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Commit fd582140 authored by Jens Axboe's avatar Jens Axboe
Browse files

loop: convert to using splice_direct_to_actor() instead of sendfile() 



This gets rid of the dependency on ->sendfile() for receiving data
and converts loop to ->splice_read() instead.

Also includes an IV offset fix from Hugh Dickins.

Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 130610d6

drivers/block/loop.c

+44 −20
Original line number Diff line number Diff line
@@ -74,6 +74,7 @@ 
#include <linux/highmem.h>

#include <linux/gfp.h>

#include <linux/kthread.h>

#include <linux/pipe_fs_i.h>



#include <asm/uaccess.h>
@@ -401,50 +402,73 @@ struct lo_read_data { 
};



static int

lo_read_actor(read_descriptor_t *desc, struct page *page,

	      unsigned long offset, unsigned long size)

lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,

		struct splice_desc *sd)

{

	unsigned long count = desc->count;

	struct lo_read_data *p = desc->arg.data;

	struct lo_read_data *p = sd->u.data;

	struct loop_device *lo = p->lo;

	struct page *page = buf->page;

	sector_t IV;

	size_t size;

	int ret;



	IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9);

	ret = buf->ops->pin(pipe, buf);

	if (unlikely(ret))

		return ret;



	if (size > count)

		size = count;

	IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +

							(buf->offset >> 9);

	size = sd->len;

	if (size > p->bsize)

		size = p->bsize;



	if (lo_do_transfer(lo, READ, page, offset, p->page, p->offset, size, IV)) {

		size = 0;

	if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {

		printk(KERN_ERR "loop: transfer error block %ld\n",

		       page->index);

		desc->error = -EINVAL;

		size = -EINVAL;

	}



	flush_dcache_page(p->page);



	desc->count = count - size;

	desc->written += size;

	if (size > 0)

		p->offset += size;



	return size;

}



static int

lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)

{

	return __splice_from_pipe(pipe, sd, lo_splice_actor);

}



static int

do_lo_receive(struct loop_device *lo,

	      struct bio_vec *bvec, int bsize, loff_t pos)

{

	struct lo_read_data cookie;

	struct splice_desc sd;

	struct file *file;

	int retval;

	long retval;



	cookie.lo = lo;

	cookie.page = bvec->bv_page;

	cookie.offset = bvec->bv_offset;

	cookie.bsize = bsize;



	sd.len = 0;

	sd.total_len = bvec->bv_len;

	sd.flags = 0;

	sd.pos = pos;

	sd.u.data = &cookie;



	file = lo->lo_backing_file;

	retval = file->f_op->sendfile(file, &pos, bvec->bv_len,

			lo_read_actor, &cookie);

	return (retval < 0)? retval: 0;

	retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);



	if (retval < 0)

		return retval;



	return 0;

}



static int
@@ -679,8 +703,8 @@ static int loop_change_fd(struct loop_device *lo, struct file *lo_file, 
	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))

		goto out_putf;



	/* new backing store needs to support loop (eg sendfile) */

	if (!inode->i_fop->sendfile)

	/* new backing store needs to support loop (eg splice_read) */

	if (!inode->i_fop->splice_read)

		goto out_putf;



	/* size of the new backing store needs to be the same */
@@ -760,7 +784,7 @@ static int loop_set_fd(struct loop_device *lo, struct file *lo_file, 
		 * If we can't read - sorry. If we only can't write - well,

		 * it's going to be read-only.

		 */

		if (!file->f_op->sendfile)

		if (!file->f_op->splice_read)

			goto out_putf;

		if (aops->prepare_write && aops->commit_write)

			lo_flags |= LO_FLAGS_USE_AOPS;