[PATCH 4/6] fuse: rework fuse_readpages()

From: Maxim Patlasov
Date: Fri Sep 07 2012 - 13:41:29 EST


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);
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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