Several fixes to our use of splice
authorVolker Lendecke <vl@samba.org>
Wed, 7 Jan 2009 10:39:34 +0000 (10:39 +0000)
committerVolker Lendecke <vl@samba.org>
Wed, 7 Jan 2009 11:04:44 +0000 (12:04 +0100)
The splice manpage explicitly requires loff_t as offset. Copy "offset" there.
Probably not required, but I wanted to make sure it's as required.

Splice blocks with large buffers. For me it worked with 16k and blocked with
32k and beyond. It would be nice to see a clarification in the manpage of
splice for this behaviour.

Splice if used with an offset increments the offset. From the manpage this was
at least not entirely obvious :-)

I haven't yet activated this (try_splice_call ist still false by default), it
needs more testing.

Volker

source3/lib/recvfile.c

index c9710a7..ea01596 100644 (file)
@@ -148,6 +148,7 @@ ssize_t sys_recvfile(int fromfd,
        static int pipefd[2] = { -1, -1 };
        static bool try_splice_call = false;
        size_t total_written = 0;
+       loff_t splice_offset = offset;
 
        DEBUG(10,("sys_recvfile: from = %d, to = %d, "
                "offset=%.0f, count = %lu\n",
@@ -180,7 +181,8 @@ ssize_t sys_recvfile(int fromfd,
        while (count > 0) {
                int nread, to_write;
 
-               nread = splice(fromfd, NULL, pipefd[1], NULL, count, 0);
+               nread = splice(fromfd, NULL, pipefd[1], NULL,
+                              MIN(count, 16384), SPLICE_F_MOVE);
                if (nread == -1) {
                        if (errno == EINTR) {
                                continue;
@@ -197,12 +199,12 @@ ssize_t sys_recvfile(int fromfd,
                to_write = nread;
                while (to_write > 0) {
                        int thistime;
-                       thistime = splice(pipefd[0], NULL, tofd, &offset,
-                                         to_write, 0);
+                       thistime = splice(pipefd[0], NULL, tofd,
+                                         &splice_offset, to_write,
+                                         SPLICE_F_MOVE);
                        if (thistime == -1) {
                                goto done;
                        }
-                       offset += thistime;
                        to_write -= thistime;
                }