splice: implement default splice_write method
If f_op->splice_write() is not implemented, fall back to a plain write.
Use vfs_writev() to write from the pipe buffers.
This will allow splice on all filesystems and file types. 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>
diff --git a/fs/splice.c b/fs/splice.c
index 3bd9cb2..eefd96b 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -535,6 +535,21 @@
return res;
}
+static ssize_t kernel_writev(struct file *file, const struct iovec *vec,
+ unsigned long vlen, loff_t *ppos)
+{
+ mm_segment_t old_fs;
+ ssize_t res;
+
+ old_fs = get_fs();
+ set_fs(get_ds());
+ /* The cast to a user pointer is valid due to the set_fs() */
+ res = vfs_writev(file, (const struct iovec __user *)vec, vlen, ppos);
+ set_fs(old_fs);
+
+ return res;
+}
+
ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
@@ -988,6 +1003,122 @@
EXPORT_SYMBOL(generic_file_splice_write);
+static struct pipe_buffer *nth_pipe_buf(struct pipe_inode_info *pipe, int n)
+{
+ return &pipe->bufs[(pipe->curbuf + n) % PIPE_BUFFERS];
+}
+
+static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
+ struct file *out, loff_t *ppos,
+ size_t len, unsigned int flags)
+{
+ ssize_t ret = 0;
+ ssize_t total_len = 0;
+ int do_wakeup = 0;
+
+ pipe_lock(pipe);
+ while (len) {
+ struct pipe_buffer *buf;
+ void *data[PIPE_BUFFERS];
+ struct iovec vec[PIPE_BUFFERS];
+ unsigned int nr_pages = 0;
+ unsigned int write_len = 0;
+ unsigned int now_len = len;
+ unsigned int this_len;
+ int i;
+
+ BUG_ON(pipe->nrbufs > PIPE_BUFFERS);
+ for (i = 0; i < pipe->nrbufs && now_len; i++) {
+ buf = nth_pipe_buf(pipe, i);
+
+ ret = buf->ops->confirm(pipe, buf);
+ if (ret)
+ break;
+
+ data[i] = buf->ops->map(pipe, buf, 0);
+ this_len = min(buf->len, now_len);
+ vec[i].iov_base = (void __user *) data[i] + buf->offset;
+ vec[i].iov_len = this_len;
+ now_len -= this_len;
+ write_len += this_len;
+ nr_pages++;
+ }
+
+ if (nr_pages) {
+ ret = kernel_writev(out, vec, nr_pages, ppos);
+ if (ret == 0)
+ ret = -EIO;
+ if (ret > 0) {
+ len -= ret;
+ total_len += ret;
+ }
+ }
+
+ for (i = 0; i < nr_pages; i++) {
+ buf = nth_pipe_buf(pipe, i);
+ buf->ops->unmap(pipe, buf, data[i]);
+
+ if (ret > 0) {
+ this_len = min_t(unsigned, vec[i].iov_len, ret);
+ buf->offset += this_len;
+ buf->len -= this_len;
+ ret -= this_len;
+ }
+ }
+
+ if (ret < 0)
+ break;
+
+ while (pipe->nrbufs) {
+ const struct pipe_buf_operations *ops;
+
+ buf = nth_pipe_buf(pipe, 0);
+ if (buf->len)
+ break;
+
+ ops = buf->ops;
+ buf->ops = NULL;
+ ops->release(pipe, buf);
+ pipe->curbuf = (pipe->curbuf + 1) % PIPE_BUFFERS;
+ pipe->nrbufs--;
+ if (pipe->inode)
+ do_wakeup = 1;
+ }
+
+ if (pipe->nrbufs)
+ continue;
+ if (!pipe->writers)
+ break;
+ if (!pipe->waiting_writers) {
+ if (total_len)
+ break;
+ }
+
+ if (flags & SPLICE_F_NONBLOCK) {
+ ret = -EAGAIN;
+ break;
+ }
+
+ if (signal_pending(current)) {
+ ret = -ERESTARTSYS;
+ break;
+ }
+
+ if (do_wakeup) {
+ wakeup_pipe_writers(pipe);
+ do_wakeup = 0;
+ }
+
+ pipe_wait(pipe);
+ }
+ pipe_unlock(pipe);
+
+ if (do_wakeup)
+ wakeup_pipe_writers(pipe);
+
+ return total_len ? total_len : ret;
+}
+
/**
* generic_splice_sendpage - splice data from a pipe to a socket
* @pipe: pipe to splice from
@@ -1015,11 +1146,10 @@
static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
loff_t *ppos, size_t len, unsigned int flags)
{
+ ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
+ loff_t *, size_t, unsigned int);
int ret;
- if (unlikely(!out->f_op || !out->f_op->splice_write))
- return -EINVAL;
-
if (unlikely(!(out->f_mode & FMODE_WRITE)))
return -EBADF;
@@ -1030,7 +1160,11 @@
if (unlikely(ret < 0))
return ret;
- return out->f_op->splice_write(pipe, out, ppos, len, flags);
+ splice_write = out->f_op->splice_write;
+ if (!splice_write)
+ splice_write = default_file_splice_write;
+
+ return splice_write(pipe, out, ppos, len, flags);
}
/*