Commit 2d45ba38 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

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: default avatarMiklos Szeredi <mszeredi@suse.cz>
parent a1d75f25
......@@ -239,7 +239,6 @@ static u64 fuse_get_unique(struct fuse_conn *fc)
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 @@ static void flush_bg_queue(struct fuse_conn *fc)
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 @@ void fuse_request_send(struct fuse_conn *fc, struct fuse_req *req)
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 @@ void fuse_request_send_background(struct fuse_conn *fc, struct fuse_req *req)
}
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 @@ static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
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 @@ static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
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;
......
......@@ -272,6 +272,7 @@ struct fuse_req {
struct fuse_write_in in;
struct fuse_write_out out;
} write;
struct fuse_notify_retrieve_in retrieve_in;
struct fuse_lk_in lk_in;
} misc;
......
......@@ -40,6 +40,7 @@
*
* 7.15
* - add store notify
* - add retrieve notify
*/
#ifndef _LINUX_FUSE_H
......@@ -254,6 +255,7 @@ enum fuse_opcode {
FUSE_DESTROY = 38,
FUSE_IOCTL = 39,
FUSE_POLL = 40,
FUSE_NOTIFY_REPLY = 41,
/* CUSE specific operations */
CUSE_INIT = 4096,
......@@ -264,6 +266,7 @@ enum fuse_notify_code {
FUSE_NOTIFY_INVAL_INODE = 2,
FUSE_NOTIFY_INVAL_ENTRY = 3,
FUSE_NOTIFY_STORE = 4,
FUSE_NOTIFY_RETRIEVE = 5,
FUSE_NOTIFY_CODE_MAX,
};
......@@ -579,4 +582,22 @@ struct fuse_notify_store_out {
__u32 padding;
};
struct fuse_notify_retrieve_out {
__u64 notify_unique;
__u64 nodeid;
__u64 offset;
__u32 size;
__u32 padding;
};
/* Matches the size of fuse_write_in */
struct fuse_notify_retrieve_in {
__u64 dummy1;
__u64 offset;
__u32 size;
__u32 dummy2;
__u64 dummy3;
__u64 dummy4;
};
#endif /* _LINUX_FUSE_H */
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