1 files changed, 524 insertions, 0 deletions

diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
new file mode 100644
index 00000000..23413753
--- /dev/null
+++ b/fs/autofs4/waitq.c
@@ -0,0 +1,524 @@
+/* -*- c -*- --------------------------------------------------------------- *
+ *
+ * linux/fs/autofs/waitq.c
+ *
+ *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
+ *  Copyright 2001-2006 Ian Kent <raven@themaw.net>
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * ------------------------------------------------------------------------- */
+
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/signal.h>
+#include <linux/file.h>
+#include "autofs_i.h"
+
+/* We make this a static variable rather than a part of the superblock; it
+   is better if we don't reassign numbers easily even across filesystems */
+static autofs_wqt_t autofs4_next_wait_queue = 1;
+
+/* These are the signals we allow interrupting a pending mount */
+#define SHUTDOWN_SIGS	(sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))
+
+void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
+{
+	struct autofs_wait_queue *wq, *nwq;
+
+	mutex_lock(&sbi->wq_mutex);
+	if (sbi->catatonic) {
+		mutex_unlock(&sbi->wq_mutex);
+		return;
+	}
+
+	DPRINTK("entering catatonic mode");
+
+	sbi->catatonic = 1;
+	wq = sbi->queues;
+	sbi->queues = NULL;	/* Erase all wait queues */
+	while (wq) {
+		nwq = wq->next;
+		wq->status = -ENOENT; /* Magic is gone - report failure */
+		if (wq->name.name) {
+			kfree(wq->name.name);
+			wq->name.name = NULL;
+		}
+		wq->wait_ctr--;
+		wake_up_interruptible(&wq->queue);
+		wq = nwq;
+	}
+	fput(sbi->pipe);	/* Close the pipe */
+	sbi->pipe = NULL;
+	sbi->pipefd = -1;
+	mutex_unlock(&sbi->wq_mutex);
+}
+
+static int autofs4_write(struct file *file, const void *addr, int bytes)
+{
+	unsigned long sigpipe, flags;
+	mm_segment_t fs;
+	const char *data = (const char *)addr;
+	ssize_t wr = 0;
+
+	/** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
+
+	sigpipe = sigismember(&current->pending.signal, SIGPIPE);
+
+	/* Save pointer to user space and point back to kernel space */
+	fs = get_fs();
+	set_fs(KERNEL_DS);
+
+	while (bytes &&
+	       (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
+		data += wr;
+		bytes -= wr;
+	}
+
+	set_fs(fs);
+
+	/* Keep the currently executing process from receiving a
+	   SIGPIPE unless it was already supposed to get one */
+	if (wr == -EPIPE && !sigpipe) {
+		spin_lock_irqsave(&current->sighand->siglock, flags);
+		sigdelset(&current->pending.signal, SIGPIPE);
+		recalc_sigpending();
+		spin_unlock_irqrestore(&current->sighand->siglock, flags);
+	}
+
+	return (bytes > 0);
+}
+	
+static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
+				 struct autofs_wait_queue *wq,
+				 int type)
+{
+	union {
+		struct autofs_packet_hdr hdr;
+		union autofs_packet_union v4_pkt;
+		union autofs_v5_packet_union v5_pkt;
+	} pkt;
+	struct file *pipe = NULL;
+	size_t pktsz;
+
+	DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
+		wq->wait_queue_token, wq->name.len, wq->name.name, type);
+
+	memset(&pkt,0,sizeof pkt); /* For security reasons */
+
+	pkt.hdr.proto_version = sbi->version;
+	pkt.hdr.type = type;
+	switch (type) {
+	/* Kernel protocol v4 missing and expire packets */
+	case autofs_ptype_missing:
+	{
+		struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
+
+		pktsz = sizeof(*mp);
+
+		mp->wait_queue_token = wq->wait_queue_token;
+		mp->len = wq->name.len;
