提交 4d53dc99 编写于 作者: M Maxim Patlasov 提交者: Miklos Szeredi

fuse: rework fuse_retrieve()

The patch reworks fuse_retrieve() to allocate only so many page pointers
as needed. The core part of the patch is the following calculation:

	num_pages = (num + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;

(thanks Miklos for formula). All other changes are mostly shuffling lines.
Signed-off-by: NMaxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
上级 b111c8c0
......@@ -1577,13 +1577,24 @@ static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode,
unsigned int num;
unsigned int offset;
size_t total_len = 0;
int num_pages;
req = fuse_get_req(fc, FUSE_MAX_PAGES_PER_REQ);
offset = outarg->offset & ~PAGE_CACHE_MASK;
file_size = i_size_read(inode);
num = outarg->size;
if (outarg->offset > file_size)
num = 0;
else if (outarg->offset + num > file_size)
num = file_size - outarg->offset;
num_pages = (num + offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
num_pages = min(num_pages, FUSE_MAX_PAGES_PER_REQ);
req = fuse_get_req(fc, num_pages);
if (IS_ERR(req))
return PTR_ERR(req);
offset = outarg->offset & ~PAGE_CACHE_MASK;
req->in.h.opcode = FUSE_NOTIFY_REPLY;
req->in.h.nodeid = outarg->nodeid;
req->in.numargs = 2;
......@@ -1592,14 +1603,8 @@ static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode,
req->end = fuse_retrieve_end;
index = outarg->offset >> PAGE_CACHE_SHIFT;
file_size = i_size_read(inode);
num = outarg->size;
if (outarg->offset > file_size)
num = 0;
else if (outarg->offset + num > file_size)
num = file_size - outarg->offset;
while (num && req->num_pages < FUSE_MAX_PAGES_PER_REQ) {
while (num && req->num_pages < num_pages) {
struct page *page;
unsigned int this_num;
......
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