The commit is pushed to "branch-rh7-3.10.0-693.17.1.vz7.45.x-ovz" and will 
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.17.1.vz7.43.7
------>
commit e00e6b130677c3ed9a773a9fd40ad4293224de25
Author: Dmitry Monakhov <dmonak...@openvz.org>
Date:   Mon Feb 19 14:16:28 2018 +0300

    fuse kio: minimal noop engine skeleton
    
    https://jira.sw.ru/browse/PSBM-80680
    Signed-off-by: Dmitry Monakhov <dmonak...@openvz.org>
---
 fs/fuse/Kconfig        |   8 +++
 fs/fuse/Makefile       |   3 ++
 fs/fuse/kio/kio_noop.c | 130 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 141 insertions(+)

diff --git a/fs/fuse/Kconfig b/fs/fuse/Kconfig
index 1b2f6c2c3aaf..fcbb5a565fc6 100644
--- a/fs/fuse/Kconfig
+++ b/fs/fuse/Kconfig
@@ -25,3 +25,11 @@ config CUSE
 
          If you want to develop or use a userspace character device
          based on CUSE, answer Y or M.
+
+config FUSE_KIO_NOOP
+       tristate "Enable kdirect noop io engine"
+       depends on FUSE_FS
+       help
+         This FUSE extension allows to handle io requests directly inside 
kernel
+
+         This is for kdirect io feature debugging only, answer Y or M.
diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index e95eeb445e58..4a250c083f0d 100644
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -5,4 +5,7 @@
 obj-$(CONFIG_FUSE_FS) += fuse.o
 obj-$(CONFIG_CUSE) += cuse.o
 
+obj-$(CONFIG_FUSE_KIO_NOOP)    += fuse_kio_noop.o
+fuse_kio_noop-objs := kio/kio_noop.o
+
 fuse-objs := dev.o dir.o file.o inode.o control.o
diff --git a/fs/fuse/kio/kio_noop.c b/fs/fuse/kio/kio_noop.c
new file mode 100644
index 000000000000..914ed542e762
--- /dev/null
+++ b/fs/fuse/kio/kio_noop.c
@@ -0,0 +1,130 @@
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/printk.h>
+
+#include "../fuse_i.h"
+
+static struct fuse_kio_ops noop_ops;
+static struct kmem_cache *noop_req_cachep;
+
+/* Conn hooks */
+
+static int noop_probe(struct fuse_conn *fc, char *name)
+{
+       if (!strncmp(name, noop_ops.name, FUSE_KIO_NAME))
+               return 1;
+
+       return 0;
+}
+
+static int noop_conn_init(struct fuse_conn *fc)
+{
+       /* Just for sanity checks */
+       fc->kio.ctx = noop_req_cachep;
+       pr_debug("fuse_kio_noop: init");
+
+       /*This one is mandatary */
+       fuse_set_initialized(fc);
+       wake_up_all(&fc->blocked_waitq);
+
+       return 0;
+}
+
+static void noop_conn_fini(struct fuse_conn *fc)
+{
+       BUG_ON(fc->kio.ctx != noop_req_cachep);
+       pr_debug("fuse_kio_noop: fini");
+
+}
+
+static void noop_conn_abort(struct fuse_conn *fc)
+{
+       BUG_ON(fc->kio.ctx != noop_req_cachep);
+       pr_debug("fuse_kio_noop: abort");
+}
+
+/* Request hooks */
+static struct fuse_req *noop_req_alloc(struct fuse_conn *fc, unsigned npages,
+                                      gfp_t flags)
+{
+       return fuse_generic_request_alloc(fc, noop_req_cachep, npages, flags);
+}
+
+static int noop_req_send(struct fuse_conn *fc, struct fuse_req *req, bool bg,
+                        bool locked)
+{
+       /* Do not intercept request for unconnected channel */
+       if (!fc->initialized)
+               return 1;
+
+       BUG_ON(fc->kio.ctx != noop_req_cachep);
+       BUG_ON(req->cache != noop_req_cachep);
+
+       /* fall back to generic fuse io-flow */
+       return 1;
+}
+
+/* Optional inode scope hooks
+static int noop_file_open(struct fuse_conn *fc, struct file *file,
+                         struct inode *inode)
+{
+       return 0;
+}
+
+static void noop_inode_release(struct fuse_inode *fi)
+{
+}
+*/
+
+static struct fuse_kio_ops noop_ops = {
+       .name           = "noop",
+       .owner          = THIS_MODULE,
+       .probe          = noop_probe,
+
+       .conn_init      = noop_conn_init,
+       .conn_fini      = noop_conn_fini,
+       .conn_abort     = noop_conn_abort,
+       .req_alloc      = noop_req_alloc,
+       .req_send       = noop_req_send,
+       /* Optional inode state hooks
+        *.file_open    = noop_file_open,
+        *.inode_release= noop_inode_release,
+        */
+};
+
+static int __init kio_noop_mod_init(void)
+{
+       int err;
+
+       noop_req_cachep = kmem_cache_create("noop_fuse_request",
+                                           sizeof(struct fuse_req),
+                                           0, 0, NULL);
+       if (!noop_req_cachep)
+               return -ENOMEM;
+
+       err = -EINVAL;
+       if (fuse_register_kio(&noop_ops))
+               goto free_cache;
+
+       return 0;
+
+free_cache:
+       kmem_cache_destroy(noop_req_cachep);
+       return err;
+}
+
+static void __exit kio_noop_mod_exit(void)
+{
+       fuse_unregister_kio(&noop_ops);
+       kmem_cache_destroy(noop_req_cachep);
+}
+
+module_init(kio_noop_mod_init);
+module_exit(kio_noop_mod_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Virtuozzo <devel@openvz.org>");
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