+		memcpy(mp->name, wq->name.name, wq->name.len);
+		mp->name[wq->name.len] = '\0';
+		break;
+	}
+	case autofs_ptype_expire_multi:
+	{
+		struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;
+
+		pktsz = sizeof(*ep);
+
+		ep->wait_queue_token = wq->wait_queue_token;
+		ep->len = wq->name.len;
+		memcpy(ep->name, wq->name.name, wq->name.len);
+		ep->name[wq->name.len] = '\0';
+		break;
+	}
+	/*
+	 * Kernel protocol v5 packet for handling indirect and direct
+	 * mount missing and expire requests
+	 */
+	case autofs_ptype_missing_indirect:
+	case autofs_ptype_expire_indirect:
+	case autofs_ptype_missing_direct:
+	case autofs_ptype_expire_direct:
+	{
+		struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
+
+		pktsz = sizeof(*packet);
+
+		packet->wait_queue_token = wq->wait_queue_token;
+		packet->len = wq->name.len;
+		memcpy(packet->name, wq->name.name, wq->name.len);
+		packet->name[wq->name.len] = '\0';
+		packet->dev = wq->dev;
+		packet->ino = wq->ino;
+		packet->uid = wq->uid;
+		packet->gid = wq->gid;
+		packet->pid = wq->pid;
+		packet->tgid = wq->tgid;
+		break;
+	}
+	default:
+		printk("autofs4_notify_daemon: bad type %d!\n", type);
+		return;
+	}
+
+	/* Check if we have become catatonic */
+	mutex_lock(&sbi->wq_mutex);
+	if (!sbi->catatonic) {
+		pipe = sbi->pipe;
+		get_file(pipe);
+	}
+	mutex_unlock(&sbi->wq_mutex);
+
+	if (pipe) {
+		if (autofs4_write(pipe, &pkt, pktsz))
+			autofs4_catatonic_mode(sbi);
+		fput(pipe);
+	}
+}
+
+static int autofs4_getpath(struct autofs_sb_info *sbi,
+			   struct dentry *dentry, char **name)
+{
+	struct dentry *root = sbi->sb->s_root;
+	struct dentry *tmp;
+	char *buf = *name;
+	char *p;
+	int len = 0;
+
+	spin_lock(&dcache_lock);
+	for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
+		len += tmp->d_name.len + 1;
+
+	if (!len || --len > NAME_MAX) {
+		spin_unlock(&dcache_lock);
+		return 0;
+	}
+
+	*(buf + len) = '\0';
+	p = buf + len - dentry->d_name.len;
+	strncpy(p, dentry->d_name.name, dentry->d_name.len);
+
+	for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
+		*(--p) = '/';
+		p -= tmp->d_name.len;
+		strncpy(p, tmp->d_name.name, tmp->d_name.len);
+	}
+	spin_unlock(&dcache_lock);
+
+	return len;
+}
+
+static struct autofs_wait_queue *
+autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
+{
+	struct autofs_wait_queue *wq;
+
+	for (wq = sbi->queues; wq; wq = wq->next) {
+		if (wq->name.hash == qstr->hash &&
+		    wq->name.len == qstr->len &&
+		    wq->name.name &&
+			 !memcmp(wq->name.name, qstr->name, qstr->len))
+			break;
+	}
+	return wq;
+}
+
+/*
+ * Check if we have a valid request.
+ * Returns
+ * 1 if the request should continue.
+ *   In this case we can return an autofs_wait_queue entry if one is
+ *   found or NULL to idicate a new wait needs to be created.
+ * 0 or a negative errno if the request shouldn't continue.
+ */
+static int validate_request(struct autofs_wait_queue **wait,
+			    struct autofs_sb_info *sbi,
+			    struct qstr *qstr,
+			    struct dentry*dentry, enum autofs_notify notify)
+{
+	struct autofs_wait_queue *wq;
+	struct autofs_info *ino;
+
+	/* Wait in progress, continue; */
+	wq = autofs4_find_wait(sbi, qstr);
+	if (wq) {
+		*wait = wq;
+		return 1;
+	}
+
+	*wait = NULL;
+
+	/* If we don't yet have any info this is a new request */
+	ino = autofs4_dentry_ino(dentry);
+	if (!ino)
+		return 1;
+
+	/*
+	 * If we've been asked to wait on an existing expire (NFY_NONE)
+	 * but there is no wait in the queue ...
