| Re: [PATCH 4/6] fuse: rework fuse_readpages() [message #47814 is a reply to message #47761] |
Wed, 12 September 2012 16:41   |
Miklos Szeredi
Messages: 161
Registered: April 2007
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Senior Member |
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Maxim Patlasov <mpatlasov@parallels.com> writes:
> The patch uses 'nr_pages' argument of fuse_readpages() as the heuristics for
> number of page pointers to allocate.
>
> This can be improved further by taking in consideration fc->max_read and gaps
> between page indices, but it's not clear wheteher it's worthy or not.
> ---
> fs/fuse/file.c | 10 ++++++++--
> 1 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index c811f3d..9a6dcc6 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -641,6 +641,7 @@ struct fuse_fill_data {
> struct fuse_req *req;
> struct file *file;
> struct inode *inode;
> + unsigned nr_pages;
> };
>
> static int fuse_readpages_fill(void *_data, struct page *page)
> @@ -656,8 +657,10 @@ static int fuse_readpages_fill(void *_data, struct page *page)
> (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
> (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
> req->pages[req->num_pages - 1]->index + 1 != page->index)) {
> + int nr_alloc = min_t(unsigned, data->nr_pages,
> + FUSE_MAX_PAGES_PER_REQ);
> fuse_send_readpages(req, data->file);
> - data->req = req = fuse_get_req_multipage(fc, FUSE_MAX_PAGES_PER_REQ);
> + data->req = req = fuse_get_req_multipage(fc, nr_alloc);
> if (IS_ERR(req)) {
> unlock_page(page);
> return PTR_ERR(req);
> @@ -666,6 +669,7 @@ static int fuse_readpages_fill(void *_data, struct page *page)
> page_cache_get(page);
Okay, this is where things get hairy and where we should do something like:
if (WARN_ON(req->num_pages >= req->max_pages))
return -EIO;
> req->pages[req->num_pages] = page;
> req->num_pages++;
> + data->nr_pages--;
> return 0;
> }
>
> @@ -676,6 +680,7 @@ static int fuse_readpages(struct file *file, struct address_space *mapping,
> struct fuse_conn *fc = get_fuse_conn(inode);
> struct fuse_fill_data data;
> int err;
> + int nr_alloc = min_t(unsigned, nr_pages, FUSE_MAX_PAGES_PER_REQ);
>
> err = -EIO;
> if (is_bad_inode(inode))
> @@ -683,7 +688,8 @@ static int fuse_readpages(struct file *file, struct address_space *mapping,
>
> data.file = file;
> data.inode = inode;
> - data.req = fuse_get_req_multipage(fc, FUSE_MAX_PAGES_PER_REQ);
> + data.req = fuse_get_req_multipage(fc, nr_alloc);
> + data.nr_pages = nr_pages;
> err = PTR_ERR(data.req);
> if (IS_ERR(data.req))
> goto out;
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