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Diffstat (limited to 'Documentation/ABI/testing/sysfs-class-rnbd-client')
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diff --git a/Documentation/ABI/testing/sysfs-class-rnbd-client b/Documentation/ABI/testing/sysfs-class-rnbd-client new file mode 100644 index 000000000..0b5997ab3 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-rnbd-client @@ -0,0 +1,133 @@ +What: /sys/class/rnbd-client +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com> +Description: Provide information about RNBD-client. + All sysfs files that are not read-only provide the usage information on read: + + Example:: + + # cat /sys/class/rnbd-client/ctl/map_device + + > Usage: echo "sessname=<name of the rtrs session> path=<[srcaddr,]dstaddr> + > [path=<[srcaddr,]dstaddr>] device_path=<full path on remote side> + > [access_mode=<ro|rw|migration>] > map_device + > + > addr ::= [ ip:<ipv4> | ip:<ipv6> | gid:<gid> ] + +What: /sys/class/rnbd-client/ctl/map_device +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com> +Description: Expected format is the following:: + + sessname=<name of the rtrs session> + path=<[srcaddr,]dstaddr> [path=<[srcaddr,]dstaddr> ...] + device_path=<full path on remote side> + [access_mode=<ro|rw|migration>] + + Where: + + sessname: + accepts a string not bigger than 256 chars, which identifies + a given session on the client and on the server. + I.e. "clt_hostname-srv_hostname" could be a natural choice. + + path: + describes a connection between the client and the server by + specifying destination and, when required, the source address. + The addresses are to be provided in the following format:: + + ip:<IPv6> + ip:<IPv4> + gid:<GID> + + for example:: + + path=ip:10.0.0.66 + + The single addr is treated as the destination. + The connection will be established to this server from any client IP address. + + :: + + path=ip:10.0.0.66,ip:10.0.1.66 + + First addr is the source address and the second is the destination. + + If multiple "path=" options are specified multiple connection + will be established and data will be sent according to + the selected multipath policy (see RTRS mp_policy sysfs entry description). + + device_path: + Path to the block device on the server side. Path is specified + relative to the directory on server side configured in the + 'dev_search_path' module parameter of the rnbd_server. + The rnbd_server prepends the <device_path> received from client + with <dev_search_path> and tries to open the + <dev_search_path>/<device_path> block device. On success, + a /dev/rnbd<N> device file, a /sys/block/rnbd<N>/ + directory and an entry in /sys/class/rnbd-client/ctl/devices + will be created. + + If 'dev_search_path' contains '%SESSNAME%', then each session can + have different devices namespace, e.g. server was configured with + the following parameter "dev_search_path=/run/rnbd-devs/%SESSNAME%", + client has this string "sessname=blya device_path=sda", then server + will try to open: /run/rnbd-devs/blya/sda. + + access_mode: + the access_mode parameter specifies if the device is to be + mapped as "ro" read-only or "rw" read-write. The server allows + a device to be exported in rw mode only once. The "migration" + access mode has to be specified if a second mapping in read-write + mode is desired. + + By default "rw" is used. + + nr_poll_queues + specifies the number of poll-mode queues. If the IO has HIPRI flag, + the block-layer will send the IO via the poll-mode queue. + For fast network and device the polling is faster than interrupt-base + IO handling because it saves time for context switching, switching to + another process, handling the interrupt and switching back to the + issuing process. + + Set -1 if you want to set it as the number of CPUs + By default rnbd client creates only irq-mode queues. + + NOTICE: MUST make a unique session for a device using the poll-mode queues. + + Exit Codes: + + If the device is already mapped it will fail with EEXIST. If the input + has an invalid format it will return EINVAL. If the device path cannot + be found on the server, it will fail with ENOENT. + + Finding device file after mapping + --------------------------------- + + After mapping, the device file can be found by: + o The symlink /sys/class/rnbd-client/ctl/devices/<device_id>@<session_name> + points to /sys/block/<dev-name>. The last part of the symlink destination + is the same as the device name. By extracting the last part of the + path the path to the device /dev/<dev-name> can be build. + + * /dev/block/$(cat /sys/class/rnbd-client/ctl/devices/<device_id>@<session_name>/dev) + + How to find the <device_id> of the device is described on the next + section. + +What: /sys/class/rnbd-client/ctl/devices/ +Date: Feb 2020 +KernelVersion: 5.7 +Contact: Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com> +Description: For each device mapped on the client a new symbolic link is created as + /sys/class/rnbd-client/ctl/devices/<device_id>@<session_name>, which points + to the block device created by rnbd (/sys/block/rnbd<N>/). + The <device_id> of each device is created as follows: + + - If the 'device_path' provided during mapping contains slashes ("/"), + they are replaced by exclamation mark ("!") and used as as the + <device_id>. Otherwise, the <device_id> will be the same as the + "device_path" provided. |