fuse: add retrieve request
Userspace filesystem can request data to be retrieved from the inode's
mapping. This request is synchronous and the retrieved data is queued
as a new request. If the write to the fuse device returns an error
then the retrieve request was not completed and a reply will not be
sent.
Only present pages are returned in the retrieve reply. Retrieving
stops when it finds a non-present page and only data prior to that is
returned.
This request doesn't change the dirty state of pages.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 8e01c86..69ad053 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -239,7 +239,6 @@
static void queue_request(struct fuse_conn *fc, struct fuse_req *req)
{
- req->in.h.unique = fuse_get_unique(fc);
req->in.h.len = sizeof(struct fuse_in_header) +
len_args(req->in.numargs, (struct fuse_arg *) req->in.args);
list_add_tail(&req->list, &fc->pending);
@@ -261,6 +260,7 @@
req = list_entry(fc->bg_queue.next, struct fuse_req, list);
list_del(&req->list);
fc->active_background++;
+ req->in.h.unique = fuse_get_unique(fc);
queue_request(fc, req);
}
}
@@ -398,6 +398,7 @@
else if (fc->conn_error)
req->out.h.error = -ECONNREFUSED;
else {
+ req->in.h.unique = fuse_get_unique(fc);
queue_request(fc, req);
/* acquire extra reference, since request is still needed
after request_end() */
@@ -450,6 +451,23 @@
}
EXPORT_SYMBOL_GPL(fuse_request_send_background);
+static int fuse_request_send_notify_reply(struct fuse_conn *fc,
+ struct fuse_req *req, u64 unique)
+{
+ int err = -ENODEV;
+
+ req->isreply = 0;
+ req->in.h.unique = unique;
+ spin_lock(&fc->lock);
+ if (fc->connected) {
+ queue_request(fc, req);
+ err = 0;
+ }
+ spin_unlock(&fc->lock);
+
+ return err;
+}
+
/*
* Called under fc->lock
*
@@ -1316,6 +1334,114 @@
return err;
}
+static void fuse_retrieve_end(struct fuse_conn *fc, struct fuse_req *req)
+{
+ int i;
+
+ for (i = 0; i < req->num_pages; i++) {
+ struct page *page = req->pages[i];
+ page_cache_release(page);
+ }
+}
+
+static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode,
+ struct fuse_notify_retrieve_out *outarg)
+{
+ int err;
+ struct address_space *mapping = inode->i_mapping;
+ struct fuse_req *req;
+ pgoff_t index;
+ loff_t file_size;
+ unsigned int num;
+ unsigned int offset;
+ size_t total_len;
+
+ req = fuse_get_req(fc);
+ 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;
+ req->in.argpages = 1;
+ req->page_offset = offset;
+ 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) {
+ struct page *page;
+ unsigned int this_num;
+
+ page = find_get_page(mapping, index);
+ if (!page)
+ break;
+
+ this_num = min_t(unsigned, num, PAGE_CACHE_SIZE - offset);
+ req->pages[req->num_pages] = page;
+ req->num_pages++;
+
+ num -= this_num;
+ total_len += this_num;
+ }
+ req->misc.retrieve_in.offset = outarg->offset;
+ req->misc.retrieve_in.size = total_len;
+ req->in.args[0].size = sizeof(req->misc.retrieve_in);
+ req->in.args[0].value = &req->misc.retrieve_in;
+ req->in.args[1].size = total_len;
+
+ err = fuse_request_send_notify_reply(fc, req, outarg->notify_unique);
+ if (err)
+ fuse_retrieve_end(fc, req);
+
+ return err;
+}
+
+static int fuse_notify_retrieve(struct fuse_conn *fc, unsigned int size,
+ struct fuse_copy_state *cs)
+{
+ struct fuse_notify_retrieve_out outarg;
+ struct inode *inode;
+ int err;
+
+ err = -EINVAL;
+ if (size != sizeof(outarg))
+ goto copy_finish;
+
+ err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+ if (err)
+ goto copy_finish;
+
+ fuse_copy_finish(cs);
+
+ down_read(&fc->killsb);
+ err = -ENOENT;
+ if (fc->sb) {
+ u64 nodeid = outarg.nodeid;
+
+ inode = ilookup5(fc->sb, nodeid, fuse_inode_eq, &nodeid);
+ if (inode) {
+ err = fuse_retrieve(fc, inode, &outarg);
+ iput(inode);
+ }
+ }
+ up_read(&fc->killsb);
+
+ return err;
+
+copy_finish:
+ fuse_copy_finish(cs);
+ return err;
+}
+
static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
unsigned int size, struct fuse_copy_state *cs)
{
@@ -1332,6 +1458,9 @@
case FUSE_NOTIFY_STORE:
return fuse_notify_store(fc, size, cs);
+ case FUSE_NOTIFY_RETRIEVE:
+ return fuse_notify_retrieve(fc, size, cs);
+
default:
fuse_copy_finish(cs);
return -EINVAL;