fuse: add store request

Userspace filesystem can request data to be stored in the inode's
mapping.  This request is synchronous and has no reply.  If the write
to the fuse device returns an error then the store request was not
fully completed (but may have updated some pages).

If the stored data overflows the current file size, then the size is
extended, similarly to a write(2) on the filesystem.

Pages which have been completely stored are marked uptodate.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

1 files changed, 88 insertions, 0 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 7eb80d33c4f3..8e01c865586e 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1231,6 +1231,91 @@ err:
         return err;
 }
 
+static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
+                             struct fuse_copy_state *cs)
+{
+        struct fuse_notify_store_out outarg;
+        struct inode *inode;
+        struct address_space *mapping;
+        u64 nodeid;
+        int err;
+        pgoff_t index;
+        unsigned int offset;
+        unsigned int num;
+        loff_t file_size;
+        loff_t end;
+
+        err = -EINVAL;
+        if (size < sizeof(outarg))
+                goto out_finish;
+
+        err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+        if (err)
+                goto out_finish;
+
+        err = -EINVAL;
+        if (size - sizeof(outarg) != outarg.size)
+                goto out_finish;
+
+        nodeid = outarg.nodeid;
+
+        down_read(&fc->killsb);
+
+        err = -ENOENT;
+        if (!fc->sb)
+                goto out_up_killsb;
+
+        inode = ilookup5(fc->sb, nodeid, fuse_inode_eq, &nodeid);
+        if (!inode)
+                goto out_up_killsb;
+
+        mapping = inode->i_mapping;
+        index = outarg.offset >> PAGE_CACHE_SHIFT;
+        offset = outarg.offset & ~PAGE_CACHE_MASK;
+        file_size = i_size_read(inode);
+        end = outarg.offset + outarg.size;
+        if (end > file_size) {
+                file_size = end;
+                fuse_write_update_size(inode, file_size);
+        }
+
+        num = outarg.size;
+        while (num) {
+                struct page *page;
+                unsigned int this_num;
+
+                err = -ENOMEM;
+                page = find_or_create_page(mapping, index,
+                                           mapping_gfp_mask(mapping));
+                if (!page)
+                        goto out_iput;
+
+                this_num = min_t(unsigned, num, PAGE_CACHE_SIZE - offset);
+                err = fuse_copy_page(cs, &page, offset, this_num, 0);
+                if (!err && offset == 0 && (num != 0 || file_size == end))
+                        SetPageUptodate(page);
+                unlock_page(page);
+                page_cache_release(page);
+
+                if (err)
+                        goto out_iput;
+
+                num -= this_num;
+                offset = 0;
+                index++;
+        }
+
+        err = 0;
+
+out_iput:
+        iput(inode);
+out_up_killsb:
+        up_read(&fc->killsb);
+out_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)
 {
@@ -1244,6 +1329,9 @@ static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
         case FUSE_NOTIFY_INVAL_ENTRY:
                 return fuse_notify_inval_entry(fc, size, cs);
 
+        case FUSE_NOTIFY_STORE:
+                return fuse_notify_store(fc, size, cs);
+
         default:
                 fuse_copy_finish(cs);
                 return -EINVAL;