1 files changed, 303 insertions, 0 deletions
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
new file mode 100644
index 000000000000..1ab24a662e09
--- /dev/null
+++ b/fs/autofs4/waitq.c
@@ -0,0 +1,303 @@
+/* -*- c -*- --------------------------------------------------------------- *
+ *
+ * linux/fs/autofs/waitq.c
+ *
+ *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
+ *  Copyright 2001-2003 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;
+
+	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 */
+		kfree(wq->name);
+		wq->name = NULL;
+		wake_up_interruptible(&wq->queue);
+		wq = nwq;
+	}
+	if (sbi->pipe) {
+		fput(sbi->pipe);	/* Close the pipe */
+		sbi->pipe = NULL;
+	}
+
+	shrink_dcache_sb(sbi->sb);
+}
+
+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 autofs_packet_union pkt;
+	size_t pktsz;
+
+	DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
+		wq->wait_queue_token, wq->len, wq->name, type);
+
+	memset(&pkt,0,sizeof pkt); /* For security reasons */
+
+	pkt.hdr.proto_version = sbi->version;
+	pkt.hdr.type = type;
+	if (type == autofs_ptype_missing) {
+		struct autofs_packet_missing *mp = &pkt.missing;
+
+		pktsz = sizeof(*mp);
+
+		mp->wait_queue_token = wq->wait_queue_token;
+		mp->len = wq->len;
+		memcpy(mp->name, wq->name, wq->len);
+		mp->name[wq->len] = '\0';
+	} else if (type == autofs_ptype_expire_multi) {
+		struct autofs_packet_expire_multi *ep = &pkt.expire_multi;
+
+		pktsz = sizeof(*ep);
+
+		ep->wait_queue_token = wq->wait_queue_token;
+		ep->len = wq->len;
+		memcpy(ep->name, wq->name, wq->len);
+		ep->name[wq->len] = '\0';
+	} else {
+		printk("autofs4_notify_daemon: bad type %d!\n", type);
+		return;
+	}
+
+	if (autofs4_write(sbi->pipe, &pkt, pktsz))
+		autofs4_catatonic_mode(sbi);
+}
+
+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 > 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;
+}
+
+int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
+		enum autofs_notify notify)
+{
+	struct autofs_wait_queue *wq;
+	char *name;
+	int len, status;
+
+	/* In catatonic mode, we don't wait for nobody */
+	if ( sbi->catatonic )
+		return -ENOENT;
+	
+	name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
+	if (!name)
+		return -ENOMEM;
+
+	len = autofs4_getpath(sbi, dentry, &name);
+	if (!len) {
+		kfree(name);
+		return -ENOENT;
+	}
+
+	if (down_interruptible(&sbi->wq_sem)) {
+		kfree(name);
+		return -EINTR;
+	}
+
+	for (wq = sbi->queues ; wq ; wq = wq->next) {
+		if (wq->hash == dentry->d_name.hash &&
+		    wq->len == len &&
+		    wq->name && !memcmp(wq->name, name, len))
+			break;
+	}
+
+	if ( !wq ) {
+		/* Create a new wait queue */
+		wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
+		if ( !wq ) {
+			kfree(name);
+			up(&sbi->wq_sem);
+			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);
+		wq->hash = dentry->d_name.hash;
+		wq->name = name;
+		wq->len = len;
+		wq->status = -EINTR; /* Status return if interrupted */
+		atomic_set(&wq->wait_ctr, 2);
+		up(&sbi->wq_sem);
+
+		DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d",
+			(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
+		/* autofs4_notify_daemon() may block */
+		if (notify != NFY_NONE) {
+			autofs4_notify_daemon(sbi,wq, 
+					notify == NFY_MOUNT ?
+						  autofs_ptype_missing :
+						  autofs_ptype_expire_multi);
+		}
+	} else {
+		atomic_inc(&wq->wait_ctr);
+		up(&sbi->wq_sem);
+		kfree(name);
+		DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
+			(unsigned long) wq->wait_queue_token, wq->len, wq->name, notify);
+	}
+
+	/* wq->name is NULL if and only if the lock is already released */
+
+	if ( sbi->catatonic ) {
+		/* We might have slept, so check again for catatonic mode */
+		wq->status = -ENOENT;
+		if ( wq->name ) {
+			kfree(wq->name);
+			wq->name = NULL;
+		}
+	}
+
+	if ( wq->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 == 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;
+
+	/* Are we the last process to need status? */
+	if (atomic_dec_and_test(&wq->wait_ctr))
+		kfree(wq);
+
+	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;
+
+	down(&sbi->wq_sem);
+	for ( wql = &sbi->queues ; (wq = *wql) != 0 ; wql = &wq->next ) {
+		if ( wq->wait_queue_token == wait_queue_token )
+			break;
+	}
+
+	if ( !wq ) {
+		up(&sbi->wq_sem);
+		return -EINVAL;
+	}
+
+	*wql = wq->next;	/* Unlink from chain */
+	up(&sbi->wq_sem);
+	kfree(wq->name);
+	wq->name = NULL;	/* Do not wait on this queue */
+
+	wq->status = status;
+
+	if (atomic_dec_and_test(&wq->wait_ctr))	/* Is anyone still waiting for this guy? */
+		kfree(wq);
+	else
+		wake_up_interruptible(&wq->queue);
+
+	return 0;
+}
+