Commit c66ab6fa authored by Jens Axboe's avatar Jens Axboe
Browse files

splice: abstract out actor data 



For direct splicing (or private splicing), the output may not be a file.
So abstract out the handling into a specified actor function and put
the data in the splice_desc structure earlier, so we can build on top
of that.

This is the first step in better splice handling for drivers, and also
for implementing vmsplice _to_ user memory.

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 71780f59

fs/ocfs2/file.c

+8 −3
Original line number Diff line number Diff line
@@ -1636,9 +1636,14 @@ static ssize_t __ocfs2_file_splice_write(struct pipe_inode_info *pipe, 
	int ret, err;

	struct address_space *mapping = out->f_mapping;

	struct inode *inode = mapping->host;

	struct splice_desc sd = {

		.total_len = len,

		.flags = flags,

		.pos = *ppos,

		.file = out,

	};



	ret = __splice_from_pipe(pipe, out, ppos, len, flags,

				 ocfs2_splice_write_actor);

	ret = __splice_from_pipe(pipe, &sd, ocfs2_splice_write_actor);

	if (ret > 0) {

		*ppos += ret;

fs/splice.c

+70 −29
Original line number Diff line number Diff line
@@ -668,31 +668,24 @@ out_ret: 
 * key here is the 'actor' worker passed in that actually moves the data

 * to the wanted destination. See pipe_to_file/pipe_to_sendpage above.

 */

ssize_t __splice_from_pipe(struct pipe_inode_info *pipe,

			   struct file *out, loff_t *ppos, size_t len,

			   unsigned int flags, splice_actor *actor)

ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,

			   splice_actor *actor)

{

	int ret, do_wakeup, err;

	struct splice_desc sd;



	ret = 0;

	do_wakeup = 0;



	sd.total_len = len;

	sd.flags = flags;

	sd.file = out;

	sd.pos = *ppos;



	for (;;) {

		if (pipe->nrbufs) {

			struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;

			const struct pipe_buf_operations *ops = buf->ops;



			sd.len = buf->len;

			if (sd.len > sd.total_len)

				sd.len = sd.total_len;

			sd->len = buf->len;

			if (sd->len > sd->total_len)

				sd->len = sd->total_len;



			err = actor(pipe, buf, &sd);

			err = actor(pipe, buf, sd);

			if (err <= 0) {

				if (!ret && err != -ENODATA)

					ret = err;
@@ -704,10 +697,10 @@ ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, 
			buf->offset += err;

			buf->len -= err;



			sd.len -= err;

			sd.pos += err;

			sd.total_len -= err;

			if (sd.len)

			sd->len -= err;

			sd->pos += err;

			sd->total_len -= err;

			if (sd->len)

				continue;



			if (!buf->len) {
@@ -719,7 +712,7 @@ ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, 
					do_wakeup = 1;

			}



			if (!sd.total_len)

			if (!sd->total_len)

				break;

		}
@@ -732,7 +725,7 @@ ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, 
				break;

		}



		if (flags & SPLICE_F_NONBLOCK) {

		if (sd->flags & SPLICE_F_NONBLOCK) {

			if (!ret)

				ret = -EAGAIN;

			break;
@@ -772,6 +765,12 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, 
{

	ssize_t ret;

	struct inode *inode = out->f_mapping->host;

	struct splice_desc sd = {

		.total_len = len,

		.flags = flags,

		.pos = *ppos,

		.file = out,

	};



	/*

	 * The actor worker might be calling ->prepare_write and
@@ -780,7 +779,7 @@ ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, 
	 * pipe->inode, we have to order lock acquiry here.

	 */

	inode_double_lock(inode, pipe->inode);

	ret = __splice_from_pipe(pipe, out, ppos, len, flags, actor);

	ret = __splice_from_pipe(pipe, &sd, actor);

	inode_double_unlock(inode, pipe->inode);



	return ret;
@@ -804,6 +803,12 @@ generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out, 
{

	struct address_space *mapping = out->f_mapping;

	struct inode *inode = mapping->host;

	struct splice_desc sd = {

		.total_len = len,

		.flags = flags,

		.pos = *ppos,

		.file = out,

	};

	ssize_t ret;

	int err;
@@ -811,7 +816,7 @@ generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out, 
	if (unlikely(err))

		return err;



	ret = __splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);

	ret = __splice_from_pipe(pipe, &sd, pipe_to_file);

	if (ret > 0) {

		unsigned long nr_pages;
@@ -956,14 +961,17 @@ static long do_splice_to(struct file *in, loff_t *ppos, 
	return in->f_op->splice_read(in, ppos, pipe, len, flags);

}



long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,

		      size_t len, unsigned int flags)

/*

 * Splices from an input file to an actor, using a 'direct' pipe.

 */

ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,

			       splice_direct_actor *actor)

{

	struct pipe_inode_info *pipe;

	long ret, bytes;

	loff_t out_off;

	umode_t i_mode;

	int i;

	size_t len;

	int i, flags;



	/*

	 * We require the input being a regular file, as we don't want to
@@ -999,7 +1007,13 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, 
	 */

	ret = 0;

	bytes = 0;

	out_off = 0;

	len = sd->total_len;

	flags = sd->flags;



	/*

	 * Don't block on output, we have to drain the direct pipe.

	 */

	sd->flags &= ~SPLICE_F_NONBLOCK;



	while (len) {

		size_t read_len, max_read_len;
@@ -1009,19 +1023,19 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, 
		 */

		max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));



		ret = do_splice_to(in, ppos, pipe, max_read_len, flags);

		ret = do_splice_to(in, &sd->pos, pipe, max_read_len, flags);

		if (unlikely(ret < 0))

			goto out_release;



		read_len = ret;

		sd->total_len = read_len;



		/*

		 * NOTE: nonblocking mode only applies to the input. We

		 * must not do the output in nonblocking mode as then we

		 * could get stuck data in the internal pipe:

		 */

		ret = do_splice_from(pipe, out, &out_off, read_len,

				     flags & ~SPLICE_F_NONBLOCK);

		ret = actor(pipe, sd);

		if (unlikely(ret < 0))

			goto out_release;
@@ -1066,6 +1080,33 @@ out_release: 
		return bytes;



	return ret;



}

EXPORT_SYMBOL(splice_direct_to_actor);



static int direct_splice_actor(struct pipe_inode_info *pipe,

			       struct splice_desc *sd)

{

	struct file *file = sd->file;



	return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags);

}



long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,

		      size_t len, unsigned int flags)

{

	struct splice_desc sd = {

		.len		= len,

		.total_len	= len,

		.flags		= flags,

		.pos		= *ppos,

		.file		= out,

	};

	size_t ret;



	ret = splice_direct_to_actor(in, &sd, direct_splice_actor);

	*ppos = sd.pos;

	return ret;

}



/*

include/linux/pipe_fs_i.h

+6 −4
Original line number Diff line number Diff line
@@ -94,13 +94,15 @@ struct splice_desc { 


typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,

			   struct splice_desc *);

typedef int (splice_direct_actor)(struct pipe_inode_info *,

				  struct splice_desc *);



extern ssize_t splice_from_pipe(struct pipe_inode_info *, struct file *,

				loff_t *, size_t, unsigned int,

				splice_actor *);



extern ssize_t __splice_from_pipe(struct pipe_inode_info *, struct file *,

				  loff_t *, size_t, unsigned int,

				  splice_actor *);

extern ssize_t __splice_from_pipe(struct pipe_inode_info *,

				  struct splice_desc *, splice_actor *);

extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,

				      splice_direct_actor *);



#endif

CRA Git | Maintained and supported by SUSTech CRA and CCSE