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authorSachin Bhamare <sbhamare@panasas.com>2012-03-20 07:47:58 +0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2012-03-21 17:31:47 +0400
commit18d98f6c04991dd3c12acf6f39cea40e9510640a (patch)
tree2057833de8c2c6bb4e3530eed44249b3941b99d8 /Documentation/filesystems/nfs
parentc6bfa1a16377b42496ecc0490a33516c0e414e7b (diff)
downloadlinux-18d98f6c04991dd3c12acf6f39cea40e9510640a.tar.xz
pnfs-obj: autologin: Add support for protocol autologin
The pnfs-objects protocol mandates that we autologin into devices not present in the system, according to information specified in the get_device_info returned from the server. The Protocol specifies two login hints. 1. An IP address:port combination 2. A string URI which is constructed as a URL with a protocol prefix followed by :// and a string as address. For each protocol prefix the string-address format might be different. We only support the second option. The first option is just redundant to the second one. NOTE: The Kernel part of autologin does not parse the URI string. It just channels it to a user-mode script. So any new login protocols should only update the user-mode script which is a part of the nfs-utils package, but the Kernel need not change. We implement the autologin by using the call_usermodehelper() API. (Thanks to Steve Dickson <steved@redhat.com> for pointing it out) So there is no running daemon needed, and/or special setup. We Add the osd_login_prog Kernel module parameters which defaults to: /sbin/osd_login Kernel try's to upcall the program specified in osd_login_prog. If the file is not found or the execution fails Kernel will disable any farther upcalls, by zeroing out osd_login_prog, Until Admin re-enables it by setting the osd_login_prog parameter to a proper program. Also add text about the osd_login program command line API to: Documentation/filesystems/nfs/pnfs.txt and documentation of the new osd_login_prog module parameter to: Documentation/kernel-parameters.txt TODO: Add timeout option in the case osd_login program gets stuck Signed-off-by: Sachin Bhamare <sbhamare@panasas.com> Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'Documentation/filesystems/nfs')
-rw-r--r--Documentation/filesystems/nfs/pnfs.txt54
1 files changed, 54 insertions, 0 deletions
diff --git a/Documentation/filesystems/nfs/pnfs.txt b/Documentation/filesystems/nfs/pnfs.txt
index 983e14abe7e9..c7919c6e3bea 100644
--- a/Documentation/filesystems/nfs/pnfs.txt
+++ b/Documentation/filesystems/nfs/pnfs.txt
@@ -53,3 +53,57 @@ lseg maintains an extra reference corresponding to the NFS_LSEG_VALID
bit which holds it in the pnfs_layout_hdr's list. When the final lseg
is removed from the pnfs_layout_hdr's list, the NFS_LAYOUT_DESTROYED
bit is set, preventing any new lsegs from being added.
+
+layout drivers
+--------------
+
+PNFS utilizes what is called layout drivers. The STD defines 3 basic
+layout types: "files" "objects" and "blocks". For each of these types
+there is a layout-driver with a common function-vectors table which
+are called by the nfs-client pnfs-core to implement the different layout
+types.
+
+Files-layout-driver code is in: fs/nfs/nfs4filelayout.c && nfs4filelayoutdev.c
+Objects-layout-deriver code is in: fs/nfs/objlayout/.. directory
+Blocks-layout-deriver code is in: fs/nfs/blocklayout/.. directory
+
+objects-layout setup
+--------------------
+
+As part of the full STD implementation the objlayoutdriver.ko needs, at times,
+to automatically login to yet undiscovered iscsi/osd devices. For this the
+driver makes up-calles to a user-mode script called *osd_login*
+
+The path_name of the script to use is by default:
+ /sbin/osd_login.
+This name can be overridden by the Kernel module parameter:
+ objlayoutdriver.osd_login_prog
+
+If Kernel does not find the osd_login_prog path it will zero it out
+and will not attempt farther logins. An admin can then write new value
+to the objlayoutdriver.osd_login_prog Kernel parameter to re-enable it.
+
+The /sbin/osd_login is part of the nfs-utils package, and should usually
+be installed on distributions that support this Kernel version.
+
+The API to the login script is as follows:
+ Usage: $0 -u <URI> -o <OSDNAME> -s <SYSTEMID>
+ Options:
+ -u target uri e.g. iscsi://<ip>:<port>
+ (allways exists)
+ (More protocols can be defined in the future.
+ The client does not interpret this string it is
+ passed unchanged as recieved from the Server)
+ -o osdname of the requested target OSD
+ (Might be empty)
+ (A string which denotes the OSD name, there is a
+ limit of 64 chars on this string)
+ -s systemid of the requested target OSD
+ (Might be empty)
+ (This string, if not empty is always an hex
+ representation of the 20 bytes osd_system_id)
+
+blocks-layout setup
+-------------------
+
+TODO: Document the setup needs of the blocks layout driver