Subversion Repositories test_project

/* -*- 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;

        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;

        }

        fput(sbi->pipe);        /* Close the pipe */

        sbi->pipe = NULL;

}

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;

        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;

        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->len;

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

                mp->name[wq->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->len;

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

                ep->name[wq->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->len;

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

                packet->name[wq->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;

        }

        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;

}

static struct autofs_wait_queue *

autofs4_find_wait(struct autofs_sb_info *sbi,

                  char *name, unsigned int hash, unsigned int len)

{

        struct autofs_wait_queue *wq;

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

                if (wq->hash == hash &&

                    wq->len == len &&

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

                        break;

        }

        return wq;

}

int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,

                enum autofs_notify notify)

{

        struct autofs_info *ino;

        struct autofs_wait_queue *wq;

        char *name;

        unsigned int len = 0;

        unsigned int hash = 0;

        int status, type;

        /* 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;

        /* If this is a direct mount request create a dummy name */

        if (IS_ROOT(dentry) && (sbi->type & AUTOFS_TYPE_DIRECT))

                len = sprintf(name, "%p", dentry);

        else {

                len = autofs4_getpath(sbi, dentry, &name);

                if (!len) {

                        kfree(name);

                        return -ENOENT;

                }

        }

        hash = full_name_hash(name, len);

        if (mutex_lock_interruptible(&sbi->wq_mutex)) {

                kfree(name);

                return -EINTR;

        }

        wq = autofs4_find_wait(sbi, name, hash, len);

        ino = autofs4_dentry_ino(dentry);

        if (!wq && ino && 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)) {

                                kfree(name);

                                return -EINTR;

                        }

                        wq = autofs4_find_wait(sbi, name, hash, len);

                        if (wq)

                                break;

                }

                /*

                 * 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.

                 */

                if (!wq) {

                        kfree(name);

                        mutex_unlock(&sbi->wq_mutex);

                        return 0;

                }

        }

        if (!wq) {

                /* Create a new wait queue */

                wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);

                if (!wq) {

                        kfree(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);

                wq->hash = hash;

                wq->name = name;

                wq->len = len;

                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 */

                atomic_set(&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 = (sbi->type & AUTOFS_TYPE_DIRECT) ?

                                        autofs_ptype_missing_direct :

                                         autofs_ptype_missing_indirect;

                        else

                                type = (sbi->type & AUTOFS_TYPE_DIRECT) ?

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

                /* autofs4_notify_daemon() may block */

                autofs4_notify_daemon(sbi, wq, type);

        } else {

                atomic_inc(&wq->wait_ctr);

                mutex_unlock(&sbi->wq_mutex);

                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;

                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;

        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 */

        mutex_unlock(&sbi->wq_mutex);

        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;

}