sys_sendfile: switch to using ->splice_read, if available

This patch makes sendfile prefer to use ->splice_read(), if it's
available in the file_operations structure.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 20 insertions, 4 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index 4d03008f015b..47da8a4a0fbe 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/syscalls.h>
 #include <linux/pagemap.h>
+#include <linux/pipe_fs_i.h>
 #include "read_write.h"
 
 #include <asm/uaccess.h>
@@ -25,7 +26,7 @@ const struct file_operations generic_ro_fops = {
         .read           = do_sync_read,
         .aio_read       = generic_file_aio_read,
         .mmap           = generic_file_readonly_mmap,
-        .sendfile       = generic_file_sendfile,
+        .splice_read    = generic_file_splice_read,
 };
 
 EXPORT_SYMBOL(generic_ro_fops);
@@ -708,7 +709,7 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
         struct inode * in_inode, * out_inode;
         loff_t pos;
         ssize_t retval;
-        int fput_needed_in, fput_needed_out;
+        int fput_needed_in, fput_needed_out, fl;
 
         /*
          * Get input file, and verify that it is ok..
@@ -723,7 +724,8 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
         in_inode = in_file->f_path.dentry->d_inode;
         if (!in_inode)
                 goto fput_in;
-        if (!in_file->f_op || !in_file->f_op->sendfile)
+        if (!in_file->f_op || (!in_file->f_op->sendfile &&
+            !in_file->f_op->splice_read))
                 goto fput_in;
         retval = -ESPIPE;
         if (!ppos)
@@ -776,7 +778,21 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
                 count = max - pos;
         }
 
-        retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
+        if (in_file->f_op->splice_read) {
+                fl = 0;
+#if 0
+                /*
+                 * We need to debate whether we can enable this or not. The
+                 * man page documents EAGAIN return for the output at least,
+                 * and the application is arguably buggy if it doesn't expect
+                 * EAGAIN on a non-blocking file descriptor.
+                 */
+                if (in_file->f_flags & O_NONBLOCK)
+                        fl = SPLICE_F_NONBLOCK;
+#endif
+                retval = do_splice_direct(in_file, ppos, out_file, count, fl);
+        } else
+                retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
 
         if (retval > 0) {
                 add_rchar(current, retval);