Implement client side NFS locks.

Obtained from: BSD/os
Import Ok'd by: mckusick, jkh, motd on builder.freebsd.org

1 files changed, 269 insertions, 0 deletions

diff --git a/sys/nfs/nfs_lock.c b/sys/nfs/nfs_lock.c
new file mode 100644
index 0000000..aaac361
--- /dev/null
+++ b/sys/nfs/nfs_lock.c
@@ -0,0 +1,269 @@
+/*-
+ * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Berkeley Software Design Inc's name may not be used to endorse or
+ *    promote products derived from this software without specific prior
+ *    written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *      from BSDI nfs_lock.c,v 2.4 1998/12/14 23:49:56 jch Exp
+ * $FreeBSD$
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/fcntl.h>
+#include <sys/malloc.h>
+#include <sys/mbuf.h>
+#include <sys/mount.h>
+#include <sys/namei.h>
+#include <sys/proc.h>
+#include <sys/socket.h>
+#include <sys/unistd.h>
+#include <sys/vnode.h>
+#include <sys/resourcevar.h>
+#include <sys/kernel.h>			/* for hz */
+#include <sys/lockf.h>			/* for hz */
+
+#include <net/if.h>
+
+#include <nfs/rpcv2.h>
+#include <nfs/nfsproto.h>
+#include <nfs/nfs.h>
+#include <nfs/nfsmount.h>
+#include <nfs/nfsnode.h>
+#include <nfs/nfs_lock.h>
+#include <nfs/nlminfo.h>
+
+#define NFSOWNER_1ST_LEVEL_START	1	       /* initial entries */
+#define NFSOWNER_2ND_LEVEL	      256		/* some power of 2 */
+
+#define NFSOWNER(tbl, i)	\
+		(tbl)[(i) / NFSOWNER_2ND_LEVEL][(i) % NFSOWNER_2ND_LEVEL]
+
+/*
+ * XXX
+ * We have to let the process know if the call succeeded.  I'm using an extra
+ * field in the p_nlminfo field in the proc structure, as it is already for 
+ * lockd stuff.
+ */
+
+/*
+ * nfs_advlock --
+ *      NFS advisory byte-level locks.
+ */
+int
+nfs_dolock(ap)
+	struct vop_advlock_args /* {
+		struct vnode *a_vp;
+		caddr_t a_id;
+		int  a_op;
+		struct flock *a_fl;
+		int a_flags;
+	} */ *ap;
+{
+	LOCKD_MSG msg;
+	struct nameidata nd;
+	struct proc *p;
+	uid_t	saved_uid;
+	struct vnode *vp, *wvp;
+	int error, error1;
+	struct flock *fl;
+	int fmode, ioflg;
+
+	p = curproc;
+	vp = ap->a_vp;
+	fl = ap->a_fl;
+
+	/*
+	 * the NLM protocol doesn't allow the server to return an error
+	 * on ranges, so we do it.  Note that we should be returning 
+	 * EOVERFLOW in some cases, but we don't have it.
+	 */
+	if (fl->l_start < 0 || fl->l_len < 0 ||
+	    ((fl->l_len != 0 &&
+	     (fl->l_start + fl->l_len - 1) < 0)))
+		return (EINVAL);
+
+	/*
+	 * Fill in the information structure.
+	 */
+	msg.lm_version = LOCKD_MSG_VERSION;
+	msg.lm_msg_ident.pid = p->p_pid;
+	/*
+	 * if there is no nfsowner table yet, allocate one.
+	 */
+	if (p->p_nlminfo == NULL) {
+		MALLOC(p->p_nlminfo, struct nlminfo *,
+			sizeof(struct nlminfo), M_LOCKF, M_WAITOK | M_ZERO);
+		p->p_nlminfo->pid_start = p->p_stats->p_start;
+	}
+	msg.lm_msg_ident.pid_start = p->p_nlminfo->pid_start;
+	msg.lm_msg_ident.msg_seq = ++(p->p_nlminfo->msg_seq);
+
+	msg.lm_fl = *fl;
+	msg.lm_wait = ap->a_flags & F_WAIT;
+	msg.lm_getlk = ap->a_op == F_GETLK;
+	/*
+	 * XXX  -- I think this is wrong for anything other AF_INET.
+	 */
+	msg.lm_addr = *(VFSTONFS(vp->v_mount)->nm_nam);
+	msg.lm_fh_len = NFS_ISV3(vp) ? VTONFS(vp)->n_fhsize : NFSX_V2FH;
+	bcopy(VTONFS(vp)->n_fhp, msg.lm_fh, msg.lm_fh_len);
+	msg.lm_nfsv3 = NFS_ISV3(vp);
+	msg.lm_cred = *(p->p_ucred);
+
+	/*
+	 * Open the lock fifo.  If for any reason we don't find the fifo, it
+	 * means that the lock daemon isn't running.  Translate any missing
+	 * file error message for the user, otherwise the application will
+	 * complain that the user's file is missing, which isn't the case.
+	 * Note that we use proc0's cred, so the fifo is opened as root.
