Kernel currently does not allow to queue work into some entity which
will perform it in the process context and have simple way to extend
number of worker and work with them not as separate objects, but with
pool as a whole. So thread pool model was implemented in the DST.
Thread pool abstraction allows to schedule a work to be performed
on behalf of kernel thread. One does not operate with threads itself,
instead user provides setup and cleanup callbacks for thread pool itself,
and action and cleanup callbacks for each submitted work.
Each worker has private data initialized at creation time and data,
provided by user at scheduling time.
When action is being performed, thread can not be used by other users,
instead they will sleep until there is free thread to pick their work.
Thread pool is used for crypto processing of incoming and outgoing IO
requests to reduce the overall overhead.
Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch introduces remote (export) node machinery: initialization
address/port (and other socket parameters), export block device (can be
another DST storage for example or local device like /dev/sda1), local
IO processing engine (BIO state machines, receiving/submitting logic).
Network management for the export node like accepting new client, scheduling
its command processing thread, receiving/sending IO requests, all are placed
here.
Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Each DST device contains of two nodes: local and remote (called also as export node).
This patch contains local node processing engine: network state storage,
socket processing loops and state machine, socket polling machinery, reconnection
logic, send/receive basic helpers, related IO commands and so on.
Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This patch contains DST core files, which introduce
block layer, connector and sysfs registration glue and main headers.
Connector is used for the configuration of the node (its type, address,
device name and so on). Sysfs provides bits of information about running
devices in the following format:
+/*
+ * DST sysfs tree for device called 'storage':
+ *
+ * /sys/bus/dst/devices/storage/
+ * /sys/bus/dst/devices/storage/type : 192.168.4.80:1025
+ * /sys/bus/dst/devices/storage/size : 800
+ * /sys/bus/dst/devices/storage/name : storage
+ */
DST header contains structure definitions and protocol command description.
Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
