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>
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6818173bd6
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0b0a47f5c4
1 changed files with 138 additions and 4 deletions
142
fs/splice.c
142
fs/splice.c
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@ -535,6 +535,21 @@ static ssize_t kernel_readv(struct file *file, const struct iovec *vec,
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return res;
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}
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static ssize_t kernel_writev(struct file *file, const struct iovec *vec,
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unsigned long vlen, loff_t *ppos)
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{
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mm_segment_t old_fs;
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ssize_t res;
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old_fs = get_fs();
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set_fs(get_ds());
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/* The cast to a user pointer is valid due to the set_fs() */
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res = vfs_writev(file, (const struct iovec __user *)vec, vlen, ppos);
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set_fs(old_fs);
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return res;
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}
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ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
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struct pipe_inode_info *pipe, size_t len,
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unsigned int flags)
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@ -988,6 +1003,122 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
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EXPORT_SYMBOL(generic_file_splice_write);
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static struct pipe_buffer *nth_pipe_buf(struct pipe_inode_info *pipe, int n)
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{
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return &pipe->bufs[(pipe->curbuf + n) % PIPE_BUFFERS];
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}
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static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
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struct file *out, loff_t *ppos,
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size_t len, unsigned int flags)
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{
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ssize_t ret = 0;
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ssize_t total_len = 0;
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int do_wakeup = 0;
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pipe_lock(pipe);
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while (len) {
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struct pipe_buffer *buf;
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void *data[PIPE_BUFFERS];
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struct iovec vec[PIPE_BUFFERS];
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unsigned int nr_pages = 0;
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unsigned int write_len = 0;
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unsigned int now_len = len;
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unsigned int this_len;
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int i;
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BUG_ON(pipe->nrbufs > PIPE_BUFFERS);
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for (i = 0; i < pipe->nrbufs && now_len; i++) {
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buf = nth_pipe_buf(pipe, i);
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ret = buf->ops->confirm(pipe, buf);
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if (ret)
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break;
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data[i] = buf->ops->map(pipe, buf, 0);
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this_len = min(buf->len, now_len);
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vec[i].iov_base = (void __user *) data[i] + buf->offset;
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vec[i].iov_len = this_len;
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now_len -= this_len;
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write_len += this_len;
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nr_pages++;
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}
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if (nr_pages) {
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ret = kernel_writev(out, vec, nr_pages, ppos);
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if (ret == 0)
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ret = -EIO;
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if (ret > 0) {
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len -= ret;
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total_len += ret;
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}
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}
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for (i = 0; i < nr_pages; i++) {
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buf = nth_pipe_buf(pipe, i);
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buf->ops->unmap(pipe, buf, data[i]);
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if (ret > 0) {
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this_len = min_t(unsigned, vec[i].iov_len, ret);
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buf->offset += this_len;
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buf->len -= this_len;
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ret -= this_len;
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}
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}
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if (ret < 0)
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break;
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while (pipe->nrbufs) {
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const struct pipe_buf_operations *ops;
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buf = nth_pipe_buf(pipe, 0);
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if (buf->len)
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break;
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ops = buf->ops;
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buf->ops = NULL;
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ops->release(pipe, buf);
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pipe->curbuf = (pipe->curbuf + 1) % PIPE_BUFFERS;
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pipe->nrbufs--;
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if (pipe->inode)
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do_wakeup = 1;
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}
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if (pipe->nrbufs)
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continue;
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if (!pipe->writers)
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break;
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if (!pipe->waiting_writers) {
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if (total_len)
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break;
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}
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if (flags & SPLICE_F_NONBLOCK) {
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ret = -EAGAIN;
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break;
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}
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if (signal_pending(current)) {
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ret = -ERESTARTSYS;
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break;
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}
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if (do_wakeup) {
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wakeup_pipe_writers(pipe);
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do_wakeup = 0;
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}
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pipe_wait(pipe);
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}
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pipe_unlock(pipe);
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if (do_wakeup)
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wakeup_pipe_writers(pipe);
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return total_len ? total_len : ret;
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}
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/**
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* generic_splice_sendpage - splice data from a pipe to a socket
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* @pipe: pipe to splice from
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@ -1015,11 +1146,10 @@ EXPORT_SYMBOL(generic_splice_sendpage);
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static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
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loff_t *ppos, size_t len, unsigned int flags)
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{
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ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
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loff_t *, size_t, unsigned int);
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int ret;
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if (unlikely(!out->f_op || !out->f_op->splice_write))
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return -EINVAL;
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if (unlikely(!(out->f_mode & FMODE_WRITE)))
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return -EBADF;
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@ -1030,7 +1160,11 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
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if (unlikely(ret < 0))
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return ret;
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return out->f_op->splice_write(pipe, out, ppos, len, flags);
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splice_write = out->f_op->splice_write;
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if (!splice_write)
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splice_write = default_file_splice_write;
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return splice_write(pipe, out, ppos, len, flags);
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}
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/*
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