+	 */
+	NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, _PATH_LCKFIFO, p);
+
+	/*
+	 * XXX Hack to temporarily allow this process (regardless of it's creds)
+	 * to open the fifo we need to write to. vn_open() really should
+	 * take a ucred (and once it does, this code should be fixed to use
+	 * proc0's ucred.
+	 */
+	saved_uid = p->p_ucred->cr_uid;
+	p->p_ucred->cr_uid = 0;		/* temporarly run the vn_open as root */
+
+	fmode = FFLAGS(O_WRONLY);
+	error = vn_open(&nd, &fmode, 0);
+	p->p_ucred->cr_uid = saved_uid;
+	if (error != 0) {
+		return (error == ENOENT ? EOPNOTSUPP : error);
+	}
+	wvp = nd.ni_vp;
+	VOP_UNLOCK(wvp, 0, p);		/* vn_open leaves it locked */
+
+
+	ioflg = IO_UNIT;
+	for (;;) {
+		VOP_LEASE(wvp, p, proc0.p_ucred, LEASE_WRITE);
+
+		error = vn_rdwr(UIO_WRITE, wvp, (caddr_t)&msg, sizeof(msg), 0,
+		    UIO_SYSSPACE, ioflg, proc0.p_ucred, NULL, p);
+
+		if (error && (((ioflg & IO_NDELAY) == 0) || error != EAGAIN)) {
+			break;
+		}
+		/*
+		 * If we're locking a file, wait for an answer.  Unlocks succeed
+		 * immediately.
+		 */
+		if (fl->l_type == F_UNLCK)
+			/*
+			 * XXX this isn't exactly correct.  The client side
+			 * needs to continue sending it's unlock until
+			 * it gets a responce back.
+			 */
+			break;
+
+		/*
+		 * retry after 20 seconds if we haven't gotten a responce yet.
+		 * This number was picked out of thin air... but is longer
+		 * then even a reasonably loaded system should take (at least
+		 * on a local network).  XXX Probably should use a back-off 
+		 * scheme.
+		 */
+		if ((error = tsleep((void *)p->p_nlminfo, 
+					PCATCH | PUSER, "lockd", 20*hz)) != 0) {
+			if (error == EWOULDBLOCK) {
+				/*
+				 * We timed out, so we rewrite the request
+				 * to the fifo, but only if it isn't already
+				 * full.
+				 */
+				ioflg |= IO_NDELAY;
+				continue;
+			}
+
+			break;
+		}
+
+		if (msg.lm_getlk && p->p_nlminfo->retcode == 0) {
+			if (p->p_nlminfo->set_getlk_pid) {
+				fl->l_pid = p->p_nlminfo->getlk_pid;
+			} else {
+				fl->l_type = F_UNLCK;
+			}
+		}
+		error = p->p_nlminfo->retcode;
+		break;
+	}
+
+	if ((error1 = vn_close(wvp, FWRITE, proc0.p_ucred, p)) && error == 0)
+		return (error1);
+
+	return (error);
+}
+
+/*
+ * nfslockdans --
+ *      NFS advisory byte-level locks answer from the lock daemon.
+ */
+int
+nfslockdans(p, ansp)
+	struct proc *p;
+	struct lockd_ans *ansp;
+{
+	int error;
+
+	/* Let root, or someone who once was root (lockd generally
+	 * switches to the daemon uid once it is done setting up) make 
+	 * this call
+	 */
+	if ((error = suser(p)) != 0 && p->p_cred->p_svuid != 0)
+		return (error);
+
+	/* the version should match, or we're out of sync */
+	if (ansp->la_vers != LOCKD_ANS_VERSION)
+		return (EINVAL);
+
+	/* Find the process, set its return errno and wake it up. */
+	if ((p = pfind(ansp->la_msg_ident.pid)) == NULL)
+		return (ESRCH);
+
+	/* verify the pid hasn't been reused (if we can), and it isn't waiting 
+	 * for an answer from a more recent request.  We return an EPIPE if
+	 * the match fails, because we've already used ESRCH above, and this
+	 * is sort of like writing on a pipe after the reader has closed it.
+	 */
+	if (p->p_nlminfo == NULL ||
+	    ((ansp->la_msg_ident.msg_seq != -1) &&
+	      (timevalcmp(&p->p_nlminfo->pid_start,
+			&ansp->la_msg_ident.pid_start, !=) ||
+	       p->p_nlminfo->msg_seq != ansp->la_msg_ident.msg_seq)))
+		return (EPIPE);
+
+	p->p_nlminfo->retcode = ansp->la_errno;
+	p->p_nlminfo->set_getlk_pid = ansp->la_set_getlk_pid;
+	p->p_nlminfo->getlk_pid = ansp->la_getlk_pid;
+
+	(void)wakeup((void *)p->p_nlminfo);
+
+	return (0);
+}