diff options
| author | Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> | 2012-08-09 21:30:50 +0900 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2012-09-28 15:05:12 +0930 |
| commit | ec8fc870156b2b144f55b6a5a7d135018f04b30e (patch) | |
| tree | 449d9375e37f7ff938d214690f4ed72779abf522 /drivers/char | |
| parent | eb5e89fc70bb3f115b3206ed0c57d3aba1fdd155 (diff) | |
virtio/console: Add a failback for unstealable pipe buffer
Add a failback memcpy path for unstealable pipe buffer.
If buf->ops->steal() fails, virtio-serial tries to
copy the page contents to an allocated page, instead
of just failing splice().
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/virtio_console.c | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index 730816cdeb45..22b737353017 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -794,7 +794,7 @@ static int pipe_to_sg(struct pipe_inode_info *pipe, struct pipe_buffer *buf, struct splice_desc *sd) { struct sg_list *sgl = sd->u.data; - unsigned int len = 0; + unsigned int offset, len; if (sgl->n == MAX_SPLICE_PAGES) return 0; @@ -807,9 +807,31 @@ static int pipe_to_sg(struct pipe_inode_info *pipe, struct pipe_buffer *buf, len = min(buf->len, sd->len); sg_set_page(&(sgl->sg[sgl->n]), buf->page, len, buf->offset); - sgl->n++; - sgl->len += len; + } else { + /* Failback to copying a page */ + struct page *page = alloc_page(GFP_KERNEL); + char *src = buf->ops->map(pipe, buf, 1); + char *dst; + + if (!page) + return -ENOMEM; + dst = kmap(page); + + offset = sd->pos & ~PAGE_MASK; + + len = sd->len; + if (len + offset > PAGE_SIZE) + len = PAGE_SIZE - offset; + + memcpy(dst + offset, src + buf->offset, len); + + kunmap(page); + buf->ops->unmap(pipe, buf, src); + + sg_set_page(&(sgl->sg[sgl->n]), page, len, offset); } + sgl->n++; + sgl->len += len; return len; } |