svcshare.c

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

/*
 * linux/fs/lockd/svcshare.c
 *
 * Management of DOS shares.
 *
 * Copyright (C) 1996 Olaf Kirch <[e-mail]>
 */

#include <linux/sched.h>
#include <linux/unistd.h>
#include <linux/string.h>
#include <linux/slab.h>

#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/lockd/lockd.h>
#include <linux/lockd/share.h>

static inline int
nlm_cmp_owner(struct nlm_share *share, struct xdr_netobj *oh)
{
	return share->s_owner.len == oh->len
	    && !memcmp(share->s_owner.data, oh->data, oh->len);
}

u32
nlmsvc_share_file(struct nlm_host *host, struct nlm_file *file,
			struct nlm_args *argp)
{
	struct nlm_share	*share;
	struct xdr_netobj	*oh = &argp->lock.oh;
	u8			*ohdata;

	for (share = file->f_shares; share; share = share->s_next) {
		if (share->s_host == host && nlm_cmp_owner(share, oh))
			goto update;
		if ((argp->fsm_access & share->s_mode)
		 || (argp->fsm_mode   & share->s_access ))
			return nlm_lck_denied;
	}

	share = (struct nlm_share *) kmalloc(sizeof(*share) + oh->len,
						GFP_KERNEL);
	if (share == NULL)
		return nlm_lck_denied_nolocks;

	/* Copy owner handle */
	ohdata = (u8 *) (share + 1);
	memcpy(ohdata, oh->data, oh->len);

	share->s_file	    = file;
	share->s_host       = host;
	share->s_owner.data = ohdata;
	share->s_owner.len  = oh->len;
	share->s_next       = file->f_shares;
	file->f_shares      = share;

update:
	share->s_access = argp->fsm_access;
	share->s_mode   = argp->fsm_mode;
	return nlm_granted;
}

/*
 * Delete a share.
 */
u32
nlmsvc_unshare_file(struct nlm_host *host, struct nlm_file *file,
			struct nlm_args *argp)
{
	struct nlm_share	*share, **shpp;
	struct xdr_netobj	*oh = &argp->lock.oh;

	for (shpp = &file->f_shares; (share = *shpp); shpp = &share->s_next) {
		if (share->s_host == host && nlm_cmp_owner(share, oh)) {
			*shpp = share->s_next;
			kfree(share);
			return nlm_granted;
		}
	}

	/* X/Open spec says return success even if there was no
	 * corresponding share. */
	return nlm_granted;
}

/*
 * Traverse all shares for a given file (and host).
 * NLM_ACT_CHECK is handled by nlmsvc_inspect_file.
 */
int
nlmsvc_traverse_shares(struct nlm_host *host, struct nlm_file *file, int action)
{
	struct nlm_share	*share, **shpp;

	shpp = &file->f_shares;
	while ((share = *shpp) !=  NULL) {
		if (action == NLM_ACT_MARK)
			share->s_host->h_inuse = 1;
		else if (action == NLM_ACT_UNLOCK) {
			if (host == NULL || host == share->s_host) {
				*shpp = share->s_next;
				kfree(share);
				continue;
			}
		}
		shpp = &share->s_next;
	}

	return 0;
}