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/* -*- 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;

}