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1What: /sys/class/rnbd-client
2Date: Feb 2020
3KernelVersion: 5.7
4Contact: Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
5Description: Provide information about RNBD-client.
6 All sysfs files that are not read-only provide the usage information on read:
7
8 Example:
9 # cat /sys/class/rnbd-client/ctl/map_device
10
11 > Usage: echo "sessname=<name of the rtrs session> path=<[srcaddr,]dstaddr>
12 > [path=<[srcaddr,]dstaddr>] device_path=<full path on remote side>
13 > [access_mode=<ro|rw|migration>] > map_device
14 >
15 > addr ::= [ ip:<ipv4> | ip:<ipv6> | gid:<gid> ]
16
17What: /sys/class/rnbd-client/ctl/map_device
18Date: Feb 2020
19KernelVersion: 5.7
20Contact: Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
21Description: Expected format is the following:
22
23 sessname=<name of the rtrs session>
24 path=<[srcaddr,]dstaddr> [path=<[srcaddr,]dstaddr> ...]
25 device_path=<full path on remote side>
26 [access_mode=<ro|rw|migration>]
27
28 Where:
29
30 sessname: accepts a string not bigger than 256 chars, which identifies
31 a given session on the client and on the server.
32 I.e. "clt_hostname-srv_hostname" could be a natural choice.
33
34 path: describes a connection between the client and the server by
35 specifying destination and, when required, the source address.
36 The addresses are to be provided in the following format:
37
38 ip:<IPv6>
39 ip:<IPv4>
40 gid:<GID>
41
42 for example:
43
44 path=ip:10.0.0.66
45 The single addr is treated as the destination.
46 The connection will be established to this server from any client IP address.
47
48 path=ip:10.0.0.66,ip:10.0.1.66
49 First addr is the source address and the second is the destination.
50
51 If multiple "path=" options are specified multiple connection
52 will be established and data will be sent according to
53 the selected multipath policy (see RTRS mp_policy sysfs entry description).
54
55 device_path: Path to the block device on the server side. Path is specified
56 relative to the directory on server side configured in the
57 'dev_search_path' module parameter of the rnbd_server.
58 The rnbd_server prepends the <device_path> received from client
59 with <dev_search_path> and tries to open the
60 <dev_search_path>/<device_path> block device. On success,
61 a /dev/rnbd<N> device file, a /sys/block/rnbd_client/rnbd<N>/
62 directory and an entry in /sys/class/rnbd-client/ctl/devices
63 will be created.
64
65 If 'dev_search_path' contains '%SESSNAME%', then each session can
66 have different devices namespace, e.g. server was configured with
67 the following parameter "dev_search_path=/run/rnbd-devs/%SESSNAME%",
68 client has this string "sessname=blya device_path=sda", then server
69 will try to open: /run/rnbd-devs/blya/sda.
70
71 access_mode: the access_mode parameter specifies if the device is to be
72 mapped as "ro" read-only or "rw" read-write. The server allows
73 a device to be exported in rw mode only once. The "migration"
74 access mode has to be specified if a second mapping in read-write
75 mode is desired.
76
77 By default "rw" is used.
78
79 Exit Codes:
80
81 If the device is already mapped it will fail with EEXIST. If the input
82 has an invalid format it will return EINVAL. If the device path cannot
83 be found on the server, it will fail with ENOENT.
84
85 Finding device file after mapping
86 ---------------------------------
87
88 After mapping, the device file can be found by:
89 o The symlink /sys/class/rnbd-client/ctl/devices/<device_id>
90 points to /sys/block/<dev-name>. The last part of the symlink destination
91 is the same as the device name. By extracting the last part of the
92 path the path to the device /dev/<dev-name> can be build.
93
94 o /dev/block/$(cat /sys/class/rnbd-client/ctl/devices/<device_id>/dev)
95
96 How to find the <device_id> of the device is described on the next
97 section.
98
99What: /sys/class/rnbd-client/ctl/devices/
100Date: Feb 2020
101KernelVersion: 5.7
102Contact: Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
103Description: For each device mapped on the client a new symbolic link is created as
104 /sys/class/rnbd-client/ctl/devices/<device_id>, which points
105 to the block device created by rnbd (/sys/block/rnbd<N>/).
106 The <device_id> of each device is created as follows:
107
108 - If the 'device_path' provided during mapping contains slashes ("/"),
109 they are replaced by exclamation mark ("!") and used as as the
110 <device_id>. Otherwise, the <device_id> will be the same as the
111 "device_path" provided.