patch-2.0.31 linux/fs/autofs/waitq.c

• Lines: 172
• Date: Fri Sep 5 20:43:59 1997
• Orig file: v2.0.30/linux/fs/autofs/waitq.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.0.30/linux/fs/autofs/waitq.c linux/fs/autofs/waitq.c
@@ -0,0 +1,171 @@
+/* -*- linux-c -*- --------------------------------------------------------- *
+ *
+ * linux/fs/autofs/waitq.c
+ *
+ *  Copyright 1997 Transmeta Corporation -- All Rights Reserved
+ *
+ * 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/malloc.h>
+#include <linux/sched.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 int autofs_next_wait_queue = 1;
+
+void autofs_catatonic_mode(struct autofs_sb_info *sbi)
+{
+	struct autofs_wait_queue *wq, *nwq;
+
+	DPRINTK(("autofs: entering catatonic mode\n"));
+
+	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(&wq->queue);
+		wq = nwq;
+	}
+	fput(sbi->pipe, sbi->pipe->f_inode);	/* Close the pipe */
+}
+
+static int autofs_write(struct file *file, const void *addr, int bytes)
+{
+	unsigned short fs;
+	unsigned long old_signal;
+	const char *data = (const char *)addr;
+	int written = 0;
+
+	/** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
+
+	/* Save pointer to user space and point back to kernel space */
+	fs = get_fs();
+	set_fs(KERNEL_DS);
+
+	old_signal = current->signal;
+
+	while ( bytes && (written = file->f_op->write(file->f_inode,file,data,bytes)) > 0 ) {
+		data += written;
+		bytes -= written;
+	}
+
+	if ( written == -EPIPE && !(old_signal & (1 << (SIGPIPE-1))) ) {
+		/* Keep the currently executing process from receiving a
+		   SIGPIPE unless it was already supposed to get one */
+		current->signal &= ~(1 << (SIGPIPE-1));
+	}
+	set_fs(fs);
+
+	return (bytes > 0);
+}
+	
+static void autofs_notify_daemon(struct autofs_sb_info *sbi, struct autofs_wait_queue *wq)
+{
+	struct autofs_packet_missing pkt;
+
+	DPRINTK(("autofs_wait: wait id = 0x%08lx, name = ", wq->wait_queue_token));
+	autofs_say(wq->name,wq->len);
+
+	memset(&pkt,0,sizeof pkt); /* For security reasons */
+
+	pkt.hdr.proto_version = AUTOFS_PROTO_VERSION;
+	pkt.hdr.type = autofs_ptype_missing;
+	pkt.wait_queue_token = wq->wait_queue_token;
+	pkt.len = wq->len;
+        memcpy(pkt.name, wq->name, pkt.len);
+	pkt.name[pkt.len] = '\0';
+
+	if ( autofs_write(sbi->pipe,&pkt,sizeof(struct autofs_packet_missing)) )
+		autofs_catatonic_mode(sbi);
+}
+
+int autofs_wait(struct autofs_sb_info *sbi, autofs_hash_t hash, const char *name, int len)
+{
+	struct autofs_wait_queue *wq;
+	int status;
+
+	for ( wq = sbi->queues ; wq ; wq = wq->next ) {
+		if ( wq->hash == 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 )
+			return -ENOMEM;
+
+		wq->name = kmalloc(len,GFP_KERNEL);
+		if ( !wq->name ) {
+			kfree(wq);
+			return -ENOMEM;
+		}
+		wq->wait_queue_token = autofs_next_wait_queue++;
+		init_waitqueue(&wq->queue);
+		wq->hash = hash;
+		wq->len = len;
+		wq->status = -EINTR; /* Status return if interrupted */
+		memcpy(wq->name, name, len);
+		wq->next = sbi->queues;
+		sbi->queues = wq;
+
+		/* autofs_notify_daemon() may block */
+		wq->wait_ctr = 2;
+		autofs_notify_daemon(sbi,wq);
+	} else
+		wq->wait_ctr++;
+
+	if ( wq->name ) {
+		/* wq->name is NULL if and only if the lock is released */
+		interruptible_sleep_on(&wq->queue);
+	} else {
+		DPRINTK(("autofs_wait: skipped sleeping\n"));
+	}
+
+	status = wq->status;
+
+	if ( ! --wq->wait_ctr )	/* Are we the last process to need status? */
+		kfree(wq);
+
+	return status;
+}
+
+
+int autofs_wait_release(struct autofs_sb_info *sbi, unsigned long wait_queue_token, int status)
+{
+	struct autofs_wait_queue *wq, **wql;
+
+	for ( wql = &sbi->queues ; (wq = *wql) ; wql = &wq->next ) {
+		if ( wq->wait_queue_token == wait_queue_token )
+			break;
+	}
+	if ( !wq )
+		return -EINVAL;
+
+	*wql = wq->next;	/* Unlink from chain */
+	kfree(wq->name);
+	wq->name = NULL;	/* Do not wait on this queue */
+
+	wq->status = status;
+
+	if ( ! --wq->wait_ctr )	/* Is anyone still waiting for this guy? */
+		kfree(wq);
+	else
+		wake_up(&wq->queue);
+
+	return 0;
+}
+