+	 */
+	if (notify == NFY_NONE) {
+		/*
+		 * Either we've betean the pending expire to post it's
+		 * wait or it finished while we waited on the mutex.
+		 * So we need to wait till either, the wait appears
+		 * or the expire finishes.
+		 */
+
+		while (ino->flags & AUTOFS_INF_EXPIRING) {
+			mutex_unlock(&sbi->wq_mutex);
+			schedule_timeout_interruptible(HZ/10);
+			if (mutex_lock_interruptible(&sbi->wq_mutex))
+				return -EINTR;
+
+			wq = autofs4_find_wait(sbi, qstr);
+			if (wq) {
+				*wait = wq;
+				return 1;
+			}
+		}
+
+		/*
+		 * Not ideal but the status has already gone. Of the two
+		 * cases where we wait on NFY_NONE neither depend on the
+		 * return status of the wait.
+		 */
+		return 0;
+	}
+
+	/*
+	 * If we've been asked to trigger a mount and the request
+	 * completed while we waited on the mutex ...
+	 */
+	if (notify == NFY_MOUNT) {
+		/*
+		 * If the dentry was successfully mounted while we slept
+		 * on the wait queue mutex we can return success. If it
+		 * isn't mounted (doesn't have submounts for the case of
+		 * a multi-mount with no mount at it's base) we can
+		 * continue on and create a new request.
+		 */
+		if (have_submounts(dentry))
+			return 0;
+	}
+
+	return 1;
+}
+
+int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
+		enum autofs_notify notify)
+{
+	struct autofs_wait_queue *wq;
+	struct qstr qstr;
+	char *name;
+	int status, ret, type;
+
+	/* In catatonic mode, we don't wait for nobody */
+	if (sbi->catatonic)
+		return -ENOENT;
+
+	if (!dentry->d_inode) {
+		/*
+		 * A wait for a negative dentry is invalid for certain
+		 * cases. A direct or offset mount "always" has its mount
+		 * point directory created and so the request dentry must
+		 * be positive or the map key doesn't exist. The situation
+		 * is very similar for indirect mounts except only dentrys
+		 * in the root of the autofs file system may be negative.
+		 */
+		if (autofs_type_trigger(sbi->type))
+			return -ENOENT;
+		else if (!IS_ROOT(dentry->d_parent))
+			return -ENOENT;
+	}
+
+	name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
+	if (!name)
+		return -ENOMEM;
+
+	/* If this is a direct mount request create a dummy name */
+	if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
+		qstr.len = sprintf(name, "%p", dentry);
+	else {
+		qstr.len = autofs4_getpath(sbi, dentry, &name);
+		if (!qstr.len) {
+			kfree(name);
+			return -ENOENT;
+		}
+	}
+	qstr.name = name;
+	qstr.hash = full_name_hash(name, qstr.len);
+
+	if (mutex_lock_interruptible(&sbi->wq_mutex)) {
+		kfree(qstr.name);
+		return -EINTR;
+	}
+
+	ret = validate_request(&wq, sbi, &qstr, dentry, notify);
+	if (ret <= 0) {
+		if (ret == 0)
+			mutex_unlock(&sbi->wq_mutex);
+		kfree(qstr.name);
+		return ret;
+	}
+
+	if (!wq) {
+		/* Create a new wait queue */
+		wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
+		if (!wq) {
+			kfree(qstr.name);
+			mutex_unlock(&sbi->wq_mutex);
+			return -ENOMEM;
+		}
+
+		wq->wait_queue_token = autofs4_next_wait_queue;
+		if (++autofs4_next_wait_queue == 0)
+			autofs4_next_wait_queue = 1;
+		wq->next = sbi->queues;
+		sbi->queues = wq;
+		init_waitqueue_head(&wq->queue);
+		memcpy(&wq->name, &qstr, sizeof(struct qstr));
+		wq->dev = autofs4_get_dev(sbi);
+		wq->ino = autofs4_get_ino(sbi);
+		wq->uid = current_uid();
+		wq->gid = current_gid();
+		wq->pid = current->pid;
+		wq->tgid = current->tgid;
+		wq->status = -EINTR; /* Status return if interrupted */
+		wq->wait_ctr = 2;
+		mutex_unlock(&sbi->wq_mutex);
+
+		if (sbi->version < 5) {
+			if (notify == NFY_MOUNT)
+				type = autofs_ptype_missing;
+			else
+				type = autofs_ptype_expire_multi;
+		} else {
+			if (notify == NFY_MOUNT)
+				type = autofs_type_trigger(sbi->type) ?
