pnfs-obj: autologin: Add support for protocol autologin

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

			information.

	objlayoutdriver.osd_login_prog=

			[NFS] [OBJLAYOUT] sets the pathname to the program which

			is used to automatically discover and login into new

			osd-targets. Please see:

			Documentation/filesystems/pnfs.txt for more explanations

	nmi_debug=	[KNL,AVR32,SH] Specify one or more actions to take

			when a NMI is triggered.

			Format: [state][,regs][,debounce][,die]

	struct objio_dev_ent *ode;

	struct osd_dev *od;

	struct osd_dev_info odi;

	bool retry_flag = true;

	int err;

	ode = _dev_list_find(NFS_SERVER(pnfslay->plh_inode), d_id);

		goto out;

	}

retry_lookup:

	od = osduld_info_lookup(&odi);

	if (unlikely(IS_ERR(od))) {

		err = PTR_ERR(od);

		dprintk("%s: osduld_info_lookup => %d\n", __func__, err);

		if (err == -ENODEV && retry_flag) {

			err = objlayout_autologin(deviceaddr);

			if (likely(!err)) {

				retry_flag = false;

				goto retry_lookup;

			}

		}

		goto out;

	}

 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include <linux/kmod.h>

#include <linux/moduleparam.h>

#include <linux/ratelimit.h>

#include <scsi/osd_initiator.h>

#include "objlayout.h"

	__free_page(odi->page);

	kfree(odi);

}

enum {

	OBJLAYOUT_MAX_URI_LEN = 256, OBJLAYOUT_MAX_OSDNAME_LEN = 64,

	OBJLAYOUT_MAX_SYSID_HEX_LEN = OSD_SYSTEMID_LEN * 2 + 1,

	OSD_LOGIN_UPCALL_PATHLEN  = 256

};

static char osd_login_prog[OSD_LOGIN_UPCALL_PATHLEN] = "/sbin/osd_login";

module_param_string(osd_login_prog, osd_login_prog, sizeof(osd_login_prog),

		    0600);

MODULE_PARM_DESC(osd_login_prog, "Path to the osd_login upcall program");

struct __auto_login {

	char uri[OBJLAYOUT_MAX_URI_LEN];

	char osdname[OBJLAYOUT_MAX_OSDNAME_LEN];

	char systemid_hex[OBJLAYOUT_MAX_SYSID_HEX_LEN];

};

static int __objlayout_upcall(struct __auto_login *login)

{

	static char *envp[] = { "HOME=/",

		"TERM=linux",

		"PATH=/sbin:/usr/sbin:/bin:/usr/bin",

		NULL

	};

	char *argv[8];

	int ret;

	if (unlikely(!osd_login_prog[0])) {

		dprintk("%s: osd_login_prog is disabled\n", __func__);

		return -EACCES;

	}

	dprintk("%s uri: %s\n", __func__, login->uri);

	dprintk("%s osdname %s\n", __func__, login->osdname);

	dprintk("%s systemid_hex %s\n", __func__, login->systemid_hex);

	argv[0] = (char *)osd_login_prog;

	argv[1] = "-u";

	argv[2] = login->uri;

	argv[3] = "-o";

	argv[4] = login->osdname;

	argv[5] = "-s";

	argv[6] = login->systemid_hex;

	argv[7] = NULL;

	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);

	/*

	 * Disable the upcall mechanism if we're getting an ENOENT or

	 * EACCES error. The admin can re-enable it on the fly by using

	 * sysfs to set the objlayoutdriver.osd_login_prog module parameter once

	 * the problem has been fixed.

	 */

	if (ret == -ENOENT || ret == -EACCES) {

		printk(KERN_ERR "PNFS-OBJ: %s was not found please set "

			"objlayoutdriver.osd_login_prog kernel parameter!\n",

			osd_login_prog);

		osd_login_prog[0] = '\0';

	}

	dprintk("%s %s return value: %d\n", __func__, osd_login_prog, ret);

	return ret;

}

/* Assume dest is all zeros */

static void __copy_nfsS_and_zero_terminate(struct nfs4_string s,

					   char *dest, int max_len,

					   const char *var_name)

{

	if (!s.len)

		return;

	if (s.len >= max_len) {

		pr_warn_ratelimited(

			"objlayout_autologin: %s: s.len(%d) >= max_len(%d)",

			var_name, s.len, max_len);

		s.len = max_len - 1; /* space for null terminator */

	}

	memcpy(dest, s.data, s.len);

}

/* Assume sysid is all zeros */

static void _sysid_2_hex(struct nfs4_string s,

		  char sysid[OBJLAYOUT_MAX_SYSID_HEX_LEN])

{

	int i;

	char *cur;

	if (!s.len)

		return;

	if (s.len != OSD_SYSTEMID_LEN) {

		pr_warn_ratelimited(

		    "objlayout_autologin: systemid_len(%d) != OSD_SYSTEMID_LEN",

		    s.len);

		if (s.len > OSD_SYSTEMID_LEN)

			s.len = OSD_SYSTEMID_LEN;

	}

	cur = sysid;

	for (i = 0; i < s.len; i++)

		cur = hex_byte_pack(cur, s.data[i]);

}

int objlayout_autologin(struct pnfs_osd_deviceaddr *deviceaddr)

{

	int rc;

	struct __auto_login login;

	if (!deviceaddr->oda_targetaddr.ota_netaddr.r_addr.len)

		return -ENODEV;

	memset(&login, 0, sizeof(login));

	__copy_nfsS_and_zero_terminate(

		deviceaddr->oda_targetaddr.ota_netaddr.r_addr,

		login.uri, sizeof(login.uri), "URI");

	__copy_nfsS_and_zero_terminate(

		deviceaddr->oda_osdname,

		login.osdname, sizeof(login.osdname), "OSDNAME");

	_sysid_2_hex(deviceaddr->oda_systemid, login.systemid_hex);

	rc = __objlayout_upcall(&login);

	if (rc > 0) /* script returns positive values */

		rc = -ENODEV;

	return rc;

}

	struct xdr_stream *,

	const struct nfs4_layoutreturn_args *);

extern int objlayout_autologin(struct pnfs_osd_deviceaddr *deviceaddr);

#endif /* _OBJLAYOUT_H */