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/* -*- c -*- --------------------------------------------------------------- *

 *

 * linux/fs/autofs/waitq.c

 *

 *  Copyright 1997-1998 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/slab.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 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(("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;

        }

        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->sigmask_lock, flags);

                sigdelset(&current->pending.signal, SIGPIPE);

                recalc_sigpending(current);

                spin_unlock_irqrestore(&current->sigmask_lock, 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(("autofs_notify: wait id = 0x%08lx, name = %.*s, type=%d\n",

                 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("autofs_notify_daemon: bad type %d!\n", type);

                return;

        }

        if (autofs4_write(sbi->pipe, &pkt, pktsz))

                autofs4_catatonic_mode(sbi);

}

int autofs4_wait(struct autofs_sb_info *sbi, struct qstr *name,

                enum autofs_notify notify)

{

        struct autofs_wait_queue *wq;

        int status;

        /* In catatonic mode, we don't wait for nobody */

        if ( sbi->catatonic )

                return -ENOENT;

        /* We shouldn't be able to get here, but just in case */

        if ( name->len > NAME_MAX )

                return -ENOENT;

        for ( wq = sbi->queues ; wq ; wq = wq->next ) {

                if ( wq->hash == name->hash &&

                     wq->len == name->len &&

                     wq->name && !memcmp(wq->name,name->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(name->len,GFP_KERNEL);

                if ( !wq->name ) {

                        kfree(wq);

                        return -ENOMEM;

                }

                wq->wait_queue_token = autofs4_next_wait_queue;

                if (++autofs4_next_wait_queue == 0)

                        autofs4_next_wait_queue = 1;

                init_waitqueue_head(&wq->queue);

                wq->hash = name->hash;

                wq->len = name->len;

                wq->status = -EINTR; /* Status return if interrupted */

                memcpy(wq->name, name->name, name->len);

                wq->next = sbi->queues;

                sbi->queues = wq;

                DPRINTK(("autofs_wait: new wait id = 0x%08lx, name = %.*s, nfy=%d\n",

                         wq->wait_queue_token, wq->len, wq->name, notify));

                /* autofs4_notify_daemon() may block */

                wq->wait_ctr = 2;

                if (notify != NFY_NONE) {

                        autofs4_notify_daemon(sbi,wq,

                                              notify == NFY_MOUNT ? autofs_ptype_missing :

                                                                    autofs_ptype_expire_multi);

                }

        } else {

                wq->wait_ctr++;

                DPRINTK(("autofs_wait: existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",

                         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->sigmask_lock, irqflags);

                oldset = current->blocked;

                siginitsetinv(&current->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);

                recalc_sigpending(current);

                spin_unlock_irqrestore(&current->sigmask_lock, irqflags);

                interruptible_sleep_on(&wq->queue);

                spin_lock_irqsave(&current->sigmask_lock, irqflags);

                current->blocked = oldset;

                recalc_sigpending(current);

                spin_unlock_irqrestore(&current->sigmask_lock, irqflags);

        } else {

                DPRINTK(("autofs_wait: skipped sleeping\n"));

        }

        status = wq->status;

        if (--wq->wait_ctr == 0) /* Are we the last process to need status? */

                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;

        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 == 0) /* Is anyone still waiting for this guy? */

                kfree(wq);

        else

                wake_up(&wq->queue);

        return 0;

}