+					autofs_ptype_missing_direct :
+					 autofs_ptype_missing_indirect;
+			else
+				type = autofs_type_trigger(sbi->type) ?
+					autofs_ptype_expire_direct :
+					autofs_ptype_expire_indirect;
+		}
+
+		DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
+			(unsigned long) wq->wait_queue_token, wq->name.len,
+			wq->name.name, notify);
+
+		/* autofs4_notify_daemon() may block */
+		autofs4_notify_daemon(sbi, wq, type);
+	} else {
+		wq->wait_ctr++;
+		mutex_unlock(&sbi->wq_mutex);
+		kfree(qstr.name);
+		DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
+			(unsigned long) wq->wait_queue_token, wq->name.len,
+			wq->name.name, notify);
+	}
+
+	/*
+	 * wq->name.name is NULL iff the lock is already released
+	 * or the mount has been made catatonic.
+	 */
+	if (wq->name.name) {
+		/* Block all but "shutdown" signals while waiting */
+		sigset_t oldset;
+		unsigned long irqflags;
+
+		spin_lock_irqsave(&current->sighand->siglock, irqflags);
+		oldset = current->blocked;
+		siginitsetinv(&current->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
+		recalc_sigpending();
+		spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
+
+		wait_event_interruptible(wq->queue, wq->name.name == NULL);
+
+		spin_lock_irqsave(&current->sighand->siglock, irqflags);
+		current->blocked = oldset;
+		recalc_sigpending();
+		spin_unlock_irqrestore(&current->sighand->siglock, irqflags);
+	} else {
+		DPRINTK("skipped sleeping");
+	}
+
+	status = wq->status;
+
+	/*
+	 * For direct and offset mounts we need to track the requester's
+	 * uid and gid in the dentry info struct. This is so it can be
+	 * supplied, on request, by the misc device ioctl interface.
+	 * This is needed during daemon resatart when reconnecting
+	 * to existing, active, autofs mounts. The uid and gid (and
+	 * related string values) may be used for macro substitution
+	 * in autofs mount maps.
+	 */
+	if (!status) {
+		struct autofs_info *ino;
+		struct dentry *de = NULL;
+
+		/* direct mount or browsable map */
+		ino = autofs4_dentry_ino(dentry);
+		if (!ino) {
+			/* If not lookup actual dentry used */
+			de = d_lookup(dentry->d_parent, &dentry->d_name);
+			if (de)
+				ino = autofs4_dentry_ino(de);
+		}
+
+		/* Set mount requester */
+		if (ino) {
+			spin_lock(&sbi->fs_lock);
+			ino->uid = wq->uid;
+			ino->gid = wq->gid;
+			spin_unlock(&sbi->fs_lock);
+		}
+
+		if (de)
+			dput(de);
+	}
+
+	/* Are we the last process to need status? */
+	mutex_lock(&sbi->wq_mutex);
+	if (!--wq->wait_ctr)
+		kfree(wq);
+	mutex_unlock(&sbi->wq_mutex);
+
+	return status;
+}
+
+
+int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
+{
+	struct autofs_wait_queue *wq, **wql;
+
+	mutex_lock(&sbi->wq_mutex);
+	for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
+		if (wq->wait_queue_token == wait_queue_token)
+			break;
+	}
+
+	if (!wq) {
+		mutex_unlock(&sbi->wq_mutex);
+		return -EINVAL;
+	}
+
+	*wql = wq->next;	/* Unlink from chain */
+	kfree(wq->name.name);
+	wq->name.name = NULL;	/* Do not wait on this queue */
+	wq->status = status;
+	wake_up_interruptible(&wq->queue);
+	if (!--wq->wait_ctr)
+		kfree(wq);
+	mutex_unlock(&sbi->wq_mutex);
+
+	return 0;
+}
+