write-size: add command line option

This option forces the buffer size when writing a file on the receiver
side.

fileio.c

@@ -34,6 +34,7 @@
 #define ALIGNED_LENGTH(len) ((((len) - 1) | (ALIGN_BOUNDARY-1)) + 1)
 
 extern int sparse_files;
+extern int write_size;
 
 OFF_T preallocated_len = 0;
 
@@ -158,7 +159,7 @@ int write_file(int f, int use_seek, OFF_T offset, const char *buf, int len)
 			offset += r1;
 		} else {
 			if (!wf_writeBuf) {
-				wf_writeBufSize = WRITE_SIZE * 8;
+				wf_writeBufSize = write_size * 8;
 				wf_writeBufCnt  = 0;
 				wf_writeBuf = new_array(char, wf_writeBufSize);
 			}

options.c

@@ -137,6 +137,7 @@ int inplace = 0;
 int delay_updates = 0;
 int32 block_size = 0;
 int max_map_size = 256*1024;
+int write_size = 32*1024;
 time_t stop_at_utime = 0;
 char *skip_compress = NULL;
 char *copy_as = NULL;
@@ -742,6 +743,7 @@ static struct poptOption long_options[] = {
   {"cc",               0,  POPT_ARG_STRING, &checksum_choice, 0, 0, 0 },
   {"block-size",      'B', POPT_ARG_STRING, 0, OPT_BLOCK_SIZE, 0, 0 },
   {"max-map-size",     0,  POPT_ARG_INT,    &max_map_size, 0, 0, 0 },
+  {"write-size",       0,  POPT_ARG_INT,    &write_size, 0, 0, 0 },
   {"compare-dest",     0,  POPT_ARG_STRING, 0, OPT_COMPARE_DEST, 0, 0 },
   {"copy-dest",        0,  POPT_ARG_STRING, 0, OPT_COPY_DEST, 0, 0 },
   {"link-dest",        0,  POPT_ARG_STRING, 0, OPT_LINK_DEST, 0, 0 },
@@ -2778,6 +2780,12 @@ void server_options(char **args, int *argc_p)
         args[ac++] = arg;
     }
 
+    if (write_size) {
+        if (asprintf(&arg, "--write-size=%d", write_size) < 0)
+            goto oom;
+        args[ac++] = arg;
+    }
+
     if (io_timeout) {
 		if (asprintf(&arg, "--timeout=%d", io_timeout) < 0)
 			goto oom;

rsync.1.md

@@ -473,6 +473,7 @@ has its own detailed description later in this manpage.
 --one-file-system, -x    don't cross filesystem boundaries
 --block-size=SIZE, -B    force a fixed checksum block-size
 --max-map-size           force mmap read block size (expressed in bytes, useful for fast storage, default 256K)
+--write-size             force write block size (expressed in bytes, default 32K)
 --rsh=COMMAND, -e        specify the remote shell to use
 --rsync-path=PROGRAM     specify the rsync to run on remote machine
 --existing               skip creating new files on receiver
@@ -2138,6 +2139,12 @@ expand it.
     >     --max-map-size 4194304
 
 
+0.  `--write-size=SIZE`
+
+    This option forces the buffer size when writing a file on the receiver side.
+
+    By default, 32K and expressed in Bytes.
+
 0.  `--rsh=COMMAND`, `-e`
 
     This option allows you to choose an alternative remote shell program to use

rsync.h

@@ -153,7 +153,6 @@
 #define RSYNC_PORT 873
 
 #define SPARSE_WRITE_SIZE (1024)
-#define WRITE_SIZE (32*1024)
 #define CHUNK_SIZE (32*1024)
 #define IO_BUFFER_SIZE (32*1024)
 #define MAX_BLOCK_SIZE ((int32)1 << 17)