splice: Make splice from a DAX file use copy_splice_read()

[linux-block.git] / fs / splice.c

diff --git a/fs/splice.c b/fs/splice.c
index d815a69f65899567d8fdfbf0e05779fe8158f84b..8268248df3a908d7e617c945904f0e15a9a05acc 100644 (file)
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -891,6 +891,8 @@ long vfs_splice_read(struct file *in, loff_t *ppos,
 
        if (unlikely(!(in->f_mode & FMODE_READ)))
                return -EBADF;
+       if (!len)
+               return 0;
 
        /* Don't try to read more the pipe has space for. */
        p_space = pipe->max_usage - pipe_occupancy(pipe->head, pipe->tail);
@@ -905,6 +907,12 @@ long vfs_splice_read(struct file *in, loff_t *ppos,
 
        if (unlikely(!in->f_op->splice_read))
                return warn_unsupported(in, "read");
+       /*
+        * O_DIRECT and DAX don't deal with the pagecache, so we allocate a
+        * buffer, copy into it and splice that into the pipe.
+        */
+       if ((in->f_flags & O_DIRECT) || IS_DAX(in->f_mapping->host))
+               return copy_splice_read(in, ppos, pipe, len, flags);
        return in->f_op->splice_read(in, ppos, pipe, len, flags);
 }
 EXPORT_SYMBOL_GPL(vfs_splice_read);