On Thu, May 31 2007, Jens Axboe wrote:
> > This change is wrong. loop or any existing user of ->sendfile absolutely
> > needs to go through a file operations vector so that file-system specific
> > actions such as locking are performed. This is required at least for the
> > clustered filesystems and XFS. The right way to implement this is
> > via do_splice_direct or something similar.
> >
> > do_generic_file_read is only a library function for filesystem use
> > and should never be called directly.
>
> I'll convert it to do_splice_direct(), thanks.
So how does this look? Totally untested, will do that now. It only
covers the read side, the write conversion to splice will happen later.
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 92bac14..3714e60 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -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>
@@ -401,58 +402,70 @@ 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->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 (lo_do_transfer(lo, READ, page, offset, p->page, p->offset, size,
IV)) {
+ if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset,
size, IV)) {
size = 0;
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;
- p->offset += 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;
- read_descriptor_t desc;
-
- desc.written = 0;
- desc.count = bvec->bv_len;
- desc.arg.data = &cookie;
- desc.error = 0;
+ int retval;
cookie.lo = lo;
cookie.page = bvec->bv_page;
cookie.offset = bvec->bv_offset;
cookie.bsize = bsize;
+
+ sd.len = 0;
+ sd.total_len = bsize;
+ sd.flags = 0;
+ sd.pos = pos;
+ sd.data = &cookie;
+
file = lo->lo_backing_file;
+ retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
- do_generic_file_read(file, &pos, &desc, lo_read_actor);
- if (desc.written)
- return 0;
+ if (retval < 0)
+ return retval;
- return desc.error;
+ return 0;
}
static int
@@ -687,8 +700,8 @@ 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 readpage) */
- if (!file->f_mapping->a_ops->readpage)
+ /* 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 */
@@ -768,7 +781,7 @@ 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 (!aops->readpage)
+ if (!file->f_op->splice_read)
goto out_putf;
if (aops->prepare_write && aops->commit_write)
lo_flags |= LO_FLAGS_USE_AOPS;
--
Jens Axboe
-
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