* ASCII art..... JRA.