From 2d45ba381a74a743eeaa2b06c7c5c0d2bf73ba1a Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 12 Jul 2010 14:41:40 +0200 Subject: [PATCH] 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 --- fs/fuse/dev.c | 131 ++++++++++++++++++++++++++++++++++++++++++- fs/fuse/fuse_i.h | 1 + include/linux/fuse.h | 21 +++++++ 3 files changed, 152 insertions(+), 1 deletion(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 8e01c865586e..69ad053ffd78 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -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 @@ out_finish: 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; diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 61267d8d527b..57d4a3a0f102 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -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; diff --git a/include/linux/fuse.h b/include/linux/fuse.h index a90bd49834aa..c3c578e09833 100644 --- a/include/linux/fuse.h +++ b/include/linux/fuse.h @@ -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 */ -- 2.20.1