splice: implement default splice_read method

If f_op->splice_read() is not implemented, fall back to a plain read.
Use vfs_readv() to read into previously allocated pages.

This will allow splice and functions using splice, such as the loop
device, to work on all filesystems.  This includes "direct_io" files
in fuse which bypass the page cache.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 1 insertions, 6 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index 9d1e76bb9ee1..6c8c55dec2bc 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -805,12 +805,6 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
                 goto out;
         if (!(in_file->f_mode & FMODE_READ))
                 goto fput_in;
-        retval = -EINVAL;
-        in_inode = in_file->f_path.dentry->d_inode;
-        if (!in_inode)
-                goto fput_in;
-        if (!in_file->f_op || !in_file->f_op->splice_read)
-                goto fput_in;
         retval = -ESPIPE;
         if (!ppos)
                 ppos = &in_file->f_pos;
@@ -834,6 +828,7 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
         retval = -EINVAL;
         if (!out_file->f_op || !out_file->f_op->sendpage)
                 goto fput_out;
+        in_inode = in_file->f_path.dentry->d_inode;
         out_inode = out_file->f_path.dentry->d_inode;
         retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count);
         if (retval < 0)